Matrix isolation infrared spectroscopy combined with quantum-chemical calculations were employed to study the reactions of calcium atoms with silane, germane, and stannane in a 4 K argon matrix. The ion pairs [HCa](+) and [EH3](-) (E = Si, Ge, and Sn) in both the classical structure HCaEH3 and the bridged structure HCa(mu-H)(3)E were identified based on the H/D isotopic substitution experiments and quantum-chemical calculations. The results show that the reaction between ground-state Ca and EH4 proceeds inefficiently, and only after the photolytic activation of Ca atoms to the Ca(P-1:4s4p) state does insertion occur to give HCaEH3, which rearranges to HCa(mu-H)(3)E upon photolysis. Topological analysis of the electronic structure suggests that the nonclassical structure HCa(mu-H)(3)E is formed by the electrostatic interaction with charge-inverted hydrogen bridge bond, while HCaEH3 is dominated by (HCa)(+)(EH3)(-) ion pair interactions.`