Metal ions directing the geometry and nuclearity of azido-metal(ii) complexes derived from bis(2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl)amine

Abstract

The reaction of a methanolic solution containing M(ClO₄)₂·nH₂O (M = Cu, Ni, Zn or Cd) or CoCl₂·6H₂O with bis(2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl)amine (bedmpza) in the presence of NaN₃ afforded the complexes [Cu(bedmpza)(μ_1,1-N₃)]₂(ClO₄)₂ (1), [Ni(bedmpza)(N₃)(μ_1,1-N₃)]₂·1.5H₂O (2), [Co(bedmpza)(N₃)₂] (3), [Zn(bedmpza)(N₃)]ClO₄ (4) and [Cd(bedmpza)(N₃)(μ_1,1-N₃)]₂·1.5H₂O (5). The five complexes were characterized by spectroscopic techniques and their molecular structures were determined by single crystal X-ray crystallography. The two mononuclear complexes 3 and 4 display distorted TBP and tetrahedral geometry, respectively with the azide ions acting as monodentate ligands. Doubly bridged end-on-azido dinuclear complexes were obtained in the remaining compounds. Compounds 2 and 5 are isomorphic with distorted octahedral geometry, whereas distorted square pyramidal geometry was determined in the Cu(II) complex 1. The magnetic properties for complexes 1 and 2 were investigated by measuring the magnetic susceptibilities at variable temperatures (300–2 K). The Ni(II) complex exhibits moderate ferromagnetic coupling, whereas [Cu(bedmpza)(μ_1,1-N₃)]₂(ClO₄)₂ (1) which contains two crystallographic independent dinuclear subunits in the unit cell, with different Cu–N(N3)–Cu bond angles, reveals different signs in the magnetic coupling. The complex represents the first example in the literature that has simultaneously two moieties with ferro- (J = 15.4 cm⁻¹) and antiferromagnetic (J = −18.9 cm⁻¹) interactions.