{Bis(3,5-Di-tert-butyl-2-oxidobenzyl)[2-(N,N-dimethylamino)ethyl]amine-κ4N,N',O ,O'}zinc(II) and {bis(3-tert-butyl-5-methyl-2-oxidobenzyl)[2-(N ,N-dimethylamino)ethyl]amine-κ4N,N',O,O'}(tetrahdyrofuran)zinc(II)

The title zinc(II) complexes, [Zn(C34H54N2O2)], (II), and [Zn(C28H42N2O2)(C4H8O)], (III), were obtained as monomeric 1:1 complexes, in contrast with the calcium complexes supported by the same ligand class. Complex (II) crystallizes with two independent mol­ecules in the asymmetric unit, which have similar geometric parameters. The donor atoms in (II) form a distorted trigonal-pyramidal arrangement around the zinc centre. Complex (III) contains a coordinated tetra­hydro­furan mol­ecule, resulting in a five-coordinate trigonal-bipyramidal arrangement around the Zn atom. The electron density provided by the coordination of this tetra­hydro­furan mol­ecule elongates the Zn-O and Zn-N bonds by approximately 0.07 and 0.10 Å, respectively, in comparison with (II). Neither (II) nor (III) is active as an [epsilon]-caprolactone polymerization catalyst. The data presented here demonstrate that Zn may bind both an ONNO ligand and an additional oxygen-based ligand. The lack of activity is thus not due to steric hinderance at the metal atom.