Synthesis of cis-[Pt(CCr)2(PPh3)2] and trans-[PtCl(CCR)(PPh3)2] complexes. Crystal and molecular structures of cis-[Pt{CCC(OH)Me2}2(PPh3)2]·H2O, trans-[PtCl{CCC(OH)Me2}(PPh3)2]·0.5PhMe, and trans-[PtCl{CCC(OH)MeEt}(PPh3)2]·Me2CO. Influence of bases and their concentration on the reactivity of cis-[PtCl2(PPh3)2]

Abstract

Complexes cis-[Pt(CCR)₂(PPh₃)₂][R = C(OH)Me₂, C(OH)MeEt, CH(OH)Ph, or Ph] can be obtained from cis-[PtCl₂(PPh₃)₂] and HCCR in 30% aqueous ammonia as solvent. Complexes trans-[PtCl(CCR)(PPh₃)₂][R = CH₂OH, CH(OH)Me, C(OH)Me₂, C(OH)MeEt, C₆H₁₀OH, or CH₂NEt₂] are obtained by using chloroform (or dichloromethane)–diethylamine as solvent. No dehydration reactions of the acetylenic alcohols are observed. X-Ray analyses on cis-[Pt{CCC(OH)Me₂}₂(PPh₃)₂]·H₂O, trans-[PtCl{CCC(OH)Me₂}(PPh₃)₂]·0.5PhMe, and trans-[PtCl{CCC(OH)MeEt}(PPh₃)₂]·Me₂CO revealed in the, cis complex the presence of a water molecule forming two strong hydrogen bonds with the two cis-oriented hydroxy-groups of the acetylide ligands. In all the complexes the co-ordination around platinum is distorted square planar with the acetylide ligands σ-bonded to platinum. Crystallographic details: cis-[Pt{CCC(OH)Me₂}₂(PPh₃)₂]·H₂O, monoclinic, space group P2₁/c, with a= 15.473(5), b= 21.725(6), c= 13.439(4)Å, β= 113.95(3)°, and Z= 4; R= 0.052 for 3 110 observed reflections; trans-[PtCl{CCC(OH)Me₂}(PPh₃)₂]·0.5PhMe, triclinic, space group P, with a= 11.695(3), b= 19.690(6), c= 9.214(2)Å, α= 101.88(3), β= 104.26(3), γ= 85.55(3)°, and Z= 2; R= 0.053 for 3 961 observed reflections; [PtCl{CCC(OH)MeEt}(PPh₃)₂]·Me₂CO, triclinic, space group P, with a= 15.544(6), b= 12.567(4), c= 11.719(3)Å, α= 91.12(3), β= 105.36(3), γ= 111.39(3)°, and Z= 2; R= 0.046 for 4 704 observed reflections. The influence of NH₃, NHEt₂, and H₂NNH₂ on the reactivity of cis-[PtCl₂(PPh₃)₂] with monosubstituted acetylenes is discussed.