Crystal structure and magnetic properties of dimeric [2-hydroxypropane-1,3-diylbis(3′-t-butyl-5′-methylsalicylideneiminato)]copper(II)

Abstract

The crystal and molecular structure of the title compound has been determined from single-crystal X-ray diffraction data and refined to a final R value of 0.0882 (R′= 0.0521) using 2 527 independent reflections. The copper(II) complex crystallizes in the tetragonal space group I4₁/a with dimensions a= 14.740(2) and c= 47.512(8)Å. The copper atom is co-ordinated in a distorted square planar fashion by the deprotonated phenolic oxygens and the Schiff-base nitrogen atoms. Discrete dimeric units are built up by an additional weak co-ordination of the hydroxy oxygen [Cu(1)–O(2′) 2.697(5)Å] approximately perpendicular to the plane defined by the four chelate ligand donor atoms. This arrangement is also stabilized by three hydrogen bond bridges per dimer. Despite the long copper–copper distance [Cu(1)–Cu(1′) 5.457(2)Å] and unusual bridging units the e.s.r. spectra and the temperature dependence of the magnetic moment show a weak antiferromagnetic spin coupling with a singlet–triplet splitting of about 3 cm^–1.