Mixed bis(morpholine‐4‐dithiocarbamato‐S,S′)antimony(III) complexes: synthesis, characterization and biological studies

Abstract

Some mixed bis(morpholine‐4‐dithiocarbamato‐S,S′)antimony(III) complexes [(OC4H8NCS2)2SbL] with oxygen or sulfur donor ligands [L = ―OOCCH3 (1), ―OOCC6H5 (2), ―SOCCH3 (3), ―SCH2COOH (4), ―OOCC6H4(OH) (5), ―SCH2CH2CH3 (6), ―OC6H5 (7), ½ ―SCH2CH2S― (8)] have been synthesized by reacting the chloro‐bis(morpholine‐4‐dithiocarbamato‐S,S′)antimony(III) with corresponding oxygen or sulfur donor ligands in 1:1 or 2:1 stoichiometries. These have been characterized by melting point, molecular weight determination (cryoscopically), antimony (iodometrically) and sulfur (gravimetrically) estimation, elemental analyses (C, H and N), UV–visible, FT‐IR, far IR, multinuclear NMR (1H and 13C)], TG/DTA analysis, ESI–mass and powder X‐ray diffraction studies. The splitting of the strong band observed at 1046–1066 cm−1 due to υ(C―S) indicated anisobidentate mode of binding of the dithiocarbamate group, which was further supported by a 13C NMR signal appearing at around δ 200 due to NCS2 moiety. The base peak observed at m/z 444.9 supports the strong chelating nature of the morpholine‐4‐dithiocarbamate compared to the other hetero ligands used. TGA revealed that, complexes 21 and 4 were decomposed in three steps; also 6 was decomposed in two steps, followed by the formation of Sb2S3. The results obtained by antimicrobial screening tests indicate that complex 3 showed a maximum zone of inhibition (20 mm) against Trichoderma ressie at a concentration of 200 µg ml−1. Complexes 2, 3 and 8 are most active (zone of inhibition (ZI) 17–20 mm) against both of the fungal species Aspergillus niger and Trichoderma ressie as well as complex 4 (ZI 17 mm) and 6 (ZI 18 mm) against Trichoderma ressie. Copyright © 2014 John Wiley & Sons, Ltd.