Reactions of icosahedral carborones with iminotris(dimethylamino) phosphorane HNP(NMe2)3: A deboronation intermediate nido-C2B10H12·N(H)P(NMe 2)3, deboronation reactions and hydrogen-bonded closo-carborane systems

Abstract

Reactions between the icosahedral carboranes 1,2-C2B 10H12 (1), 1,7-C2B10H12 (2) and 1,12-C2B10H12 (3) and the iminophosphorane HNP(NMe2)3 (4) are described that have afforded a variety of products whose structures have been characterised by X-ray diffraction. They include the adduct between (1) and (4), C2B 10H12·HNP(NMe2)3 (5) the 12-atom 14-skeletal pair supra-icosahedral nido structure of which illustrates an early step in the deboronation of ortho-carborane (1) by Lewis Bases, and the C-H⋯N hydrogen-bonded adducts of meta- and para-carborane with the iminophosphorane, [1,7-C2B10H12⋯ HNP(NMe2)3]n and 1,12-C2B 10H12·2HNP(NMe2)3. The iminophosphorane (4) readily converts ortho-carborane (1) into the nido anion [7,8-C2B9H12]- and less readily meta-carborane (2) into the nido-anion [7,9-C2B9H 12]-, which have been isolated from solution as salts of the cations [H2NP(NMe2)3]+ or [{(Me2N)3PN}2BNHP(NMe2) 3]+, the latter evidently incorporating a boron atom removed from the carborane cage. Adventitious presence of water in the attempted recrystallization of [{(Me2N)3PN} 2BNHP(NMe2)3]+ [7,8-C 2B9H12]- led to a salt of the cation [{(Me2N)3PNBN(H)P(NMe2)3} 2O]2+. Other unexpected products isolated from reactions carried out under moist air included the salt [H2NP(NMe 2)3+]2[CO32-]·2B(OH)3 (from the reaction between 2 and 4) and the salt 1,12-C2B10H12·2H2NP (NMe2)3+HCO3- (from the reaction between 3 and 4). © 2006 Springer Science+Business Media, Inc.