Synthesis and structural characterisation of the mixed metal clusters [Rh2Pt3(µ-CO)5(CO)4(PPh3)3] and [Rh2Pt2(µ-CO)3(CO)4(PPh3)3]; crystal structure of [Rh2Pt3(µ-CO)5(CO)4(PPh3)3]†

Abstract

Two novel mixed metal rhodium–platinum clusters have been synthesized by the reaction of [Rh₄(CO)₁₂] with [Pt(PPh₃)₃]. The structure of [Rh₂Pt₃(µ-CO)₅(CO)₄(PPh₃)₃] 1 has been established by a single crystal X-ray diffraction study. The tetranuclear cluster [Rh₂Pt₂(µ-CO)₃(CO)₄(PPh₃)₃] 2 has been characterised by FAB mass spectrometry and shown by various multinuclear NMR techniques (¹³C, ³¹P, {³¹P–³¹P} COSY and {¹³C–¹⁰³Rh} and {³¹P–¹⁰³Rh} heteronuclear multiple quantum coherence, HMQC) to adopt a butterfly type structure. The carbonyl migration pathways in 2 have been established by a combination of EXSY and 1-D variable temperature measurements; independent localised exchange about the hinge rhodium atoms and interchange of bridging and semi-bridging carbonyls on the Pt–Rh bonds occur.