Ligand redistribution reactions of tris(3,5-dimethylpyrazolyl)hydroboratomagnesium alkyl derivatives: crystal structure of {η 3-HB(3,5-Me 2pz) 3} 2Mg

Abstract

Tris(pyrazolyl)hydroboratomagnesium alkyl derivatives {η 3-HB(3,5-Me 2pz) 3}-MgR (3,5-Me 2pz = 3,5-C 3N 2Me 2H; R = CH 3, CH 2CH 3, (CH 2) 3CH 3, CH(CH 3) 2, C(CH 3) 3, CHCH 2, C 6H 5) undergo ligand redistribution reactions, analogous to the Schlenk equilibrium, to give the bis complex {η 3-HB(3,5-Me 2pz) 3} 2Mg. In contrast, magnesium alkyl derivatives of the more sterically demanding tris(3-t-butylpyrazolyl)hydroborato ligand, {η 3-HB(3-Bu tpz) 3}MgR (3-Bu tpz = 3-C 3N 2Bu tH 2), are stable with respect to the formation of {η 3-HB(3-Bu tpz) 3} 2Mg.