Crystal and molecular structures and magnetic properties of bromo(3-dimethylaminopropan-1-olato)copper(II), chloro(3-dimethylaminopropan-1-olato) copper(II), and (3-diethylaminopropan-1-olato)isocyanatocopper(II)

Abstract

The crystal and molecular structures of the title compounds have been determined using three-dimensional X-ray diffractometer data and refined to a final R value of 0.0263 for bromo(3-dimethylaminopropan-1-olato)copper(II)(1), 0.0349 for chloro(3-dimethylaminopropan-1-olato)copper(II)(2), and 0.0268 for (3-diethylaminopropan-1-olato)isocyanatocopper(II)(3). The compounds crystallize in the monoclinic space group P2₁/c. The unit-cell dimensions are a= 6.273(3), b= 10.282(5), c= 12.403(5)Å, β= 99.62(2)°, Z= 4 for (1); a= 7.484(3), b= 6.145(3), c= 17.152(6)Å, β= 101.55(2)°, Z= 4 for (2); and a= 7.363(3), b= 12.422(5), c= 11.117(5)Å, β= 96.37(2)°, Z= 4 for (3). The structures of (1) and (2) consist of infinite chains of alkoxo-bridged copper(II) dimers connected by halogen bridges with long halogen–copper bonds [3.127(1)Å for (1) and 2.905(1)Å for (2)]. Neglecting these additional fifth co-ordination sites the co-ordination of the copper ions is distorted square planar. The structure of (3) consists of discrete dimeric molecules. The copper–copper distances are 3.063(1) for (1), 3.060(1) for (2), and 3.044(1)Å for (3). The magnetic susceptibilities measured from 11.1 K show very strong antiferromagnetic spin coupling for all three compounds. The magnetic behaviour can be explained using the Bleaney–Bowers equation. By fitting the experimental data to the Bleaney–Bowers equation good agreement can be obtained with the parameters g= 2.18(2), 2J₁₂=–1 065(20) cm^–1, x= 0.004(1), Nα= 63(5)× 10^–6 c.g.s.u. for (1), g= 2.21 (2), 2J₁₂=–1 020(20) cm^–1, x= 0.003(1), Nα= 54(5)× 10^–6 c.g.s.u. for (2) and g= 2.26(2), 2J₁₂=–1 056(20) cm^–1, x= 0.013(3), Nα= 108(5)× 10^–6 c.g.s.u. for (3). The evident differences between these results and those expected from magnetostructural correlations for related compounds are discussed. A magnetostructural correlation is presented which shows the influence of the co-ordination geometry at the copper atom on the exchange interaction in spin-coupled alkoxo-bridged copper(II) complexes.