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Planar divalent nickel dithiocarbamates Ni(dtc)2 (dtc− = dithiocarbamato anions) show interesting reactivity patterns in their reactions with Lewis bases. These complexes form mixed ligand complexes with PR3 easily. But, simple hard nitrogen bases do not displace all the nickel dithiocarbamates. A chelating base like en displaces the dithiocarbamate anion completely from the complexes and formed pink colored solution in an aqueous medium. The chromophore was identified to be [Ni(en)3]2+ and the counter anion was dtc−. On ageing, pink crystals separated out from the solution. Chemical analysis of the crystals showed a 1 : 2 ratio of Ni to S and the absence of dtc− ion. The possibility of S2O32− being the counter anion was tested. Even though infrared spectrum could not confirm the S2O32− anion, the final confirmation came form the X-ray analysis of the authentic crystals. This is a rare occasion of metal ion catalyzed oxidation of S2− to S2O32− ions.

Abstract. M r= , triclinic, P1, a = 9.008 (2), b=17.194(4), c= 14. 501(2) /~,, ct=128.34(2), fl =95.60(2), y=97.13(2) ° , V=1703.44/~3, Z=2, D x= 1.654Mgm -3, MoKet, 2=0.71069./k, p= 1.295 mm -~, F(000) = 864, T = 293 K, R = 0.042 and R w = 0.045 for 3482 unique observed reflections. In the molecule, the central tellurium atom is bonded to all eight sulphur atoms in a highly distorted dodecahedral configuration. The two planar trapezoids, each containing a TeS4 group, make an angle of 86.50 (1) ° with each other. The Te-S bond lengths are in the range 2.637 (4)-2.857 (4) A, the average being 2.738 (4) A. The extensive hydrogen bonding of the terminal hydroxyl groups in the range 2.678 (13)-2.763 (14) ,~ hinders the auto redox reaction in TeL 4 and also provides stability for the crystal packing.

In the structure of bis(diethyldithiocarbamato