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

Article abstract of DOI:10.1039/DT9850002121

Treatment of with gave <(MeC(*)C)Pt(μ-dppm)2(?,η-C(*)CMe)Rh(CO)>Cl readily converted into the corresponding PF6(1-) salt (1b) the crystal structure of which was determined.Other complexes of the type <(RC(*)C)Pt(μ-dppm)2(?,η-C(*)CR)Rh(CO)>Cl were made similarly; with R = Ph, p-tolyl, CH2CH2Ph, or C(Me)=CH2.The complexes are fluxional with the low-temperature limiting 1H-<31P> n.m.r. spectrum showing non-equivalent pseudo-equatorial and pseudo-axial CH2 protons, H_e coupled to 195Pt and H_a not.The fluxional process corresponds to interchange of H_e and H_a and interchange of terminal and bridging C(*)CR.When heated in toluene for 3 h, <(RC(*)C)Pt(μ-dppm)2(?,η-C(*)CR)RhCl>.With CO, <(p-MeC6H4C(*)CPt(μ-dppm)2(?,η-C(*)CC6H4Me-p)RhCl> rapidly gave back <(p-MeC6H4C(*)C)Pt(μ-dppm)2(?,η-C(*)CC6H4Me-p)-Rh(CO)>Cl.Treatment of with (C8H14 = cyclo-octene) also gave <(RC(*)C)Pt(μ-dppm)2(?,η-C(*)CR)RhCl> (R = p-tolyl or Ph) but the complexes were not isolated pure.Treatment of <(PhC(*)C)2Pt(μ-dppm)2HgCl2> with caused rapid and complete displacement of HgCl2, giving <(PhC(*)C)Pt(μ-dppm)2(?,η-C(*)CPh)Rh(CO)>(1+); similarly treatment of <(PhC(*)C)2Pt(μ-dppm)2AgCl>, <(PhC(*)C)2Pt(μ-dppm)2CuI>, or <(PhC(*)C)2Pt(μ-dppm)2Au>Cl with gave <(PhC(*)C)Pt(μ-dppm)2(?,η-C(*)CPh)Rh(CO)>(1+).Treatment of <(Cl(RC(*)C)Pt(μ-dppm)2AgCl> 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 <(MeC(*)C)Pt(μ-dppm)2(?,η-C(*)CMe)Rh(CO)>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.

Full text of DOI:10.1039/DT9850002121

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