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 and13C)], TG/DTA analysis, ESI–mass and powder X‐ray diffraction studies. The splitting of the strong band observed at 1046–1066 cm−1due to υ(C―S) indicated anisobidentate mode of binding of the dithiocarbamate group, which was further supported by a13C NMR signal appearing at aroundδ200 due to NCS2moiety. The base peak observed atm/z444.9 supports the strong chelating nature of the morpholine‐4‐dithiocarbamate compared to the other hetero ligands used. TGA revealed that, complexes 21 and4were decomposed in three steps; also6was decomposed in two steps, followed by the formation of Sb2S3. The results obtained by antimicrobial screening tests indicate that complex3showed a maximum zone of inhibition (20 mm) againstTrichoderma ressieat a concentration of 200 µg ml−1. Complexes2,3and8are most active (zone of inhibition (ZI) 17–20 mm) against both of the fungal speciesAspergillus nigerandTrichoderma ressieas well as complex4(ZI 17 mm) and6(ZI 18 mm) againstTrichoderma ressie.