Hydrido-carbonyl complexes, structures

The reductive dehalogenation of haloalkanes has also been achieved in high yield using polymer supported hydridoiron tetracarbonyl anion (Table 11.15). In reactions where the structure of the alkyl group is such that anionic cleavage is not favoured, carbonylation of the intermediate alkyl(hydrido)iron complex produces an aldehyde (see Chapter 8) [3]. 

The carbonylation of methane is catalyzed by RhCl(P(CH3)3)3 under irradiation to yield acetaldehyde (eq. (49)) (11). The utilization of dense CO2 as a stable and CH4-miscible reaction medium is the key to accomplish the reaction. The reaction presumably proceeds via the oxidative addition of the C—H bond to the rhodium center. The C—H oxidative addition product obtained from RhCl(P(CH3)3)3 and benzene was successfully isolated, and the structure was unambiguously determined by X-ray analysis (compound B, eq. (50) (76). The resulting complex is a (phenyl)(hydrido)rhodium complex, as expected and gave benzene and benzaldehyde upon treating with CO. 

Fig. 11.12 Equilibrium between methyl and /i-hydrido-/i-methylene structures in an osmium carbonyl complex.

In 2003, Morales-Morales and Jensen reported [35] on the reactivity of different (PCP)Ir derivatives with carbon monoxide. Thus, direct reactions of the dihydride species (82) (in the presence of TBE), dinitrogen (83), and hydrido-hydroxy (84) afforded the (PCP)Ir(I) carbonyl complex (85) (Scheme 2.38). Worth noting is the reaction of compound (84) with CO, which besides complex (85) also affords a very small amount of a pale yellow air sensitive (PCP)Ir(I) carboxyl compound (86) (Scheme 2.38). The structure of this compound was unequivocally determined by single-crystal X-ray diffraction analysis. 

A few representative examples of simple organometallic compounds of nickel(II) including carbonyl and hydrido compounds are reported here. A more complete listing of such types of compound is given in Comprehensive Organometallic Chemistry (vol. 6, p. 37) and references therein. Selected structural data for organometallic nickel(II) complexes with monodentate phosphines are reported in Table 61. 

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