Search

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 6π-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:···YH3F system, and the Eint 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 Eint 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:···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. [ABSTRACT FROM AUTHOR]

The dual binding behavior of the metallylenes TH2 (T = Si, Ge, Sn, Pb) with some selected Lewis acids (T'H3F, T' = Si, Ge, Sn, Pb) and bases (N2, HCN, CO, and C6H6) has been investigated by using the high-level quantum chemical method. Two types (type-A and type-B) of tetrel-bonded complexes can be formed for TH2 due to their ambiphilic character. TH2 act as Lewis bases in type-A complexes, and they act as Lewis acids in type-B ones. CO exhibits two binding modes in the type-B complexes, one of which is TH2···CO and the other is TH2···OC. The TH2···OC complexes possess a weaker binding strength than the other type-B complexes. The TH2···OC complexes are referred to as the type-B2 complexes, and the other type-B complexes are referred to as the type-B1 complexes. The type-A complexes exhibit a relatively weak binding strength with Eint (interaction energy) values ranging from –7.11 to –15.55 kJ/mol, and the type-B complexes have a broad range of Eint values ranging from −9.45 to −98.44 kJ/mol. The Eint values of the type-A and type-B1 complexes go in the order SiH2 > GeH2 > SnH2 > PbH2. The AIM (atoms in molecules) analysis suggests that the tetrel bonds in type-A complexes are purely closed-shell interactions, and those in most type-B1 complexes have a partially covalent character. The EDA (Energy decomposition analysis) results indicate that the contribution values of the three energy terms go in the order electrostatic > dispersion > induction for the type-A and type-B2 complexes, and this order is electrostatic > induction > dispersion for the type-B1 complexes. [ABSTRACT FROM AUTHOR]