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Recent Studies of Group 14 Derivatives of Small nido ‐Boranes
Author(s) -
Barton Lawrence,
Fang Hong,
Srivastava Dileep K.,
Schweitzer Tracy A.,
Rath Nigam P.
Publication year - 1996
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/(sici)1099-0739(199604)10:3/4<183::aid-aoc465>3.0.co;2-e
Subject(s) - chemistry , boranes , substituent , crystal structure , borane , stereochemistry , nuclear magnetic resonance spectroscopy , nmr spectra database , crystallography , medicinal chemistry , organic chemistry , catalysis , spectral line , boron , physics , astronomy
This article briefly reviews this area, describes some of our own recent work and also presents some new data. The preparation and characterization of a series of triphenyltin‐substituted penta‐ and hexaboranes is described. The species 1‐(SnPh 3 )B 5 H 8 (1) and 2,3‐μ‐(SnPh 3 )B 5 H 8 (3) are prepared from SnPh 3 Cl and K[B 5 H 8 ] by careful selection of solvent and conditions, and the intermediacy of 2‐(SnPh 3 )B 5 H 8 (2), in the formation of 1 from 3, was demonstrated by NMR spectroscopy. The species 1, 2 and 3 were characterized by 11 B, 1 H and 119 Sn NMR spectra and 11 B– 119 Sn coupling was observed for the first time in a polyhedral borane. Crystal structures were determined for 3 and the chloro‐derivative of 1, 1‐(SnClPh 2 )B 5 H 8 (4). Using similar techniques, three of the six possible linkage isomers of SnPh 2 (B 5 H 8 ) 2 namely μ,μ‐SnPh 2 (B 5 H 8 ) 2 (10), μ,2‐SnPh 2 (B 5 H 8 ) 2 (11) and μ,1‐SnPh 2 (B 5 H 8 ) 2 (12) were isolated and completely characterized including crystal structure determinations. The use of non‐basic solvents such as CH 2 Cl 2 allows the isolation of the bridging species 3 and 10 whereas basic solvents such as Et 2 O or THF catalyse the rearrangement to species with the substituent in the 1‐position, namely the 1 and 12 isomers. Isomer 11 is prepared by carrying out reactions in EtO 2 and 12 is also prepared by the reaction between 4 and K[B 5 H 8 ] in CH 2 Cl 2 . The hexaborane derivatives 2,3‐μ‐(SnPh 3 )B 6 H 9 , 2,3‐μ‐(SnMe 3 )B 6 H 9 and 2,3‐μ‐(SiPh 3 )B 6 H 9 were also prepared and characterized although all three species were too unstable to afford crystals suitable for X‐ray analysis. Finally, attempts to prepare pentaboranyl derivatives containing two SnPh 3 substituents provided evidence for the formation of μ,1‐(SnPh 3 ) 2 B 5 H 7 and 1,2‐(SnPh 3 ) 2 B 5 H 7 .