CHEMISTRY OF POLYNUCLEAR METAL-COMPLEXES WITH BRIDGING CARBENE OR CARBYNE LIGANDS .106. SYNTHESIS AND REACTIONS OF THE ALKYLIDYNE COMPLEXES [M(=CR)(CO)2((C6F5)AUC(PZ)3)](M = W OR MO, R = ALKYL OR ARYL, PZ = PYRAZOL-1-YL) - CRYSTAL-STRUCTURE OF [WPTAU(C6F5)(MU-3-CME)(CO)2(PME2PH)2((C6F5)AUC(PZ)3)]

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(mu-CMe)(CO)2{(C6F5)AuC(pz)3}] (X = Cl or C6F5), [WCo2(mu-3-CR)(CO)8{(C6F5)AuC(pz)3}], [WPt(mu-CR)(CO)2(PMePh)2{(C6F5)AuC(pz)3}], and [W2Pt(mu-CR)2(CO)4{(C6F5)AuC(pz)3}2]. The cluster compound [WPtAu(C6F5)(mu-3-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) angstrom] assymmetrically capped by an ethylidyne group [mu-C-W 2.06(3), mu-C-Pt 2.05(3), and mu-C-Au2.31 (3) angstrom]. 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)-degrees] and W-Au [W-C-O 165(3)-degrees] bonds. The Pt atom carries the PMe2Ph groups [P-Pt 2.26(1) and 2.32(1) angstrom], and the Au atom is co-ordinated by the C6F5 group [C-Au 2.04(3) angstrom]. The W atom is ligated by the three nitrogens of the (C6F5)AuC(pz)3 moiety (N-W average 2.21 angstrom). The n.m.r. data (H-1, C-13-{H-1}, P-31-{H-1}, and F-19-{H-1}) for the new compounds are reported and discussed where appropriate.