Seven new organotin complexes of 5-mercapto-3-phenyl-1,3,4-thiadiazoline-2-thione (I), RnSn(PhN2C2S3)4-n [n = 1, R = Bu (1); n = 2, R = Ph (2), Bu (3), Me (4) and n = 3, Ph (5), Bu (6), Me (7)] along with the 4,4'-Bipy and 4-PyNH2 adducts of 7, [Me3Sn(PhN2C2S3)]2.(4,4´-bipy) (8) and [Me3Sn(4-PyNH2)2]+[PhN2C2S3]- (9) respectively, have been synthesised. The coordination behaviour of I in 1 - 8 ranges from S(1) monodentate to S(1) + S(3) bidentate