Metallaboratranes: Bis- and Tris(methimazolyl)borane Complexes of Group 9 Metal Carbonyls and Thiocarbonyls

Crossley, Ian R, Hill, Anthony F and Willis, Anthony C (2010) Metallaboratranes: Bis- and Tris(methimazolyl)borane Complexes of Group 9 Metal Carbonyls and Thiocarbonyls. Organometallics, 29 (2). pp. 326-336. ISSN 0276-7333

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Abstract

The iridium poly(methimazolyl)borane complexes [IrH(CE)(PPh3){3-B,S,S0-B(mt)2R}](IrfB)8 (mt=methimazolyl=2-mercapto-3-methylimidazol-1-yl; E=O, S; R=mt, H) are described in detail. For R = mt, these materials are elucidated as paradigms for the final mechanistic intermediate in metallaboratrane formation, a role illustrated through hydride abstraction to afford the cationic salts [Ir(CE)(PPh3){4-B(mt)3}]X(IrfB)8 (E=O, S; X=Cl, BF4). The rhodium poly(methimazolyl)borate complexes [Rh(CO)(PPh3){2-S,S0-HB(mt)2R}] (R=mt, H) are also reported. These compounds are obtained in preference to the respective borane complexes (analogous to iridium); however [Rh(CO)- (PPh3){2-S,S0-HB(mt)3}] is observed to undergo facile solution-phase conversion to [Rh(CO)(PPh3)- {4-B,S,S0,S00-B(mt)3}]Cl(RhfB)8 in chlorinated solvents. The ramifications of these results,with respect to metallaboratrane formation, are discussed, substantiating previous mechanistic conjecture. In an attempt to establish an alternative route to iridaboratranes, the first isolable tris(methimazolyl)borate complex of iridium, cis,cis-[IrHCl(PPh3)2{2-S,S0-HB(mt)3], is reported and shown not to evolve to the iridaboratrane [IrCl(PPh3){4-B(mt)3}](IrfB)8 under conditions that lead to the corresponding rhodaboratrane. Factors are discussed that may contribute to this fine balance between the formation of methimazolylborate and methimazolylborane complexes.

Item Type: Article
Schools and Departments: School of Life Sciences > Chemistry
Subjects: Q Science
Depositing User: Ian Crossley
Date Deposited: 06 Feb 2012 19:47
Last Modified: 03 Oct 2012 11:00
URI: http://srodev.sussex.ac.uk/id/eprint/22203
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