The currently most reliable theoretical estimates of the adiabatic ionization energies (AIE(0)) from the X̃(2)B(1) state of AsCl(2) to the X̃(1)A(1) and ã(3)B(1) states of AsCl 2+, and the electron affinity (EA(0)) of AsCl(2) , including ΔZPE corrections, are calculated as 8.687(11), 11.320(23), and 1.845(12) eV, respectively (estimated uncertainties based on basis-set effects at the RCCSD(T) level). State-of-the-art ab initio calculations, which include RCCSD(T), CASSCF/MRCI, and explicitly correlated RHF/UCCSD(T)-F12x (x = a or b) calculations with basis sets of up to quintuple-zeta quality, have been carried out on the X̃(2)B(1) state of AsCl(2) , the X̃(1)A(1) , ã(3)B(1) , and Ã(1)B(1) states of AsCl 2+, and the X̃(1)A(1) state of AsCl 2-. Relativistic, core correlation and complete basis-set (CBS) effects have been considered. In addition, computed UCCSD(T)-F12a potential energy functions of relevant electronic states of AsCl(2) , AsCl (2)(+), and AsCl( 2)(-) were used to calculate Franck-Condon factors, which were then used to simulate the valence photoelectron spectrum of AsCl(2) and the photodetachment spectrum of AsCl (2)(-), both yet to be recorded. Lastly, we have also computed the AIE and EA values for NCl(2) , PCl(2) , and AsCl(2) at the G4 level and for SbCl(2) at the RCCSD(T)/CBS level. The trends in the AIE and EA values of the group V pnictogen dichlorides, PnCl(2) , where Pn = N, P, As, and Sb, were examined. The AIE and EA of PCl(2) were found to be smaller than those of AsCl(2) , contrary to the order expected from the IE values of P and As.

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