Neutral and anionic binuclear perhalogenophenyl platinum–silver complexes with Pt→Ag bonds unsupported by covalent bridges. Molecular structures of [(tht)(C6Cl5)(C6F5)2-PtAg(PPh3)], [NBu4][(C6F5)4PtAg(tht)] and [NBu4][cis-(C6Cl5)2(C6F5)2PtAg(tht)](tht = tetrahydrothiophene)

Abstract

Heterobinuclear complexes of general formula [L(C₆Cl₅)_3-x(C₆F₅)_xPtAg(PPh₃)][x= 2–0; L = tht (tetrahydrothiophene), PPh₃ or pyridine (py)]14–21 have been prepared by treating the anionic platinum derivatives [NBu₄][PtL(C₆F₅)_x(C₆Cl₅)_3-x] with [Ag(OCIO₃)(PPh₃)](molar ratio 1 : 1) in dichloromethane. The anionic [NBu₄][(C₆F₅)₄PtAgL](L = OEt₂, PPh₃ or tht)22–24 and [NBu₄][cis-(C₆Cl₅)₂(C₆F₅)₂PtAg(tht)]25 have been obtained from the corresponding [NBu₄]₂[Pt(C₆X₅)₂(C₆X′₅)₂] and [Ag(OCIO₃)L](molar ratio 1 : 1) in CH₂Cl₂–diethyl ether. The reaction between [NBu₄][Pd(C₆F₅)₃(tht)] and [Ag(OCIO₃)(PPh₃)] renders Ag(C₆F₅) and cis-[Pd(C₆F₅)₂(PPh₃)(tht)]. The salts [NBu₄]₂[Pt(C₆Cl₅)₄] and [NBu₄]₂[Pd(C₆F₅)₄] react with [Ag(OCIO₃)(tht)] yielding [NBu₄][Pt(C₆Cl₅)₃(tht)] and [NBu₄][Pd(C₆F₅)₃(tht)], respectively. The reactions between [NBu₄]₂[Pt(C₆F₅)₄] and [Ag(OCIO₃)(tht)] or [Ag(OCIO₃)(PPh₃)](molar ratio 1:2) render in the first case complex 24 while in the second an unstable material which evolves to [(Ph₃P)(C₆F₅)₃PtAg(PPh₃)]27 is obtained. The reaction between [NBu₄]₂[trans-PtCl₂(C₆X₅)₂](X = F or Cl) and [Ag(OCIO₃)(tht)] or [Ag(tht)₂]ClO₄ have also been studied. The structures of [(tht)(C₆Cl₅)(C₆F₅)₂PtAg(PPh₃)]14, [NBu₄][(C₆F₅)₄PtAg(tht)]24 and [NBu₄][cis-(C₆Cl₅)₂PtAg(tht)]25 have been established by single-crystal X-ray diffraction studies. The complexes contain a strong Pt→Ag bond [2.650(2), 14; 2.641(1), 24; and 2.692(2)Å, 25] unsupported by covalent bridges, and short contacts between the o-F or o-Cl atoms of the C₆X₅(X = F or Cl) groups and the Ag atom are present. The relative strength of such contacts is discussed. Methods for the synthesis of mixed pentachloro-pentafluoro-phenyl starting complexes 1–13 have been investigated.