Synthesis, structure and properties of TTF-carboxylate bridged paddlewheel dirhodium complexes, Rh2(ButCO2)3(TTFCO2) and Rh2(ButCO2)2(TTFCO2)2
摘要:
Reaction of tetrathiafulvalene carboxylic acid (TTFCO2H) with paddlewheel dirhodium complex Rh-2((BuCO2)-C-t)4 yielded TTFCO2-bridged complexes Rh-2((BuCO2)-C-t)(3)(TTFCO2) (1) and cis- and trans-Rh-2((BuCO2)-C-t)(2)(TTFCO2)(2) (cis- and trans-2). Their triethylamine adducts [1(NEt3)(2)] and cis-[2(NEt3)(2)] were purified and isolated with chromatographic separation, and characterized with single crystal X-ray analysis. Trans-[2(NEt3)(2)] is not completely separated from a mixture of cis- and trans- [2(NEt3)(2)], but its single crystals were obtained from a solution of the mixture. A three-step quasi-reversible oxidation process was observed for 1 in MeCN. The first two steps correspond to the oxidation of the TTFCO2 moiety and the last one is the oxidation of the Rh-2 core. The oxidation of cis-2 is observed as a two-step process with very similar E-1/2 values to those of the first two processes for 1. Both 1(+) and cis-2(2+) in MeCN at room temperature show isotropic ESR spectra with a g value of 2.008 and a(H) = 0.135 mT for two equivalent H atoms and aH = 0.068 mT for one H atom. The redox and ESR data of cis-2 suggest that the intramolecular interaction between the TTF moieties is very small. (C) 2006 Elsevier B.V. All rights reserved.