Organometallic Compounds of Zn, Cd, and Hg

Although zinc, cadmium, and mercury are not members of the so-called main-group elements, their behavior is very similar because of their having complete d orbitals that are not normally used in bonding. By having the filled s orbital outside the closed d shell, they resemble the group IIA elements. Zinc is an essential trace element that plays a role in the function of carboxypeptidase A and carbonic anhydrase enzymes. The first of these enzymes is a catalyst for the hydrolysis of proteins, whereas the second is a catalyst for the equilibrium involving carbon dioxide and carbonate, 

Zinc forms numerous organometallic compounds, with the dialkyls being the most important. Although these compounds do not associate to give aggregates, they are spontaneously flammable. The reaction of a zinc halide with a Grignard reagent can be used to prepare the compounds. 

Other alkyl compounds can be obtained by transfer reactions such as that with BR3. 

This process is the result of the stability of trimethylboron. Alkyl group transfer also occurs in the reaction 

In terms of their chemical behavior, dialkylzinc compounds generally react to transfer alkyl groups to other metals. Dialkyls of cadmium are usually prepared by the reaction of a Grignard reagent with a cadmium halide. 

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