The first copper(I) halide π-complexes with allyl derivatives of urea and parabanic acid

Abstract

By means of alternating current electrochemical synthesis with wire copper electrodes in methanolic solutions of corresponding ligands and copper(II) halide salts, two novel copper(I) π-complexes [Cu2(dau)Cl1.58Br0.42] (I) and [Cu2(dapa)Cl1.74Br0.26] (II) (where dau and dapa are 1,3-diallylurea and 1,3-diallylparabanate, respectively) were prepared in well-shaped crystalline form and studied with X-ray diffraction method. Compound I crystallizes in orthorhombic crystal system, space group P212121: a=8.047(3) Å, b=8.154(3) Å, c=16.533(5) Å, V=1085.8(76) Å3, Z=4. Compound II crystalizes in monoclinic crystal system, space group I2/a: a=6.420(3) Å, b=8.088(3) Å, c=49.020(9) Å, β=90.92(3)0, V=2545.03(16) Å3, Z=8. Both structures contain two crystallographically independent copper(I) ions with one half in trigonal planar coordination environment and the other half in trigonal pyramidal one. Both compounds are built of parallel copper halide polymeric chains of one type in I and two types in II, cross-linked by organic ligand molecules to produce 3D-polymer bulk in I and 2D-layered structure in II. In compound I, 1,3-diallylurea is both π- and π-bonded to copper(I) halide chains (by means of two allylic C=C bonds and carbonyl O atom), whereas 1,3-diallylparabanate is a solely π-donor ligand in compound II. The structure of II is noteworthy due to the combination of two different chain types that have been previously observed only separately in copper(I) halide coordination compounds.