Activation of CO2 by Alkaline-Earth Metal Hydrides: Matrix Infrared Spectra and DFT Calculations of HM(O2CH) and (MH2)(HCOOH) Complexes (M = Sr, Ba)

Reactions of MH2 (M = Sr, Ba) with CO2 were explored in pure parahydrogen at 3.5 K using matrix isolation infrared spectroscopy and quantum chemical calculations. The formate complex HM(eta(2)-O2CH) and formic acid complex (MH2)(HCOOH) were trapped and identified by isotopic substitutions and density functional theory (DFT) frequency calculations. Natural population analysis and the CO2 reduction mechanism demonstrate that hydride ion transfer from a metal hydride to a CO2 moiety facilitates the stabilization of such complexes.

Automated summary

Reactions of MH2 (M = Sr, Ba) with CO2 were investigated using matrix isolation infrared spectroscopy and quantum chemical calculations at 3.5 K. Isotopic substitutions and density functional theory (DFT) frequency calculations helped identify formate complex HM(eta(2)-O2CH) and formic acid complex (MH2)(HCOOH). The study also showed that transfer of hydride ions from a metal hydride to a CO2 moiety plays a crucial role in stabilizing these complexes.