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Bimetallic Systems. Part 12. Mixed Rhodium(I)-Platinum(II) Acetylide Complexes containing Bridging Ph2PCH2PPh2. Crystal Structures of PF6 and of PF6

Treatment of with gave Cl readily converted into the corresponding PF6(1-) salt (1b) the crystal structure of which was determined.Other complexes of the type Cl were made similarly; with R = Ph, p-tolyl, CH2CH2Ph, or C(Me)=CH2.The complexes are fluxional with the low-temperature limiting 1H- n.m.r. spectrum showing non-equivalent pseudo-equatorial and pseudo-axial CH2 protons, He coupled to 195Pt and Ha not.The fluxional process corresponds to interchange of He and Ha and interchange of terminal and bridging C(*)CR.When heated in toluene for 3 h, .With CO, rapidly gave back Cl.Treatment of with (C8H14 = cyclo-octene) also gave (R = p-tolyl or Ph) but the complexes were not isolated pure.Treatment of with caused rapid and complete displacement of HgCl2, giving (1+); similarly treatment of , , or Cl with gave (1+).Treatment of with gave (1+) (R = Me, Ph, or p-tolyl) isolated as PF6(1-) or AgCl2(1-) salts.These complexes could also be made in 'one-pot' syntheses, viz. successive treatment of Cl2 with AgO2CMe-PhC(*)CH followed by treatment with , without isolation of the intermediate platinum-silver complex.The crystal structures of PF6 (1b) as the dichloromethane solvate and of PF6 (5a) were determined.Crystals of (1b) are orthorhombic, space group Pbca, a = 19.212(7), b = 27.364(6), c = 21.468(5) Angstroem, and Z = 8; those of (5a) are orthorhombic, space group Pn21a, a = 43.39(1), b = 25.178(9), c = 10.164(6) Angstroem, and Z = 8.Final R factors were 0.088 for 4500 and 0.058 for 6320 observed reflections, respectively.In each complex cation the two metal centres are bridged by a methylacetylide group ?-bonded to Pt and ?-bonded in an unsymmetrical side-on fashion to Rh , giving rise to an A-frame structure.