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

Two novel mixed metal rhodium-platinum clusters have been synthesized by th e reaction of [Rh-4(CO)(12)] with [Pt(PPh3)(3)]. The structure of [Rh2Pt3(m u-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 adop t a butterfly type structure. The carbonyl migration pathways in 2 have bee n established by a combination of EXSY and 1-D variable temperature measure ments; independent localised exchange about the hinge rhodium atoms and int erchange of bridging and semi-bridging carbonyls on the Pt-Rh bonds occur.