CARBONYLMETALATE-INDUCED PHOSPHORUS MIGRATION AND PH2PCH2PPH2-(DPPM-) ASSISTED SYNTHESIS OF BIMETALLIC COMPLEXES AND CLUSTERS OF PD AND PT WITH MO, W, MN, AND CO

The new triangular clusters [PtCo2(CO)7(mu-dppm)] (1), [PtMo2Cp2(CO)5(mu-dppm)] (2), and [PtW2Cp2(CO)5-(mu-dppm)] (3) were obtained from the reactions of[PtCl2(eta2-dppm)] with 2 equiv of the carbonyl metalates[CO(CO)4]-, [MO(CO)3CP]-, or [W(CO)3CP]-, respectively. In the case of [Mn(CO)5]- and depending on the stoichiometry used, the bimetallic [(eta2-dppm)PtCl{Mn(CO)5}] (4) or the trinuclear chain [(OC)5MnPt(CO)(mu-dppm)Mn(CO)4] (5) were obtained instead. Clusters 2 and 3 react reversibly with CO to give respectively the chain complexes [CP(OC)3MoPt(CO)(mu-dppm)MO(CO)2CP] (6) and [Cp(OC)3WPt(CO)(mu-dppm)W(CO)2CP] (7), analogous to 5. Cluster 1 undergoes CO substitution by dppm to give [PtCo2(CO)5(mu-dppm)2] (8) in which the Pt-Co bonds are bridged by dppm ligands. Dppm also reacts with clusters 2, 3, and 5 to afford the bimetallic ionic complexes [(eta2-dppm)Pt(mu-dppm)MO(CO)2CP] [MO(CO)3CP] (9), [(eta2-dppm)Pt(mu-dppm)W(CO)2CP][W(CO)3CP] (10), and [(eta2-dppm)Pt(mu-dppm)Mn(CO)4] [Mn(CO)5] (11). Alternatively, these complexes as well as the analogous [(eta2-dppm)Pt(mu-dppm)CO(CO)3][CO(CO)4] (12) may be prepared from [Pt(eta2-dppm)2]Cl2 and the corresponding carbonylmetalates. The reaction of [PdCl2(eta2-dppm)] with 2 equiv of the carbonylmetalate [CO(CO)4]- affords at -30-degrees-C the cluster [PdCo2(CO)7(mu-dppm)] which was not isolated but is analogous to 1. In solution, this cluster undergoes a redox process leading to the known [Pd2Co2(CO)7(mu-dppm)2] (13) or, alternatively, reacts with dppm to yield the stable complex [PdCo2(CO)5(mu-dppm)2] (14), analogous to 8. The latter cluster was also prepared from [Pd(eta2-dppm)2][BF4]2 and 2 equiv of [CO(CO)4]-. If chloride ions are added in the latter reaction, [ClPd(mu-dppm)2Co(CO)2] (15) is formed instead. It reacts in toluene with [CO(CO)4]- to give [(OC)4CoPd(mu-dppm)2Co-(CO)2] (16), which transforms slowly in 14 by loss of CO and formal insertion of a CO(CO)3 moiety into a Co-P bond. On the basis of these results, the influence of the nature of the d8 metal (Pd or Pt), of the carbonylmetalates, and of the dppm stoichiometry on the structure of the products is discussed.