Chemistry of polynuclear metal complexes with bridging carbene or carbyne ligands. Part 59. Reactions of the alkylidyne compounds [M(CR)(CO)2{HB(pz)3}][M = Cr, Mo, or W, R = C6H4Me-4; M = W, R = Me, HB(pz)3= hydrotris(pyrazol-1-yl)borate] with d10 complexes; crystal structure of [PtW2(µ-CMe)2(CO)4{HB(pz)3}2]

Abstract

Treatment of the compound [W(CMe)(CO)₂{HB(pz)₃}][{HB(pz)₃}= hydrotris(pyrazol-1-yl)borate] with [Ni(cod)₂](cod = cyclo-octa-1,5-diene) or [Pt(C₂H₄)₃] affords the trimetal complexes [M′W₂(µ-CMe)₂(CO)₄{HB(pz)₃}₂](M′= Ni or Pt). Similarly, reactions between the species [M (CC₆H₄Me-4)(CO)₂{HB(pz)₃}](M = Cr, Mo, or W) and [Pt(C₂H₄)₃] yield the related compounds [PtM₂(µ-CC₆H₄Me-4)₂(CO)₄{HB(pz)₃}₂]. The molecular structure of [PtW₂(µ-CMe)₂(CO)₄{HB(pz)₃}₂] has been established by X-ray diffraction. The molecule has a nearly linear W–Pt–W spine [172.8(1)°], with mean Pt–W separations of 2.716 Å. Each metal–metal bond is bridged by an ethylidyne group [mean values µ-C–W 1.885, µ-C–Pt 2.040 Å] and semi-bridged by a carbonyl ligand [W–C–O 166°]. The dihedral angle between the two dimetallacyclopropene rings is 79°. Each tungsten atom carries a terminally bound CO ligand and a HB(pz)₃ group. If the metal–metal bonds are ignored, each tungsten is in a pseudo-octahedral environment defined by the three nitrogen atoms of its associated HB(pz)₃ ligand, the two CO groups and a µ-CMe fragment. A gold salt [AuW₂(µ-CMe)₂(CO)₄{HB(pz)₃}₂][PF₆] has been obtained by treating [W(CMe)(CO)₂{HB(pz)₃}] with [AuCl(tht)](tht = tetrahydrothiophene) in the presence of TIPF₆. Reactions between the complexes [M(CR)(CO)₂{HB(pz)₃}](M = Cr, Mo, or W, R = C₆H₄Me-4; M = W, R = Me) and [Pt(C₂H₄){P(OMe)₃}₂] give dimetal compounds [PtM(µ-CR)(CO)₂{P(OMe)₃}₂{HB(pz)₃}], but only the ethylidyne-bridged platinum–tungsten compound is reasonably stable in solution. A molybdenum–platinum salt formulated as [PtMo{µ-σ:η³-CH(C₆H₄Me-4)}(CO)₂{P(OMe)₃}₂{HB(pz)₃}][BF₄] has also been prepared. Spectroscopic data for the new compounds are reported.