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Methods: The intermolecular interactions between the heavy-atom analogues of acetylene T2H2 (T = Si, Ge, Sn, Pb) and HCN have been investigated by theoretical calculations at the CCSD(T)/aug-cc-pVTZ//MP2/aug-cc-pVDZ level. Results: The global energy minimum of T2H2 is the butterfly structure A, and another energy minimum is the planar structure B. Both structures A and B exhibit the dual behavior when binding with HCN. The various hydrogen bond (HB), dihydrogen bond (DB) and tetrel bond (TB) complexes can be found according to the MEP maps of T2H2. One TB and three HB complexes formed between structure A and HCN can be located for Si2H2 and Ge2H2. One TB, two HB and one DB complexes formed between structure A and HCN can be located for Sn2H2 and Pb2H2. Four TB and one HB complexes formed between structure B and HCN can be located for all the T2H2. The geometries and binding strengths of the complexes are compared and analyzed. Conclusions: The interactions in these complexes are generally weak, and the interaction energies of these complexes range from −0.53 to −8.23 kcal/mol. The interaction energies of the TB complexes are larger than those of the corresponding HB and DB complexes for structure A···HCN systems. The relative binding strength of the four TB complexes exhibits different order for different structure B···HCN systems, which is consistent with the MEP maps of the isolated monomers. [ABSTRACT FROM AUTHOR]

Methods: The intermolecular interactions between the heavy-atom analogues of acetylene T 2 H 2 (T = Si, Ge, Sn, Pb) and HCN have been investigated by theoretical calculations at the CCSD(T)/aug-cc-pVTZ//MP2/aug-cc-pVDZ level., Results: The global energy minimum of T 2 H 2 is the butterfly structure A, and another energy minimum is the planar structure B. Both structures A and B exhibit the dual behavior when binding with HCN. The various hydrogen bond (HB), dihydrogen bond (DB) and tetrel bond (TB) complexes can be found according to the MEP maps of T 2 H 2 . One TB and three HB complexes formed between structure A and HCN can be located for Si 2 H 2 and Ge 2 H 2 . One TB, two HB and one DB complexes formed between structure A and HCN can be located for Sn 2 H 2 and Pb 2 H 2 . Four TB and one HB complexes formed between structure B and HCN can be located for all the T 2 H 2 . The geometries and binding strengths of the complexes are compared and analyzed., Conclusions: The interactions in these complexes are generally weak, and the interaction energies of these complexes range from -0.53 to -8.23 kcal/mol. The interaction energies of the TB complexes are larger than those of the corresponding HB and DB complexes for structure A···HCN systems. The relative binding strength of the four TB complexes exhibits different order for different structure B···HCN systems, which is consistent with the MEP maps of the isolated monomers., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

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