Reactions of [Ru-5(mu(5)-C2PPh2)(mu-PPh2)(CO)(13)] with dimethyl disulfide. Synthesis of an open Ru-5 cluster containing the dicarbon (C-2) ligand and related chemistry

The reaction between [Ru-5(mu(5)-C2PPh2)(mu-PPh2)(CO)(13)] and Me2S2 yielded [Ru-5(mu(5)-C2PPh2)(mu-SMe)(2)(mu-PPh2)(CO)(13)]as the major product. When heated the latter yielded the dicarbon complexes [Ru-5(mu(5)-C-2)(mu-SMe)(2)(mu-PPh2)(2)(CO)(12)] and [Ru-5(mu(5)-C-2)(mu-SMe)(2)(mu-PPh2)(2)(CO)(11)]. In large-scale preparations of the latter four minor products were isolated: two isomers of [Ru-5(mu(5)-C2PPh2)(mu-SMe)(2)(mu-PPh2)(CO)(12)], the tetranuclear complex [Ru-4(mu(4)-C2PPh2)(mu-SMe)(2)(mu-PPh2)(2)(CO)(12)] and [Ru-3(mu(5)-C-2)(mu-SMe)(4)(mu-PPh2)(2)(CO)(10)]. The latter is also formed by direct reaction of [Ru-5(mu(5)-C-2)(mu-SMe)(2)(mu-PPh2)(2)(CO)(11)] with Me2S2. All new complexes have been fully characterised by single-crystal X-ray studies. In the three Ru-5(C2PPh2) complexes the C2PPh2 ligand acts as a seven-electron donor, whereas in the Ru-4 complex it donates only five electrons to the cluster. In the C-2 complexes, the different C-C separations [between 1.26(2) and 1.305(5) Angstrom] suggest a variable degree of interaction with the metal core (electron donation and back-bonding), the ligand formally donating either six or four electrons to the cluster. This is borne out by the Ru-Ru separations, average values of which range between 2.791 and 2.916 Angstrom. The conversion of [Ru-5(mu(5)-C2PPh2)(gamma-PPh2)(CO)(13)] into [Ru-5(mu(5)-C-2)(mu(-)SMe)(2)(mu-PPh2)(2)(CO)(11)] involves sequential formation of several of these complexes, which reactions are discussed.