Additional Reaction and Mechanism of Dicyanobenzene: Formation of Amidinium or Amidine Compounds

Abstract The interaction of LiN(SiMe3)2 with one equivalent of 1,3- or 1,4-dicyanobenzene followed by the addition of one equivalent of chlorodiphenylphosphine and oxidation by hydrogen peroxide gave amidinium diphenylphosphinate compounds of the general formula [ArC(NH2)2]+[Ph2PO2]− (Ar = 3-cyanophenyl for 1, 4-cyanophenyl for 2). These compounds, in which the polymeric networks are interconnected through a featured type of synthon, show the typical solid-state and film fluorescence. When the above reactions were carried out with half of an equivalent of 1,3-dicyanobenzene, compound 1 and ammonium diphenylphosphinate were produced; with half of an equivalent of 1,4-dicyanobenzene, compound 3 (1,4-phenylene-bis(N-diphenylphosphinato)amidine) was obtained. A mechanism for the formation of compounds 1-3 was proposed. Results of DFT calculations suggested that the nucleophilic addition reaction to the second cyano group of the dicyanobenzene is a HOMO-controlled process.