Intermolecular interactions between the heavy alkenes H₂Si = TH₂ (T = C, Si, Ge, Sn, Pb) and acetylene

The intermolecular interactions between the heavy alkenes H₂Si = TH₂ (T = C, Si, Ge, Sn, Pb) and C₂H₂ 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 H₂Si = TH₂···C₂H₂ system. The complexes involving H₂Si = TH₂···C₂F₂ and H₂Si = TH₂···C₂(CN)₂ have also been examined to explore the substituent effects. Some complexes which are stable for H₂Si = TH₂···C₂H₂ system become unstable for H₂Si = TH₂···C₂F₂ or H₂Si = TH₂···C₂(CN)₂ system, while other complexes which are unstable for H₂Si = TH₂···C₂H₂ system become stable for H₂Si = TH₂···C₂F₂ or H₂Si = TH₂···C₂(CN)₂ system.