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The rate of reductive elimination of the complexes dpppPd(CH2TMS)(CNER3) (E = B, Al) is accelerated up to 60-fold over dpppPd(CH2TMS)(CN). Based on kinetic considerations and the isoelectronic relationship of CN- and CO, a migration-type mechanism for reductive elimination is proposed. The rate acceleration correlates directly with Lewis acid strength, the latter determined by solution calorimetric analyses of the Lewis acid adduct forming reaction Pd−CN + ER3 → Pd−CN−ER3.

A series of 3,4-dicarboethoxy-N-pyrrolyl phosphine ligands (R2P−NC4H2(CO2Et)2) is described. A number of techniques, including reaction calorimetry, infrared spectroscopy, and X-ray crystallography, demonstrate that these ligands are potent π-acceptors and that the electronic substituent parameter χi for the 3,4-(EtO2C)2C4H2N moiety is ca. 16, placing it in a position between fluorine and chlorine.