Hexacoordinated carbon or tetracovalent silicon?

Chirality

Volumn 10, Issue 1-2, 1998, Pages 180-189

  Schiemenz, G P ^a   Schiemenz, B ^a   Petersen, S ^a   Wolff, C ^a  

^a UNIVERSITY OF KIEL   (Germany)

Author keywords

Hypercoordinate silicon in naphthylsilanes; NMR spectra; Reinterpretation; X ray structures

Indexed keywords

CARBON; METHANOL DERIVATIVE; SILANE DERIVATIVE; SILICON;

ARTICLE; CHEMICAL STRUCTURE; CHIRALITY; MOLECULAR INTERACTION; NUCLEAR MAGNETIC RESONANCE; PRIORITY JOURNAL; X RAY ANALYSIS;

EID: 0031882590     PISSN: 08990042     EISSN: None     Source Type: Journal    
DOI: 10.1002/chir.28     Document Type: Article

References (83)

1. cf., e.g., Timosheva, N.V., Prakasha, T.K., Chandrasekaran, A., Day, R.O., Holmes, R.R. Sulfur-induced pentacoordination in cyclic silanes. Inorg. Chem. 35:3614-3621, 1996. "The results . . . suggest that the attainment of hypervalency through donor action may be a more common feature of silane chemistry than previously thought."
2. 2N-group, the positional number 8 is used throughout, even where this is at variance with IUPAC nomenclature (cf. Scheme 1).
3. 11,12; c) heptacoordinate Si: Brelière, C., Carré, F., Corriu, R.J.P., Royo, G., Wong Chi Man, M., Lapasset, J. Possibility of heptacoordination at silicon: synthesis and X-ray crystal structures of tris[8-(dimethylamino)naphthyl]silane and tris[2-((dimethylamino)methyl)phenyl]fluorosilane. Organometallics 13: 307-314, 1994. octacoordinate Si: Carré, F., Chuit, C., Corriu, R.J.P., Mehdi, A., Reyé, C. Struktur eines Vorläufermoleküls mit (4 + 4)fach koordiniertem Silicium für hyperkoordinierte Silylmono- und -dikationen. Angew. Chem. 106:1152-1154. 1994 (Angew. Chem. Int. Ed. Engl. 33:1097-1099, 1994).
4. 11,12; c) heptacoordinate Si: Brelière, C., Carré, F., Corriu, R.J.P., Royo, G., Wong Chi Man, M., Lapasset, J. Possibility of heptacoordination at silicon: synthesis and X-ray crystal structures of tris[8-(dimethylamino)naphthyl]silane and tris[2-((dimethylamino)methyl)phenyl]fluorosilane. Organometallics 13: 307-314, 1994. octacoordinate Si: Carré, F., Chuit, C., Corriu, R.J.P., Mehdi, A., Reyé, C. Struktur eines Vorläufermoleküls mit (4 + 4)fach koordiniertem Silicium für hyperkoordinierte Silylmono- und -dikationen. Angew. Chem. 106:1152-1154. 1994 (Angew. Chem. Int. Ed. Engl. 33:1097-1099, 1994).
5. 11,12; c) heptacoordinate Si: Brelière, C., Carré, F., Corriu, R.J.P., Royo, G., Wong Chi Man, M., Lapasset, J. Possibility of heptacoordination at silicon: synthesis and X-ray crystal structures of tris[8-(dimethylamino)naphthyl]silane and tris[2-((dimethylamino)methyl)phenyl]fluorosilane. Organometallics 13: 307-314, 1994. octacoordinate Si: Carré, F., Chuit, C., Corriu, R.J.P., Mehdi, A., Reyé, C. Struktur eines Vorläufermoleküls mit (4 + 4)fach koordiniertem Silicium für hyperkoordinierte Silylmono- und -dikationen. Angew. Chem. 106:1152-1154. 1994 (Angew. Chem. Int. Ed. Engl. 33:1097-1099, 1994).
6. 11,12; c) heptacoordinate Si: Brelière, C., Carré, F., Corriu, R.J.P., Royo, G., Wong Chi Man, M., Lapasset, J. Possibility of heptacoordination at silicon: synthesis and X-ray crystal structures of tris[8-(dimethylamino)naphthyl]silane and tris[2-((dimethylamino)methyl)phenyl]fluorosilane. Organometallics 13: 307-314, 1994. d) octacoordinate Si: Carré, F., Chuit, C., Corriu, R.J.P., Mehdi, A., Reyé, C. Struktur eines Vorläufermoleküls mit (4 + 4)fach koordiniertem Silicium für hyperkoordinierte Silylmono- und -dikationen. Angew. Chem. 106:1152-1154. 1994 (Angew. Chem. Int. Ed. Engl. 33:1097-1099, 1994).
7. 11,12; c) heptacoordinate Si: Brelière, C., Carré, F., Corriu, R.J.P., Royo, G., Wong Chi Man, M., Lapasset, J. Possibility of heptacoordination at silicon: synthesis and X-ray crystal structures of tris[8-(dimethylamino)naphthyl]silane and tris[2-((dimethylamino)methyl)phenyl]fluorosilane. Organometallics 13: 307-314, 1994. octacoordinate Si: Carré, F., Chuit, C., Corriu, R.J.P., Mehdi, A., Reyé, C. Struktur eines Vorläufermoleküls mit (4 + 4)fach koordiniertem Silicium für hyperkoordinierte Silylmono- und -dikationen. Angew. Chem. 106:1152-1154. 1994 (Angew. Chem. Int. Ed. Engl. 33:1097-1099, 1994).
8. 4-n (A, n = 2) "suggests that the coordination number 8 is the upper limit for silicon in molecular compounds." We are unable to see how this structure of A (n = 2) permits a prediction that in A (n = 3), the coordination number 10 will be impossible.
9. cf., e.g., Hellwinkel, D. at-Komplexe mit sechsbindigem. Phosphor. Chem. Berichte. 98:576-587, 1965, and later papers.
10. In phosphoranes with a DAN group, even a sixth bond is not formed: Hellwinkel, D., Lindner, W., Wilfinger, H.-J. Zur Stabilisierung der trigonal-bipyramidalen Grundzustände spirocyclischer Pentaorganylphosphorane und-arsorane. Chem. Berichte. 107:1428-1443, 1974.
11. e.g., Boyer, J., Breliere, C., Corriu, R.J.P., Kpoton, A., Poirier, M., Royo, G. Enhancement of Si-H bond reactivity in pentacoordinated structures. J. Organomet. Chem. 311:C39-C43, 1986; Corriu, R.J.P. Hypervalent species of silicon: structure and reactivity. J. Organomet. Chem. 400:81-106, 1990.
12. e.g., Boyer, J., Breliere, C., Corriu, R.J.P., Kpoton, A., Poirier, M., Royo, G. Enhancement of Si-H bond reactivity in pentacoordinated structures. J. Organomet. Chem. 311:C39-C43, 1986; Corriu, R.J.P. Hypervalent species of silicon: structure and reactivity. J. Organomet. Chem. 400:81-106, 1990.
13. a) heptacoordinate Ge: Brelière, C., Carré, F., Corriu, R.J.P., Royo, G. Synthesis and structure of hypervalent species of silicon and germanium: toward heptacoordination? Organometallics 7:1006-1008, 1988;
14. Sn)-[8-(dimethylamino)naphthyl]-(-)-menthylmethyltin bromide. Organometallics 12:3051-3063, 1993 ("a substantial bonding interaction");
15. Sn)-[8-(dimethylamino)naphthyl]-(-)-menthylmethyltin bromide. Organometallics 12:3051-3063, 1993 ("a substantial bonding interaction");
16. c) hexacoordination: Jastrzebski, J.T.B.H., van der Schaaf, P.A., Boersma, J., van Koten, G., de Wit, M., Wang, Y., Heijdenrijk, D., Stam, C.H. Oxidative-addition reactions of molecular diiodine and dibromine to divalent organotin compounds. Crystal structures of bis[8-(dimethylamino)-1-naphthyl]tin(IV) dibromide and {2,6-[bis(dimethylamino)methyl]phenyl}(4-tolyl)tin(IV) diodide. J. Organomet. Chem. 407:301-311, 1991; Jastrzebski, J.T.B.H., van der Schaaf, P.A., Boersma, J., van Koten, G., de Ridder, D.J.A., Heijdenrijk, D. Evidence for hexacoordinate tin centers in triorganotin halides containing two 8-(dimethylamino)-1-naphthyl ligands. Organometallics 11:1521-1526, 1992;
17. c) hexacoordination: Jastrzebski, J.T.B.H., van der Schaaf, P.A., Boersma, J., van Koten, G., de Wit, M., Wang, Y., Heijdenrijk, D., Stam, C.H. Oxidative-addition reactions of molecular diiodine and dibromine to divalent organotin compounds. Crystal structures of bis[8-(dimethylamino)-1-naphthyl]tin(IV) dibromide and {2,6-[bis(dimethylamino)methyl]phenyl}(4-tolyl)tin(IV) diodide. J. Organomet. Chem. 407:301-311, 1991; Jastrzebski, J.T.B.H., van der Schaaf, P.A., Boersma, J., van Koten, G., de Ridder, D.J.A., Heijdenrijk, D. Evidence for hexacoordinate tin centers in triorganotin halides containing two 8-(dimethylamino)-1-naphthyl ligands. Organometallics 11:1521-1526, 1992;
18. d) heptacoordination: Dostal, S., Stoudt, S.J., Fanwick, P., Sereatan, W.F., Kahr, B., Jackson, J.E. Correlation of structure and internal dynamics for (Tris(2,6-dimethoxyphenyl) methyl) tin trihalides: a homologous series of seven-coordinate tin compounds. Organometallics 12:2284-2291, 1993.
19. 30b, pp. 111-113.
20. cf. Ogilvie, J.F. The nature of the chemical bond, 1990. There are no such things as orbitals! J. Chem. Educ. 67:280-289, 1990.
21. This must be discriminated from Olah's hypervalent carbon, which is due to nucleophilic rather than electrophilic properties of carbon; cf., e.g., Olah, G.A. Meine suche nach carbokationen und deren bedeutung in der chemie (nobel-vortrag). Angew. Chem. 107:1519-1532, 1995 (Int. Ed. Engl. 34:1393, 1995).
22. This must be discriminated from Olah's hypervalent carbon, which is due to nucleophilic rather than electrophilic properties of carbon; cf., e.g., Olah, G.A. Meine suche nach carbokationen und deren bedeutung in der chemie (nobel-vortrag). Angew. Chem. 107:1519-1532, 1995 (Int. Ed. Engl. 34:1393, 1995).
23. Brelière, C., Carré, F., Corriu, R.J.P., Poirier, M., Rojo, G., Zwecker, J. Hexacoordinated silicon species: a possible model for reaction intermediates. 1. X-ray determination of the geometry in the solid state. Organometallics 8:1831-1833, 1989.
24. Brelière, C., Corriu, R.J.P., Rojo, G., Zwecker, J. Hexacoordinate silicon species: a possible model for reaction intermediates. 2. Nondissociative permutational isomerization in solution. Organometallics 8: 1834-1836, 1989.
25. Horner, L., Simons, G. Phosphororganische Verbindungen, 102. Tertiäre Phosphine mit o-Dialkylaminophenyl- und ortho-Dialkylaminobenzylgruppen. Phosphorus Sulfur 15:165-175, 1983; Narasimham, N.S., Chandrachood, S.P., Chandrachood, P.S., Barve, M.V. Mechanism of aromatic lithiation reactions: importance of steric factors. Proc. Ind. Acad. Sci., Chem. Sci. 93:625-634, 1984 (C.A. 101: 91016c, 1984) (modified procedure).
26. Horner, L., Simons, G. Phosphororganische Verbindungen, 102. Tertiäre Phosphine mit o-Dialkylaminophenyl- und ortho-Dialkylaminobenzylgruppen. Phosphorus Sulfur 15:165-175, 1983; Narasimham, N.S., Chandrachood, S.P., Chandrachood, P.S., Barve, M.V. Mechanism of aromatic lithiation reactions: importance of steric factors. Proc. Ind. Acad. Sci., Chem. Sci. 93:625-634, 1984 (C.A. 101: 91016c, 1984) (modified procedure).
27. Horner, L., Simons, G. Phosphororganische Verbindungen, 102. Tertiäre Phosphine mit o-Dialkylaminophenyl- und ortho-Dialkylaminobenzylgruppen. Phosphorus Sulfur 15:165-175, 1983; Narasimham, N.S., Chandrachood, S.P., Chandrachood, P.S., Barve, M.V. Mechanism of aromatic lithiation reactions: importance of steric factors. Proc. Ind. Acad. Sci., Chem. Sci. 93:625-634, 1984 (C.A. 101: 91016c, 1984) (modified procedure).
28. Sheldrick, G.M., SHELX76, University of Cambridge: 1976: Sheldrick, G.M., SHELXTL PLUS, Universität Göttingen: 1988.
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31. 14N NQR studies of 1,8-bis(dimethylamino) naphthalene. J. Chem. Soc. Faraday Trans. 91: 3925-3932, 1995. In view of the figures for 4, it is doubtful whether this "elongation" is a response to steric crowding, which, in addition, is not evident in the bond angles around C(1) and C(8) (see below, Table 1). However, in order to remain on the safe side, the data of 7 have not been used. With d(C(1)-C(9)/C(8)-C(9)) = 144.7 pm (Wozniak et al.) rather than 142.5 pm, the "ideal distance" between equal perisubstituents is calculated as 250.6 pm, for N-C as 250.9 pm, and for N-Si as 255.0 pm. These values would change some figures in Table 1. but not the quality of the arguments.
32. 14N NQR studies of 1,8-bis(dimethylamino) naphthalene. J. Chem. Soc. Faraday Trans. 91: 3925-3932, 1995. In view of the figures for 4, it is doubtful whether this "elongation" is a response to steric crowding, which, in addition, is not evident in the bond angles around C(1) and C(8) (see below, Table 1). However, in order to remain on the safe side, the data of 7 have not been used. With d(C(1)-C(9)/C(8)-C(9)) = 144.7 pm (Wozniak et al.) rather than 142.5 pm, the "ideal distance" between equal perisubstituents is calculated as 250.6 pm, for N-C as 250.9 pm, and for N-Si as 255.0 pm. These values would change some figures in Table 1. but not the quality of the arguments.
33. 14N NQR studies of 1,8-bis(dimethylamino) naphthalene. J. Chem. Soc. Faraday Trans. 91: 3925-3932, 1995. In view of the figures for 4, it is doubtful whether this "elongation" is a response to steric crowding, which, in addition, is not evident in the bond angles around C(1) and C(8) (see below, Table 1). However, in order to remain on the safe side, the data of 7 have not been used. With d(C(1)-C(9)/C(8)-C(9)) = 144.7 pm (Wozniak et al.) rather than 142.5 pm, the "ideal distance" between equal perisubstituents is calculated as 250.6 pm, for N-C as 250.9 pm, and for N-Si as 255.0 pm. These values would change some figures in Table 1. but not the quality of the arguments.
34. Bondi, A. van der Waals. Volumes and radii. J. Phys. Chem. 68:441-451, 1964.
35. Glidewell, C., Sheldrick, G.M. Crystal and molecular structure of tetraphenylsilane. J. Chem. Soc. A 1971:3127-3129. cf. the similar value of 192.5 pm in a naphthylsilicate anion with pentacoordinate silicon, Harland, J.J., Payne, J.S., Day, R.O., Holmes, R.R. Steric hindrance in pentacoordinated fluorosilicates. Synthesis and molecular structure of the diphenyl-1-naphthyldifluorosilicate anion and the phenylmethyltrifluorosilicate anion. Inorg. Chem. 26:760-765, 1987.
36. Glidewell, C., Sheldrick, G.M. Crystal and molecular structure of tetraphenylsilane. J. Chem. Soc. A 1971:3127-3129. cf. the similar value of 192.5 pm in a naphthylsilicate anion with pentacoordinate silicon, Harland, J.J., Payne, J.S., Day, R.O., Holmes, R.R. Steric hindrance in pentacoordinated fluorosilicates. Synthesis and molecular structure of the diphenyl-1-naphthyldifluorosilicate anion and the phenylmethyltrifluorosilicate anion. Inorg. Chem. 26:760-765, 1987.
37. Lister, D.G., Tyler, J.K., Høg, J.H., Larsen, N.W. The microwave spectrum, structure and dipole moment of aniline. J. Mol. Struct. 23:253-264, 1974.
38. Delugeard, Y., Messager, J.C. Structure cristalline et moléculaire de la m-nitro N,N-diméthyl aniline. Acta Cryst. B 31:2809-2812, 1975. The angles N-C(1)-C(2) (122.3°) and N-C(1)-C(6) (120.0°) are different and the former significantly >120°. This deviation from ideal behaviour in an unstrained molecule once more testifies to the limited value of bond angle considerations.
39. cf. Schweizer, W.B., Procter, G., Kaftory, M., Dunitz, J.D. Structural studies of 1,8-disubstituted naphthalenes as probes for nucleophile-electrophile interactions. Helv. Chim. Acta 61:2783-2808, 1978.
40. 17
41. Ehrlich, H.W.W. A refinement of the crystal and molecular structure of acenaphthene. Acta Cryst. 10:699-705, 1957.
42. Accidentally, the former two angles are close to the tetrahedral angle (109.5°), even a little smaller. The fact calls for caution in drawing conclusions from bond angles concerning hybridization. In the discussion of distorted trigonal or tetragonal bipyramids as "evidence" for penta- and hexacoordination, this point is generally neglected.
43. - intramolecular hydrogen bonds in the complex of 1,8-bis(dimethylamino)naphthalene with 1,8-bis(4-toluenesulphonamido)-2,4,5,7-tetranitronaphthalene. J. Mol. Struct. 221:227-238, 1990.
44. Grech, E., Nowicka-Scheibe, J., Olejnik, Z., Lis, T., Pawelka, Z., Malarski, Z., Sobczyk, L. An IR, NMR, dipole moment and x-ray study on intramolecular O-H ⋯ N hydrogen bonding in 8-hydroxy-N,N-dimethyl-1-naphthylamine. J. Chem. Soc. Perkin Trans. II:343-348, 1996.
45. 13C-NMR data strongly support this caveat; see below.
46. 55; Bayler, A., Schier, A., Bowmaker, G.A., Schmidbaur, H. Gold is smaller than silver. Crystal structures of [bis(trimesitylphosphine)gold(I)] and [bis(trimesitylphosphine) silver(I)] tetrafluoroborate. J. Am. Chem. Soc. 118: 7006-7007, 1996.
47. 55; Bayler, A., Schier, A., Bowmaker, G.A., Schmidbaur, H. Gold is smaller than silver. Crystal structures of [bis(trimesitylphosphine)gold(I)] and [bis(trimesitylphosphine) silver(I)] tetrafluoroborate. J. Am. Chem. Soc. 118: 7006-7007, 1996.
48. 11, note 14), von Schnering, H.G. (not J.; ibid.) Die Kristall- und Molekülstruktur von 1,1,2,2-Tetrachlor-1,2-dimethyldisilan-2,2′-Bipyridyl. Chem. Berichte. 109:3728-3734, 1976.
49. 11, note 14), von Schnering, H.G. (not J.; ibid.) Die Kristall- und Molekülstruktur von 1,1,2,2-Tetrachlor-1,2-dimethyldisilan-2,2′-Bipyridyl. Chem. Berichte. 109:3728-3734, 1976.
50. 11, note 14), von Schnering, H.G. (not J.; ibid.) Die Kristall- und Molekülstruktur von 1,1,2,2-Tetrachlor-1,2-dimethyldisilan-2,2′-Bipyridyl. Chem. Berichte. 109:3728-3734, 1976.
51. 11, note 14), von Schnering, H.G. (not J.; ibid.) Die Kristall- und Molekülstruktur von 1,1,2,2-Tetrachlor-1,2-dimethyldisilan-2,2′-Bipyridyl. Chem. Berichte. 109:3728-3734, 1976.
52. Brelière, C., Carré, F., Corriu, R.J.P., Poirier, M., Rojo, G. Pentacoordinated silicon hydrides: very high affinity of the Si-HH bond for the equatorial position. Organometallics 5:388-390, 1986.
53. Boyer, J., Brelière, C., Carré, F., Corriu, R.J.P., Kpoton, A., Poirier, M., Rojo, G., Young, J.C. Five-co-ordinated silicon compounds: geometry of formation by intramolecular co-ordination. Crystal structure of 2-(dimethylaminomethyl)phenyl-1-naphthylsilane. J. Chem. Soc. Dalton Trans. 43-51, 1989.
54. 30a p. 1253.
55. 30a, p. 1252, the pertinent formula 37 is in error: The compound is a DAN-silane, not a quinoline derivative (37 ought to be a cation rather than a neutral species).
56. The interesting fact that in 11, 12, the dimethylaminomethyl side chain adopts a cisoid arrangement, is not pertinent for the DAN series and will be discussed elsewhere.
57. Lang, H., Weinmann, M., Frosch, W., Büchner, M., Schiemenz, B. Novel inter- and intra-molecular donor-stabilized 1-metalla-2-sila-1,3-dienes. J. Chem. Soc. Chem. Commun. 1299-1300, 1996.
58. 5; Schiemenz, G.P. Ionen 6. Das Tetraphenyloborat-ion als Kernresonanz-Verschiebungsreagens bei Anilinium-Kationen. Org. Magn. Res. 5:257-261, 1973; Schiemenz, G.P. Ionen 8. Das Tetraphenyloborat-ion als Kernresonanz-verschiebungsreagens bei quartären Ammonium-Kationen. Tetrahedron 29:741-745, 1973.
59. 5; Schiemenz, G.P. Ionen 6. Das Tetraphenyloborat-ion als Kernresonanz-Verschiebungsreagens bei Anilinium-Kationen. Org. Magn. Res. 5:257-261, 1973; Schiemenz, G.P. Ionen 8. Das Tetraphenyloborat-ion als Kernresonanz-verschiebungsreagens bei quartären Ammonium-Kationen. Tetrahedron 29:741-745, 1973.
60. Schiemenz, G.P., Papageorgiou, E. Ionen, 12. Ionenpaarassoziation als Hilfsmittel bei der Strukturbestimmung. Phosphorus Sulfur 13:41-58, 1982.
61. 3 H-atoms.
62. 11 p. 1832, no relative intensity given.
63. 38), at that time being unaware of the corresponding IUPAC rule, which is consistently followed by Chemical Abstracts (cf., e.g., Chuit, C., Corriu, R.J.P., Monforte, P., Reyé, C., Declercq, J.-P., Dubourg, A. Die Strukturen von Tris(8-dimethylamino-1-napththyDphosphan und Tris[2-(dimethylamino-methyl)phenyl]phosphan: der kristallographische Nachweis von siebenfach koordiniertem Phosphor. Angew. Chem. 105:1529-1531, 1993 (Int. Ed. Engl. 32:1430-1432, 1993) (. . . phosphane), C.A. 120:77344u, 1994 (. . . phosphine)).
64. 38), at that time being unaware of the corresponding IUPAC rule, which is consistently followed by Chemical Abstracts (cf., e.g., Chuit, C., Corriu, R.J.P., Monforte, P., Reyé, C., Declercq, J.-P., Dubourg, A. Die Strukturen von Tris(8-dimethylamino-1-napththyDphosphan und Tris[2-(dimethylamino-methyl)phenyl]phosphan: der kristallographische Nachweis von siebenfach koordiniertem Phosphor. Angew. Chem. 105:1529-1531, 1993 (Int. Ed. Engl. 32:1430-1432, 1993) (. . . phosphane), C.A. 120:77344u, 1994 (. . . phosphine)).
65. 38), at that time being unaware of the corresponding IUPAC rule, which is consistently followed by Chemical Abstracts (cf., e.g., Chuit, C., Corriu, R.J.P., Monforte, P., Reyé, C., Declercq, J.-P., Dubourg, A. Die Strukturen von Tris(8-dimethylamino-1-napththyDphosphan und Tris[2-(dimethylamino-methyl)phenyl]phosphan: der kristallographische Nachweis von siebenfach koordiniertem Phosphor. Angew. Chem. 105:1529-1531, 1993 (Int. Ed. Engl. 32:1430-1432, 1993) (. . . phosphane), C.A. 120:77344u, 1994 (. . . phosphine)).
66. 38), at that time being unaware of the corresponding IUPAC rule, which is consistently followed by Chemical Abstracts (cf., e.g., Chuit, C., Corriu, R.J.P., Monforte, P., Reyé, C., Declercq, J.-P., Dubourg, A. Die Strukturen von Tris(8-dimethylamino-1-napththyDphosphan und Tris[2-(dimethylamino-methyl)phenyl]phosphan: der kristallographische Nachweis von siebenfach koordiniertem Phosphor. Angew. Chem. 105:1529-1531, 1993 (Int. Ed. Engl. 32:1430-1432, 1993) (. . . phosphane), C.A. 120:77344u, 1994 (. . . phosphine)).
67. 31 NMR data. Topics Phosphorus Chem. 5:227-457, 1967.
68. 29Si chemical shifts as a probe for molecular and electronic structure. J. Mol. Struct. 313/Theochem. 119:91-109, 1994) need not be discussed here, because it is devoted to cations rather than to neutral species.
69. Only an unsubstituted α-naphthyl group.
70. 2N-group cannot (and actually does not) adopt the conformation coplanar with the π-system, which is a prerequisite for such an effect. In addition, note that the peri positions, unlike the 1,4-positions in benzene, are not "positions of through-conjugation."
71. 13C-NMR-Spektroskopie. Stuttgart: Thieme, 1984, pp. 168-177.
72. 13C-NMR-Spektroskopie. Stuttgart: Thieme, 1984, pp. 168-177.
73. 13C NMR Spectroscopy. Weinheim: Verlag Chemie, 1974, pp. 156, 224.
74. The same argument has recently been used by Merckling, F.A., Rüedi, P. Diastereoselectivity in nucleophilic displacement reactions at phosphorus; isolation and characterization of a pentacoordinated intermediate. Tetrahedron Lett. 37:2217-2220, 1996, to elucidate the structure of a compound with pentacoordinate phosphorus.
75. 5
76. 5
77. cf. Mislow, K., Raban, M. Stereoisomeric relationships of groups in molecules. Topics Stereochem. 1:1-38, 1967.
78. cf. Shvo, Y., Taylor, E.C., Mislow, K., Raban, M. Chemical shift nonequivalence of diastereotopic protons due to restricted rotation around aryl-nitrogen bonds in substituted amides. J. Am. Chem. Soc. 89:4910-4917, 1967, note 7.
79. Hesse, M., Meier, H., Zeeh, B. Spektroskopische Methoden in der organischen Chemie, 4th ed. Stuttgart: Thieme, 1991, p. 96.
80. 41: Crystallographic proof of heptacoordinated phosphorus.
81. Qiao, X., Padula, M.A., Ho, D.M., Vogelaar, N.J., Schutt, C.E., Pascal, R.A., Jr. Octaphenylnaphthalene and decaphenylanthracene. J. Am. Chem. Soc. 118:741-745, 1996.
82. Batsanov, S.S. Van der Waals radii of elements from the data of structural inorganic chemistry. Izvest. Akad. Nauk, Ser. Khim., 24-29, 1995, Russian Chem. Bull. 44:18-23, 1995.
83. Batsanov, S.S. Van der Waals radii of elements from the data of structural inorganic chemistry. Izvest. Akad. Nauk, Ser. Khim., 24-29, 1995, Russian Chem. Bull. 44:18-23, 1995.