Carbido clusters bonding

Addition of electrophilic metal reagents to ketenylidene (CCO) clusters is a source of several carbido clusters via cleavage of the C-CO bond.468... 

The reactions between W4(OR)i2 (R = CH2Pr , CH2-c-Pent) and the isonitriles RNC (R = Bn, CH2Ph, CeH2Me3-2,4,6) in hydrocarbon solvents yielded /u,4-carbido clusters W4(/Li4-C)(OR)i4 by cleavage of the C=N bond. ° " By contrast, under similar conditions, the tetranuclear alkoxides fail to react with nitriles (MeC N and NC(CH2)sCN) and internal alkynes (MeC CMe, EtC=CEt). 

Cu couple) affords a mixture of the /i3-vinylidene 78, /i3-ethynyl 79, and /X3-C=GOTiCl(THF)4 complexes 80, of which 78 and 79 result from reductive C-O bond cleavage reactions (Scheme 9). On the other hand, condensation of the (/ 3-chloromethylidyne)tricobalt cluster compound, Co3(GO)9(/X3-GCl), with 76 produces the heterometallic fi -carbido cluster compound, [Fe3Go3(/X6-G) //3-GG(=0)0Et (G0)i8] 81 (after treatment with EtOH), with retention of the G-G=0 linkage in contrast to the reaction with [Fe3(GO)n] , which affords the /x-G2-complex, Fc Co2, fJ.e-G2)(GO)i7 82, via a G-G coupling reaction/ ... 

F.G.A. Stone Yes, I would expect cleavage of the W=C bond in [(n-C5H5)(0C)2W=CR] to occur in certain reactions. Indeed, we believe we have observed C=W bond cleavage in a reaction of the tungsten compound with a carbido(carbonyl)iron cluster. Interestingly, [(n-C5H5)(0C)2W=CR] reacts with sulphur to yield [(n-C5H5)(0C) W S CR S] (I. Moore, Bristol University). 

Heating 26 with an excess of PPhj under pressure in chlorobenzene leads to the loss of one coordination site. One more Os-Os bond is broken upon formation of the complex Os3(CO)6(CNR)(p3-CNCH2QH4)-(PPh3)(p-PPh2)(p-T r -C6o) [74], The T r binding mode observed in this complex is very unusual for Cg0. One further example, where can act as a four-electron ligand is the fullerene carbido pentaosmium cluster complex 28 shown in Scheme 7.13 [75,76], The ri T -complex 28 is formed in a mixture with the normal T r r carbido pentaosmium complex 27. The two complexes can be converted into one another at elevated temperatures. 

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