Investigation of cooperativity in triple adducts of phosphangulene PG(HX)(Y) – : a theoretical study

A theoretical study of the model dyad and triad complexes of general formula PG(HX), PG(Y)− and PG(HX)(Y)− (HX = HF, HCl and Y = F−, Cl−, C≡N−, N≡C−) has been carried out using density functional theory at B3LYP/6-311++G(2d,2p) computational level and basis set. Four distinctive non-covalent interaction patterns, including pnictogen bond (PnB), tetrel bond (TtB), chalcogen bond (ChB), and hydrogen bond (HB), were found for complex formation between phosphangulene (PG) with CN−, NC−, F−, Cl− anions and HF, HCl neutral molecules. Each HX and Y component can interact on the apex or at basal sites of the PG molecule and result in PG(HX)a(Y)b− or PG(Y)a(HX)b− aggregates. From the anticipated models, stabilities of the PG(CN)a(HF)b−, PG(NC)a(HF)b−, PG(F)a(HF)b−, PG(F)a(HF)b−, and PG(Cl)a(HF)b− triads are greater than other types. The electron release of PG to the HX molecules helps it to take electron from Y ions, thus PG(HX)(Y)− triads show greater stability and considerable cooperative effect relative to corresponding dyad adducts. Natural bond orbital theory (NBO) and Bader’s theory of “atoms in molecules” (AIM) methods have been applied to analyze the intermolecular interactions. Strong correlations have been observed between stabilities and charge transfer (qCT) in the analyzed systems.