Synthesis and crystal structures of dinuclear zinc complexes with the 1,3-bis(2-pyridylmethyl)acetamidinato ligand

The reaction of an equimolar mixture of N,N′-bis(2-pyridylmethyl)acetamidine (1) and di(tert-butyl)phosphane with dimethylzinc yields dinuclear bis(methylzinc) bis(2-pyridylmethyl)acetamidinate di(tert-butyl)phosphanide (2). A similar protocol allows the preparation of bis(alkylzinc) bis(2-pyridylmethyl)acetamidinate tert-butylamide [zinc-bound methyl (3) or trimethylsilylmethyl group (4)]. The reactions of 3 and 4 with diphenylsilane lead to the formation of insoluble dimeric bis(alkylzinc) N,N′-bis(2-pyridylmethyl)acetamidinate hydrides [zinc-bound methyl (5) or trimethylsilylmethyl group (6)]. These zinc hydrides decompose once dissolved under formation of elemental zinc thus hampering catalytic applications. Molecular structures of [(1)ZnCl2] as well as of the zinc complexes 2 to 6 are discussed.