Study on the intramolecular transannular chalcogen–tin interactions in dithiastannecine compounds

Abstract

Dithiastannecine compounds of the type [{D(C6H4CH2S)2}SnR1R2] with different donor atoms D were prepared, where D=O and R1=R2=Ph (4a); R1=Ph, R2=Cl (5a); R1=n-Bu, R2=Cl (6a); D=S and R1=R2=Ph (4b); R1=Ph, R2=Cl (5b); R1=n-Bu, R2=Cl (6b). The molecular structures of the monochloro compounds 5a, 5b, 6a, and 6b were established by single-crystal X-ray diffraction and exhibit trigonal bipyramidal geometry at the tin atom with different degrees of distortion being due a D⋯Sn interaction. The spiro compounds [{D(C6H4CH2S)2}2Sn] with D=O (7a) and D=S (7b) were also synthesized and structurally characterized; the molecular structure of 7a showed the tin atom with a bicapped tetrahedral geometry. The behavior of all tin compounds in solution was investigated by NMR spectroscopy revealing that the D⋯Sn interaction in solution was practically absent on the basis of the NMR chemical shifts values. DFT calculations with ADF package using VWN/QZ4P were carried out for the 6a and 6b compounds and showed that, in the topological analysis, bond critical points are present along the D⋯Sn direction.