The heavy Carbene analogues and . Convergent quantum mechanical studies*

AbstractIn 2021 Olaru, Mebs, and Beckmann reported the synthesis of remakrable cationic carbene analogues PR2+ and AsR2+. This work followed the same group's synthesis of SbR2+ and BiR2+. To better understand these important systems, SbH2+ and BiH2+ have been studied with high level ab initio quantum mechanical methods. Geometries were optimised with the CCSDT(Q) method with the cc-pwCVTZ-PP basis set using small core pseudopotentials. Fundamental vibrational frequencies were computed to provide theoretical predictions for future synthetic studies. Relative energies with respect to Pn+ + H2 (Pn = Sb, Bi) were determined at the CCSDT/CBS level of theory via the Focal Point Analysis method, and anharmonic zero-point vibrational energy and higher order contributions were also computed. For SbH2+, we obtained R = 1.697 Å and θ=90.8∘ with Sb++H2→SbH2+ reaction enthalpy of ΔH=−18.71kcalmol−1. For BiH2+, the analogous results were R = 1.774 Å, θ=89.7∘, and ΔH=−7.64kcalmol−1 for Bi++H2→BiH2+.Keywords: Pnictogenium cationsantimonybismuthab initioCCSDT(Q) Disclosure statementNo potential conflict of interest was reported by the author(s).Additional informationFundingWe acknowledge support from the US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences (BES) under Contract No. DE-SC0018412.