Copper(II) complexes of pyrrole-containing Schiff-base macrocycles: crystal and molecular structures of a mononuclear macrocyclic complex, and of pyrrole-2,5-dicarbaldehyde

Abstract

Mono- and homodi-nuclear copper(II) complexes of macrocyclic Schiff-bases derived from the condensation of pyrrole-2,5-dicarbaldehyde and α,ω-alkanediamines are reported. The crystal structure of the mononuclear complex (3,7,14,18,23,24-hexa-azatricyclo[18.2.1.1^9,12]tetracosane2,7,9,11,13,18,20,22-octaene-N³,N⁷,N²³,N²⁴)copper(II) has been determined. Crystals are orthorhombic, of space group Pbcn(D_2h¹⁴, no. 60), with a= 11.701(9), b= 13.702(9), c= 10.600(6)Å, and Z= 4.557 Independent reflections with I/σ(I) > 3.0 gave R= 0.0518. The copper(II) atom is sited at one end of the macrocycle where it is bonded to two pyrrole and two imino nitrogen atoms in a co-ordination geometry having a 30.3° tetrahedral distortion from square planar. The pyrrole-dicarbimine fragments adopt cis–trans conformations. The crystal structure of pyrrole-2,5-dicarbaldehyde has also been determined. Crystals are monoclinic, of space group Pn(a non-standard setting of Pc; C_s², no. 7), with a= 3.81 66(6), b= 14.637(3), c= 20.755(5)Å,β= 91.665(16)°, and Z= 8.1 876 Independent reflections with |F|/σ(|F|) > 3.0 gave R= 0.0449.