Intermolecular interactions involving the N-heterocyclic carbene and its heavier analogues C2H4N2X: (X = C, Si, Ge, Sn, Pb) with YH3F (Y = Si, Ge, Sn, Pb)

The intermolecular complexes formed between imidazol-2-ylidene and its heavy-atom analogues C2H4N2X: (X = C, Si, Ge, Sn, Pb) and YH3F (Y = Si, Ge, Sn, Pb) have been optimized at the MP2/aug-cc-pVTZ level. C2H4N2X: have two electron-rich moieties, one of which is the lone pair on the X atom and the other is the 6 pi-electron system. Three types of binding modes (type-A, type-B and type-C) can be distinguished for C2H4N2X: according to the locations of YH3F. The type-A and type-B complexes can be located for C2H4N2C:center dot center dot center dot YH3F system, and the E-int values of the type-A complexes are much larger than those of the type-B complexes. The type-A, type-B and type-C complexes can be located for the other four systems, and the E-int values of these complexes go in the order type-B > type-C > type-A. The binding strength of the type-A complexes becomes weaker, and that of the type-B and type-C complexes becomes stronger with the increase of the X atomic number for C2H4N2X:center dot center dot center dot YH3F system, which can be clarified by the MEP maps of C2H4N2X:. The NBO, AIM and SAPT analysis was employed to explore the nature of the interactions in these complexes.

Automated summary

The intermolecular complexes formed by imidazol-2-ylidene and its heavy-atom analogues C2H4N2X: (X = C, Si, Ge, Sn, Pb) and YH3F (Y = Si, Ge, Sn, Pb) were optimized at the MP2/aug-cc-pVTZ level. The binding modes were classified into three types (A, B, and C) based on the locations of YH3F. The interaction strength of the complexes varied with the atomic number of X, with type-B complexes showing the strongest binding.