An Atoms-In-Molecules (AIM) Interpretation of Organotin-Peptide System: I. Di-N-Butyltin(IV) Derivative of Glycyltryptophane

The topological and energetic properties of the electron density distribution ρ(r) for the tin-ligand interaction in di-n-butyltin(IV) derivative of glycyltryptophane (H₂L) (n-Bu₂SnL), the geometric configuration of which was optimized at B3LYP/3-21G/LANL2DZ(Sn) level of theory, have been theoretically calculated at the bonds around the central Sn atom in terms of atoms-in-molecules (AIM) theory using AIMAll (Version16.01.09, standard). In n-Bu₂SnL, the formation of a (3,-1) critical point in the internuclear region between tin atom and bonded/coordinated atoms provided an evidence of a bonding interatomic interaction, and calculated bond path angles indicated a distorted trigonal bipyramidal geometry. The calculated topological and energetic parameters suggested a weak closed-shell interaction in all the bonded/coordinated bonds to Sn atom, as a result this interaction possessed covalent character in Sn-N_amino,Sn-O_carboxyl, Sn-N_peptide, Sn-C_α and Sn-C_α' bonds.