부산대학교 도서관

Substituted thiourea ligands bind in a bidentate manner forming a four-membered ring through the sulfur atom and a deprotonated thiourea nitrogen atom when reacted with [(en)[sub 2]Co(OSO[sub 2]CF[sub 3])[sub 2]][sup +] in tetramethylene sulfone. Reaction of unsymmetrical ligands results in the formation of coordination isomers, some of which can be separated by column chromatography using Sephadex SPC-25. Coordination isomers are easily distinguishable based on visible and 1H NMR spectroscopy . Twelve para-substituted and one meta-substituted ligands were studied: N,N'-dibenzylthiourea (1a); N-(R)phenyl-N'-benzylthiourea {R = H (2a), NO[sub 2] (2b), CH[sub 3] (2c)}; N-(R)phenyl-N'-(R')phenylthiourea {R, R': H, H (3a), H, CH[sub 3] (3b), OCH[sub 3], NO[sub 2] (3c), CH[sub 3], NO[sub 2] (3d)}; N-methyl-N'-(R)phenylthiourea {R=H (4a), CH[sub 3] (4b), OCH[sub 3] (4c), NO[sub 2] (4d), 3-CH[sub 3] (4e)}. The solid state structure (X-ray) of one isomer of Co-4a as its perchlorate salt confirms the coordination mode suggested by 1H NMR spectroscopy and shows that the Co-N bond trans to the coordinated thiourea sulfur induces a structural trans effect of 0.019 Å. [ABSTRACT FROM AUTHOR]