A 1:2 adduct of tin tetrachloride with substituted urea was reported. By applying different techniques and conditions various coordination complexes of tin (IV) have been obtained. A series of tin (IV) complexes were synthesized and identified by the reaction of SnQ4 or the disubstituted tin (IV) tetrachloride, R2SnCI2, with 1,3-disubsti­tuted urea or thiourea. In all these complexes, the coordination number (4) of tin is thus inereasedto (6). The complexes were characterized by elemental analysis as well as by physical methods such as i.r., lH-n.m.r. and mass spectroscopy.