Synthesis and structural characterization of methanide silver(I) complexes. Unprecedented co-ordination of the methanide ligand in [Ag2(PPh3)2(SPPh2CHPPh2CHCO2Me)]ClO4·4CH2Cl2

Abstract

The mixed phosphine-phosphonium salt [PPh₂CH₂PPh₂CH₂CO₂Me]ClO₄ reacts with [Ag(acac)(PPh₃)](acac = acetylacetonate), with deprotonation of the ligand, displacing acac as acetylacetone and yielding the complex [Ag(OClO₃)(PPh₃)(PPh₂CH₂PPh₂CHCO₂Me)], where the methanide ligand chelates the four-co-ordinate metal centre. The sulfide or oxide derivatives [XPPh₂CH₂PPh₂R]ClO₄(X = S or O; R = Me or CH₂CO₂Me) also react with [Ag(acac)(PPh₃)] in various stoichiometries to give [Ag(PPh₃)(XPPh₂CHPPh₂Me)]ClO₄ or [Ag₂(PPh₃)₂(XPPh₂CHPPh₂CHCO₂Me)]ClO₄; in the latter the methanide ligand co-ordinates both silver atoms through four donor centres (X, C, C, CO). Two of these derivatives have been characterized by X-ray analysis: [Ag(OClO₃)(PPh₃)(PPh₃(CH₂PPh₂CHCO₂Me)] crystallizes in the monoclinic space group P2₁/n, a= 12.448(4), b= 21.021(7), c= 19.803(7)Å, β= 108.60(3)°, Z= 4, T=–100 °C; [Ag₂(PPh₃)₂(SPPh₂CHPPh₂CHCO₂Me)]ClO₄ crystallizes in the same space group with a= 13.759(3), b= 12.074(3), c= 43.353(9)Å, β= 92.62(2)°, Z= 4, T=–100 °C.