Structural/bonding insights from new geometrical varieties of two Pt–Au carbonyl/phosphine clusters, [Pt3(AuPPh3)5(μ2-CO)2L3]+ (L3 = (CO)2PPh3) and [(μ6-Au){Pt3(μ2-CO)3L4}2]+ (L = PMe3)

Abstract

Structural/bonding considerations of two new Pt–Au clusters, [Pt₃(AuPPh₃)₅(μ₂-CO)₂(CO)₂PPh₃]⁺ (1) and [(μ₆-Au){Pt₃(μ₂-CO)₃(PMe₃)₄}₂]⁺ (2) isolated (as chloride salts), revealed: (i) that the heretofore unknown 20-electron Pt-centered Pt₂Au₅ icosahedral cage fragment (five missing vertices) of 1 is best viewed as a 44-electron triangular Pt₃ adduct of a nearly planar 39-electron [Pt₃(μ₂-CO)₂L₃]⁺ (L₃ = (CO)₂PPh₃) and five one-electron donating AuPPh₃ ligands; and (ii) that the geometrically distorted trimethylphosphine “full” Pt₃AuPt₃ sandwich of 2 is the first example of two nucleophilic 44-electron triangular Pt₃(μ₂-CO)₃L₄ (3 : 3 : 4) units (L = PMe₃) which asymmetrically encapsulate a central electrophilic Au(I).