Platinum complexes tetracyanoethylene

It has recently been shown 90> that the olefin tetracyanoethylene, (CN)2C= C(CN)2, can displace phenylacetylene from the bis-triphenylacetylene from the bis-triphenylphosphine platinum(O) complex, the first time such a reaction has been achieved. Preparative work on olefin complexes of platinum(0) of the same type has also shown that electron-withdrawing substituents on the olefin increase the stability of the complex, e.g. trans-4,4-dinitrostilbene forms a more stable complex than trans-stilbene itself 86L... 

Refluxing Pt(PPh3)4 with activated olefins gives platinum(0)-olefin complexes with chloroolefins , fluoroolefins °, tetracyanoethylene and fumaronitrile ... 

Isomerization and polymerization reactions of alkenes and alkynes are to be expected because both the MLCT and LMCT excited states have diradical character. Both the tetracyanoethylene and dicyanoacetylene 7r-complexes of Pt(PPh3>2 undergo a photoinduced intramolecular oxidative addition reaction to give the cyano vinyl and cyano acetylide complexes of platinum(II) respectively ... 

The mechanism shown in the Scheme is suggested for the reaction of hydridoplatinum(n) complexes with tetracyanoethylene, which involves reductive elimination of hydrogen chloride from the platinum. 

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