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.
Cluster [WRe2(C5Me5)(O)(C0),(CCPh)] l a possessing a terminal 0x0 ligand is prepared by treatment of the acetylide cluster [WRe2(C5Me5)(C0),(CCPh)] with O2 or N20; hydrogenation of l a affords three isolable clusters, showing an example of 0x0-ligand mediated sequential conversion of acetylide t o alkenyl and alkylidene.
The title complex (II~-C~H~)WRU,(CO),(~-NP~)(CZCP~), containing a bridging imido ligand and a p4-V2-acetylide ligand, has been prepared by means of the condensation between ( T ~~-C ~H ~) W ( C O ) ~C = C P ~ and Ru~(CO)&~-NP~), and its reactions with dihydrogen and disubstituted alkyne ligands are presented; the products have been fully characterized by spectroscopic methods and X-ray diffraction studies for two complexes.
Treatment of O S~( C O )~O ( C J~~Z ) with C p W -(CO)z(=CTol) produced the alkylidyne-alkyne cluster C~WOS~(CO)IO(~~~-CM~)(CM~CTO~) (2) and the dimeta 1 loa 1 ly 1 complex C p WOs3(CO),[C(Me) C(Me) C( To01 (3) in sequence. Thermolysis of 3 induced the selective scission of one C-C bond t o give a second alkylidynealkyne cluster, Cp WOS~(CO)B(~~-CTO~)(CJ~~Z) (4, providing a model of alkyne metathesis through a dimetalloallyl intermediate.We have recently prepared and examined the reactivity of Os3W clusters with ligated Cq hydrocarbons by addition of tungsten acetylide complexes to Os3 alkyne complexes.' Our work has been motivated by attempts to develop a generalized strategy to mixed-metal clusters2 and to learn about the reaction pathway of chemisorbed hydrocarbon intermediates on metal surface^.^ This investigation is now extended to tetranuclear Os3W cluster compounds with the asymmetric C3 dimetalloallyl ligand p3-q3-C(Tol)C(Me)C(Me). Before our investigation of these tetranuclear dimetalloallyl clusters, others have also studied syntheses and reactivities of dinuclear and trinuclear derivative^.^ Among the various chemical reactions probed, that of forming and breaking the C-C bond is important because it provides valuable mechanistic insight into alkyne metathe~is.~ In this paper, we report a novel example of transformation of ligand pairs [p3-CMe + MeCzTol] to [p&Tol+ MeC2Mel through the ~ t National Tsing Hua University. ligand ~13-q3-[C(Tol)C(Me)C(Me)l. This experimental result substantiates an earlier report by Stone and coworkers, who demonstrated that two ligated CS allyl fragments, differing in the arrangement of substituents, were produced via cleavage and formation of a C-C bond, providing compelling evidence for scrambling of [CR + R'CzR'] and [CR' + R'CzRl fragments? Such rearrangement on metal complexes is noteworthy because it could in theory allow a dimetalloallyl species to be considered a possible intermediate of catalytic alkyne metathesis.The alkyne cluster Os3(CO)&2Mez) (1) reacts with approximately 3 equiv of CpW (C0)2(=CTol) in refluxing toluene solution (30 min) to afford the red-orange alkylidyne-alkyne complex CpWOs3(CO)&&Me)(CMeC-Tol) (2) and dark green dimetalloallyl complex CpWOs3-(CO)s[C(Me)C(Me)C(Tol)l (3) in 27 and 38% yields, respectively. These two cluster compounds were fully characterized by spectroscopic7 and X-ray measuremenh8The X-ray analysis of 2 indicated that it consists of a OSSW butterfly arrangement with the W atom located at the hinge position ( Figure 1). The alkylidyne group, which connects to both wingtip Os atoms with two long bonds (2.23(2) and 2.13(2) A) and to the W atom with a short interaction (2.01(2) A), carries a methyl substituent but not a tolyl substituent. This information suggests that the alkylidyne ligand is derived from the 2-butyne ligand but not from the CTol unit of CpW(C0)2(=CTol). In addition, the ligated alkyne [C(Me)C(Tol)l, generated from coupling of the second CMe unit and the incoming CTol fragment, lies on the W-Os(l)-Os(2) face o...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.