REGIOSELECTIVE AND STEREOSELECTIVE PPH(3) SUBSTITUTION IN THE IMIDO-CAPPED CLUSTER RU-3(CO)(10)(MU(3)-NPH) - ELECTROCHEMICAL PROPERTIES AND X-RAY DIFFRACTION STRUCTURES OF RU-3(CO)(9)(PPH(3))(MU(3)-NPH) AND RU-3(CO)(8)(PPH(3))(2)(MU(3)-NPH)CENTER-DOT

摘要

The imido-capped cluster Ru-3(CO)(10)(mu(3)-NPh) (1) reacts with PPh(3) under thermal and Me(3)NO activation to give the corresponding phosphine-substituted clusters Ru-3(CO)(9)(PPh(3))(mu(3)-NPh) (2) and Ru-3(CO)(8)(PPh(3))(2)(mu(3)-NPh) (3). Both 2 and 3 have been isolated and fully characterized in solution by IR and P-31 NMR spectroscopy, and the solid-state structure of each new cluster compound has been established by X-ray diffraction analysis. 2 crystallizes in the monoclinic space group P2(1): a = 13.091(2), b = 11.405(2), c = 22.687(4) Angstrom, beta = 99.80(1)degrees, V = 3338(1) Angstrom(3), Z = 4, D-calc = 1.808 g cm(-3); R = 0.0399, R(W) = 0.0511 for 3515 observed reflections. 3, as the CH2Cl2 solvate, crystallizes in the triclinic space group P (1) over bar: a = 9.5678(8), b = 14.425(1), c = 17.986(1) Angstrom, alpha = 81.692(5), beta = 88.078(6), gamma = 77.716(6)degrees, V = 2400.1(3) Angstrom(3), Z = 2, D-calc = 1.640 g cm(-3); R = 0.0439, R(W) = 0.0479 for 3570 observed reflections. The X-ray data establish the site of the first PPh(3) group at an axial position in the cluster 2 while cluster 3 derives from the formal replacement of an equatorial CO group on an adjacent ruthenium center in 2 by the second PPh(3) group. These results confirm the highly stereo- and regioselective ligand substitution reactivity attendant in this particular imido-capped cluster. The redox properties of 1-3 have also been explored by cyclic voltammetry at a platinum electrode in THF solvent. [References: 45]