Alkyl substituent effects in diamagnetic dithiocarbamate cobalt(III) and Nickel(II) complexes

Abstract

Single-crystal X-ray structure determinations have been recorded at 295 K for the tris(dithiocarbamato)cobalt(III) compounds: [Co(S2CN(CH2)4)3], [Co(S2CNEt2)3] (redeterminations), [Co(S2CN(CH2Ph)2)3], and [Co(S2CNPri2)3] at 120 and 295 K. [Co(S2CN(CH2)4)3] crystallizes in the space group C2/c with a 28.984(15), b 14.416(2), c 16.206(15)?, ߠ104.20(5)ଠZ 12; [Co(S2CNEt2)3] also crystallizes in space group C2/c with a 14.097(3), b 10.305(2), c 17.070(7)?, ߠ110.19(3)ଠZ 4; [Co(S2CN(CH2Ph)2)3] crystallizes in space group P21 with a 11.851(6), b 29.920(8), c 12.395(3)?, ߠ97.74(4)໠[Co(S2CNPri2)3] crystallizes in space group R3c with a 13.367(6)?, a 58.04(2)ࠨ295 K); a 13.155(6)?, a 58.59(3)ࠨ120 K), Z 2. The structure of [Ni(S2CNPri2)2] has been redetermined, the complex crystallizing in the space group P21/c with a 8.147(2), b 17.820(3), c 15.630(3)?, ߠ110.32(2)ଠZ 4. The results obtained from this study support the hypothesis, put forward by Ymen and Stahl, that the influence of aliphatic hydrocarbon substituents on the ligand-field strength at the sulfur atoms of the dithiocarbamate ligand is not through the p bonding network of the conjugated S2CN moiety, but, rather, intraligand S刭C interactions which increase with increasing bulk of the substituent atoms. Unlike the free anion systems, or the iron(III) complexes, however, the changes in the S-C-S angles with increasing field strength, while observable, are very small.