Conformational Studies on Divalent Seven-membered Ring C6H6M (M = C, Si, Ge, Sn and Pb): DFT Calculations

Abstract

Conformational studies are carried out on divalent sevenmembered   C₆H₆M (M = Si, Ge, Sn and Pb) through DFT   calculations. The most stable tautomers and conformers are   suggested for singlet and triplet states of C₆H₆M. The Gibbs   free energy differences between singlet and triplet states, ΔG_s-t,   are calculated for C₆H₆C, C₆H₆Si, C₆H₆Ge, C₆H₆Sn and   C₆H₆Pb, at B3LYP/6-311++G (3df,2p). The singlet-triplet gap,   ΔG_s-t, of C₆H₆M (M = C, Si, Ge, Sn and Pb) are generally   increased from M = C to M = Pb.