Cluster Complexes with Three Cobalt Atoms

1 Cluster Complexes with Three Cobalt Atoms 

The isolation (in rather low yield) of the //-bridging CO isomer CpCo3(/i3-CO)3, 395, together with the known CpCo3(/i2-CO)2(/U3-CO) was achieved by Geiger et 395 displayed near-G3 symmetry with all-Cp being 

The reduction of Cp Co(acac-0,0 ) with potassium metal in pyridine as solvent resulted in the formation of Cp Co(pentamethyl- j -cyclopentadiene) and to the trinuclear cluster (Cp Co)3(/r2-(C5H4N)(/r3-H), 397, containing an orthometallated pyridine ligand.  

While attempting the synthesis of (/t3-arene)Co3 clusters (see Section 7.01.5.1.3.) through the reaction between styrenes and CpCo(C2H4)2, Wadepohl et al. observed, besides the formation of the expected product 399, the double C-H activation reaction at the vinyl unit 400 (Equation (65)).  

A route to new clusters 408 and 409 has been obtained through the reaction between alkynedicobalt hexacarbonyl complexes and Co dimer derivatives (Equation (66)).  

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Cobalt. In cobalt clusters Co3(CO)6( t3-CR)(/t3-l,3,5-trithiane (2,4,6-trisubstituted with alkyl/benzyl substituents, R = Cl, Ph, Me) and Co3(CO)9( t-CPh3)(l,3,5-trithiane), 1,3,5-trithiane also unequivocally occupies the axial coordination sites on the three cobalt atoms <1996JCD1875, 1997JOM(548)263>. Additionally, a number of mixed Ru/Co clusters have been published <1992JOM(436)55>. Besides A, structure G (Figure 8) has also been found for the complex H2Ru4(CO)i2(l,3,5-trithiane). 

Crystal structure analysis of one of these complexes (R = Me) reveals that the three cobalt atoms are arranged linearly [436]. The two terminal ones are equivalent with each being coordinated to a cyclopentadienyl ring and the phosphorus atoms of three phosphonate groups. The middle cobalt atom is located at the center of synunetry of the metal cluster and is surrounded octahedrally by six oxygen atoms. 

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