Mixed-ligand complexes exchange reactions

Ligand exchange-displacement reactions employing bis(dithiolene) complexes have been used to synthesize mixed-ligand complexes (Eq. 5) (54, 55). The reaction proceeds smoothly in dichloromethane with good yields (60-70%) (55). 

The donor acceptor properties of isonitrile are intermediate between those of CO and tertiary phosphines, and isontrile stabilizes the complexes in their higher oxidation state more and stabilizes the complexes in their lower oxidation state less than CO does. Thus, a direct reaction of zero-valent metal carbonyls with isonitrile usually results to the formation of the partially exchanged mixed-ligand complexes e.g., Cr(CO)g reacts with RNC at 120 130°C to give only the monosubstituted complex ... 

---