The effect of hydrogen-bonding cooperativity on the strength and properties of σ-hole interactions: an ab initio study

Ab initio calculations at the MP2/aug-cc-pVTZ level of theory are performed to investigate the effect of hydrogen-bonding cooperativity on the strength and bonding properties of σ-hole interaction in linear FCl⋅⋅⋅(NCH)_n=2–5, FHS⋅⋅⋅(NCH)_n=2–5, FH₂P⋅⋅⋅(NCH)_n=2–5 and FH₃Si⋅⋅⋅(NCH)_n=2–5 clusters. It is found that the cooperative effects in the hydrogen-bonding tend to strengthen the σ-hole interaction. However, these effects are almost saturated in the larger clusters (n > 5). For a given cluster, the amount of bond contraction in FCl⋅⋅⋅(NCH)_n is more important than other systems. A nice linear relationship is found between the σ-hole bond energies and absolute ¹⁵N chemical shieldings or spin–spin coupling constants across the σ-hole bond.