We describe the preparation of a series of organoruthenium tetrathiometalates and tetraselenometalates of the general formula (RC5H4)2Ru2L2ME 4 (R = H, CH3; L = PR3, RNC, CO; M = W, Mo; E = S, Se). The compound Cp2Ru2(PPh3)2WS4 (1) reacts with PMe3 to give Cp2Ru2(PMe3)2WS4 and with isocyanides to give Cp2Ru2(RNC)2WS4 (R = t-Bu, Me, C6H5CH2). Only one of the PPh3 ligands in 1 is substituted by an excess of carbon monoxide to give Cp2Ru2(PPh3)(CO)WS4. The kinetics of the ligand substitution of 1 by t-BuNC was examined by using 1H NMR spectroscopy. The rate of the first substitution was found to be independent of [t-BuNC], the first-order rate constant being 5.6 × 10-4 s-1. The rate of the first substitution was found to be approximately 4 times that of the second. All of the compounds studied undergo reversible or quasi-reversible oxidations. On the basis of the measured E1/2 values, the donor powers of the chalcogenometalates are ranked as follows: MoSe42- > WSe42- > MoS42- > WS42-. The compound Cp2Ru2(MeNC)2WS4 crystallizes in the monoclinic space group I2/a with a = 13.840 (13) Å, b = 12.234 (9) Å, c = 14.224 (11) Å, β = 105.48 (7)°, V = 2321 (3) Å3, and Z = 4 and refined to R = 0.038 and Rw = 0.049. The short Ru-W distances (2.870 (2) Å) and the acute Ru-S-W angles (77° average) are indicative of metal-metal bonding. The reactivity, redox properties, and structures of these compounds are discussed in the context of the donation of t2g electrons on ruthenium to tungsten.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry