摘要：

Tl(acac) reacts quantitatively with B(2)butcat(3) (butcat = 3,5-di-tert-butylcatecholato) to give butcatB(acac) and Tl(Bbutcat(2)) (1), the latter of which is soluble in common organic solvents such as THF and dichloromethane. Addition of 1 to a mixture of [RhCl(coe)(2)](2) (coe = cis-cyclooctene) and diphosphine in THF gave the thallium bridged dinuclear complexes [(P-2)Rh(mu-Cl)(2)(mu-Tl)Rh(P-2)][Bbutcat(2)] (2-5, P-2 is dppm = 1,1'-bis(diphenylphosphino)methane, dppe = 1,2-bis(diphenylphosphino)ethane, dppp = 1,3-bis(diphenylphosphino)propane and dppb = 1,4-bis(diphenylphosphino)butane) as the only new rhodium containing species. Unsymmetrical binding of the thallium atom is observed in some cases owing to a secondary interaction with the phenyl rings of the phosphine ligands. Mononuclear cationic species of the type [(P-2)Rh(NCCH3)(2)][Bbutcat(2)] (6-9) were formed when reactions were carried out in acetonitrile, where preferential binding of the solvent was observed over the bulky arylspiroborate ligand. The zwitterionic species Rh(eta(6)-butcatBbutcat)(P-2), 11 and 12, could be generated via a different route, by addition of B(2)butcat(3) to Rh(acac)(P-2), but only for the sterically-constrained diphosphines dppm and dppe, respectively. While all new complexes effectively catalyzed the addition of catecholborane to 4-vinylanisole and alpha-methylstyrene, product distributions suffered from a competing dehydrogenative borylation pathway. (C) 2012 Elsevier Ltd. All rights reserved.

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