A quest for substituent effects on novel diamino(phosphino)phosphinidenes using density functional theory method.

Substituent effects on singlet (s) and triplet (t), symmetric acyclic (1X), cyclic‐saturated (2X), and cyclic‐unsaturated (3X) diamino(phosphino)phosphinidenes are investigated, at B3LYP/6‐311++G** level of theory (X = H, Me, t‐Bu, NH2, OH, Ph, CF3, and CN). All novel phosphinidenes scrutinized show singlet ground state, suggested by the conductor‐like polarizable continuum model (CPCM) on both gas‐phase and solvent‐phase optimized structures. Singlet–triplet energy gap (ΔES–T) increases in going from acyclic to cyclic‐saturated and cyclic‐unsaturated structures in gas phase. Band gap (ΔEH–L) decreases in going from cyclic‐saturated to cyclic‐unsaturated and to acyclic structures. Proton affinity (PA) decreases in going from acyclic to cyclic‐unsaturated and cyclic‐saturated structures in gas phase. Inverse pKa increases in both polar solvents (water and DMSO). Most our phosphinidenes appear as superacids in gas phase. [ABSTRACT FROM AUTHOR]