Crystal structure of (Me3Sn)2N2C

The crystal structure of (Me3Sn)2N2C has been determined by single-crystal X-ray diffraction, and the absolute configuration established for the particular crystal employed. The crystals are hexagonal, space group P6422, a= 8·74(1), c= 14·28(2)Å, Z= 3. The structure consists of an infinite helical network of planar trimethyltin groups linked by linear NCN units. The nitrogen atoms complete a trigonal-bipyramidal arrangement about tin, with Sn–N 2·47(1) and Sn–C (mean) 2·14(2)Å. The Sn2NCNSn2 moieties have exact D2(222) symmetry with a dihedral angle of 68° between the two Sn2NC planes; C–N 1·24(2)Å and angle SnNC 117·6(4)°. The structure can be considered to be intermediate between carbodi-imide, cyanamide, and ionic extremes.