Synthesis and structural characterization of polynuclear complexes containing the eight-electron donor bis(diphenylphosphino)methanediide ligand

Abstract

The compound [AuR₂{(Ph₂P)₂CH}](R = C₆H₅) reacts with various gold(I) or silver(I) compounds possessing a labile ligand such as tetrahydrothiophene or perchlorate to give [AuR₂{(Ph₂P)₂CH(ML)}]ClO₄(ML = AuPPh₃, AuCH₂PPh₃ or AgPPh₃). Treatment of these derivatives with [Au(acac)(PPh₃)] or [N(PPh₃)₂][Au(acac)Cl](acac = acetylacetonate) leads to [AuR₂{(Ph₂P)₂C(AuPPh₃)(ML)}]ClO₄ or [AuR₂{(Ph₂P)₂C(AuPPh₃)(AuCl)}], in which the doubly deprotonated bis(diphenylphosphino)methanediide ligand is an eight-electron donor. The compound [AuR₂{(Ph₂P)₂C(AuPPh₃)₂}]ClO₄ can also be obtained by reaction of [AuR₂{(Ph₂P)₂CH₂}]ClO₄ and [Au(acac)(PPh₃)] in 1 : 2 molar ratio. The reaction of [AuR₂{(Ph₂P)₂CH(AuR)}] with [Au(acac)(PPh₃)] or [N(PPh₃)₂][Au(acac)Cl] gives the trinuclear complexes [AuR₂{(Ph₂P)₂C(AuR)(AuPPh₃)}] or [N(PPh₃)₂][AuR₂{(Ph₂P)₂C(AuR)(AuCl)}], whereas it reacts with [N(PPh₃)₂][Au(acac)₂](molar ratio 2 : 1) affording the pentanuclear complex [N(PPh₃)₂][{AuR₂[(Ph₂P)₂C(AuR)]}₂Au]. Another pentanuclear derivative [{AuR₂[(Ph₂P)₂C(AuPPh₃)]}₂Au]ClO₄ is obtained by treatment of [{AuR₂[(Ph₂P)₂CH]}₂Au]ClO₄ with 2 equivalents of [Au(acac)(PPh₃)]. The compounds were characterized by elemental analysis, IR and NMR spectroscopy, and some by fast atom bombardment mass spectrometry. The crystal structure of [AuR₂{(Ph₂P)₂C(AuPPh₃)₂}]ClO₄·CH₂Cl₂ was confirmed by X-ray diffraction analysis. The complex contains a triangular Au₂C unit with a short Au ⋯ Au contact of 2.826(2)Å and a narrow Au(1)–C(1)–Au(2) angle of 85.4(7)°.