Use of aryltin compounds in the preparation of diaryl- and diaroyl-di-µ-chloro-bis(triorganophosphine)diplatinum(II) complexes

Abstract

The complexes cis-[Pt(C₂H₄)Cl₂L](L = triorganophosphine) react with compounds SnRMe, (R = aryl)(1 mol equivalent) to give the chloride-bridged arylplatinum complexes [Pt₂R₂Cl₂L₂], which exist in solution as mixtures of cis and trans isomers. The [Pt₂R₂Cl₂L₂] complexes react with ligand species L′[L′= NCMe, SBu^t₂, pyridine, NBuⁿH₂, AsPh₃, PEt₃, PBuⁿ₃, PPh₃, or P(OPh)₃] to give the mononuclear complexes [PtR(Cl)L(L′)], and this represents an excellent route to mononuclear complexes having four different ligands on platinum. Cyclo-octa 1,5-diene (cod), however, gives [PtR(Cl)L₂] and [Pt(cod)R(Cl)], while 2,2′-bipyridyl (bipy) gives the salt [PtR(bipy)L]Cl. Sodium thiocyanate reacts with [Pt₂(C₆H₄Me-p)₂Cl₂(PEt₂Ph)₂] to give the thiocyanate-bridged [Pt₂(C₆H₄Me-p)₂(PEt₂Ph)₂(µ-SCN)₂], and [NEt₄]Cl reacts with [Pt₂(C₆H₄Buⁿ-p)₂(PMe₂Ph)₂] to give the salt [NEt₄][Pt(C₆H₄Buⁿ-p)Cl₂(PMe₂Ph)]. Excess of SnRMe₃ causes decomposition of [Pt₂R₂Cl₂L₂] to give the mononuclear complexes [PtR(Cl)L₂]. The carbonyl complexes cis-[Pt(CO)Cl₂L] react with SnRMe₃ to give the binuclear aroyl complexes [Pt₂(COR)₂Cl₂L₂], which also exist in solution as mixtures of cis and trans isomers. These complexes react with neutral ligand species L′= NBuⁿH₂ or P(OPh)₃ to give the mononuclear complexes [Pt(COR)Cl(L)L′]. but cod reacts with [Pt₂(COC₆H₄Bu^t-p)₂Cl₂(PMe₂Ph)₂] to give [Pt(COC₆H₆Bu^t-p)Cl-(PMe₂Ph)₂]. Again excess of SnRMe₃ causes decomposition, to give [Pt(COR)Cl(L)] complexes. Heating of the aroyl complex [Pt₂(COC₆H₄Me-p)₂Cl₂(PEt₃)₂] gives some of the corresponding aryl complex [Pt₂(C₆H₄Me-p)₂-Cl₂(PEt₃)₂]. The ³¹P-{¹H} n.m.r. spectra of the complexes have been recorded, and are used extensively in the identification of products.