Lewis acidity of coordinatively unsaturated bis(2-mercaptobenzothiazolato)nickel(II) towards azoles and morpholine

Abstract

The reactions of bis(2-mercaptobenzothiazolato)nickel(II) with some azoles and morpholine afforded the corresponding mixed ligand complexes. The studied azoles were 2-aminothiazole, benzothiazole, benzoxazole, 2-methylbenzoxazole and 2-mercapto-benzoxazole. The formation of new compounds was confirmed from the spectral data. The thermal decompositions of the compounds together with some related compounds reported in the literature, for comparison, were studied. The activation energies and other kinetic parameters were calculated from the Coats-Redfern and Horowitz-Metzger equations.2-Mercaptobenzothiazole(merBTz) exhibits biological activity in the sense that it can cause inhibition of tumour tissue [1]. Metal chelation is most probably involved in this effect. Further, the compound is used as a precipitant for gravimetrie analysis of many metals [2]; it has found applications in the vulcanization of rubber [3] and as a corrosion inhibitor [4]. Several metal complexes of merBtz have been reported in the literature [5]. These complexes could form mixed ligand complexes with nitrogen-containing ligands [6].Due to the above-mentioned particular importance of merBtz and because oxazole and thiazole derivatives are being used as analytical reagents in both industry and medicine [7,8], we embarked on a study of the interaction of Ni(merBtz)2 with a number of azoles and morpholine (morph).

Thermal and Microbicidal Study of Coordination Polymers: Transition Metal with 8HQMIT Ligand

“…[40] The negative S # values for all decomposition steps in the coordination polymer indicate that the polymers are more ordered. [41] The kinetic parameters, especially energy of activation (E a ), is helpful in assigning the strength of the bonding of ligand moieties with the metal ion. The calculated E a values of the investigated coordination polymer for the degradation stage of ligand are in the range 13.64-20.54 kJ mol −1 .…”

Spectral, magnetic, thermal and electrochemical studies on phthaloyl bis(thiosemicarbazide) complexes

“…Kinetic and thermodynamic parameters for some decomposition steps of some of the complexes.r ¼ Correlation coefficient, n ¼ order of the decomposition reaction; E, ÁH # and ÁG # are in kJ mol À1 , ÁS # in JK mol À1 .The negative ÁS # values for all decomposition steps in the complexes indicate that the complexes are more ordered[36]. The negative value is high in the VO 2þ complex due to the calculation being done for the second step in which the removed part leaves a less ordered species while the low value calculated for the Co(II) complex (fourth step) indicates more order.The TG thermogram of [Zn(H 2 PBT)(C 2 H 5 OH)] indicates stability till 152 C indicating that the ethanol participates in coordination or is inside the coordination with a hydrogen bond to one of the free coordination sites.TheTG thermogram [(VO) 2 (PBT)(C 2 H 5 OH)(H 2 O) 2 ] is taken as a representative example for the decomposition of these complexes.…”