Quantum chemical study of molecular properties of AsXn (X = F and Cl, n = 1–5) and AsXn− (X = F and Cl, n = 1–6)

[Display omitted] •Molecular properties of arsenic fluorides and chlorides were calculated using CCSD(T).•The results of CCSD(T) with large basis sets are in good agreement with the experimental results.•The variations in the molecular structures are rationalized via molecular orbital analysis.•MN12-SX and MN15 show excellent overall performance for calculating the molecular properties. The molecular properties (i.e., molecular structures, vibrational frequencies, electron affinities, and bond dissociation energies) of AsXn (X = F and Cl, n = 1–5) and AsXn− (X = F and Cl, n = 1–6) were calculated using coupled-cluster singles and doubles with perturbative triples (CCSD(T)) with large basis sets up to quintuple-ζ level. The variations in the molecular structures were rationalized via molecular orbital analysis. The results of the calculations show that the electronic structures of AsCln (n = 1–5) and AsCln− (n = 1–6) are the same as those of AsFn (n = 1–5) and AsFn− (n = 1–6), respectively. The results of the CCSD(T) are generally in good agreement with the empirical data. Density functional theory methods were assessed to find the optimal functional, yielding results comparable to those obtained with CCSD(T). The recently developed functionals MN12-SX and MN15 showed good overall performance for calculating the molecular properties.