Three-Coordinate Nickel(II) and Nickel(I) Thiolate Complexes Based on the β‑Diketiminate Ligand System

Mononuclear nickel­(II) thiolate complexes [LtBuNi­(SEt)] (1) and [LtBuNi­(aet)] (2, aet = −S­(CH2)2NH2) (LtBu = [HC­(C­(tBu)­NC6H3(iPr)2)2]−), supported by a bulky nacnac ligand, were synthesized
by treatment of the nickel­(II) bromide precursor [LtBuNi­(Br)] (I) with the potassium
salts of ethanethiol and cysteamine, respectively. The nickel atom
in 1 features a planar T-shaped environment, while the
Ni ion within 2 shows a distorted square planar coordination
geometry, as the aminoethanethiolate (aet) is coordinated as a chelating
ligand. In 2 the β-diketiminate ligand binds in
a rarely observed κ2C,N coordination mode. Reduction of complex 1 or its benzenethiolate
analogue [LtBuNi­(SPh)] (II) by KC8 resulted in the formation of dinuclear
NiI thiolates (K·OEt2)­(K)­[LtBuNi­(SEt)]2 (3) and (K·OEt2)2[LtBuNi­(SPh)]2 (4), respectively.
In these compounds [LtBuNi­(SR)]− units are held together by potassium cations produced
in the reduction process. All compounds mentioned were structurally
characterized by single-crystal X-ray crystallography.