Two six coordinate tantalum(V) oxazoline complexes, [Ta(OX)(NMe2)4] (1) and [Ta(OX)2(NMe2)3] (2), formed by the reaction of [Ta(NMe2)5] with the chelating di-nitrogen ligand 4,4-dimethyl-2-pyrrole-2- oxazoline in 1:1, 1:2 and/or 1:3 molar ratios have been investigated. The structural study of 1 and 2 by X-ray crystallography shows that they both adopt geometries best described as distorted octahedral with N–Ta–N angles of 172.6(3) and 169.4(2), respectively. The nitrogen atoms of the oxazoline are bound directly to the tantalum, leading to a five-membered metallacycle in the basal plane. The N–Ta– N and Ta–N–C angles of the basal five-membered oxazoline ring are 71 and 113–117, respectively.
