Organometallic compounds bridging ligands

Furan is typically tiVC) coordinated in a series of organometallic compounds. However, it is its ti (C=C) coordination that opened a perspective toward a broad series of derivatized furans. It can be a bridging ligand forming (C=C)... 

The first organometallic compound of the transition metals to be characterized (1827) was Zeise s salt, K[(C2H4)PtCl3]-H20 (Fig. 18.1). It forms when K2[PtCl4] in aqueous ethanol is exposed to ethylene (ethene) a dimeric Pt—C2H4 complex with Cl bridges is also formed. In both species, the ethylene is bonded sideways to the platinum(II) center so that the two carbon atoms are equidistant from the metal. This is called the dihapto-or T]2 mode. A ligand such as an allyl radical with three adjacent carbons directly bonded to a metal atom would be trihapto- or t 3, and so on. 

Molybdenum(II) and molybdenum(III) form an extensive array of multiply bonded dimers, which contain Mo-Mo quadruple and triple bonds respectively. Much of the organometallic chemistry of this class of compound has come principally from the work of one research group. Homoleptic compounds suchas [Mo2Me8]" , [Mo() -allyl)4], which contains bridging and terminal allyl ligands (see Bridging Ligand), are readily synthesized from [Mo2(OAc)4]... 

A large number of mixed-metal organometallic compounds have been prepared in which the hydrocarbon ligands bridge the lithium and the other metal atoms. These mixed-metal analogues of type II, B organolithium... 

Reactions with BucNC lead to new organometallic compounds containing an 72-C,N-bound cyclopentadiene imine, which was structurally characterized as a pyridine adduct (Scheme 118). Reactions with benzonitrile lead to the elimination of 1 equiv. of the corresponding pyridine and formation of the dimeric titanium derivative (ArO)2Ti(/x-PhCN)2Ti(OAr)2 containing two bridging benzonitrile ligands. The compound has been structurally characterized... 

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