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

A copper(II) dimer with the deprotonated anion of 2-bromo­nicotinic acid (2-BrnicH), namely, tetrakis(μ-2-bromonicotinato-κ(2) O:O′)bis[aquacopper(­II)](Cu—Cu), [Cu(2)(H(2)O)(2)(C(6)H(3)BrNO(2))(4)] or [Cu(2)(H(2)O)(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.