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(PPh(3))(2)(CF3){OC(OCH3)=C(H)(PPh(3))}][BF4]center dot 0.5CH(2)Cl(2)

The carbonyl stabilized P and As ylides Ph(3)PCHCOR (R = CH3, Ph, OCH3) and Ph(3)AsCHCOR (R = CH3, Ph, OCH3) have been reacted with some platinum(II) complexes bearing ancillary ligands with different steric hindrance, in order to determine the factors that influence the C- versus O-coordination mode of the ylides. Thus, the reactions of [(dppe)PtCl2] and [(dppv)PtCl2] with Ph(3)PCHCOR (R = CH3, Ph) give the O-coordinated complexes, while with Ph(3)PCHCOOCH(3) they give the corresponding C-coordinated derivatives. The reactions of trans-[(PPh(3))(2)(CF3)Pt(solv)](BF4-)-B-+ yield the O-coordinated compounds and the reactions with [Pt(C3H5)Cl](4) give selectively the C-coordinated derivatives as well as the reactions with the dimer [PtCl{P(Bu(t))(2)C(Me)(2)CH2}](2). The derivative trans-[Pt(PPh(3))(2)CF3) (OC(OCH3)=C(H)(PPh(3))}] [BF4] crystallizes in the triclinic space group P (1) over bar (No. 2), a = 10.385(4), b = 14.844(5), c = 18.511 (6) Angstrom, alpha = 96.46(2), beta = 99.79(2), gamma = 97.00(2)degrees, V = 2765(1) Angstrom(3), Z = 2. The values of coordination distances and of the Pt-O-C angle appear influenced by steric factors.