Chemistry of polynuclear metal complexes with bridging carbene or carbyne ligands. Part 106. Synthesis and reactions of the alkylidyne complexes [M(CR)(CO)2{(C6F5)AuC(pz)3}](M = WorMo, R = alkyloraryl, pz = pyrazol-1-yl); crystal structure of [WPtAU(C6F5)(µ3-CMe)(CO)2(PMe2Ph)2{(C6F5)AuC(pz)3}]

Abstract

Treatment of the salts [M (CR)(CO)₂{HC(pz)₃}][BF₄][M = W or Mo, R = alkyl or aryl, HC(pz)₃= tris(pyrazol-1 -yl)methane] in thf (tetrahydrofuran) with NaOEt, followed by [Au(C₆F₅)(tht)](tht = tetrahydrothiophene), affords the neutral alkylidynemetal compounds [M(CR)(CO)₂{(C₆F₅)AuC(pz)₃}](M = W or Mo, R = C₆H₄Me-4; M = W, R = Me or C₆H₃Me₂-2,6). The complexes (M = W, R = Me or C₆H₄Me-4) have been used to prepare several compounds containing heteronuclear metal–metal bonds, including [WAuX(µ-CMe)(CO)₂{(C₆F₅)AuC(pz)₃}](X = Cl or C₆F₅), [WCo₂(µ₃-CR)(CO)₈{(C₆F₅)AuC(pz)₃}], [WPt(µ-CR)(CO)₂(PMe₂Ph)₂{(C₆F₅)AuC(pz)₃}], and [W₂Pt(µ-CR)₂(CO)₄{(C₆F₅)AuC(pz)₃}₂]. The cluster compound [WPtAu(C₆F₅)(µ₃-CMe)(CO)₂(PMe₂Ph)₂{(C₆F₅)AuC(pz)₃}] has been synthesised by different routes, and its structure established by X-ray diffraction. The core of the molecule consists of a WPtAu triangle [W–Pt 2.798(2), W–Au 2.841(2), and Pt–Au 2.932(2)Å] asymmetrically capped by an ethylidyne group [µ-C–W 2.06(3), µ-C–Pt 2.05(3), and µ-C–Au 2.31 (3)Å]. The latter lies appreciably further from the Au atom than from the W or Pt atoms. The two carbonyl ligands semi-bridge the W–Pt [W–C–O 160(2)°] and W–Au [W–C–O 165(3)°] bonds. The Pt atom carries the PMe₂Ph groups [P–Pt 2.26(1) and 2.32(1)Å], and the Au atom is co-ordinated by the C₆F₅ group [C–Au 2.04(3)Å]. The W atom is ligated by the three nitrogens of the (C₆F₅)AuC(pz)₃ moiety (N–W average 2.21 Å). The n.m.r. data (¹H, ¹³C-{¹H}, ³¹P-{¹H}, and ¹⁹F-{¹H}) for the new compounds are reported and discussed where appropriate.