Steric Effects of Alkyl Substituents at <em>N</em>-Donor Bidentate Amines Direct the Nuclearity, Bonding and Bridging Modes in Thiocyanato-Copper(II) Complexes

Abstract

A series of Cu(II)-thiocyanato complexes derived from sterically hindered N-donors diamines were synthesized and characterized: catena-[Cu(Me3en)(&amp;mu;-NCS)(NCS)] (1), catena-[Cu(NEt2Meen)(&amp;mu;-NCS)(NCS)] (2), catena-[Cu(N,N,2,2-Me4pn)(&amp;mu;-NCS)(NCS)] (3), the dimeric: [Cu2(N,N&amp;prime;-isp2en)2(&amp;mu;-NCS)2(NCS)2] (4) and the monomeric complex [Cu(N,N&amp;prime;-t-Bu2en)(NCS)2] (5), where Me3en = N,N,N&amp;prime;-Trimethylethylenediamine, NEt2Meen = N,N-diethyl-N&amp;prime;-methylethylenediamine, N,N,2,2-Me4pn = N,N,2,2-tetramethylpropylenediamine, N,N&amp;prime;-isp2en = N,N&amp;prime;-diisopropylethylenediamine and N,N&amp;prime;-t-Bu2en = N,N&amp;prime;-di(tert-butyl)ethylenediamine. The complexes were characterized by elemental microanalyse, IR and UV-Vis spectroscopy and single crystal X-ray crystallography. Density Functional Theory was used to evaluate the role of steric effects in compounds 4 and 5 and how this may affect the adaption of a specific geometry, NCS-bonding mode and the dimensionality of the resulting complex.