Some mixed bis(morpholine-4-dithiocarbamato-S,S′)antimony(III) complexes [(OC 4 H 8 NCS 2 ) 2 SbL] with oxygen or sulfur donor ligands [L = -OOCCH 3 (1), -OOCC 6 H 5 (2), -SOCCH 3 (3), -SCH 2 COOH (4), -OOCC 6 H 4 (OH) (5), -SCH 2 CH 2 CH 3 (6), -OC 6 H 5 (7), ½ -SCH 2 CH 2 S-(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 ( 1 H and 13 C)], TG/DTA analysis, ESI-mass and powder X-ray diffraction studies. The splitting of the strong band observed at 1046-1066 cm À1 due to υ(C-S) indicated anisobidentate mode of binding of the dithiocarbamate group, which was further supported by a 13 C NMR signal appearing at around δ 200 due to NCS 2 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 Sb 2 S 3 . 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 À1 . 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.

On thermal decomposition of the mixed sulfur donor antimony(iii) complexes, we obtained antimony sulfide at 600 °C, which was confirmed by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX).

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