Transition metal nanocluster formation kinetic and mechanistic studies. A new mechanism when hydrogen is the reductant: Slow, continuous nucleation and fast autocatalytic surface growth

Journal of the American Chemical Society

Volumn 119, Issue 43, 1997, Pages 10382-10400

  Watzky, Murielle A ^a   Finke, Richard G ^a  

^a Department of Environmental and Radiological Health Sciences   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

METAL OXIDE;

ARTICLE; CATALYSIS; DRUG STRUCTURE; DRUG SYNTHESIS; GAS LIQUID CHROMATOGRAPHY; IN VITRO STUDY; REACTION ANALYSIS; TEMPERATURE;

EID: 0030714094     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja9705102     Document Type: Article

References (153)

1. Reviews on nanoclusters: (a) Jena, P.; Rao B. K.; Khanna, S. N. Physics and Chemistry of Small Clusters; Plenum: New York, 1987. (b) Andres, R. P.; Averback, R. S.; Brown, W. L.; Brus, L. E. Goddard, W. A.; Kaldor, A.; Louie S. G.; Moscovits, M.; Peercy, P. S.; Riley, S. J.; Siegel, R. W.; Spaepen, F.; Wang, Y. J. Mater. Res. 1989, 4, 704. This is a Panel Report from the United States Department of Energy, Council on Materials Science on Research Opportunities on Clusters and Cluster-assembled Materials, (c) Thomas, J. M. Pure Appl. Chem. 1988, 60, 1517. (d) Henglein, A. Chem. Rev. 1989, 89, 1861. (e) A superb series of papers, complete with a record of the insightful comments by the experts attending the conference, is available in Faraday Discussions 1991, 92, 1-300. (f) Bradley, J. S. In Clusters and Colloids. From Theory to Applications; Schmid, G., Ed.; VCH: New York, 1994; pp 459-544. (g) Schmid, G. In Aspects of Homogeneous Catalysis; Ugo, R., Ed.; Kluwer: Dordrecht, 1990; Chapter 1. (h) Bönnemann, H.; Braun, G.; Brijoux, W.; Brinkmann, R.; Tilling, A. S.; Seevogel, K.; Siepen, K. J. Org. Met. Chem. 1996, 520, 143-162 and the collection of "key publications" cited as refs 2-61 therein.
2. Reviews on nanoclusters: (a) Jena, P.; Rao B. K.; Khanna, S. N. Physics and Chemistry of Small Clusters; Plenum: New York, 1987. (b) Andres, R. P.; Averback, R. S.; Brown, W. L.; Brus, L. E. Goddard, W. A.; Kaldor, A.; Louie S. G.; Moscovits, M.; Peercy, P. S.; Riley, S. J.; Siegel, R. W.; Spaepen, F.; Wang, Y. J. Mater. Res. 1989, 4, 704. This is a Panel Report from the United States Department of Energy, Council on Materials Science on Research Opportunities on Clusters and Cluster-assembled Materials, (c) Thomas, J. M. Pure Appl. Chem. 1988, 60, 1517. (d) Henglein, A. Chem. Rev. 1989, 89, 1861. (e) A superb series of papers, complete with a record of the insightful comments by the experts attending the conference, is available in Faraday Discussions 1991, 92, 1-300. (f) Bradley, J. S. In Clusters and Colloids. From Theory to Applications; Schmid, G., Ed.; VCH: New York, 1994; pp 459-544. (g) Schmid, G. In Aspects of Homogeneous Catalysis; Ugo, R., Ed.; Kluwer: Dordrecht, 1990; Chapter 1. (h) Bönnemann, H.; Braun, G.; Brijoux, W.; Brinkmann, R.; Tilling, A. S.; Seevogel, K.; Siepen, K. J. Org. Met. Chem. 1996, 520, 143-162 and the collection of "key publications" cited as refs 2-61 therein.
3. Reviews on nanoclusters: (a) Jena, P.; Rao B. K.; Khanna, S. N. Physics and Chemistry of Small Clusters; Plenum: New York, 1987. (b) Andres, R. P.; Averback, R. S.; Brown, W. L.; Brus, L. E. Goddard, W. A.; Kaldor, A.; Louie S. G.; Moscovits, M.; Peercy, P. S.; Riley, S. J.; Siegel, R. W.; Spaepen, F.; Wang, Y. J. Mater. Res. 1989, 4, 704. This is a Panel Report from the United States Department of Energy, Council on Materials Science on Research Opportunities on Clusters and Cluster-assembled Materials, (c) Thomas, J. M. Pure Appl. Chem. 1988, 60, 1517. (d) Henglein, A. Chem. Rev. 1989, 89, 1861. (e) A superb series of papers, complete with a record of the insightful comments by the experts attending the conference, is available in Faraday Discussions 1991, 92, 1-300. (f) Bradley, J. S. In Clusters and Colloids. From Theory to Applications; Schmid, G., Ed.; VCH: New York, 1994; pp 459-544. (g) Schmid, G. In Aspects of Homogeneous Catalysis; Ugo, R., Ed.; Kluwer: Dordrecht, 1990; Chapter 1. (h) Bönnemann, H.; Braun, G.; Brijoux, W.; Brinkmann, R.; Tilling, A. S.; Seevogel, K.; Siepen, K. J. Org. Met. Chem. 1996, 520, 143-162 and the collection of "key publications" cited as refs 2-61 therein.
4. Reviews on nanoclusters: (a) Jena, P.; Rao B. K.; Khanna, S. N. Physics and Chemistry of Small Clusters; Plenum: New York, 1987. (b) Andres, R. P.; Averback, R. S.; Brown, W. L.; Brus, L. E. Goddard, W. A.; Kaldor, A.; Louie S. G.; Moscovits, M.; Peercy, P. S.; Riley, S. J.; Siegel, R. W.; Spaepen, F.; Wang, Y. J. Mater. Res. 1989, 4, 704. This is a Panel Report from the United States Department of Energy, Council on Materials Science on Research Opportunities on Clusters and Cluster-assembled Materials, (c) Thomas, J. M. Pure Appl. Chem. 1988, 60, 1517. (d) Henglein, A. Chem. Rev. 1989, 89, 1861. (e) A superb series of papers, complete with a record of the insightful comments by the experts attending the conference, is available in Faraday Discussions 1991, 92, 1-300. (f) Bradley, J. S. In Clusters and Colloids. From Theory to Applications; Schmid, G., Ed.; VCH: New York, 1994; pp 459-544. (g) Schmid, G. In Aspects of Homogeneous Catalysis; Ugo, R., Ed.; Kluwer: Dordrecht, 1990; Chapter 1. (h) Bönnemann, H.; Braun, G.; Brijoux, W.; Brinkmann, R.; Tilling, A. S.; Seevogel, K.; Siepen, K. J. Org. Met. Chem. 1996, 520, 143-162 and the collection of "key publications" cited as refs 2-61 therein.
5. Reviews on nanoclusters: (a) Jena, P.; Rao B. K.; Khanna, S. N. Physics and Chemistry of Small Clusters; Plenum: New York, 1987. (b) Andres, R. P.; Averback, R. S.; Brown, W. L.; Brus, L. E. Goddard, W. A.; Kaldor, A.; Louie S. G.; Moscovits, M.; Peercy, P. S.; Riley, S. J.; Siegel, R. W.; Spaepen, F.; Wang, Y. J. Mater. Res. 1989, 4, 704. This is a Panel Report from the United States Department of Energy, Council on Materials Science on Research Opportunities on Clusters and Cluster-assembled Materials, (c) Thomas, J. M. Pure Appl. Chem. 1988, 60, 1517. (d) Henglein, A. Chem. Rev. 1989, 89, 1861. (e) A superb series of papers, complete with a record of the insightful comments by the experts attending the conference, is available in Faraday Discussions 1991, 92, 1-300. (f) Bradley, J. S. In Clusters and Colloids. From Theory to Applications; Schmid, G., Ed.; VCH: New York, 1994; pp 459-544. (g) Schmid, G. In Aspects of Homogeneous Catalysis; Ugo, R., Ed.; Kluwer: Dordrecht, 1990; Chapter 1. (h) Bönnemann, H.; Braun, G.; Brijoux, W.; Brinkmann, R.; Tilling, A. S.; Seevogel, K.; Siepen, K. J. Org. Met. Chem. 1996, 520, 143-162 and the collection of "key publications" cited as refs 2-61 therein.
6. Reviews on nanoclusters: (a) Jena, P.; Rao B. K.; Khanna, S. N. Physics and Chemistry of Small Clusters; Plenum: New York, 1987. (b) Andres, R. P.; Averback, R. S.; Brown, W. L.; Brus, L. E. Goddard, W. A.; Kaldor, A.; Louie S. G.; Moscovits, M.; Peercy, P. S.; Riley, S. J.; Siegel, R. W.; Spaepen, F.; Wang, Y. J. Mater. Res. 1989, 4, 704. This is a Panel Report from the United States Department of Energy, Council on Materials Science on Research Opportunities on Clusters and Cluster-assembled Materials, (c) Thomas, J. M. Pure Appl. Chem. 1988, 60, 1517. (d) Henglein, A. Chem. Rev. 1989, 89, 1861. (e) A superb series of papers, complete with a record of the insightful comments by the experts attending the conference, is available in Faraday Discussions 1991, 92, 1-300. (f) Bradley, J. S. In Clusters and Colloids. From Theory to Applications; Schmid, G., Ed.; VCH: New York, 1994; pp 459-544. (g) Schmid, G. In Aspects of Homogeneous Catalysis; Ugo, R., Ed.; Kluwer: Dordrecht, 1990; Chapter 1. (h) Bönnemann, H.; Braun, G.; Brijoux, W.; Brinkmann, R.; Tilling, A. S.; Seevogel, K.; Siepen, K. J. Org. Met. Chem. 1996, 520, 143-162 and the collection of "key publications" cited as refs 2-61 therein.
7. Reviews on nanoclusters: (a) Jena, P.; Rao B. K.; Khanna, S. N. Physics and Chemistry of Small Clusters; Plenum: New York, 1987. (b) Andres, R. P.; Averback, R. S.; Brown, W. L.; Brus, L. E. Goddard, W. A.; Kaldor, A.; Louie S. G.; Moscovits, M.; Peercy, P. S.; Riley, S. J.; Siegel, R. W.; Spaepen, F.; Wang, Y. J. Mater. Res. 1989, 4, 704. This is a Panel Report from the United States Department of Energy, Council on Materials Science on Research Opportunities on Clusters and Cluster-assembled Materials, (c) Thomas, J. M. Pure Appl. Chem. 1988, 60, 1517. (d) Henglein, A. Chem. Rev. 1989, 89, 1861. (e) A superb series of papers, complete with a record of the insightful comments by the experts attending the conference, is available in Faraday Discussions 1991, 92, 1-300. (f) Bradley, J. S. In Clusters and Colloids. From Theory to Applications; Schmid, G., Ed.; VCH: New York, 1994; pp 459-544. (g) Schmid, G. In Aspects of Homogeneous Catalysis; Ugo, R., Ed.; Kluwer: Dordrecht, 1990; Chapter 1. (h) Bönnemann, H.; Braun, G.; Brijoux, W.; Brinkmann, R.; Tilling, A. S.; Seevogel, K.; Siepen, K. J. Org. Met. Chem. 1996, 520, 143-162 and the collection of "key publications" cited as refs 2-61 therein.
8. Reviews on nanoclusters: (a) Jena, P.; Rao B. K.; Khanna, S. N. Physics and Chemistry of Small Clusters; Plenum: New York, 1987. (b) Andres, R. P.; Averback, R. S.; Brown, W. L.; Brus, L. E. Goddard, W. A.; Kaldor, A.; Louie S. G.; Moscovits, M.; Peercy, P. S.; Riley, S. J.; Siegel, R. W.; Spaepen, F.; Wang, Y. J. Mater. Res. 1989, 4, 704. This is a Panel Report from the United States Department of Energy, Council on Materials Science on Research Opportunities on Clusters and Cluster-assembled Materials, (c) Thomas, J. M. Pure Appl. Chem. 1988, 60, 1517. (d) Henglein, A. Chem. Rev. 1989, 89, 1861. (e) A superb series of papers, complete with a record of the insightful comments by the experts attending the conference, is available in Faraday Discussions 1991, 92, 1-300. (f) Bradley, J. S. In Clusters and Colloids. From Theory to Applications; Schmid, G., Ed.; VCH: New York, 1994; pp 459-544. (g) Schmid, G. In Aspects of Homogeneous Catalysis; Ugo, R., Ed.; Kluwer: Dordrecht, 1990; Chapter 1. (h) Bönnemann, H.; Braun, G.; Brijoux, W.; Brinkmann, R.; Tilling, A. S.; Seevogel, K.; Siepen, K. J. Org. Met. Chem. 1996, 520, 143-162 and the collection of "key publications" cited as refs 2-61 therein.
9. ∼300 nanoclusters discussed herein,
10. (b) Aiken, J. D., III; Lin, Y.; Finke, R. G. J. Mol. Catal. 1996, 114, 29-51.
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21. (j) See also ref 54c cited below.
22. 1f that "perhaps the most irritant in colloid synthesis is irreproducibility". He goes on to note that we really "don't have any idea on how to control particle size through the proper selection of polymers, solvents, precursors, reducing agents, or metal precursors". He concludes that "the true control of particle size remains the most attractive goal for the synthetic chemist in this field".
23. 1g that "the genesis of the formation of distinct large, ligand stabilized clusters is so complex that no reactions can be planned using stoichiometric rules. On the contrary, it is left to chance if larger clusters are formed at all",
24. 20a
25. 6b
26. (b) Briefly, the reason that light scattering is not the method of choice when a distribution of size-nanoclusters is present is that it involves a nonlinear least-squares fit to a multiexponential (i.e., instead of a single exponential) function. Hence, the resulting solution cannot be guaranteed to be the true global minima for the problem. We thank Dr. Jess Wilcoxon, of Sandia National Labs, for his expert assistance with this point.
27. (a) Matijevic, E. Chem. Mater. 1993, 5, 412. Professor Matijevic notes "The ultimate aim in the studies of chemical mechanisms in the precipitations from homogeneous solutions is to develop some general principles, that would make predictable the processes leading to the formation of uniform particles". Another interesting paragraph is "The quantitative explanation of a process by which a huge number of subunits aggregate into identical large particles has not been developed as of yet. It is also not clear why in some instances the final particles are spherical and in others they appear in different geometric forms, yet are of the same chemical composition."
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30. 2, etc.), that "these methods are doomed, however, because the individual reaction steps of seed formation (i.e., nucleation), the growth, and stabilization of the small particles are not well enough understood and, hence, cannot be sufficiently controlled".
31. (a) LaMer, V. K.; Dinegar, R. H. J. Am. Chem. Soc. 1950, 72, 4847.
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34. 3/3r*]) (with the curve maximum (∂AG/∂r = 0) at r*), where r is the nucleus radius, r* is the critical nucleus radius, and a is again the surface tension,
35. (b) Everett, D. H. Basic Principles of Colloid Science; Royal Society of Chemistry: London, 1988; p 56.
36. (a) Turkevich, J.; Stevenson, P. C.; Hillier, J. Faraday Discuss. Chem. Soc. 1951, 11, 55.
37. 2 oxidatively added to a catalyst, respectively). This connection to Turkevich's classic paper is another indicator (see the Discussion) of the significance and broader generality of the mechanistic insights uncovered herein.
38. Alivisatos, A. P.; Harris, A. L.; Levinos, M. L.; Steigerwald, M. L.; Brus, L. E. J. Chem. Phys. 1988, 89, 4001.
39. 13h
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47. 2- on these caytalytic sites". However, the lack of kinetic evidence to support or refute these mechanistic assertions and hence the lack of elementary mechanistic steps to summarize exactly the verbally implied mechanism are probable reasons their implied mechanism has gone virtually unnoticed until resurrected by the kinetic evidence and pseudoelementary mechanistic steps presented herein.
48. (a) Ahmadi, T. S.; Wang, Z. L.; Henglein, A.; El-Sayed, M. A. Chem. Mater. 1996, 8, 1161.
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53. 9
54. 18c in growing particles: (a) Duff, D. G.; Curtis, A. C.; Edwards, P. P.; Jefferson, D. A.; Johnson, B. F. G.; Logan, D. E. Chem. Commun. 1987, 1264. (b) Friedel, J. J. Phys. Chem. 1977, 38, Coll. C2, Supplement 7, C2-1. (c) Van Hardeveld, R.; Hartog, F. Surf. Sci. 1969, 15, 189-230.
55. 18c in growing particles: (a) Duff, D. G.; Curtis, A. C.; Edwards, P. P.; Jefferson, D. A.; Johnson, B. F. G.; Logan, D. E. Chem. Commun. 1987, 1264. (b) Friedel, J. J. Phys. Chem. 1977, 38, Coll. C2, Supplement 7, C2-1. (c) Van Hardeveld, R.; Hartog, F. Surf. Sci. 1969, 15, 189-230.
56. 18c in growing particles: (a) Duff, D. G.; Curtis, A. C.; Edwards, P. P.; Jefferson, D. A.; Johnson, B. F. G.; Logan, D. E. Chem. Commun. 1987, 1264. (b) Friedel, J. J. Phys. Chem. 1977, 38, Coll. C2, Supplement 7, C2-1. (c) Van Hardeveld, R.; Hartog, F. Surf. Sci. 1969, 15, 189-230.
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61. 20a,b
62. (a) The term "magic number" is misleading and thus somewhat controversial. A better term for these clusters is "full-shell" clusters, that is, clusters which possess some extra stability due to their close-packed, full-shell nature, a situation in which each Ir atom therefore has the maximum number of nearest neighbors and thus maximum number of stabilizing, metal-metal bonds,
63. n, but of a different type and for alkali metals (M = Na, K, Cs; n = 2, 8, 20, 40, 58, 92, 138, and so on), plus a good discussion of the difference of these magic numbers from those based on icosahedral or cubo-octahedral structures, is available in Howie, A. Faraday Discuss. 1991, 92, 1-11.
64. 11b
65. We have, however, uncovered a case (Rh(0) nanocluster formation) where diffusion-limited kinetics are seen, including its dramatic effect on the nanocluster size distribution: Aiken, J. D., III; Finke, R. G. J. Am. Chem. Soc. In press.
66. Watzky, M. A.; Finke, R. G. Chem. Mater. 1997 In press.
67. Watzky, M. A.; Finke, R. G. Submitted for publication.
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69. (a) Pohl, M.; Lyon, D. K.; Mizumo, N.; Nomiya, K.; Finke R. G. Inorg. Chem. 1995, 34, 1413.
70. 27c seen as part of the mechanism deduced herein (see Scheme 3) is a well-precedented, meta-stable complex, one which is in fact used in the synthesis of the precursor complex, 1.
71. (c) Sievert, A. C.; Multeities, E. L. Inorg. Chem. 1981, 20, 489.
72. (a) Weiner, H. W.; Aiken, J. D., III; Finke, R. G. Inorg. Chem. 1996, 35, 7905.
73. - causes variable induction periods and hydrogenation rates (typically shorter and faster, respectively).
74. For an introduction to the concept of pseudoelementary reactions, a concept created for and often necessary with the kinetics of more complex systems, see the pioneering work of Professor Richard Noyes: (a) Noyes, R. M.; Field, R. J. Acc. Chem. Res. 1977, 10, 214. (b) Noyes, R. M.; Field, R. J. Acc. Chem. Res. 1977, 10, 273. (c) Field, R. J.; Noyes, R. M. Nature 1972, 237, 390.
75. For an introduction to the concept of pseudoelementary reactions, a concept created for and often necessary with the kinetics of more complex systems, see the pioneering work of Professor Richard Noyes: (a) Noyes, R. M.; Field, R. J. Acc. Chem. Res. 1977, 10, 214. (b) Noyes, R. M.; Field, R. J. Acc. Chem. Res. 1977, 10, 273. (c) Field, R. J.; Noyes, R. M. Nature 1972, 237, 390.
76. For an introduction to the concept of pseudoelementary reactions, a concept created for and often necessary with the kinetics of more complex systems, see the pioneering work of Professor Richard Noyes: (a) Noyes, R. M.; Field, R. J. Acc. Chem. Res. 1977, 10, 214. (b) Noyes, R. M.; Field, R. J. Acc. Chem. Res. 1977, 10, 273. (c) Field, R. J.; Noyes, R. M. Nature 1972, 237, 390.
77. Press, W. H.; Flannery, B. P.; Teukolsky, S. A.; Vetterling, W. T. Numerical Recipes; Cambridge University: Cambridge, 1989.
78. Lyon, D.-K. Ph.D. Dissertation, University of Oregon, 1990; see pp 142-145.
79. 0).
80. 0).
81. 0).
82. 0).
83. 31
84. 34d (a) Steinfeld, J. I.; Fransisco, J. S.; Hase, W. L. Chemical Kinetics and Dynamics; Prentice Hall: NJ, 1989. (b) Heidmann, W.; Decker, P.; Pohlmann, R. Origins of Life 1978, 625-630. (c) Ferrone, F. A.; Hofrichter, J.; Eaton, W. A. J. Mol. Biol. 1985, 183, 611. (d) Grierer, A. Prog. Biophys. Mol. Biol. 1981, 37, 1-47.
85. 34d (a) Steinfeld, J. I.; Fransisco, J. S.; Hase, W. L. Chemical Kinetics and Dynamics; Prentice Hall: NJ, 1989. (b) Heidmann, W.; Decker, P.; Pohlmann, R. Origins of Life 1978, 625-630. (c) Ferrone, F. A.; Hofrichter, J.; Eaton, W. A. J. Mol. Biol. 1985, 183, 611. (d) Grierer, A. Prog. Biophys. Mol. Biol. 1981, 37, 1-47.
86. 34d (a) Steinfeld, J. I.; Fransisco, J. S.; Hase, W. L. Chemical Kinetics and Dynamics; Prentice Hall: NJ, 1989. (b) Heidmann, W.; Decker, P.; Pohlmann, R. Origins of Life 1978, 625-630. (c) Ferrone, F. A.; Hofrichter, J.; Eaton, W. A. J. Mol. Biol. 1985, 183, 611. (d) Grierer, A. Prog. Biophys. Mol. Biol. 1981, 37, 1-47.
87. 34d (a) Steinfeld, J. I.; Fransisco, J. S.; Hase, W. L. Chemical Kinetics and Dynamics; Prentice Hall: NJ, 1989. (b) Heidmann, W.; Decker, P.; Pohlmann, R. Origins of Life 1978, 625-630. (c) Ferrone, F. A.; Hofrichter, J.; Eaton, W. A. J. Mol. Biol. 1985, 183, 611. (d) Grierer, A. Prog. Biophys. Mol. Biol. 1981, 37, 1-47.
88. Lyon, D. K.; Finke, R. G. Inorg. Chem. 1990, 29, 1784.
89. Kaas, R. L. J. Polym. Sci. Polym. Chem. Ed. 1981, 19, 2255.
90. 2 values.
91. 2(fit).
92. 2(hydrogeneration)connected. Note that the scaling factors are different since the GLC method, for example, follows the Ir(0) formation over a different part and fraction of the nanocluster growth than does the hydrogenation method,
93. 20b and also in Figure 11 herein).
94. 2 on the hydrogenation rate (i.e., rather than some intrinsic rate effect due to the metal particle size alone).
95. 20b).
96. 20b).
97. Collman, J. P.; Hegedus, L. S.; Norton, J. R.; Finke, R. G. Principles and Applications of Organotransition Metal Chemistry; University Science Books: Mill Valley, CA, 1987; Chapter 5.
98. 31P NMR, respectively,
99. -4, as the figure below shows.
100. 9- polyoxoanion, or possibly the olefin (cyclohexene), even though this is not specifically shown in Scheme 3.
101. 43c at least in nanocluster formation reactions proceeding by diffusion-controlled pathways,
102. (c) A key paper in the homogeneous, diffusion-controlled nucleation literature: Strey, R.; Wagner, P. E.; Viisanen, Y. J. Phys. Chem. 1994, 98, 7748. We thank Prof D. Johnson, University of Oregon, for bringing this paper to our attention and for his critical commentary on the topic of nucleation.
103. 10 However, we know of no evidence in the nanocluster or colloid literature for such a process, at least to date, although it is an interesting target for future research,
104. (e) Growth at step and kink sites on surfaces: Burton, W. K.; Cabrera, N. Discuss. Faraday Soc. No. 5, 1949, 33-48.
105. See, also classic review: Burton, W. K.; Cabrera, N.; Frank, F. C. Trans. Roy. Soc. (London) 1951, A243, 299-358.
106. x nanoparticles, to aggregate to the thermodynamically favored, low-surface-area, Ir(0)-Ir(0) bonded form (and, ultimately, to bulk Ir(0)). This calculation also teaches that nanocluster and colloid stabilization is, at least to date for transition metal nanoclusters, a totally kinetic phenomenon,
107. 18 accompanying particle growth,
108. 44a is common, see: Conner, J. A. Topics Curr. Chem. 1977, 71, 71, see Table 3, p 78. Pichler, G.; Skinner, H. A. In The Chemistry of the Metal-Carbon Bond; Hartley, F. R., Patai, S., Eds.; John Wiley: New York, 1982; see p 78, Table 13.
109. 44a is common, see: Conner, J. A. Topics Curr. Chem. 1977, 71, 71, see Table 3, p 78. Pichler, G.; Skinner, H. A. In The Chemistry of the Metal-Carbon Bond; Hartley, F. R., Patai, S., Eds.; John Wiley: New York, 1982; see p 78, Table 13.
110. 3CN, at a Pt electrode).
111. growth is thus given by the ratio of the increase in the number of surface atoms divided by the increase in the total number of atoms,
112. growth)/2) vary,
113. growth is close to 0.7.
114. (a) McCarthy, T. J.; Shih, Y.-S.; Whitesides, G. M. Proc. Natl. Acad. Sci. U.S.A. 1981, 78, 4649.
115. (b) Whitesides, G. M.; Hackett, M.; Brainard, R. L.; LaVelleye, J. P.-P.; Sowinski, A. F.; Izumi, A. N.; Moore, S. S.; Brown, D. W.; Staudt, E. M. Organometallics 1985, 4, 1819.
116. (c) Miller, T. M.; Izumi, A. N.; Shih, Y.-S.; Whitesides, G. M. J. Am. Chem. Soc. 1988, 110, 3146.
117. (d) Lee, T. R.; Whitesides, G. M. Acc. Chem. Res. 1992, 25, 266 and references therein to the other papers in this series.
118. n metal. (The coordination number of surface Ir(0) actually varies from 3 to 9.) This calculation also ignores any Ir(0) solvent coordination bond energy that would have to be overcome, and thus would decrease the amount of energy released when the Ir(0) atoms combine.
119. 46
120. 46
121. 46
122. (a) Müller, F.; Aiken, J. D., III; Lyon, D. K.; Finke, R. G. Unpublished results,
123. +-assisted reductive-elimination. This mechanistic finding also bodes well for future catalytic reaction and mechanistic studies using well-defined, relatively stable nanoclusters.
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129. Kiwi, J. Grätzel, M. J. Am. Chem. Soc. 1979, 101, 7214.
130. (a) Bönnemann, H.; Brinkmann, R.; Köppler, R.; Neiteler, P.; Richter, J. Adv. Mater. 1992, 4, 804.
131. 2 (see p 155).
132. 2 as a preferred reducing agent.
133. Rampino, L. D.; Nord, F. F. J. Am. Chem. Soc. 1942, 63, 2745.
134. Henglein, A.; Ershov, B. G.; Malow, M. J. Phys. Chem. 1995, 99, 14129.
135. Toshima, N.; Takahashi, T. Bull. Chem. Soc. Jpn. 1992, 65, 400.
136. Boutonnet, M.; Kizling, J.; Stenius, P.; Maire, G. Colloids Surfaces 1982, 5, 209.
137. Harrison, J. B.; Berkheiser, V. E.; Erdos, G. W. J. Catal. 1988, 112, 126.
138. Yonezawa, T.; Tominaaa, T.; Richard, D. J. Chem. Soc., Dalton Trans. 1996, 783.
139. Vargaftik, M. N.; Zagorodnikov, V. P.; Stolarov, I. P.; Moiseev, I. I.; Kochubey, D. I.; Likholobov, V. A.; Chuvilin, A. L.; Zamaraev, K. I. J. Mol. Catal. 1989, 53, 315.
140. (a) Schmid, G.; Morun, B.; Malm, J.-O. Angew. Chem., Int. Ed. Engl. 1989, 28, 778.
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145. 2 of different metals.
146. 65c (see also the other relevant references provided therein),
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149. + and hydroquinone as the reducing agent,
150. 2. The mechanistic work provided in the present paper suggests that these authors' unproved postulate (p 2018), that the surface growth is on Ni(II), should be replaced by surface growth on Ni(0). In addition, it is unclear if the surface growth is (either Ni(II) or Ni(0)) diffusion limited or autocatalytic.
151. (a) Chen, Y.-J.; Kaesz, H. D.; Thridandam, H.; Hicks, R. F. Appl. Phys. Lett. 1988, 1591.
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153. (c) Klabunde has discussed the nucleation and diffusive-growth stages in metal-atom depositions yielding thin metal films: Davis, S. C.; Klabunde, K. J. Chem. Rev. 1982, 82, 153.