Pentacoordination at antimony in dibenzostibocines via DSb transannular interactions (D = O, S): A structural study

Addition of M2SCN(CH2R)2 to D(C6H4S)2SbCl in methylene chloride solution leaded to the formation of the stable compounds D(C6H4S)2SbS2CN(CH2R)2 (D = O, R = Me, 1; D = S, R = Me, 2; R = Ph, 3). The new dibenzostibocines derivatives containing two different types of dithioligands were characterized by elemental analysis and spectroscopic studies (IR, 1H and 13C NMR). Single crystal X-ray diffraction determinations of complexes 13 revealed that the antimony atom acts as an acceptor atom exhibiting an intramolecular transannular interaction with the donor D atom, expanding its coordination from three to five and displaying a skew trapezoidal local geometry.