ISSN:
1042-7163
Keywords:
Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Regioselective deuteration of 1-X-C2B10H12 (X = 2, 7) cage systems with C6D6/AlCl3 is correlated to ab initio calculational results on a [C2B10H13]+ intermediate. Full geometry optimizations of pertinent [C2B10H13]+ isomers, derived from each of the two 1-X-C2B10H12 carborane isomers, result in cage geometries not unlike the (nearly) icosahedral starting carborane. Each isomer contains a BH2 group having an acute H-B-H angle, long B-H bonds, and a very short H · · · H distance, hinting that the pertinent boron shares the electrons of a hydrogen molecule σ pair. It is suggested that the structural differences between the BH2 group of [C2B10H13]+ and the CH2 group of the benzenium ion, [C6H7]+ (the intermediate strongly intimated upon protonation of benzene), can be explained, in part, by (a) the availability of the π-ring electrons for bonding to the (extra) proton in the latter and (b) the unavailability of π electrons from the carborane. Thus, the C2B10H12 cage is most probably very reluctant to give up a cage electron pair in order to assist in bonding to an (externally bound) proton. Instead, it is more probable that “hydridic” B-H sigma electrons could very well play the important role in providing bonding to the attacking proton. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:95-102, 1998
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
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