Carbon dioxide insertion into metal-nitrogen bonds

Carbon dioxide does not insert into all metal-carbon bonds, as demonstrated by the lack of reaction with [HIr(PMe3)4CH2CN]+ 137). Similarly, benzylchromium complexes failed to insert C02 142), and in the reaction of Me(Me2N)2W=W(NMe2)2Me with C02, the molecule inserts into the metal-nitrogen bonds, but not into the metal-carbon bonds 143). 

In the following section we shall consider the insertion of carbon dioxide into transition nieial carbon, metal hydrogen, metal -oxygen and metal -nitrogen bonds. 

If titanium-nitrogen and titanium-oxygen bonds arc available in the same molecule, CO insertion yields carbamates [104]. If carbon dioxide has the capability (0 insert into a metal-carbon or a metal-nitrogen bond, the insertion into M-N is preferred hafnium dialkyl diarnides react with CO at room temperature to yield the carbamato derivatives HfRjfOjCNR ) [105). 

Buhro WE, Chisholm MH, Martin JD, Huffmann JC, Folting K, Streib WE (1989) Reactions involving carbon dioxide and mixed amido-phosphido dinuclear compounds M2(NMe2)4(PR2)(M=M), where M = Mo and W. Comparative study of the insertion of carbon dioxide into metal-nitrogen and metal-phosphoms bonds. J Am Chem Soc 111 8149-8156... 

Some of the substances that lead to 1,1 insertion reactions into metal-carbon ff bonds are carbon monoxide, CO alkyl- or arylisocyanide, CNR, carbenes CR2 sulfur dioxide, SO2 and nitrogen oxide NO. Most studied are CO, CNR, and SO2 therefore a more detailed account of them is presented. 

Chisolm MH, Extine M (1975) Carbon dioxide exchange reactions involving transition-metal N,N-dimethylcarbamato compounds reversible insertion of carbon dioxide into transition-metal-nitrogen o bonds. J Chem Soc Chem Commun 438-439... 

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