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.