Intermolecular interactions between the heavy alkenes HSi = TH (T = C, Si, Ge, Sn, Pb) and acetylene.

The intermolecular interactions between the heavy alkenes HSi = TH (T = C, Si, Ge, Sn, Pb) and CH have been calculated at the CCSD(T)/aug-cc-pVTZ//MP2/aug-cc-pVDZ level, and the nature of these complexes has been investigated by natural bond orbital. The four types (type-A, type-B, type-C and type-D) of complexes can be located for HSi = TH···CH system. The complexes involving HSi = TH···CF and HSi = TH···C(CN) have also been examined to explore the substituent effects. Some complexes which are stable for HSi = TH···CH system become unstable for HSi = TH···CF or HSi = TH···C(CN) system, while other complexes which are unstable for HSi = TH···CH system become stable for HSi = TH···CF or HSi = TH···C(CN) system.