Heterometallic ketenyl complex Os&O)1O(p-H) [C(O)CH2(W(CO)&p)l (la) possessing a pendant CpW(CO)3 substituent was prepared by condensation of O S ~( C O ) ~O ( N C M ~) ~ with the metal-aldehyde complex CpW(CO)&H2CHO. Pyrolysis of la in the solid state a t 185 OC afforded two heteropentametallic cluster compounds, C~~W~OS~(CO)~~(~-O)(II~-CM~) (2) and CpWOs4-(CO)12(p-O)(p3-CMe) (3), demonstrating a unique example of C-0 bond scission of a ligated ketene fragment and a cluster aggregation process. Complex 2 crystallizes in orthorhombic space group Pnma with a = 18.913(4) A, b = 16.229(3) A, c = 9.129(2) A, 2 = 4, R = 0.054, and R, = 0.055 for 2551 observed reflections. The W20s3 cluster t h a t contains 72 cluster valence electrons has a distorted square-pyramidal array of metal atoms with one Os-H-0s hydride ligand, one bridging oxo ligand associated with a W-W double bond, and a n ethylidyne ligand bridging a unique W20s triangle. Crystals of 3 are monoclinic of space group P21/n with a = 15.941(2) A, b = 19.395(4) A, c = 16.369(4) A, ,t? = 94.72(2)', 2 = 8, R = 0.050, and R, = 0.041 for 6568 observed reflections. This molecule possesses a WOS4 trigonal-bipyramidal skeleton with an oxo ligand bridging a W-Os edge and a n ethylidyne ligand capping a WOs2 face.
Condensation of the triosmium acetonitrile complex Os3(CO)~ù(NCMe) e with the sulfido complex CpW(CO)3(CHeSMe ) in refluxing THF solution produced three sulfur-containing compounds Os3(2) and CpWOs3(CO)I_~(II-CH~_)(t*-SMe) (3). Clusters 2 and 3 were products involving a 1:1 combination of starting materials and were characterized by X-ray diffraction studies. Crystals of 2 belongs to monoclinic space group P 2z/« with a=8.418(2), b=11.912(2),
The heterometallic tetranuclear ketenyl compound [Os,(CO),,(p-H){C(O)CH,W(CO),(q-C,Me,)}] 1 possessing a pendant W(q-C,Me,) (CO), substituent is prepared by condensation of [Os,(CO),,-(NCMe),] with the aldehyde complex [W(q-C,Me,)(CO),(CH,CHO)].Pyrolysis of 1 in the solid state at 185 "C afforded four tetrahedral compounds [WOs,(q-C,Me,) (CO),(p-0) (p,-CMe)] 2, [WOs,(q-C,Me,) (CO),(p-0) (p-H) (p-CHMe) J 5. [WOs,(q-C,Me,) (CO),,(p,-CMe)] 3 and [WOs,(q-C,Me,) -(CO),,(p,-CH)] 4, demonstrating a unique example of C-0 bond scission for the ligated ketene fragment. Since treatment of 2 with H, in toluene also afforded 5 in moderate yield, it is highly probable that the latter is produced via reaction with trace amounts of H, generated from the decomposition of 1. The molecular structures of 2 and 4 have been determined by single-crystal X-ray analysis.The chemistry of organic ketene molecules as well as of organometallic ketenyl complexes has been investigated extensively, ' since ketenes are important reagents in organic synthesis and ligated ketenes can serve as intermediates in hydrocarbon chain growth in CO-reduction reactions2 Diand tri-nuclear ketene complexes have been synthesised by coupling of methylene and carbon monoxide: several research groups have demonstrated that ligated methylene can link with CO to give ketene, and that the resulting ketene fragments undergo isomerization to afford a formylmethylene ligand4 and dehydration to afford a ligated acetylide fragment., Further treatment of ketene complexes with alcohol led to formation of acetate,6 while reaction with dihydrogen gives aldehydes,' reactions with electrophiles, such as H + or Me', give acyl and vinyl ligands,8 and with diazomethane affords an oxalyl ligand.9In this paper, we describe the preparation of a ketenyl comreaction of the aldehyde complex w ( q -C ,Me,)(CO),(CH,-CHO)] with [Os,(CO),,(NCMe),]. As one of our research goals is to generate heterometallic clusters, ' O we studied the solid-state pyrolysis of 1 in an attempt to generate direct W-Os bonding between the Os, triangle and the W(q-C,Me,)(CO), fragment through thermally induced CO elimination. Several tetrahedral clusters containing 0x0, alkylidyne and alkylidene functional groups were isolated, producing strong evidence for cleavage of the ketenyl C-O bond. Related C-O bond scission has been observed for the triply bridging acyl ligand of the rhomboidalclusters [MOs,(q-C,Me,)(CO) {p3-q 2-C(0)CH2-plex [Os3(CO)io(p-H){ C(~)CH~W(C~)~(~-C,M~S)}~ 1 via C&Me-p)] (M = W or Mo). '' ExperimentalGeneral.-Infrared spectra were recorded on a Bomen M-100 FT-IR spectrometer, 'H and 13C NMR spectra on a Bruker AM-400, Varian Gemini-300 or Varian Unity-400 instrument. Chemical shifts are quoted with respect to internal SiMe, ('H and 13C). Mass spectra were obtained on a JEOL-HXllO instrument operating in fast atom bombardment (FAB) mode. All reactions were performed under a nitrogen atmosphere using deoxygenated solvents dried with an appropriate reagent.
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