Asymmetric chlorine-bridged zig-zag Cu(II) chains linked together in 2D sheets by strong Watson–Crick type intermolecular double hydrogen bonds of bis(pyrimidin-2-yl)amine ligands: synthesis, structure and antiferromagnetism

Abstract

A novel polymeric, asymmetric chloro-bridged copper chain with general formula [l-Cl-CuCl(dipm] n (in which dipm = bis(pyrimidin-2-yl)amine) has been synthesized and characterised by X-ray crystallography and infrared spectroscopy. The chains are organized in 2D sheets by intermolecular double H bonds between pairs of dipm molecules. In addition, EPR and magnetic measurements have been performed, and these have been related to the dinuclear structural details.The geometry around the copper(II) ion is distorted square pyramidal with the basal plane formed by the two nitrogen atoms of the dipm ligand and two chloride atoms, one of which is bridging. The Cu-N distances are 2.0342(15) and 2.0125(15) Å and Cu-Cl distances are 2.2899(6) and 2.2658(6) Å . The apical position of Cu is occupied by a chloride atom of a neighbouring unit atom at a distance of 2.6520(6) Å , resulting in the polynuclear array in which one chloride anion and the copper ion forms a zig-zag chain. The magnetic interaction between the Cu-Cu atoms is weak antiferromagnetic with a singlet-triplet separation (J) of À3.2(1) cm À1.

Intermolecular Watson–Crick-like ligand pairing in two Cu(II) compounds with the ligand bis(pyrimidin-2-yl)amine forming 2D chain-type compounds

“…This type of hydrogen bond array has been observed earlier with this ligand [10][11][12]14]. Secondly, medium to strong hydrogen bonds are formed by the hydrogen atoms of the coordinated water molecule to the oxygen atoms of the formato anion (compound 1), and to the oxalato anion (compound 2) with OÁ Á ÁO distances of 2.799(3), 2.766(2) Å for compound 1 and from 2.732(4) to 3.125(4) for compound 2.…”

“…A ligand with interesting hydrogen-bonding properties is the recently developed ligand bis(pyrimidin-2-yl)amine (abbreviated as dipm) [10][11][12][13][14]. The dipm molecule can both donate and accept hydrogen bonds, and has a more or less linear donor-acceptor array of the A-D-A type.…”

Synthesis, Characterization and DFT-Based Investigation of a Novel Trinuclear Singly-Chloro-Bridged Copper(II)-1-Vinylimidazole Complex

“…The small bridging angle gives rise to a shorter Cu1-Cu2 seperation (4.005 Å) and probably to the formation of a monomeric structure rather than a polymeric one as compared to the similiar molecular structure reported by Ray et al 30 This type of copper(II) complexes incorporating only one bridging-chloro ligands are not common and hence are of special interest. [31][32][33] None of intramolecular H-bonds were detected in the trimer. But the weak intermolecular non-classical C12-H12···Cl3(x -1, y, -z) interactions together with C4-H4 ···Cg1(x, 1 + y, z) 3.00 Å, C8-H8···Cg2 2.81 Å and C11-H11···Cg2(1 -x, …”

Mechanistic Insights into Stereoselective Catalysis—The Effects of Counterions in a CuII–Bissulfoximine‐Catalyzed Diels–Alder Reaction

“…For bisbridged halide copper compounds this value is around 450 pm, [32] for monobridged halide chains it is larger than 470 pm. [33,34] In polymeric chains, an apical Cu-halide interaction exists among the repeating units, in which the axial Cu-halide bonds are longer than the equatorial ones. The monohalide bridged Cu chains are usually found when the ligand induces steric constraints, which prevent a symmetric bisbridging arrangement.…”