Synthesis and reactivity of mixed-metal Pd2Mo, PdPtMo and Pd2W clusters containing Ph2PCH2PPh3(dppm) ligands. Molecular structure of 3-CO)2-(μ-dppm)2>

Article abstract of DOI:10.1016/0022-328X(88)89051-X

The quantitative synthesis of the heterotrinuclear chlorocarbonyl clusters (Cp=η-C5H5, dppm=Ph2PCH2PPh2, M1=Pd, M=Mo, 1; M1=Pd, M=W, 2; M1=Pt, M=Mo, 3) was achieved by the reaction of - (M=Mo, W) with the dinuclear d⁹-d⁹ complexes (M1=Pd, Pt) in THF.These clusters are characterized by a triangular metal core, whose Pd-M1 and M1-M edges are bridged by a dppm ligand.The two carbonyl ligands attached to M interact in a triply semi-bridging fashion with the three metals, on either side of the trimetallic plane.The chloride atom is always bonded to the trimetallic core PdM1M via the Pd atom.This was established by an X-ray diffraction study on 1: triclinic, space group P1(C¹_i), with Z=2, a 13.664(2), b 13.946(5), c 18.223(6) Angstroem, α 110.30(3), β 93.89(2), χ 102.22(2) deg, V 3144.3(1) Angstroem³.The number of data used was 5675 (with I>5 ?(I)),giving values of R=0.046 and R_w=0.046 after refinement.In the presence of Tl, clusters 1 and 2 react with CO to give the cationic clusters + (M=Mo, <4>+; M=W, <5>+) which possess a CO ligand terminally bound to Pd, or with THF to give the solvento clusters + (M=Mo, <7>+; M=W, <8>+).The heterotetranuclear metalloligated clusters (M1=Pd, M=Mo, 9; M1=Pd, M=W, 10; M1=Pt, M=Mo, 11) have been prepared from 1-3, respectively.Their relevance to the mechanism of formation of clusters 1-3 is discussed, particularly in view of the lability of their exocyclic, equatorial Pd-M bond.