Tinning the carbon: hydrostannanes strike back.

Carbon possesses an important ability to be in a valence state of IV, which is essential for organic chemistry and all carbon-based life forms. In turn, tin is usually observed in the valence state of II, although it is a carbon group element. This creates an open question about the possibility of the existence of tin-based "organic" molecules. In this work, we investigate hydro-tin compounds Sn2Hx (x = 1-6) and Sn3Hy (y = 1-8) via DFT and ab initio quantum chemistry methods, studying their global minimum geometry, thermodynamic stability, and chemical bonding patterns. We show that hydrogen-saturated stoichiometries (Sn2H6 and Sn3H8) are exact analogs of hydrocarbons, while unsaturated stoichiometries are characterized by multi-center bonds, aromaticity, and different valence states of tin. In addition, a refined procedure of global geometry minimization based on simulated annealing and ab initio molecular dynamics is proposed.