PHOTOCHEMICAL LIGAND REARRANGEMENT IN DIRHODIUM(II) COMPOUNDS - STRUCTURE OF RH-2(O2CCH3)(2)(ETA(2)-O2CCH3)[(C6H4)PPH(2)](ETA(2)-PCCL) (PCCL=P(O-CLC6H4)PH(2))

The photochemical reaction of the adducts Rh-2(O2CCH3)(3)[(C6H4)P(o-ClC6H4)Ph].(P(p-XC(6)H(4))(3)) (X = H, Me, Cl), yield the compounds Rh-2(O2CCH3)(2)(eta(2)-O2CCH3)[(p-XC(6)H(3))P(p-XC(6)H(4))](eta(2)-PCCl), (PCCl = P(o-ClC6H4)Ph(2)) in a ligand rearrangment reaction that involves activation of C-H and Rh-C bonds. The factors that favour this process are studied by carrying out photochemical reactions with different phosphines. The structure of Rh-2(O2CCH3)(2)(eta(2)-O2CCH3)[(C6H4)PPh(2)](eta(2)-PCCl) has been determined by X-ray diffraction. M(r)=1321.1, orthorhombic, space group Pbcn, a = 20.339(8), b = 20.07(6), c = 23.07(3) Angstrom, V=9413(3) Angstrom(3), Z=8, D-x=1.86 g cm(-3). Mo K alpha radiation (graphite crystal monochromator, lambda=0.71073 Angstrom), mu(Mo K alpha)=13.83 cm(-1), F(000)-5280, T=293 K. Final conventional R factor=0.062 for 4889 'observed' reflections and 500 variables. The compound contains three bridging ligands, two acetates and one metalated triphenylphosphine, and two chelating ligands, one acetate and one PCCl that acts as a P,Cl ligand, taking one equatorial (P) and one axial (Cl) coordination site. The axial Rh-Cl bond distance is 2.573(4) Angstrom.