The first coordination compound of deprotonated 2-bromonicotinic acid: crystal structure of a dinuclear paddle-wheel copper(II) complex

Abstract

A copper(II) dimer with the deprotonated anion of 2-bromonicotinic acid (2-BrnicH), namely, tetrakis(μ-2-bromonicotinato-κ2 O:O′)bis[aquacopper(II)](Cu—Cu), [Cu2(H2O)2(C6H3BrNO2)4] or [Cu2(H2O)2(2-Brnic)4], (1), was prepared by the reaction of copper(II) chloride dihydrate and 2-bromonicotinic acid in water. The copper(II) ion in 1 has a distorted square-pyramidal coordination environment, achieved by four carboxylate O atoms in the basal plane and the water molecule in the apical position. The pair of symmetry-related copper(II) ions are connected into a centrosymmetric paddle-wheel dinuclear cluster [Cu...Cu = 2.6470 (11) Å] via four O,O′-bridging 2-bromonicotinate ligands in the syn-syn coordination mode. In the extended structure of 1, the cluster molecules are assembled into an infinite two-dimensional hydrogen-bonded network lying parallel to the (001) plane via strong O—H...O and O—H...N hydrogen bonds, leading to the formation of various hydrogen-bond ring motifs: dimeric R 2 2(8) and R 2 2(16) loops and a tetrameric R 4 4(16) loop. The Hirshfeld surface analysis was also performed in order to better illustrate the nature and abundance of the intermolecular contacts in the structure of 1.

Self‐Assembly of Cobalt(II) Coordination Polymers with Differently Halosubstituted Nicotinate Ligands and 4,4’‐Bipyridine – The Effect of the Halosubstituent Positions on Polymer Types

“…[14][15][16][17][18][19][20][21][22][23][24] Previously, we have studied nickel(II) coordination polymers with the selected haloderivatives of nicotinic acid (6-fluoronicotinic (6-F-nicH) or 6-chloronicotinic (6-Cl-nicH) acid) and 4,4'bipyridine (4,4'-bpy). [25][26] The 4,4'-bipyridine was used as an additional organic linker to ensure the formation of more diverse coordination polymers. These polymers were prepared under the same experimental conditions (solvent, temperature, molar ratio of the metal ion and ligands), but two different types of 1D coordination polymers were obtained: {[Ni(6-Fnic) 2 (4,4'-bpy)(H 2 O) 2 ] • 3H 2 O} n in the case of 6-fluoronicotinate [25] and {[Ni(4,4'-bpy)(H 2 O) 4 ](6-Cl-nic) 2 • 4H 2 O} n in the case of 6chloronicotinate.…”

“…[25][26] The 4,4'-bipyridine was used as an additional organic linker to ensure the formation of more diverse coordination polymers. These polymers were prepared under the same experimental conditions (solvent, temperature, molar ratio of the metal ion and ligands), but two different types of 1D coordination polymers were obtained: {[Ni(6-Fnic) 2 (4,4'-bpy)(H 2 O) 2 ] • 3H 2 O} n in the case of 6-fluoronicotinate [25] and {[Ni(4,4'-bpy)(H 2 O) 4 ](6-Cl-nic) 2 • 4H 2 O} n in the case of 6chloronicotinate. [26] In the structure of nickel(II) polymer {[Ni(6-Fnic) 2 ( [25][26] These structural differences could be solely ascribed to the type of halosubstituent (fluorine vs. chlorine) in the nicotinate ligand, as all other parameters, both synthetic and structural, were kept unchanged.…”