Carbonyl valence bond representation

In our laboratory we have examined the reactivity pattern of [0s3(y-H)2(C0)10], an unsaturated cluster which can be represented as possessing an osmium-osmium double bond in its classical valence bond representation. We find (2,3) that this compound undergoes a number of reactions with metal carbonyls which in some cases can be formulated as proceeding through intermediates analogous to metal olefin complexes ... 

Figure 6-21. Valence bond representation of nucleophilic addition (Nu" path a -0 or HNu path b) to a carbonyl.

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