Reactions of Isocyanides with Transition Metal Compounds

At present, this method is often used for the preparation of isocyanide complexes. During reaction, the addition of the ligand may take place without the change of the oxidation state. However, in many cases, reduction of the metal occurs, and complexes in which the transition element has a lower oxidation state than the starting compound are obtained. Copper (I) salts coordinate one to four RNC molecules to give [CuX(CNR) ] and [Cu(CNR)4]X. Copper(II) salts are readily reduced by isocyanides to Cu(I) compounds. However, copper(II) chlorate or tetrafluoroborate and tert-dikyl isocyanide give the cationic complex [Cu(CNR)4]X2. This compound must immediately be separated from the reaction mixture in order to avoid its reduction. 

Isocyanides themselves, solvents, main group metals and their organometallic compounds, metal iodides, etc., may serve as reducing agents. 

In the case of synthesis of Cr(CNR)6 from chromium(II) acetate, disproportionation reaction takes place  

The substitution reaction of CO ligands is often accelerated by light or catalysts. 

The substitution of carbonyl ligands in Vcp(CO)4 is catalyzed by PdO. Products of these reactions are complexes of the type [Vcp(CNR) (CO)4 ]. The substitution of CO groups may also be induced electrochemically. 

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