REACTION OF -2(MU(2)-O2CCH3)(3)[MU(2)-(C6H4)PMEPH](HO2CCH3)(2) WITH TRIPHENYLPHOSPHINE - REARRANGEMENT OF THE METALATED PMEPH, LIGAND AND FORMATION OF A COMPOUND WITH A DIPHENYLPHOSPHINOMETHANIDE GROUP IN (P,C) COORDINATION - CRYSTAL-STRUCTURE OF MU(2)-(C6H4)PPH(2))(PPH(3))]CENTER-DOT-2CH(2)CL(2)

The reaction of [Rh-2(mu(2)-O2CCH3)(3){mu(2)-(C6H4)PMePh}] (1) in CHCl 3 with one mole of PPh(3) gives the two phosphine monoadducts, which a re in rapid equilibrium above -40 degrees C. After 6 h at room tempera ture this mixture gives u(2)-(C6H4)PMePh}{mu(2)-(C6H4)PPh(2)}](HO2CCH3 )(2) (3), a doubly metalated compound with a head-to-head configuratio n. 1 reacts with two moles of PPh(3), forming the bis-adduct 1.P-2, wh ich at 10 degrees C gives a mixture of 3, in the form of its phosphine adduct 3.P, and 2){mu(2)-(CH2)PPh(2)}{mu(2)-(C6H4)PPh(2)}(PPh(3))] (2 ). It is confirmed that 3.P is not the kinetic product in the reaction from 1.P-2 to 2. The structure of ){mu(2)-(CH2)PPh(2)}{mu(2)-(C6H4)PP h(2)}(PPh(3))]. 2CH(2)Cl(2) has been determined by X-ray diffraction: M(r)=1216.55, monoclinic, space group P2(1)/c, a=19.930(8), b=15.29(2) , c=16.84(2) Angstrom, beta=90.14(9)degrees, V=5129(9) Angstrom(3), Z= 4, D-c=1.58 g cm(-3), Mo K alpha radiation (graphite monochromator, la mbda=0.71073 Angstrom), mu (Mo K alpha)=9.80 cm(-1), F(000)=2464, T=20 0 K. The final conventional R factor was 0.061 for 4749 'observed' ref lections. The compound contains an orthometalated triphenylphosphine a nd a diphenylphosphinomethanide group bridging the two rhodium atoms. The two ligands are in a head-to-head configuration. Two bridging acet ate groups and one axial PPh(3) complete the coordination around the r hodium atoms. The Rh-Rh bond distance is 2.532(2) Angstrom.