SYNTHESES AND ELECTROCHEMICAL CHARACTERIZATION OF HETEROLEPTIC CYCLOPENTADIENYL-DITHIOLENE D(2) TUNGSTEN COMPLEXES - STRUCTURES AND MAGNETIC-PROPERTIES OF CHARGE-TRANSFER SALTS

Novel diamagnetic tungsten(IV) complexes of general formula W(eta-C5H4 R)(2)(dithiolene) [R = H, SiMe3 or Bu-t; dithiolene = C3S52-(4,5-disul fanyl-1,3-dithiole-2-thionate), C3OS42- (4,5-disulfanyl-1,3-dithiole-2 -onate) or dddt(2-) (5,6-dihydro-1,4-dithiine-2,3-dithiolate)] have be en synthesized and their redox properties investigated by cyclic volta mmetry. Two reversible oxidation waves are observed for each complex. The redox half-wave potentials allow [W(cp)(2)(dddt)] (cp = eta-C5H5) to react with the organic acceptor tcnq (tetracyanoquinodimethane) whi le the C3S52- and C3OS42- compounds reduce tcnqf(4) 8,8-tetracyano-1,2 ,4,5-tetrafluoroquinodimethane). X-Ray crystallographic studies were c arried out on [W(cp)(2)(dddt)](.+)[tcnq](.-) and [W(eta-C5H4But)(2)(C3 S5)](.+)[tcnqf(4)](.-). The structural analyses and extended-Huckel ca lculations showed that the radical anions are strongly dimerised into diamagnetic moieties. The cations form centrosymmetrical dimers and ex hibit antiferromagnetic interactions, as deduced from the temperature dependence of the magnetic susceptibility, with T(chi(max)) = 18 and 2 2 K for [W(cp)(2)(dddt)](.+)[tcnq](.-) and [W(eta-C5H4But)(2)(C3S5)](. +)[tcnqf(4)](.-) respectively.