Tricarbonyl Mono- and Dinuclear Rhenium(I) Complexes with Redox-Active Bis(pyrazole)–Tetrathiafulvalene Ligands: Syntheses, Crystal Structures, and Properties

Two new bis­(3,5-dimethylpyrazole)-substituted tetrathiafulvalene
ligands, 2,6(7)-bis­(methylthio)-3,7(6)-bis­(3-sulfanyl-3,5-dimethylpyrazole)­tetrathiafulvalene
(L1) and 2,3-bis­(methylthio)-6,7-bis­(3-sulfanyl-3,5-dimethylpyrazole)­tetrathiafulvalene
(L2), have been prepared and
characterized. On the basis of the two ligands, three interesting
rhenium­(I) tricarbonyl mono- or dinuclear complexes, ClRe­(CO)3(cis-L1) (1), [ClRe­(CO)3(trans-L1)]2 (2),
and [ClRe­(CO)3(L2)]2 (3), have been prepared and structurally characterized.
Electrochemical studies show sequential oxidation processes of the
compounds to the corresponding radical cation and dication states,
suggesting that redox events are essentially dependent on the structures
of the rhenium­(I) complexes. The results have evidenced electronic
interactions between the TTF cores in complexes 1 and 2. Geometric and electronic structures as well as the spectroscopic
properties for complexes 1–3 have
been investigated by using DFT and TDDFT calculations.