Solvent-dependent assembly of mixed-metal N,N′-diphenylbenzamidinate oxide and alkoxide complexes

Abstract

The sequential reaction of ZnMe₂ with N,N′-diphenylbenzamidine (= HAm 10), LiBu^t and molecular oxygen affords various lithium triorganozincate species, the identity of which depend upon the solvent conditions used. In the presence of THF, the isolated product is a dimer [THF·Li(Me)OZnAm₂]₂  12, wherein oxygen has formally inserted into the Zn–C bond of a MeZnAm₂⁻ anion. Compound 12 is based on a (ZnO)₂ ring core with exocyclic alkali metal centres. In the absence of donor solvent, crystals are obtained of both the pseudo-octahedral oxide-encapsulation complex (μ₆-O)(Li₂ZnAm₃)₂  13 and the heterobimetallic alkoxide polymer [(LiOBu^t)(MeZnOBu^t)₃]_∞  14. The structures of 12–14 all suggest a predilection for μ₃ oxygen-capped triangulated metal arrays in oxophilic mixed Li–Zn systems.