Thiol end-capped titanium-copper complexes: Synthesis, solid state structure and electrochemical behavior

摘要

The synthesis of acetylene, acyl-thiol and thiol end-capped titanium-copper pi-tweezer complexes of the structural type {[Ti](mu-sigma, pi-C, CR) (2)} CuSC6H4-4-R ' ([Ti] = (eta(5)-C5H4SiMe3)(2)Ti; 3: R = SiMe3, R ' = C CH; 5a: R = SiMe3, R ' = SC(O) Me; 5b: R= Bu-t, R ' = SC(O) Me), {[Ti](mu-sigma, pi-C, CSiMe3)(2)} CuSC6H4-C6H4-4-SH (7) and ({[Ti](mu-sigma, pi-C CR) (2)} CuSC6H4) (2) (8) is described. Homobimetallic 3, 5a and 5b are accessible via the reaction of {[Ti](mu-sigma, pi-C, CR) (2)} CuMe (1a: R = SiMe3, 1b: R= Bu-t) with stoichiometric amounts of Me(O) CS-1-C6H4-4-C, CH (2) and C6H4-1,4-(SC(O) Me)(2) (4), respectively. Within these reactions the copper-sulfur bond formation is accompanied by the elimination of acetone. If 1a is treated with the dithiol (HS-C6H4)(2) (6) in a ratio of 1: 1 or 2: 1 than dinuclear 7 and tetranuclear 8 are produced upon formation of methane. Both types of reaction allow in a straightforward manner the synthesis of analytically pure samples in high yield. In addition, complex 8 is also formed, when equimolar amounts of 7 are reacted with 1a. The solid state structure of 5a is reported. This complex possesses a low-valent CuSC6H4-4-SC(O) Me entity with copper(I) in a planar surrounding. All other geometrical features are in agreement with the expected data relevant for Ti-Cu organometallic pi-tweezer complexes. Cyclic voltammetric studies were carried out with 3-8. The results are discussed with respect to intramolecular interactions between the various electrochemically active reaction sites. (C) 2007 Elsevier B. V. All rights reserved.