Thermal decomposition of the non-interstitial hydrides for the storage and production of hydrogen

Chemical Reviews

Volumn 104, Issue 3, 2004, Pages 1283-1315

  Grochala, Wojciech ^a,b   Edwards, Peter P ^c  

^a UNIVERSITY OF BIRMINGHAM   (United Kingdom)

^b UNIVERSITY OF WARSAW   (Poland)

^c UNIVERSITY OF OXFORD   (United Kingdom)

Author keywords

[No Author keywords available]

Indexed keywords

CATALYSIS; ELECTRONIC STRUCTURE; ENTHALPY; HYDRIDES; HYDROCARBONS; PYROLYSIS; SYNTHESIS (CHEMICAL); THERMODYNAMIC STABILITY;

MECHANOCHEMICAL SYNTHESIS; MULTINARY HYDRIDES; NON INTERSTITIAL HYDRIDES;

HYDROGEN;

EID: 1842430965     PISSN: 00092665     EISSN: None     Source Type: Journal    
DOI: 10.1021/cr030691s     Document Type: Article

References (578)

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2. 3T tritium).
3. This is called Hubbert's law; the price crisis ("Hubberts peak") may occur as early as 2010, according to some predictions (http://www.cnie.org/nle/eng-3.html; http://reporternews.com/biz/oil0802.hmtl) (a) Deffeyes, K. S. Hubbert's Peak: The Impending World Oil Shortage; Princeton University Press: Princeton, NJ, 2001.
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5. (c) Kruger, P. Int. J. Hydrogen Energy 2001, 26, 1137.
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11. For an excellent perspective, see: (a) Hoffmann, P. Tomorrow's Energy: Hydrogen, Fuel Cells and the Prospects for a Cleaner Planet; The MIT Press: Cambridge, MA, 2002.
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25. Today, hydrogen is used on a small scale and in test experiments as a transportation fuel. The first public liquid-hydrogen filling station was opened in May 1999 at Munich Airport (Pehr, K.: Sauermann, P.: Traeger, O.: Bracha, M. Int. J. Hydrogen Energy 2001, 26, 777).
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30. The reader is also referred to modern reviews: (b) Thomas, C. E.; James, B. D.; Lomax, F. D., Jr.; Kuhn, I. F., Jr. Int. J. Hydrogen Energy 2000, 25, 551.
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37. 2. Thus - remarkably - our civilization tends to use the same carbon/water - based (although chemically modified) fuel as the one which - in a quite different form - ignited the industrial evolution in England in the late 18th century. And hydrogen could become an authentically green fuel only if photoelectro-chemical methods of splitting water see, e.g., (a) Khan, S. U. M.; Al-Shahry, M.; Ingler, W. B., Jr. Science 2002, 297, 2243
38. (b) Khan, S. U. M.; Al-Shahry, M.; Ingler, W. B., Jr. Science 2003, 301, 1673d could be advanced and if hydrogen produced this way could be made significantly cheaper. Otherwise, hydrogen fuel will - environmentally - bear no real advantage over the Fisher - Tropsch synthesis
39. ((c) Liu, Z.-P.; Hu, P. J. Am. Chem. Soc. 2002, 124, 11568 and references therein)
40. which utilizes the same substrates to produce the "dirty" liquid hydrocarbons and - at least economically - seems to be the most serious alternative to hydrogen in the coming "oil shortage era". Methane conversion is another option: (d) Taylor, C. E. Catal. Today 2003, 84, 9. Still, the authors believe that developing the infrastructure for the (more realistic at present) "dirty hydrogen economy" (H comes from goal and water) in the first stage might significantly stimulate the final "clean hydrogen economy"(H comes only from water) era.
41. It is important to note that the effects of the increased circulation of water in the environment have not yet been accounted for. This is definitely necessary before hydrogen is responsibly labeled as a "green fuel". Widespread introduction of hydrogen as an energy vector may also lead to negative consequences; the range of problematic issues has been recently outlined (a) Cherry, R. S. Int. J. Hydrogen Energy, in press.
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44. (d) Grant, P. M. Nature 2003, 424, 129 and unfortunately - so far has not been sufficiently addressed by the advocates of hydrogen fuel.
45. We are convinced that the scenario of completely renouncing carbon as a fuel or its component is highly unrealistic (even in the long term), since carbon provides two-thirds of the world's energy. These financal obstacles, despite their obviousness, have not been wildey recognized (Roberts, D. Financial Times 2003, 13 May). We think that the subject of hydrogen storage is worth pursuing mainly in the context of possible exclusive production of hydrogen from water in the future.
46. Methods of producing Co-free hydrogen (CO considerably diminishes the lifetime of several important types of fuel cells) are now being advanced: (a) Choudhary, T. V.; Sivadinarayana, C.; Goodman, D. W. Chem. Eng. J. 2003, 93, 69.
47. Some use supercritical water: (b) Kruse, A.; Dinjus, E. Angew. Chem., Int. Ed. 2003, 42, 909.
48. The FCX Honda was the first fuel-cell zero-emission vehicle in the history to receive U.S. government certification; it became commercially available in December 2002 in the city of Los Angeles (http://www.hondacorporate.com/press/index.html?s=american&y=2002&r=905) .
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50. Compresson and storage of liquid hydrogen is being continuously advanced: (a) Milleron, N. Int. J. Hydrogen Energy 1999, 24, 687.
51. (b) Ewald, R. Int. J. Hydrogen Energy 1998, 23, 803.
52. Recently, 700 atm tanks have been certified (c) Fuel Cells Bull. 2002, 5
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54. while +825 atm tanks are being currently tested in laboratories: (e) Franzky, S. Fuel Cells Bull. 2002, 9.
55. See the rich www.doe.gov resources on renewable energy.
56. Data from the U.S. Department of Energy (DOE) are considered here. Indications from the European Union were initially somewhat lower (5.5 wt %), given the larger fuel tax and, consequently, the higher price of oil in the EU countries as compared to the United States. But recently a higher limiting value of 7.0 wt % has been suggested by the EU.
57. 3(l) 50 g/L. Liquid hydrogen stores 71-75 g/L.
58. Hydrides of Be, F, Si, and P and their compounds are toxic and/or very difficult to form, which limits their potential usefulness as HSMs. Be is also quite expensive ($590/kg in 2001). Binary hydrides of Na and F do not fulfill the DOE wt % content criterion, but these elements might still be used in complex lightweight hydrides. Si and P might be used in (as yet unknown) Si or BP nanotubes.
59. Classical low-temperature, reversible hydrogen-storing alloys exhibiting low storage efficiency, such as those identified in ref 11, are not considered here.
60. Here we discuss mainly thermal decomposition of hydrides. Other methods, including UV photodecomposition, solar water splitting, and photocatalytic processes, are important, as well: (a) Dougherty, D.; Herley, P. J. J. Less-Common Met. 1980, 73, 97.
61. (b) Licht, S.; Wang, B.; Mukerji, S.; Soga, T.; Umeno, M.; Tributsch, H. Int. J. Hydrogen Energy 2001, 26, 653.
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66. (g) Kong, V. C. Y.; Foulkes, F. R.; Kirk, D. W.; Hinatsu, J. T. Int. J. Hydrogen Energy 2003, 28, 205.
67. (a) Amendola, S. C.; Binder, M.; Kelly, M. T.; Petillo, P. J.; Sharp-Goldman, S. L. In Advances in Hydrogen Energy; Grégoire Padró, C. E., Lau, F., Eds.; Kluwer Academic & Plenum Publishers: New York, 2000; p 69.
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71. We mean obviously the thermodynamic stability as measured by the ΔG° value.
72. Sad past experience with thermodynamically unstable explosive boranes clearly suggests the use of thermodynamically stable materials.
73. The choice of temperature is also due to the necessity of incorporating the hydrogen store into a fuel cell; the most important polymer electrolyte membrane (PEM) fuel cells operate at 60-120°C. Alkaline fuel cells operate below 100°C. See the recent review on PEM fuel cells: Mehta, V.; Cooper, J. S. J. Power Sources 2003, 114, 32.
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78. 2 molecule: (e) Mitsui, T.; Rose, M. K.; Formin, E.; Ogletree, D. F.; Salmeron, M. Nature 2003, 422, 705.
79. A 25-kg PdH store would now cost about $145 000 (some $185/oz. in May 2003), and it would store 0.23 kg of H. This is one of the most expensive hydrogen stores (over $0.6 million for 1 kg of H). However, the price of Pd is unstable and may be significantly larger, due to increased demand. For example, it reached its maximum of $1090/oz. in January 2001 (http://www.napalladium.com/price.html). A Pd-based hydrogen store would be economically inaccessible to common end-users and would represent an ideal target for thieves.
80. 2-based hydrogen storage systems which are reversible and operate at 268°C (www.ovonic.com). But the company admits that their technology requires a lot work before it reaches the market.
81. (a) Patent application WO1998CA0000946, 1998.
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83. The solubility of H in Al is drastically low under normal conditions: (a) Birnbaum, H. K.; Buckley, C.; Zeides, F.; Sirois, E.; Rozenak, P.; Spooner, S.; Lin, J. S. J. Alloys Compd. 1997, 253, 260.
84. Hydrogen uptake by Al occurs at a huge pressure of ca. 2 GPa at temperatures over 220°C: (b) Tkacz, M.; Filipek, S. M.; Baranowski, B. Pol. J. Chem. 1983, 57, 651.
85. 2 requires similarly drastic conditions (see ref 35c).
86. (a) Suda, S.; Sun, Y.-M.; Liu, B.-H.; Zhou, Y.; Morimitsu, S.; Arai, K.; Tsukamoto, N.; Uchida, M.; Candra, Y.; Li, Z.-P. Appl. Phys. A 2001, 72, 209.
87. In fact, catalytic enhancement of hydrogen evolution from alkaline borohydride solutions by certain metal cations has been known for 50 years: (b) Davis, R. E.; Saba, A.; Cosper, D. R.; Bloomer, J. A. Inorg. Chem. 1964, 3, 460.
88. 2 itself cannot be easily obtained from the elements: (a) Li, Z. P.; Morigazaki, N.; Liu, B. H.; Suda, S. J. Alloys Compd. 2003, 349, 232.
89. (b) Li, Z. P.; Liu, B. H.; Morigazaki, N.; Suda, S. J. Alloys Compd. 2003, 354, 243.
90. 2S requires a temperature of 1300 K: (a) Faraji, F.; Safarik, I.; Strausz, O. P.; Yildirim, E.; Torres, M. E. Int. J. Hydrogen Energy 1998, 23, 451.
91. Another idea appeared recently to set up a huge windmill facility for electrolysis of water in the Orkney Islands (UK). Wind-powered hydrogen production is summarized in the review: (b) Dutton, A. G.; Bleijs, J. A. M.; Dienhart, H.; Falchetta, M.; Hug, W.; Prischich, D.; Ruddell, A. J. Int. J. Hydrogen Energy 2000, 25, 705.
92. (c) Dutton, A. G., submitted to Wind Eng. The society of Utsira Island (Norway) is supposed to become the first hydrogen-powered micro-society in the world. Iceland is next to follow.
93. (a) Chen, P.; Xiong, Z.; Luo, J.; Lin, J.; Tan, K. L. Nature 2002, 420, 302.
94. (b) Hu, Y. H.; Ruckenstein, E. Ind. Eng. Chem. Res. 2003, 42, 5135.
95. Remarkably, the symbol used by Dalton to designate H is identical with the modern quantum chemical representation of a hydrogen atom, or of its 1s orbital.
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98. -I redox pair) is around 0 V.
99. +I of -0.38 Å.
100. IF). Thus, despite its more frequent appearance above Li in the Periodic Table, H is sometimes placed by He, and over F.
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102. -: Redko, M. Y.; Vlassa, M.; Jackson, J. E.; Misiolek, A. W.; Huang, R. H.; Dye, J. L. J. Am. Chem. Soc. 2002, 124, 5928.
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104. dec is also crucial to govern the processes of metal thin films deposition from volatile hydrides, commonly used in the semiconductor industry.
105. 4, see, e.g.: (a) Walch, S. P.; Dateo, C. E. J. Phys. Chem. A 2001, 105, 2015.
106. 6: (b) Aaserud, D. J.; Lampe, F. W. J. Phys. Chem. A 1997, 101, 4114. However, for some hydrides, especially those showing significant covalency of the element-hydrogen bonding, the associative pathway may be of importance. These are characterized by a dominant character of the H⋯H coordinate even in the early phases of the reaction. And, especially for the mono-hydrides in the gas phase, this necessarily involves inter- and not intramolecular activation.
107. -I; here the H⋯H coupling occurs in the very first stages of the decomposition, and it is a driving thermodynamic force of the overall process.
108. 4, see: (a) Azatyan, V. V.; Aivazyan, R. G.; Pavlov, N. M.; Sinelnikova, T. A. Kinet. Catal. 1993, 34, 518.
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110. 1 and E modes are not IR active, and they cannot be efficiently and selectively excited in a radiative manner, instead of a wasteful use of "isotropic temperature" which excites all vibrational modes.
111. -I. In this class of materials, considered further in this paper, the coupling of two H centers is equally important at the early stage of the hydrogen evolution process to the element-hydrogen bond-stretching.
112. 0 pair is around 0 V. This explains why it is much easier to evolve molecular than atomic hydrogen.
113. The values of enthalpies of formation for gaseous hydrides have been taken from (a) Ponomarev, D. A.; Takhistov, V. V. J. Mol. Struct. 1999, 477, 91, and from the NIST database
114. (b) http://webbook.nist.gov/chemistry.
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116. These values are for the hydrides of elements at their typical available oxidation states when bound to H. The enthalpies of formation and dimerization of the lower hydrides for some of these elements have not been measured, but they were theoretically estimated: Himmel, H.-J. Eur. J. Inorg. Chem. 2003, 2153.
117. 2; this corresponds to -113 kJ/mol of H, nearly equal to the corresponding value for LiH!
118. 2(s) there are three sets of divergent data: (a) -19.25 kJ/mol, Akhachinskii, V. V.; Kopytin, L. M.; Senin, M. D. Atom. Energ. 1970, 28, 245.
119. (b) -18.86 kJ/mol, Ivanon, M. I.; Karpova, T. F. Russ. J. Phys. Chem. 1971, 45, 1202.
120. (c) -33 kJ/mol, Ducros, M.; Levy, R.; Meliava, G.; Audebert, J.-C.; Sannier, H. Bull. Soc. Chim. Fr. 1970, 2763. Here we have adopted the value of -19 kJ/mol.
121. f = -73.2 kJ/mol has recently been measured at +435°C: Bogdanović, B.; Bohmhammel, K.; Christ, B.; Reiser, A.; Schlichte, K.; Vehlen, R.; Wolf, U. J. Alloys. Compd. 1999, 282, 84.
122. Hunt, P.; Schwerdtfeger, P. Inorg. Chem. 1996, 35, 2085.
123. o values for the ionic hydrides. An alternative approach excludes ionization and electron attachment processes and uses the M-H bond energy and the heat of vaporization of the hydride. This approach, although fully equivalent with the one shown in eq 4, is more practical for covalent hydrides.
124. (n-m)+ redox pair has been used, as detailed in Table 3.
125. 2 pressure - composition isotherms.
126. The E° values have been taken from www.webelements.com, or calculated on the basis of those data.
127. Recollect that the full range of E° values available to chemistry is about 6.1 V. Our correlation covers almost two-thirds of this range.
128. 2. There are also examples known when the thermodynamically unstable hydride exhibits an unusually large barrier to decomposition and is remarkably (kinetically) stable or - taking another extreme - when the reaction leading to a weakly stable hydride is characterized by a surprisingly small barrier: (a) Himmel, H.-J. Dalton Trans. 2002, 2678.
129. (b) Köhn, A.; Himmel, H.-J.; Gaertner, B. Chem. Eur. J. 2003, 9, 3909.
130. dec should be +251°C. In fact, this compound is said to decompose fast in the temperature range of 560-100°C, but it exhibits some instability even at room temperature (Burtovyy, R.; Wlosewicz, D.; Czopnik, A.; Tkacz, M. Thermochim. Acta 2003, 400, 121).
131. dec values.
132. dec parameters, and in such cases it should be used with the greatest care.
133. dec as high as 950°C, but the protium-to-tritium exchange is known to take place at temperatures as low as 350°C (ref 74), which implies partial surface decomposition at this temperature.
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140. dec of an alkali metal hydride, and the full amount of stored hydrogen is released upon decomposition.
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161. 2, a mixed hydride-borohydride of aluminium (ref 74).
162. (a) Cinader, C.; Zamir, D.; El-Hanany, U. Solid State Commun. 1970, 8, 1703.
163. 0 pair (-2.0 V).
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183. 2.
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190. dec value for the bulk compound may lie in the fact that in some cases it may be self-catalyzed by the evolving metal nano- or macroparticles.
191. 3 is thermodynamically unstable due to both enthalpy and entropy factors, the rate of attainment of the dissociation is immeasurably slow at temperatures below several hundreds degrees Centrigrade: (a) van Wazer, J. R. Phosphorus and its compounds; Interscience Publishers: London, 1958; p 188.
192. 3 decomposition at nickel filters (decomposition on cooling starts at some 25°C and is most eminent at 40°C): (b) Mankowsky, S. J.; Leggett, G. H., report at www.mykrolis.com. Producers of phosphine recommend that the temperature where cylinders are stored should not exceed 52°C due to the risk of thermal decomposition of phosphine (www.boc.com).
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194. Wiberg, E.; Henle, W. Z. Naturforsch. 1951, 6b, 461.
195. Wiberg, E.; Henle, W. Z. Naturforsch. 1952, 7b, 575.
196. (a) Finholt, A. E.; Bond, A. C.; Wilzbach, K. E.; Schlesinger, H. I. J. Am. Chem. Soc. 1947, 69, 2692.
197. (b) Paneth, F.; Haken, W.; Rabinowitsch, E. Ber. Dtsch. Chem. Ges. 1924, 57, 1891.
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199. Wiberg, E.; Henle, W. Z. Naturforsch. 1952, 7b, 579.
200. As relativistic computations show, H acts formally as an anion in this compound, the computed Mülliken charge on H being -0.06 to -0.398 e: (a) Schwerdtfeger, P.; Heath, G. A.; Dolg, M.; Bennett, M. A. J. Am. Chem. Soc. 1992, 114, 7518.
201. (b) Wang, S. G.; Schwarz, W. H. E. J. Mol. Struct. (THEOCHEM) 1995, 338, 347.
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206. Wiberg, E.; Henle, W. Z. Naturforsch. 1952, 7b, 582.
207. Wiberg, E.; Mödritzer, K. Z. Naturforsch. 1956, 11b, 747.
208. (a) Wiberg, E.; Bauer, R. Z. Naturforsch. 1950, 5b, 397.
209. (b) Wiberg, E.; Bauer, R. Z. Naturforsch. 1952, 7b, 131.
210. James, B. D. Chem. Ind. 1971, 227.
211. Schrauzer, G. N. Naturwissenschaften 1955, 42, 438.
212. boil = -17°C: (a) Olszewski, K. Chem. Ber. 1901, 34, 3592.
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217. (b) Amberger, E. Chem. Ber. 1961, 94, 1447.
218. The most recent study confirms that bismuthine may isolated for a short time at -50°C, but it autocatalytically decomposes very fast around -40°C:(c) Jerzembeck, W.; Bürger, H.; Constantin, L.; Margulès, L.; Demaison, J.; Breidung, J.; Thiel, W. Angew. Chem., Int. Ed. 2002, 41, 2550.
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220. -I.
221. (a) Buongiorno, J.; Larson, C.; Czerwinski, K. R. Radiochim. Acta 2003, 91, 153.
222. (b) Yovanovitch, D. K. C. R. Hebd. Acad. Sci. 1958, 246, 746.
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231. (b) Dolg, M.; Küchle, W.; Stoll, H.; Preuss, H.; Schwerdtfeger, P. Mol. Phys. 1991, 74, 1265.
232. However, there are also reports of slightly positive charge on H atom: (c) Kello, V.; Sadlej, A. J. Theor. Chim. Acta 1992, 83, 351.
233. Chalkin, W. A.; Hermann, E.; Wassilewitsch, J.; Dreyer, I. Chem. Z. 1997, 101, 470.
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235. Wiberg, E.; Henle, W. Z. Naturforsch. 1951, 6b, 461.
236. As relativistic computations show, H acts formally as an anion in this compound, the computed Mülliken charge on H being -0.434 e: ref 120a. But values significantly closer to zero have also been reported: El-Issa, B. D.; Pyykkö, P.; Zanati, H. M. Inorg. Chem. 1991, 30, 2781.
237. (a) Wiberg, E.; Mödritzer, K. Naturforsch. 1956, 11b, 755. No evidence for this compound is found in solid matrixes, and its synthesis will certainly meet great difficulties (ref 128b).
238. Badalov, A.; Mirsaidov, U.; Marufi, V. K.; Shaimurodov, I. B.; Ikramov, M. Sov. J. Coord. Chem. 1992, 18, 559.
239. 0 redox pair (-1.66 V).
240. At 50°C for the ether solution: (a) Jones, C. personal communication.
241. At 150°C for the solid compound: (b) Wiberg, E.; Schmidt, M. Z. Naturforsch. 1951, 6b, 171.
242. 0 redox pair is -1.83 V.
243. Messer, C. E.; Wan-hoi Hung, G. J. Phys. Chem. 1968, 72, 3958.
244. (a) Dymova, T. N.; Dergachev, Y. M. Bull. Acad. Sci. USSR Chem. 1981, 30, 1935.
245. (b) Dergachev, Y. M.; Elizarova, T. A. Zh. Neorg. Khim. 1982, 27, 1063.
246. III redox pairs are much less positive.
247. 2 in a vacuum at 400°C.
248. -10°C for ether solution: Jones, C., personal communication.
249. -30°C for solid compound: Wiberg, E.; Schmidt, M. Z. Naturforsch. 1957, 12b, 54.
250. (a) Pulham, C. R.; Brain, P. T.; Downs, A. J.; Rankin, D. W. H.; Robertson, H. E. Chem. Commun. 1990, 1777.
251. (b) Downs, A. J.; Parsons, S.; Pulham, C. R.; Souter, P. F. Angew. Chem., Int. Ed. Engl. 1997, 36, 890.
252. (c) Downs, A. J.; Greene, T. M.; Johnsen, E.; Brain, P. T.; Morrison, C. A.; Parsons, S.; Pulham, C. R.; Rankin, D. W. H.; Aarset, K.; Mills, I. M.; Page, E. M.; Rice, D. A. Inorg. Chem. 2001, 40, 3484.
253. Wiberg, E.; Bauer, R. Z. Naturforsch. 1951, 6b, 392.
254. (a) Downs, A. J.; Thomas, P. D. P. Chem. Commun. 1976, 825.
255. (b) Barlow, M. T.; Dain, C. J.; Downs, A. J.; Laurenson, G. S.; Rankin, D. W. H. J. Chem. Soc., Dalton Trans. 1982, 597.
256. (c) Downs, A. J.; Harman, L. A.; Thomas, P. D. P. Polyhedron 1995, 7, 935.
257. (d) Downs, A. J.; Greene, T. M.; Harman, L. A.; Souter, P. F.; Brain, P. T.; Pulham, C. R.; Rankin, D. W. H.; Robertson, H. E.; Hofmann, M.; Schleyer, P. V. Inorg. Chem. 1995, 34, 1799.
258. 4 are currently being conducted in several laboratories: Jones, C., personal communication.
259. Wiberg, E.; Neumaier, H. Z. Anorg. Allg. Chem. 1965, 340, 189.
260. Bortz, M.; Hewat, A.; Yvon, K. J. Alloys Compd. 1997, 248, L1. In fact, slight decomposition of K and Rb salts occurs at temperatures abut 100°C lower than these values, via an intermediate stage involving intermetallic compounds of alkali metals with Zn.
261. Value for the ball-milled compound: Bhosle, V.; Baburaj, E. G.; Miranova, M.; Salama, K. Mater. Eng. A 2003, 356, 190.
262. (a) Grison, E. Prog. Nucl. Energy V 1959, 2, 91.
263. 3!
264. V alanate at room temperature more probable.
265. von Wartenburg, H. Z. Anorg. Chem. 1913, 79, 71.
266. Bortz, M.; Yvon, K.; Fischer, P. J. Alloys Compd. 1994, 216, 43.
267. Wiberg, E.; Dittmann, O.; Nöth, H.; Schmidt, M. Z. Naturforsch. 1957, 12b, 61.
268. Bortz, M.; Hewat, A.; Yvon, K. J. Alloys Compd. 1997, 253, 13.
269. (a) Mulford,R. N. R.; Wiewandt, T. A. J. Phys. Chem. 1965, 69, 1641.
270. (b) Mintz, M. H.; Hadari, Z.; Bixon, M. J. Less-Common Met. 1976, 48, 183.
271. (c) Ward, J. W.; Bartscher, W.; Rebizant, J. J. Less-Common Met. 1987, 130, 431.
272. (a) Wiberg, E.; Schmidt, M. Z. Naturforsch. 1951, 6b, 172.
273. (b) Wiberg, E.; Dittmann, O.; Schmidt, M. Z. Naturforsch, 1957, 12b, 57.
274. (a) Lobreyer, T.; Sundermeyer, W.; Oberhammer, H. Chem. Ber. 1994, 127, 2111.
275. -1salt: (b) Birchall, T.; Pereira, A. R. J. Chem. Soc., Dalton Trans. 1975, 1087.
276. (a) Comprehensive Inorganic Chemistry; Bailer, J. C., Jr., Emeléus, H. J., Nyholm, R., Trotman-Dickenson, A. F., Eds.; Pergamon Press: Oxford, 1973, and references therein.
277. (b) Jolly, W. L. J. Am. Chem. Soc. 1961, 83, 335.
278. 3.
279. Wiberg, E.; Henle, W. Z. Naturforsch. 1952, 7b, 250.
280. (a) Brunn, O. Chem. Ber. 1888, 21, 2546.
281. (b) Brunn, O. Chem. Ber. 1889, 22, 3205.
282. 3.
283. Wiberg, E.; Bauer, R. Z. Naturforsch. 1951, 6b, 392.
284. Heil, C. A.; Norman, A. D. Inorg. Chim. Acta 1988, 154, 9.
285. Le Maréchal, J. F.; Ephritikhine, M.; Folcher, G. J. Organomet. Chem. 1986, 309, C1.
286. Wiberg, H.; Henle, W. Z. Naturforsch. 1952, 7b, 250.
287. Wiberg, E.; Henle, W. Z. Naturforsch. 1952, 7b, 576.
288. Jander, G.; Kraffczyk, K. Z. Anorg. Allg. Chem. 1962, 283, 217.
289. A nice analysis of the H⋯H bonding and H pairing in certain materials based on MO theory may be found in: (a) Halet, J.-F.; Saillard, J.-Y.; Koudou, C.; Minot, C.; Nomikou, Z.; Hoffmann, R.; Demangeat, C. Chem. Mater. 1992, 4, 153.
290. (b) Liu, Q.; Hoffmann, R. J. Am. Chem. Soc. 1995, 117, 10108.
291. The discussed covalency increase of the M-H bond may be interpreted in the terms of the solid-state theory as a gradual introduction of holes to the hydride band by relatively electronegative metal cations. A similar correlation of the ionic character of the M-H bond was first attempted for a much more limited set of compounds (tetrahyridoborates of various metals, M = B) nearly a half-century ago: (a) Schrauzer, G. N. Naturwissenschaften 1955, 42, 438. A connection between the hole introduction to the hydride band by certain cations and superconductivity of the resulting hydride is now being advanced in our laboratories.
292. 2: (a) von Szentpály, L. J. Phys. Chem. A 2002, 106, 11945.
293. 2 molecule is linear: (b) Bernath, P. F.; Shayesteh, A.; Tereszchuk, K.; Colin, R. Science 2002, 297, 1323.
294. It was suggested that the elements with an electronegativity in the range of 1.35-1.82 do not form stable hydrides ("hydride gap"): Rittmeyer, P.; Wietelmann, U. Hydrides In Ullmann's Encyclopedia of Industrial Chemistry, 5th ed.; Bohnet, M., et al., Eds.; Wiley: New York, 1996; Vol. A13, p. 199. This observation-although not precise (e.g., Be, with a Pauling electronegativity of 1.57, does form a stable hydride)-reflects an important preference of H for ionic bonding, either as a hydride anion or as a proton.
295. To the best of our knowledge, these values are not known.
296. Pearson, R. G. Inorg. Chem. 1988, 27, 734.
297. 2 are linear molecules, while the heavier homologues are bent: (a) Martin, J. M. L.; Lee, T. J. Chem. Phys. 1992, 200, 502.
298. (b) Tschumer, G. S.; Schaefer, H. F., III. J. Chem. Phys. 1998, 108, 7511.
299. (c) Kaupp, M.; Schleyer, P. v. R.; Stoll, H.; Preuss, H. J. Chem. Phys. 1991, 94, 1360. Relativistic effects may be responsible for the increased covalency of metal-hydrogen bonding for heavier hydrides.
300. 2, in disagreement with our simple model: El Gridani, A.; El Bouzaidi, R. D.; El Mouhtadi, M. J. Mol. Struct. (THEOCHEM) 2000, 531, 193. Relativistic effects may be responsible for the increased covalency of the metal-hydrogen bonding for heavier hydrides.
301. (a) Bronger, W. Z. Anorg. Allg. Chem. 1996, 622, 9.
302. +I) and seems to be a universal property of hydrogen. It has been shown recently that chameleonic hydrogen accommodates it charge in various environments (bound to defects in semiconductors, insulators, or in solution) in such a way that its electronic level always falls at more or less the same energy: (b) van de Walle, C. G.; Neugebauer, J. Nature 2003, 423, 626 .
303. CsH could not be metallized up to 251 GPa, the band gap still being significant at this pressure (1.44 eV): (a) Ghandehari, K.; Luo, H.; Ruoff, A. L.; Trail, S. S.; DiSalvo, F. J. Solid State Commun. 1995, 95, 385.
304. On the other hand, CsI is metallic "already" at 115 GPa: (b) Eremets, M. I.; Shimizu, K.; Kobayashi, T. C.; Amaya, K. Science 1998, 281, 1333.
305. (a) Hati, S.: Datta, B.; Datta, D. J. Phys. Chem. 1996, 100, 19808.
306. Problems with the computed sign of dipole moment of the alkali metal hydride molecules arise when the assumed polarizability of the hydride anion is too large: (b) Altshuller, A. P. J. Chem. Phys. 1953, 21, 2074.
307. (a) Lewis, G. N. J. Am. Chem. Soc. 1916, 38, 762.
308. (b) Messer, C. E. J. Solid State Chem. 1970, 2, 144.
309. (c) Maeland, A. J.; Lahar, W. D. Z. Phys. Chem. 1993, 179, 193.
310. (d) Bouamrane, A.; Laval, J. P.; Soulie, J.-P. Bastide, J. P. Mater. Res. Bull. 2000, 35, 545.
311. For some talk also about the hydride-chloride analogy, see: (e) Park, H.-H.; Pezat, M.; Darriet, B.; Hagenmuller, P. Chem. Scr. 1988, 28, 447.
312. This classical division of hydrides obviously is not precise. For instance, there is an interesting example of an interstitial main group element hydride: Armstrong, D. R.; Clegg, W.; Davies, R. P.; Liddle, S. T.; Lindon, D. J.; Raithby, P. R; Snaith, R.; Wheatley, A. E H. Angew. Chem., Int. Ed. 1999, 38, 3367.
313. There have been successful attempts to synthesize hydrides which structurally fall between the "interstitial" and "covalent" hydrides. See, e.g.: Renaudin, G.; Guénée, L.; Yvon, K. J. Alloys Compd. 2003, 350, 145. More similar compounds are now expected.
314. 7. See e.g.: (a) Knappe, P.; Müller, H.; Mayer, H. W. J. Less-Common Met. 1983, 95, 323.
315. (b) Bischof, R.; Kaldis, E. J. Less-Common Met. 1983, 94, 263 and references therein.
316. Carrette, L.; Friedrich, K. A.; Stimming, U. Fuel Cells 2001, 1, 5.
317. 2: (a) Gaines, D. F.; Walsh, J. L.; Hillenbrand, D. F. Chem. Commun. 1977, 224.
318. (b) Gunderse, G.; Hedberg, L.; Hedberg, K. J. Chem. Phys. 1973, 59, 3777.
319. 4), where Ph = phenyl and Me = methyl; (c) Dou, D.; Liu, J. P.; Bauer, J. A. K.; Jordan, G. T.; Shore, S. G. Inorg. Chem. 1994, 33, 5443.
320. 5" with considerable thermal stability has been suggested, but more careful studies are needed to unequivocally confirm formation of this phase: (a) Ashby, E. C.; Prasad H. S. Inorg. Chem. 1975, 14, 2869.
321. (b) Cantrell, J. S.; Beiter, T. A.; Souers, P. C.; Barry, P. Z. Phys. Chem. Neue Folge 1989, 163, 233.
322. 7-dimeric units are also known: (a) Zhang, Q.-A.; Nakamura, Y.; Oikawa, K.; Kamiyama, T.; Akiba E. Inorg. Chem. 2002, 41, 6941.
323. 3-. Unfortunately, the thermal decomposition temperatures of these compounds have not been measured.
324. Bronger, W.; Gehlen, M.; Auffermann, G. J. Alloys Compd. 1991, 176, 255.
325. Didisheim, J. J.; Zolliker, P.; Yvon, K.; Fischer, P.; Schefer, J.; Gubelmann, M. Inorg. Chem. 1984, 23, 1953.
326. Huang, B.; Bonhomme, F.; Selvam, P.; Yvon, K.; Fischer, P. J. Less-Common Met. 1991, 171, 301.
327. Kritikos, M.; Noréus, D. J. Solid State Chem. 1991, 93, 256.
328. Ginsberg, A. P. Inorg. Chem. 1964, 3, 567.
329. 2 (M = Mn, Fe, Ni) were observed in noble gas matrixes.
330. 4 unit in the solid state: Nozik, Yu. Z.; Kuklina, E. S.; Bliznyuk, N. A.; Borisov, S. V. Kristallografiya 1991, 36, 57. The average bond length for the gas-phase molecule is probably slightly smaller.
331. 6 unit in the gas phase (ref 113b).
332. 2 unit in the gas phase (ref 156c). The value in the solid state is 1.4055 Å (ref 156b).
333. The average Ga-H bond length within the GaH unit in the gas phase (ref 158d).
334. -)(2.01 Å) being shorter than in the binary LiH (2.04 Å): Maeland, A. J.; Andresen, A. F. J. Chem. Phys. 1968, 48, 4660. Unfortunately, the decomposition temperature of this inverted perovskite is not known.
335. Care is advised in analysis of these data, since as a recent paper shows, the M-H bond lenghts prove to be very difficult to pin down accurately, and the reported Al-H and Ga-H distances span a disconcertingly wide range in various compouns. Tang, C. Y.; Downs, A. J.; Greene, T. M.; Parsons S. Dalton Trans. 2003, 540.
336. (a) Shriver, D. F.; Atkins, P. W. Inorganic Chemistry, 3rd ed.; W.H. Freeman & Co.: New York, 1999.
337. (b) Sharpe, A. G. Principles of Oxidation and Reduction; The Chemical Society: London, 1973.
338. dec of the former is much lower.
339. Popov, A. I.; Kiselev, Y. M. Russ. J. Inorg. Chem. 1988, 33, 541.
340. Zemva, B.; Lutar, K.; Jesih, A.; Casteel, Jr., W. J.; Wilkinson, A. P.; Cox, D. E.; Von Dreele, R. B.; Borrmann, H.; Bartlett, N. J. Am. Chem. Soc. 1991, 113, 4192.
341. Lucier, G. M.; Shen, C.; Casteel, W. J., Jr.; Chacon, L.; Bartlett, N. J. Fluorine Chem. 1995, 72, 157.
342. Citation from: Hoffmann, R. Am. Sci. 2001, 89, 311.
343. Remarkably, the same conclusions may be reached while analyzing theoretical results for molecular clusters presented in: (a) Nakatsuka, K.; Yoshino, M.; Yukawa, H.; Morinaga, M. J. Alloys Compd. 1999, 293-295, 222.
344. y hydride, connected with the transfer of hydride anion(s) from A to M. The covalent hydride is obviously stabilized in such reactions.
345. Other semiempirical approaches have been used in the past, in particular for the intermetallic hydrides, which are not the subject of the present study. Let us mention two valuable works (a) Miedema, A. R. J. Less-Common Met. 1973, 32, 117.
346. 4: the average stability of binary hydrides equals -38.3 kJ/mol, while the experimental average (per heavy element) is close to -96 kJ/mol! Intuitively, their simplistic "additive" approach could be successfully used for the connections of such elements which do not significantly differ in the chemical character, electronegativity, or molar enthalpy of hydride formation per 1 H atom, i.e., when an exothermic acid-base reaction between two component hydrides does not take place.
347. 2 in the presence of alkali halides: (a) Ivanov, E.; Konstanchuk, I.; Bokhonov, B.; Boldyrev, V. J. Alloys Compd. 2003, 359, 320.
348. Also, only a few examples are known of more sophisticated combinations, such as hydride-nitrides: (b) Marx, R. Z. Z. Anorg. Allg. Chem. 1997, 623, 1912.
349. Complexes containing amines are quite frequently investigated and sufficiently stable, even for the relatively oxidizing cations: (c) Mokhlesur Rahman, A. F. M.; Jackson, W. G.; Willis, A. C.; Rae, A. D. Chem. Commun. 2003, 2748.
350. Wiberg, E.; Henle, W. Z. Naturforsch. 1952, 7b, 249.
351. (a) Miyai, T.; Inoue, K.; Yasuda, M.; Shibata, I.; Baba, A. Tetrahedron Lett. 1998, 39, 1929.
352. (b) Himmel, H.-J.; Downs, A. J.; Greene, T. M. J. Am. Chem. Soc. 2000, 122, 922.
353. 4 compounds: (a) Wiberg, E.; Amberger, E.; Cambensi H. Z. Anorg. Allg. Chem. 1967, 351, 164.
354. (b) Horn, H. G. Chem. Z. 1986, 110, 131.
355. See: Schlapbach, L., Ed. Hydrogen in Intermetallic Compounds I. Electronic, Thermodynamic, and Crystallographic Properties, Preparation; Topics in Applied Physics 63; Springer: Berlin, 1988.
356. 3 will be further evaluated in section 4.7.
357. For further studies on the decomposition of alanates, see: (a) Ashby, E. C.; Kobetz, P. Inorg. Chem. 1966, 5, 1615.
358. (b) Gross, K. J.; Guthrie, S.; Takara, S.; Thomas, G. J. Alloys Compd. 2000, 297, 270 and references therein.
359. (c) Tarasov, V. P.; Bakum, S. I.; Novikov, A. V. Russ. J. Inorg. Chem. 2001, 46, 409.
360. (d) Tarasov, V. P.; Bakum, S. I.; Novikov, A. V. Russ. J. Inorg. Chem. 2000, 45, 1890.
361. The most recent data show that the decomposition path might also include a direct process described by eq 8d: (e) Wiench, J. W.; Balema, V. P.; Percharsky, V. K.; Pruski, M. J. Solid State Chem., in press.
362. dec = 252°C is obtained, very close to the experimentally found value.
363. Jerzembeck, W.; Bürger, H.; Constantin, L.; Margulès, L.; Demaison, J.; Breidung, J.; Thiel, W. Angew. Chem., Int. Ed. 2002, 41, 2550.
364. (a) Wiberg, E.; Johannsen, T. Angew. Chem. 1942, 55, 38.
365. (b) Wiberg, E.; Schmidt, M. Z. Naturforsch. 1952, 7b, 577.
366. Wiberg, E.; Schmidt, M. Z. Naturforsch. 1951, 6b, 172.
367. (a) Wiberg, E.; Schmidt, M. Z. Naturforsch. 1951, 6b, 172.
368. (b) Wiberg, E.; Nöth, H. Z. Naturforsch. 1957, 12b, 59.
369. Schlesinger, H. I.; Brown, H. C.; Schaeffer, G. W. J. Am. Chem. Soc. 1943, 65, 1786.
370. (a) Wiberg, E.; Schmidt, M. Z. Naturforsch. 1951, 6b, 335.
371. (b) Wiberg, E.; Schmidt, M. Z. Naturforsch. 1951, 6b, 335.
372. (a) Wiberg, E.; Schmidt, M. Z. Naturforsch. 1951, 6b, 334.
373. (b) Wiberg, E.; Nöth, H. Z. Naturforsch. 1957, 12b, 63.
374. Wiberg, E.; Dittmann, O.; Schmidt, M. Z. Naturforsch. 1957, 12b, 60.
375. (a) Wiberg, E.; Amberger, E. Hydrides of the elements of main groups I- IV; Elsevier: Amsterdam, 1971.
376. (b) Wiberg, E. Angew. Chem. 1951, 63, 485.
377. Wiberg, E.; Schmidt, M. Z. Naturforsch. 1951, 6b, 334.
378. (a) Shriver, D. F.; Parry, R. W.; Greenwood, N. N.; Storr, A.; Wallbridge, M. G. H. Inorg. Chem. 1963, 2, 867.
379. (b) Greenwood, N. N.; Wallbridge, M. G. H. J. Chem. Soc. 1963, 3912. Wiberg's group has claimed to have synthesized a large number of various hydrides, the majority of their results being cited here. So far, only the derivatives of Ga, In, and Tl have undergone careful scrutiny, but-as A. J. Downs warns us-given the resources then available, they were liable to overlook the effects of solvation and/or halide/hydride exchange. Thus, careful reexamination of many hydrides is now recommended.
380. (a) Pullumbi, P.; Bouteiller, Y.; Manceron, L.; Mijoule, C. Chem. Phys. 1994, 185, 25.
381. 3 may be stabilized in the form of various complexes: (b) Jones, C. Chem. Commun. 2001, 2293.
382. 2: Han, Y. K.; Bae, C.; Lee, Y. S. J. Chem. Phys. 1999, 110, 9353.
383. (a) Jones, C., personal communication.
384. Many interesting complex hydrides of In were recently obtained, including a derivative which is thermally stable up to an impressive 115°C, a record among complex In hydrides: (b) Abarnethy, C. D.; Cole, M. L.; Jones, C. Organometallics 2000, 19, 4852.
385. (a) Breisacher, P.; Siegel, B. J. Am. Chem. Soc. 1965, 87, 4255.
386. (b) Downs, A. J. Coord. Chem. Rev. 1999, 189, 55.
387. (c) Aldridge, S.; Downs, A. J. Chem. Rev. 2001, 101, 3305.
388. Trefilov, V. I.; Morozov, I. A.; Morozova, R. A.; Dobrovolsky, V. D.; Zaulichny, Y. A.; Kopylova, E. I.; Khyzhun, O. Y. Int. J. Hydrogen Energy 1999, 24, 157.
389. (a) Krasovskii, E. E.; Nemoshkalenko, V. V.; Kobzenko, G. F.; Antonov, V. N. Int. J. Hydrogen Energy 1995, 20, 373.
390. 3 has been isolated in the matrixes: (b) Wang, X.; Chertihin, G. V.; Andrews, L. J. Phys. Chem. A 2002, 106, 9213.
391. (a) Warf, J. C.; Hardcastle, K. I. J. Am. Chem. Soc. 1966, 83, 2206.
392. (b) Korst, W. L.; Warf, J. C. Inorg. Chem. 1966, 5, 1719.
393. (c) Warf, J. C.; Korst, W. L.; Hardcastle, K. I. Inorg. Chem. 1966, 5, 1726.
394. (d) Hardcastle, K. I.; Warf, J. C. Inorg. Chem. 1966, 5, 1728.
395. (e) Warf, J. C.; Hardcastle, K. I. Inorg. Chem. 1966, 5, 1736.
396. 2: (f) Bischof, R.; Kaldis, E.; Wachter, P. J. Less-Common Met. 1985, 111, 139.
397. 2: (g) Buechler, S.; Monnier, R.; Degiorgi, L. Z. Phys. Chem. 1989, 163, 579.
398. 2.67 was synthesized only recently: (h) Auffermann, G. Z. Anorg. Allg. Chem. 2002, 628, 1615.
399. 3: Müller, H.; Knappe, P. J. Less-Common Met. 1982, 87, 59.
400. 1.95 for Eu (E° = -0.35 V).
401. 3.16 is formed at about 15-21°C: Wang, L. M.; Conder, K.; Kaldis, E. J. Rare Earths 1998, 16, 10.
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403. (b) Segal, B. G.; Lippard, S. J. Inorg. Chem. 1978, 17, 844.
404. (c) Noth, H. Angew. Chem. 1961, 73, 371.
405. (d) Rosmsanith K. Monatsch. Chem. 1966, 97, 863.
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407. (a) Wilson, S. P.; Andrews, L. J. Phys. Chem. A 2000, 104, 1640.
408. (b) Chertihin, G. V.; Andrews, L. J. Am. Chem. Soc. 1995, 117, 6402.
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410. (d) Souter, P. F.; Kushto, G. P.; Andrews, L.; Neurock, M. J. Am. Chem. Soc. 1997, 119, 1682.
411. (e) Souter, P. F.; Kushto, G. P.; Andrews, L.; Neurock, M. J. Phys. Chem. A 1997, 101, 1287.
412. (f) Xiao, Z. L.; Hauge, R. H.; Margrave, J. L. J. Phys. Chem. 1991, 95, 2696.
413. (g) Xiao, Z. L.; Hauge, R. H.; Margrave, J. L. J. Phys. Chem. 1992, 96, 636.
414. (h) Wang, X.; Andrews, L. J. Am. Chem. Soc. 2003, 125, 6581.
415. 3, estimated by extrapolation of the data for hydrides of the Sc-Y-Fe alloys (Burnasheva, V. V.; Fokina, E. F.; Fokin, V. N.; Troitskaya, S. L. Russ. J. Inorg. Chem. 1986, 31, 1446), is about +50°C.
416. IV are easily obtained by stabilization with various auxiliary ligands; see ref 251e for details.
417. 7 has been obtained: (a) Smith, K. J.; Ondracek, A. L.; Gruhn, N. E.; Lichtenberger, D. L.; Fanwick, P. E.; Walton, R. A. Inorg. Chim. Acta 2000, 300, 23.
418. dec of - 75 °C. Our estimate for AgH gives a similar value of -85 °C.
419. 4 has been mentioned as a reactant in: Wojakowski, A.; Damien, D.; Hery, Y. J. Less-Common Met. 1982, 83, 169.
420. 5 has been obtained: (a) Tebbe, F. N. J. Am. Chem. Soc. 1973, 95, 5823.
421. 5 complexes decompose above 130°C.
422. V hydrides have been obtained: Donoghue, N.; Gallagher M. J. Phosphorus, Sulfur, Silicon Relat. Elem. 1997, 123, 169.
423. 5 has been obtained: Schrock, R. R. J. Organomet. Chem. 1976, 121, 373.
424. 6 has been obtained: (a) Gregson, D.; Mason, S. A.; Howard, J. A. K.; Spencer, J. L.; Turner D. G. Inorg. Chem. 1984, 23, 4103.
425. (b) Michos, D.; Luo, X. L.; Faller, J. W.; Crabtree, R. H. Inorg. Chem. 1993, 32, 1370.
426. (a) Wang, X. F.; Andrews, L. J. Am. Chem. Soc. 2002, 124, 5636.
427. (b) Wang, X. F.; Andrews L. J. Phys. Chem. A 2002, 106, 6720.
428. 6 exist: Hinze, J.; Friedrich, O.; Sundermann A. Mol. Phys. 1999, 96, 711.
429. Despite the large presumed instability of connections of Au(III) and AU(II) with hydride anion, the hydride species of Au at high oxidation states have been detected in noble gas matrixes: (a) Andrews, L.; Wang X. J. Am. Chem. Soc. 2003, 96, 711.
430. 2 orbital; this unique property should be further used to stabilize the unusual oxidation states of various metals in molecular compounds.
431. 4 exist: Wittkopp, A.; Prall, M.; Schreiner, P. R.; Schaefer, H. F., III. Phys. Chem. Chem. Phys. 2000, 2, 2239.
432. 2) have been isolated in noble gas matrixes: Wang, X.; Andrews, L. J. Am. Chem. Soc. 2001, 123, 12899.
433. A similar trick (complexation by macrocyclic ligand) allowed for stabilization of Ga hydride at room temperature: (a) Feng, Y.; Ong, S.-L.; Hu, J.; Ng, W.-J. Inorg. Chem. Commun. 2003, 6, 466.
434. 4, yielding the triptycene complexes: (b) Brynda, M.; Bernardinelli, G.; Dutan, C.; Geoffroy, M. Inorg. Chem. 2003, 42, 6586.
435. 4 (1-5%) and In and Tl derivatives. Thermal data are complicated due to the presence of intermetallic phases in the analyzed specimens. The data presented certainly await reanalysis, and these compounds should be again targeted using other synthetic approach (e.g., metathesis reactions).
436. Reifenberg, G. H.; Considine, W. J. J. Am. Chem. Soc. 1969, 91, 2401.
437. Auffermann, G.; Bronger, W. Z. Allg. Chem. 2002, 628, 2159.
438. Bronger, W.,; Sommer, T.; Auffermann, G.; Muller, P. J. Alloys Compd. 2002, 330, 536.
439. 2 has been isolated in noble gas matrixes: Wang, X.; Andrews, L. J. Phys. Chem. A 2003, 107, 4081.
440. 2 should be used to generate the ternary salts of divalent and possibly trivalent Cr.
441. 3 have been studied: (a) Bouamrane, A.; Thourey, J.; Bastide, J. P. Thermochim. Acta 1990, 159, 153.
442. (b) Bouamrane, A.; de Brauer, C.; Soulié, J.-P.; Létoffé, J. M.; Bastide, J. P. Thermochim. Acta 1999, 326, 37.
443. dec have not been given.
444. dec° is surprisingly high, much larger than for other lanthanides.
445. -. There is an excellent theoretical study of the compounds with electron-deficient bridges and three-center, two-electron bonding: Trinquier, G.; Malrieu, J.-P. J. Am. Chem. Soc. 1991, 113, 8643.
446. 3 has also beenn isolated in noble gas matrixes, in both monomer and dimer forms: (a) Kurth, F. A.; Eberlein, R. A.; Schnockel, H.; Downs, A. J.; Pulham, C. R. Chem. Commun. 1993, 1302-1304.
447. (b) Andrews, L.; Wang, X. F. Science 2003, 299, 2049.
448. (c) Wang, X.; Andrews, L.; Tam, S.; DeRose, M. E.; Fajardo, M. E. J. Am. Chem. Soc. 2003, 125, 9218.
449. 3(s).
450. dec.
451. Hydrogen has no core electrons, and the attraction between valence electron and nucleus is not screened.
452. 4 is nearly reversible, in contrast to Na and Li homologues, as a recent report shows: Morioka, H.; Kakizaki, K.; Chung, S.-C.; Yamada, A. J. Alloys Compd. 2003, 353, 310. Note that this compound decomposes at higher temperatures than its lighter siblings (250-340 °C).
453. (a) Bogdanovic, B.; Schwickardi, M. J. Alloys Compd. 1997, 253, 1.
454. (b) Bogdanovic, B. German Patent 195 26 434, 1995.
455. (a) Bogdanovic, B.; Schwickardi, M. Appl. Phys. A 2001, 72, 221.
456. (b) Chen, J.; Kuriyama, N.; Xu, Q.; Takeshita, H. T.; Sakai, T. J. Phys. Chem. B 2001, 105, 11214.
457. Zidan, R. A.; Takara, S.; Hee, A. G.; Jensen, C. M. J. Alloys Compd. 1999, 285, 119.
458. Zaluska, A.; Zaluski, L.; Ström-Olsen, J. O. J. Alloys Compd. 2000, 298, 125.
459. Jensen, C. M.; Zidan, R.; Mariels, N.; Hee, A.; Hagen, C. Int. J. Hydrogen Energy 1999, 24, 461.
460. Jensen, C. M.; Gross, K. J. Appl. Phys. A 2001, 72, 213.
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462. (b) Balema, V. P.; Wiench, J. W.; Denis, K. W.; Pruski, M.; Pecharsky, V. K. J. Alloys Compd. 2001, 329, 108.
463. The enthalpies of activation of dehydrogenation of these compounds have been recently determined: (a) Kiyobayashi, T.; Srinivasan, S. S.; Sun, D.; Jensen, C. M. J. Phys. Chem. A 2003, 107, 7671.
464. 4.
465. Balogh, M. P.; Tibbetts, G. G.; Pinkerton, F. E.; Meisner, G. P.; Olk, C. H. J. Alloys Compd. 2003, 350, 136.
466. (a) Linck, R. C.; Pafford, R. J.; Rauchfuss, T. B. J. Am. Chem. Soc. 2001, 123, 8856.
467. For the mechanism of generation of hydrogen from transition metal dithiolenes, see: (b) Alvarez S.; Hoffmann, R. Anal. Soc. Real. 1986, 82, 52.
468. 2 molecule: (c) Wander, S. A.; Miedaner, A.; Noll, B. C.; Barkley, R. M.; DuBois, D. L. Organometallics 1996, 15, 3360.
469. (d) Dahlenburg, L.; Götz, R. Inorg. Chem. Commun. 2003, 6, 443.
470. Note that the half-wave potentials for these compounds are around - 1.3 V, close to the -1.2 V value predicted to provide a standard enthalpy of formation of a hydride close to zero (ref 279). There is also nice theoretical study of dihydrogen reductive addition for a tungsten complex: (e) Lesnard, H.; Demachy, I.; Jean, Y.; Lledos, A. Chem. Commun. 2003, 850.
471. 2 electronic states with no apparent difficulty: (a) Pons, V.; Heinekey, D. M. J. Am. Chem. Soc. 2003, 125, 8428.
472. Certain bacteria have elaborated the Fe/Ni/S/Se activation sites for the reverse process, the oxidation of dihydrogen to protons: (b) Evans, D. J.; Pickett, C. J. Chem. Soc. Rev. 2003, 32, 268.
473. +) which do not completely bind dihydrogen, but they catalyze - often stereospecifically - the hydrogenation of various organic compounds: (c) Knowles, W. The Nobel Lecture, 2001.
474. 10 species are in progress: (d) Alikhani, M. E.; Minot, C. J. Phys. Chem. A 2003, 107, 5352.
475. (e) Grochala, W., unpublished results.
476. 2 down to 200 °C, resulting in a 13.5 wt % hydrogen store (reversibility issue has not been addressed): (a) Züttel, A.; Wenger, P.; Rentsch, S.; Sudan, P.; Mauron, P.; Emmenegger, C. J. Power Sources 2003, 118, 1.
477. 2 now await confirmation by other groups.
478. There is an excellent theoretical paper on the H-H bond activation: Saillard, J.Y.; Hoffmann, R. J. Am. Chem. Soc. 1984, 106, 2006.
479. In principle, catalyst providing the low decomposition temperature of the hydrogen store does not have to be same as the catalyst providing the reversible hydrogenation. However, both should survive in the reducing environment of the hydrogen stores and their decomposition products, including reactive metals.
480. 2 is not detected upon hydriding of the Mg/Al alloys (Bouarchica, S.; Dodelet, J. P.; Guay, D.; Huot, J.; Boily, S.; Schulz, R. J. Alloys Compd. 2000, 297, 282). This might happen when the acid/base reaction does not have a satisfactorily large thermodynamical driving force, or if there is a large kinetic barrier.
481. Zaluski, L.; Zaluska, A.; Ström-Olsen, J. O. Appl. Phys. A 2001, 72, 157.
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483. Zaluski, L.; Zaluska, A.; Ström-Olsen, J. O. J. Alloys Compd. 1997, 253, 70.
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486. (b) Huot, J.; Boily, S.; Güther, V.; Schulz, R. J. Alloys Compd. 1999, 383, 304.
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488. (b) Fujimoto H. J. Phys. Chem. 1974, 78, 1874
489. (c) Longuet-Higgins, H. C. Chem. Phys. 1950, 18, 1174.
490. (d) Gimarc, B. M. J. Am. Chem. Soc. 1983, 105, 1979.
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492. (f) Albright T. A. Orbittal Interactions in Chemistry; Wiley: New York, 1985; pp 84-86.
493. Allen, L. C. J. Am. Chem. Soc. 1989, 111, 9003.
494. Allred, A. L.; Rochow, E. G. J. Inorg. Nucl. Chem. 1958, 5, 264.
495. Parry, R. W.; Schultz, D. R.; Girardot, P. R. J. Am. Chem. Soc. 1958, 80, 1.
496. 4) is prohibited by decomposition.
497. 2.
498. 3: (a) Wiberg, E.; May, A. Z. Naturforsch. 1955, 10b, 229.
499. 12). The previous compound decomposes at 150 °C to amorphous GaN, while the latter solidifies at 6 °C; (b) Campbell, J. P.; Hwang, J. W.; Young, V. G.; Von Dreele, R. B.; Cramer, C. J.; Gladfelter, W. L. J. Am. Chem. Soc. 1998, 120, 521.
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501. The authors of ref 305 report 50% decomposition at 25 °C in 6 h.
502. Hayhurst, A. N.; Taylor, S. G. Phys. Chem. Chem. Phys. 2002, 4, 561.
503. Workman, D. B.; Squires, R. R. Inorg. Chem. 1988, 27, 1846.
504. The reader is referred to the review on the hydride-to-protonic interaction and dihydrogen bonding in a variety of compounds: (a) Custelcean, R.; Jackson, J. E. Chem. Rev. 2001, 101, 1963.
505. 3: (b) Trudel, S.; Gilson, D. F. R. Inorg. Chem. 2003, 42, 2814.
506. More rigorous classification of the hydrogen and dihydrogen bonds can be found in: (c) Govender, M. G.; Ford, T. A. J. Mol. Struct. (THEOCHEM) 2003, 630, 11.
507. This idealized value has been computed assuming that 100% decomposition follows in the reaction path described in ref 303.
508. 4I, which is a commercially available volatile solid.
509. 2 relief (counteranion is reduced).
510. 3 has been isolated in the noble gas matrix (ref 113b).
511. 3 adduct is known: (a) Wiberg, E.; Noth, H. Z. Naturforsch. 1955, 10b, 237.
512. 3 may also form a 2:1 adduct with ammonia in the gas phase: (b) Czerw, M.; Goldman, A. S.; Krogh-Jespersen, K. Inorg. Chem. 2000, 39, 363.
513. 3 (+65°C). There is a theoretical study on the thermodynamic stability of ammonium and phosphonium alanates and borohydrides in the gas phase (Baranov, L. Y.; Charkin, O. P. Russ. J. Inorg. Chem. 1990, 35, 1641), but no conclusions on the stability of the solid-state systems can be easily extrapolated from these data.
514. It is important to note that all these substances would be thermodynamically unstable, so their decomposition may result in the heat release, and finalize in a violent uncontrolled process, similar to other hydride-proton reactions: (a) Libowitz, G. G. The Solid State Chemistry of Binary Metal Hydrides; W. A. Benjamin: New York, 1965.
515. (b) Aiello, R.; Mathews, M. A.; Reger, D. L.; Collins, J. E. Int. J. Hydrogen Energy 1998, 23, 1103.
516. 3: (c) Dobbs, K. D.; Trachtman, M.; Bock, C. W.; Cowley, A. H. J. Phys. Chem. 1990, 94, 5210.
517. 2n species increases with the decreasing n from 4 through 3 to 2.
518. 3 (Mayumi, M.; Satoh, F.; Kumagai, Y.; Takemoto, K.; Koukitu, A. Phys. Stat. Solidi B 2001, 228, 537).
519. More continuous control of dihydrogen evolution can, of course, be obtained in complex compounds by using different ligands. An iridium compound (Lee, J. C.; Peris, E.; Rheingold, A. L.; Crabtree, R. H. J. Am. Chem. Soc. 1994, 116, 11014) is a good example of such control; it decomposes at about 80°C, and the decomposition at 20°C is very slow. But along with the increasing complexity, there comes an increase in molecular mass. Thus, hydrogen storage capacity drops significantly.
520. 4 storage, are important precursors for the blue laser crystals, such as GaN.
521. For recent progress in C-H bond activation, see: (a) Haenel, M. W.; Oevers, S.; Angermund, K.; Kaska, W. C.; Fan, H.-J.; Hall, M. B. Angew. Chem., Int. Ed. 2001, 40, 3596 and references therein.
522. See also: (b) Goddard, R. J.; Hoffmann, R.; Jemmis, E. D. J. Am. Chem. Soc. 1980, 102, 7667.
523. For N-H bond activation, see, e.g.: Zhou, M.; Chen, M.; Zhang, L.; Lu, H. J. Phys. Chem. A 2002, 106, 9017.
524. The insertion of hydrogen between the graphitic sheets has been studied since the middle 1960s: (a) Saehr, D.; Herold, A. Bull. Soc. Chim. Fr. 1965, 3130.
525. Note that nanotubes made of BN, an inorganic analogue of carbon, are also capable of storing relatively large amounts of hydrogen under high hydrogen pressures: (b) Tang, C.; Bando, Y.; Ding, X.; Qi, S.; Goldberg, D. J. Am. Chem. Soc. 2002, 124, 14550.
526. Carbon nitride has also been examined: (c) Ohkawara, Y.; Ohshio, S.; Suzuki, T.; Yatsui, K.; Ito, H.; Saitoh, H. Jpn. J. Appl. Phys. Part 1 2002, 41, 7508.
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