This contribution shows how a small change of a remote substituent (COOCH3 for e.g. OCH3) on Fischer aminocarbene complexes can change totally the LUMO location, and thus electron distribution, extent of pi-electron delocalization and, consequently, redox properties of these potential catalysts. During investigation of redox properties of extended series of title compounds, an exceptionally positive reduction potential was observed (non fitting the LFER plot) for p-COOR substituents. This effect is caused by a strong intramolecular electronic interaction, which is specific for p-phenylene dicarbonyl compounds. In this context, the CN bond in aminocarbene moiety has a double bond character and resembles carbonyl function. The interpretation was proved by DFT calculations. (C) 2011 Elsevier Ltd. All rights reserved.