Cyclopentadienyl ligand Group 2 compounds

It has been reported that the steric requirements of the (ij5 -C5 Hs ) group are approximately equal to that of 2.5 carbonyl groups159, although again the homogeneous distribution of cyclopentadienyl ligands around a cluster is often limited. Actually, the compound Fe4(CO)4Cp4, which has the structure shown in Fig. 7, formally corresponds to the unknown Fe4(C0)i4. 

King 118) has studied the spectra of some indenylmolybdenum carbonyl compounds and has observed that the indenyl ligand fragments by loss of acetylene in a similar manner to the fragmentation of the cyclopentadienyl ligand. The molecular ion of C9H7Mo(CO)3Me (V) exhibits stepwise loss of the CO groups, but after the loss of one CO, loss of methyl competes with loss of CO. 

The anionic complex, in which three dicarbonyl(cyclopentadienyl)manganese groups are connected by a bridging methanetellurolate ligand, was obtained from the corresponding /r3-tcllurido compound and methyl lithium. 

Some of the most extensively explored univalent group 13 compounds are the various cyclopentadienyl half-sandwich complexes of the general formula Cp M, where Cp is any cyclopentadienyl ligand and M is Al, Ga, In, and Tl. For Al and Ga, these compounds are typically prepared by the reduction of suitable dihalogenated M precursors, as outlined in Scheme 4, and they may also be prepared from available univalent halide precursors. For Cp ligands bearing relatively small substituents, Cp M compounds tend to form polyhedral (Cp M) clusters in the solid state and dissociate into monomers in both solution and the gas phase a depiction... 

FIG. 21. chemical shift chart for diamagnetic V — i). V(0). V( +i), and V( +v) compounds relative to external VOCI3, positive values indicating relative deshielding. Abbreviations Cp = cyclopentadienyl, L = Group V donor ligand. (189)... 

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