SYNTHETIC AND ELECTROCHEMICAL STUDIES OF SOME METAL-COMPLEXES OF 1,3,5-TRIETHYNYLBENZENE

A series of compounds featuring metallic fragments around the peripher y of a 1,3,5-triethynylbenzene core have been synthesized. By using se veral synthetic methods, metallic units such as cis-[RuCl2(dppm)(2)], cis-[OsCl2(dppm)(2)] and [RuCl(eta-C5H5)(PPh3)(2)] have been treated w ith the aromatic acetylide ligand to introduce one, two or three metal lic centres. Electrochemical studies showed that the bimetallic trans- [HC=CC6H3 {C=CRuCl(dppm)(2)}(2)] and trans-[HC=CC6H3 {C=COSCl(dppm)(2) }(2)] species undergo two separated one-electron oxidations thus indic ating that the central triethynylbenzene unit allows communication bet ween the two peripheral metal subunits. The compounds [(HC=C)(2)C6H3C= CRu(eta-C5H5)(PPh3)(2)], [HC=CC6H3 {C=CRu(eta-C5H5)(PPh3)(2)}(2)] and [C6H3 {C=CRu(eta-C5H5)(PPh3)(2)}(3)] each show separated one-electron oxidations (though these are less reversible than for the previous com pounds mentioned) again demonstrating the electronic communication amo ngst the peripheral metal centres through the organic linkage. Chemica l oxidation has been carried out on the [Ru(eta-C5H5)(PPh3)(2)]-contai ning species affording mixed-valence species consistent with those pro duced by successive electrochemical oxidation.