Experimental and ab initio study on structures and internal barriers to rotation in α-stannyl, germanium, and silicon carbamates

A detailed study of structural parameters and internal rotational barriers in α-stannyl, germanium and silicon carbamates 1 [H3 CX-CH2-N(Me)CO2Me XC, Si, Ge, Sn] were calculated at HF/6-311G, HF/3-21G and B3LYP/3-21G//HF/3-21G levels and compared with DNMR data of synthesized molecules and a literature X-ray data. Two minimum-energy conformers, namely A and B, with almost similar energies were found for these molecules. Effect of heteroatom on structure and relative energies (Erel) between the participants in the conformational equilibrium (A ↔ B) of these carbamates has been investigated.