Hydrido silyl-manganese complexes

As regards the similarity with simple coordination of two-electron ligands, it is of interest to discuss the oxidative addition of silicon hybrid to methyl cyclopentadienyl-manganese carbonyl and the nature of the bonding in the adduct. Hydrido silyl-manganese complexes were first prepared by Jetz and Graham according to... 

The easy reductive elimination process does not seem to arise from a particular lability of the hydrido silyl-manganese complex. It is stable in solution. Moreover, functionalized... 

SCHEME 11. Reactions of optically active hydrido silyl-manganese complex... 

The particular chemical behaviour of the hydrido silyl-manganese complex, which contrasts sharply with that of hydrido silyl-iron complexes56,77, has been interpreted in terms of a bonding interaction between hydrido and silyl ligands. 

FIGURE 4. Representation of hydrido silyl-manganese complexes... 

To explain their results, Hart-Davies and Graham proposed to depict manganese complexes 172 in terms of resonance hybrids between representations 178 and 179 (261) (Figure 18). However, the possibility that the close Si-H distance is due to steric constraints has been raised by Bennett and Simpson (264). Steric effects favor a cis orientation of silyl and hydrido ligands and thus facilitate reactions involving reductive elimination pathways. 

On the metal side, an electronically imsaturated metal complex is required to which the Si—H bond can be added. 16-electron complexes can easily be created in situ by UV irradiation of metal carbonyl compounds, which results in the cleavage of one CO ligand. Hydrido-silyl complexes are formed when irradiation is done in the presence of a hydridosilane R4 jcSiHjc x= 1—4). Manganese complexes of the type (tj —CsRsKCOKL)... 

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