Influence of ancillary ligands in the coordination mode of P and As carbonyl stabilized ylides on Pt(II) systems. X-ray structure of trans-[Pt(PPh3)2(CF3)*OC(OCH3)=C(H)(PPh3)*][BF4] o 0.5CH2Cl2

The carbonyl stabilized P and As ylides Ph3PCHCOR (R = CH3, Ph, OCH3) and Ph3AsCHCOR (R = CH3, Ph, OCH3) have been reacted with some platinum(II) complexes hearing ancillary ligands with different steric hindrance, in order to determine thè factors that influence thè C- versus O-coordination mode of thè ylides. Thus, thè reactions of [ (dppe)Ptd2] and [ (dppv)PtC!2] with Ph3PCHCOR (R = CH3, Ph) give thè O-coordinated complexes, while with Ph3PCHCOOCH3 they give thè corresponding C-coordinated derivatives. The reactions of fran.j-[(PPh3)2(CF3)Pt(solv)]+BF4~ yield thè O-coordinated compounds and thè reactions with [Pt(C3H5)Cl]4 give selectively thè C-coordinated derivatives as well as thè reactions with thè dimer [PtCl{P(But)2C(Me)2CH2}]2- The derivative trans-[Pt(PPh3)2(CF3) (OC(OCH3)=C(H)(PPh3)}] [BF4] crystallizes in thè triclinic space group PI (No. 2), a= 10.385(4), b= 14.844(5), e =18.511(6) A, a = 96.46(2), 0 = 99.79(2) ,7=97.00(2)°, V= 2765(1) À3,Z=2.The valuesof coordination distances and of thè Pt-O-C angle appear influenced by steric factors.