Ferromagnetic interactions in EO-azido-bridged binuclear transition metal(Ⅱ) systems: Syntheses, crystal structures and magnetostructural correlations

摘要

Three new isostructural binuclear transition metal complexes with azido ion and 1,2-bis(3-(pyridin-2-yl)-1H-pyrazol-1-yl)ethane (bppe), formulated as [M 2 (N 3 ) 2 (bppe) 2 ](ClO 4 ) 2 (M = Co, 1; Ni, 2; Cu, 3), were successfully synthesized. They were structurally and magnetically characterized. In 1-3, the double azido ions link two adjacent octahedral metal centers together in the end-to-on mode (EO), with the M-N EO -M angles of 99.41°, 100.24° and 99.80°, respectively. The co-ligand bppe acts as terminal ligand to saturate the remaining coordination sites. The magnetic properties of 1-3 have been investigated in the temperature range of 2-300 K. Fitting of the magnetic susceptibility data revealed the occurrence of the strong ferromagnetic interactions [J = 26.32 cm-1 (1), J = 38.23 cm-1 (2) and J = 139.83 cm-1 (3)]. Density functional theory calculations have been performed on 1-3 to provide a magneto-structural correlation of the ferromagnetic behavior.