Preparatiions of chloro(diene)polyfluorophenylplatinum(II) complexes and the structure of chloro(dicyclopentadiene)-pentafluorophenylplatinum(II)

The complexes, PtCl(diene)R (diene = hexa-1,5-diene (hex) or norbornadiene (nbd), R C₆F₅, p-HC₆F₄, or p-MeOC₆F₄; diene = diene = dicyclopentadiene (dcy), R = C₆F₅) have been prepared by reaction between equimolar amounts of PtCl₂(diene) and Me₃SnR in dichloromethane. Most reactions also gave some of the corresponding PtR₂(diene) complex, which was readily separated by chromatography, and Pt(p-MeOC₆F₄)₂(nbd) was obtained in high yield from PtCl₂(nbd) and Me₃Sn(p-MeOC₆F₄) when a 1 2 mole ratio was used. Attempts to prepare PtCl(dcy)R (R p-HC₆F₄ or p-MeOC₆F₄) from Me₃SnR gave only PtR₂(dcy) in boiling CH₂Cl₂ despite the use of 1 1 reactant stoichiometry, and Pt(p-MeOC₆F₄)₂(dcy) or no reaction (R p-HC₆F₄) at room temperature. Alternative reagents, R′₃ SnR (R′ Bu or Et, R C₆F₅ or p-MeOC₆F₄) had a variable effect on the selectivity of monoarylation. Thus, Bu₃SnC₆F₅ was more selective and Et₃SnC₆F₅ less selective in formation of PtCl(hex)C₆F₅ than Me₃SnC₆F₅. With Et₃SnR (R C₆F₅ or p-MeOC₆F₄) and an equimolar amount of PtCl₂(dcy), PtCl(dcy)R was the major product. The crystal structure of ptCl(dcy)C₆F₅ shows near square planar stereochemistry for platinum and steric congestion. The double bond from the six-membered ring of dcy is unsymmetrically coordinated to platinum trans to C₆F₅ and is further from the metal than the other double bond, which is symmetrically bonded trans to chlorine. The pentafluorophenyl group is approximately normal to the coordination plane, and gives two ortho-fluorine resonances in the ¹⁹F NMR spectrum.