The complex [Pt3Gt3-CO) (#t-dppm)3]2+ (1; dppm = Ph2PCH2PPh2) adds phosphorus donors L to give the adducts [Pt3U3-CO)(M-dppm)3L]2+ (2), where L = P(OMe)3 (2a), P(OEt)3 (2b), P(OPh)3 (2c), PMe2Ph (2d), PMePh2 (2e), PPh3 (2D, PF3 (2g). Complexes 2a-d are thermally stable, but 2e-g readily dissociate the phosphorus donor ligand to regenerate 1. Complex 2c has been characterized crystallographically.The phosphite ligand binds as a terminal ligand to a single platinum center, and the triply bridging carbonyl ligand is bound most strongly to the same platinum atom. The same structure is believed to be present in solutions of 2a-f at low temperature, but the complexes 2a-e exhibit a new type of fluxionality at higher temperatures in which the phosphorus donor ligand migrates around the Pt3 triangle. The "time-averaged" structure therefore appears to have a µ3-3 ligand. For complex 2g, the fluxional process was not frozen out at -90 °C and it is possible that the 3(µ3-3) group is present in the ground state.
Novel complexes containing Pt3 (p3-SnX3) groups have been prepared by reaction of [Pt3(p3-CO)(p-dppm)3][PF6]2 (dppm = Ph2PCH2PPh2) with organotin hydrides or with SnX3-and are of interest as possible models for heterogeneous Pt-Sn/support catalysts; the structures of [Pt3{ p3-SnMe2(P02F2)} ( p -d ~p m ) ~] + and disordered { [Pt3(p3-snF3)(p3-CO)(p-dppm)~][PFGI)0.~~ [Pt3(p3-SnF3)(p3-CI)(p-dppm)310.25 are determined, the latter being the first SnF3-complex to be crystallographically characterized.Pt-Sn complexes and Pt-Sdsupport combinations are very Ph2PCH2PPh2), which can mimic some properties of a Pt useful in homogeneous and heterogeneous catalysis, respec-~u r f a c e . ~ The only structurally characterized Pt3Sn complexes tively.1-2 In the heterogeneous system there is much tin(11)3 as appear to be [Pt3(p3-SnC13)&od),1 (cod = cyclo-octa-1,5well as tin(0) and this prompted a study of how tin(I1) diene)s*6 and the p2-Sn species [Pt3(CO)3{p2-Sn(NR2)2}3] (R fragments might interact with the co-ordinatively unsaturated = SiMe3).7 Some results are given in Scheme 1. cluster cation [Pt3( p3-CO)(p-dppm)3]2+, (1) (dppm = Initially, reactions of (l), as the PF6salt, with organotin
The q2-C,C vinyl complexes [M{q3-C(CF,)C(CF,)SR}(CF3C=CCF,)(q5-C5H5)] 1 (M = Mo, R = Pr'; M = W, R = Me, Et or Pr') reacted with dimethyl acetylenedicarboxylate R ' C X R ' (R' = C0,Me) to give products of alkyne trimerisation containing two different oligomerisation sequences depending on whether R ' C K R ' occupies a terminal or central position in the alkyne trimer chain, i.e.
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