PHOTOCHEMICAL LIGAND REARRANGEMENT IN DIRHODIUM(II) COMPOUNDS - STRUCTURE OF CCH3)(2)(ETA(2)-O2CCH3)[(C6H4)PPH(2)](ETA(2)-PCCL) (PCCL=P(O-CLC6H4)PH(2))

The photochemical reaction of the adducts 2CCH3)(3)[(C6H4)P(o-ClC6H4)P h].(P(p-XC(6)H(4))(3)) (X = H, Me, Cl), yield the compounds 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 o f CCH3)(2)(eta(2)-O2CCH3)[(C6H4)PPh(2)](eta(2)-PCCl) has been determin ed 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 mo nochromator, 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 'observ ed' reflections and 500 variables. The compound contains three bridgin g 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.