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

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. Mixed bis(morpholine‐4‐dithiocarbamato‐S,S’)antimony(III) complexes with oxygen or sulfur donor ligands complexes have been synthesized and characterized. These complexes give antimony sulfide upon thermal degradation and show potent activity than the free ligands against bacterial and fungal species as well as equal or greater activity than the standard antibacterial (chloramphenicol) and antifungal (terbinafine) drugs.