Description of Weak Halogen Bonding Using Various Levels of Symmetry-Adapted Perturbation Theory Combined with Effective Core Potentials

Table 1

Distance between the X and N atoms (; in Å), maximal value of electrostatic potential in the σ-hole region on the X atom (; in kcal/mol), CCSD(T)/CBS and SAPT(DFT) interaction energies between MH₃X and HCN (; in kcal/mol), and SAPT(DFT) principal interaction energy components (, , , and ; in kcal/mol) for the investigated MH₃X⋯NCH complexes. The percentage of each attractive SAPT(DFT) component relative to the total attraction is given in parentheses.

Complex
			CCSD(T)/CBS	SAPT(DFT)
CH3I⋯NCH	3.261	12.2	−1.46	−1.23	−2.23	−0.52	−2.45	3.97
SiH3I⋯NCH	3.451	8.7	−1.14	−1.08	−1.41	−0.35	−1.83	2.51
GeH3I⋯NCH	3.426	7.3	−1.01	−0.94	−1.34	−0.38	−1.95	2.73
SnH3I⋯NCH	3.470	4.4	−0.79	−0.74	−1.02	−0.36	−1.86	2.50
PbH3I⋯NCH	3.481	1.6	−0.55	−0.49	−0.73	−0.37	−1.87	2.47
CH3At⋯NCH	3.171	18.4	−2.36	−2.02	−3.95	−0.84	−3.19	5.96
SiH3At⋯NCH	3.357	13.6	−1.80	−1.72	−2.58	−0.55	−2.41	3.83
GeH3At⋯NCH	3.322	12.9	−1.74	−1.59	−2.68	−0.60	−2.59	4.28
SnH3At⋯NCH	3.353	10.8	−1.52	−1.38	−2.37	−0.57	−2.51	4.08
PbH3At⋯NCH	3.343	8.1	−1.33	−1.15	−2.25	−0.59	−2.61	4.30