Electrochemistry of chromium(0)–aminocarbene complexes: The use of intramolecular interaction LFER for characterization of the oxidation and reduction centre of the complex

Two series of chromium(0)–(aryl)aminocarbene complexes substituted on the ligand phenyl ring were prepared and electrochemically investigated: pentacarbonyl((N,N-dimethylamino)(phenyl)carbene(chromium(0) (Ia–e) and chelated tetracarbonyl((η2-N-allyl-N-allylamino)(phenyl)carbene(chromium(0) (IIa, c–e). For comparison, a tungsten analogue of IIc (III) and a chromium chelate bearing a methyl substituent instead of the phenyl group IV were taken into the study.The intramolecular interactions of p-substituents on the ligand phenyl ring with the reduction and oxidation centres of the molecule of complex (followed electrochemically using LFER [P. Zuman, Substituent Effects in Organic Polarography, Plenum Press, New York, 1967]) enabled to localize the corresponding electron transfer. The influence of the type of coordination, the substituent on the ligand phenyl ring and the central metal atom on oxidation and reduction potentials is discussed.