Four complexes with general formulas MIIL2·CH3OH (M = Co, Zn) and MIIL2 (M = Ni, Cu) were synthesized by transition metal ions MII (Co, Ni, Cu, Zn) reacting with 2-(2-hydroxyphenyl)benzimidazole (HL). Their thermal properties were studied; the probable thermal decomposition mechanism for the first step of the Co(II) and Zn(II) complexes was suggested, and the kinetic parameters were also given.

The title compound (systematic name: aqua{4,4′‐di­bromo‐2,2′‐[1,2‐ethanediyl­bis­(nitrilo­methyl­idyne)]­diphenolato]­chloro­manganese(III)), [Mn(C16H12Br2N2O2)Cl(H2O)] or [Mn(Br2salen)Cl(H2O)], was prepared from a methanol solution. The Mn3+ ion displays an elongated octahedral geometry, coordinated by two N and two O atoms from salen, one O atom from the water ligand and one Cl− anion, and is slightly displaced out of the Schiff base N2O2 plane toward the axial Cl− ion. Hydro­gen bonds between the coordinated water O and Cl atoms link pairs of mol­ecules into a three‐dimensional network.