Metal complexes with pyrazole-derived ligands

Abstract

The thermal decomposition of tetrahedral eobalt(ll) complexes with 3(5)-amino-4-aeetyl-5(3)-methyipyrazole (HL) of the general formula [Co(HL)2X2] (X=CI, Br, I, NCO, NCS) and oetahedral [Co(HL)2(H20)4I(NO3)2 and ICo(HL)z{N(CN)2}2I complexes was investigated in air atmosphere in the interval from room temperature to 1000~ Decomposition of the complexes occurred in several successive endothermie and exothermic processes, and the residue was in all cases CoO.

Cobalt(II) complexes with disubstituted 3-aminopyrazole derivative: Mononuclear Co(II) complex with in situ prepared formamidine ligand

“…N 1 N 2 -bridge formation was also observed in [Zn-(l-aamp-H)(aamp)OAc] [16]. In our earlier papers [14] the syntheses, some physicochemical properties and thermal characterization [15] of tetrahedral [Co(aamp) 2 X 2 ] (X = Cl, Br, I, NCS, NCO), the pseudo-octahedral [Co(aamp) 2 (H 2 O) 4 ](NO 3 ) 2 and that of [Co{l-N(CN)} 2 (aamp) 2 ] has been reported. All these reactions were carried out in the presence of a small amount of water originating from the crystal hydrates of the metal salts used in the synthesis.…”

“…[15]. Here we give only some comments on the evaporation mechanism of water molecules from 1 compared to the evaporation of MeOH from 2.…”

“…To see how the experimental conditions affect the course of formation of complexes with 4-acetyl-3-amino-5-methylpyrazole (aamp) we have prepared complexes of Cu(II) [1], Co(II) [14,15], Zn(II) [1,16], Hg(II) [1] and Pt(II) [2] with the aamp ligand. It was found that in its neutral form this ligand coordinates mostly monodentately through the N2 nitrogen atom of the pyrazole ring.…”

Transition metal complexes with pyrazole based ligands, part 27: Structural and thermal characterization of cobalt(II) halide and pseudohalide complexes with 4-acetyl-3-amino-5-methylpyrazole

“…Namely, in a previous paper, 15 the thermal decomposition was described in detail. The sample masses used for the TA measurements in 1996 were about 100 mg and the heating rate was 10 K min -1 .…”

“…For instance, at small pyrazole molecules, the type and position of the substituents, the solvent or the temperature of the reaction mixture, as well as the central atoms and their corresponding anions were changed. 8−11 With the title ligand, 4-acetyl-3-amino-5-methylpyrazole, compounds, 12,13 including the title compounds, 14,15 have already been prepared. However, more than ten years ago there was no the possibility to determine the crystal structure of the microcrystalline title compounds.…”