Spectroscopic and magnetic properties of transition metal(II) triflouromethanesulfonate compounds with bridging asymmetric 3,4-dialkyl substituted 1,2,4-triazole ligands

Abstract

The spectroscopic and magnetic properties are described of coordination compounds with asymmetric 3,4-diakyl substituted 1,2,4-triazoles. The ligands 3-methyl-4-ethyl-1,2,4-traizole and 3-methyl-4-t-butyl-1,2,4-triazole have been investigated. Using M(CF 3SO 3) 2 (M = Mn, Co, Ni, Cu, Zn) compounds have been obtained with a linear trinuclear structure, in which the metal ions are linked to each other by two pairs of three bridging triazoles. The coordination sphere around the terminal ligands is completed by monodentate ligands and/or water molecules. The structure has been confirmed by an X-ray structure determination of [Co 3(metz) 6(H 2O) 6][Co 3 (metz) 8(H 2O) 4](CF 3SO 3) 12(H 2O) 8. this compound crystallizes in the space group P 1 with lattice constants a = 13.793(4), b = 14.401(3), c = 23.258(4) Å, α = 80.58(2), β = 83.23(2) and γ = 64.33(2)°. The unit cell contains two independent trinuclear clusters of different composition. These two clusters have the same overall structure. Differences are related to the presence of monodentately coordinating ligands as well as to the position of the C3-methyl substituent. The complete refinement of this structure was obstructed by disorder problems in the anions and the non-coordinating water molecules. The magnetic susceptibilities of the compounds have been recorded and could be fitted to theoretical expressions for linear trimers. The compound [Ni 2- (mtbtz) 5(H 2O) 4](CF 3SO 3) 4(H 2O) 4 appears to be a dimeric species as concluded from its magnetic behaviour.