Département de chimie moléculaire

Several mono- and bimetallic complexes involving organometallic fragments such as M(CO)4 (M = Mo, W), Re(CO)3Cl and Fe(CO)3 coordinated to the chelating diphosphine 3,4-dimethyl-3',4'-bis(diphenylphosphino)tetrathiafulvalene (P2) or tetraphosphine tetrakis(diphenylphosphino)tetrathiafulvalene (P4) were synthesized and characterized. X-ray diffraction structures were detd. for P4[W(CO)4]2, P2Re(CO)3Cl, P2Fe(CO)3 and P4[Fe(CO)3]2. Octahedral geometries around the metallic center are obsd. for the W and Re complexes, with a fac arrangement of the ligands for the latter, whereas slightly distorted trigonal bipyramid are found for both Fe counter parts. Although the complexes are more difficult to oxidize than the corresponding free phosphines, as evidenced by cyclic voltammetry measurements, the 1st oxidn. potentials remain in the usual range, thus offering the opportunity to generate stable radical cation salts. In the case of Fe complexes, the 1st oxidn. wave corresponds to the formation of paramagnetic d7 Fe(I) species, whereas in the Mo, W and Re complexes the metallic center is much more difficult to oxidize than the TTF core. [on SciFinder(R)]