Organometallic Tantalum Tris(methimazolyl)borato Complexes: [Ta(η2-RC⋮CR)Cl2{HB(mt)3}] (R = Ph, Et; mt = methimazolyl)

The reactions of Na[HB(mt) 3 ] (mt = methimazolyl) with [Ta(η 2 -RC⋮CR)Cl 3 (dme)] (R = Ph, Et) provide the structurally characterized complexes [Ta(η 2 -RC⋮CR)Cl 2 {HB(mt) 3 }], the first examples of organometallic tris(methimazolyl)borato derivatives of group 5. The intrinsic chirality of the HB(mt) 3 ligand is expressed in a skewing of the alkyne orientation.