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]

Two novel mixed metal rhodium-platinum clusters have been synthesized by the reaction of [Rh-4(CO)(12)] with [Pt(PPh3)(3)]. The structure of [Rh2Pt3(mu-CO)(5)(CO)(4)(PPh3)(3)] 1 has been established by a single cryst al X-ray diffraction study. The tetranuclear cluster [Rh2Pt2(mu-CO)(3)(CO)(4)(PPh3)(3)] 2 has been characterised by FAB mass spectrometry and shown by various multinuclear NMR techniques (C-13, P-31, (P-31-P-31) COSY and (C-13-Rh-103) and (P-31-Rh-103) 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.