Structural features of a series of S-alkylated and non-S-alkylated aminothiolate nickel(II) complexes

Abstract

The structural aspects of a family of S-alkylated complexes, generated by reacting iodoacetamide or iodoethanol with two mononuclear Ni(II) diaminodithiolate complexes are discussed. The S-alkylation reactions were investigated with particular attention paid to the size of the chelate ring that straps the N,N′-methylamine donors. In one complex the N-methyl groups are cis to each other and in the other they are trans. Both complexes undergo S-alkylation with two equivalents of either reagent, that coordinates through the pendant oxygen to the Ni(II), forming dications with an N2S2O2 ligand donor set. Crystal structures of [NiC12H26N4O2S2]I2 · MeOH, [NiC12H28N2O2S2]I2, and [NiC13H30N2O2S2]I2 · 1/2MeOH, are determined by single crystal X-ray analysis. The N-methyl groups in each of the alkylated derivatives are trans to each other, suggesting that the cis configuration is highly unfavored for such complexes in octahedral conformation. Crystal packing data shows that each of the alkylated complexes interacts closely with the iodide counterions, and with solvent if present; some of these interactions include H-bonds. Only the iodoacetamide derivative shows any significant interaction with a neighboring molecule.