Moncol Jan, Mikloš Dušan, Segla Peter, Koman Marian
Department of Inorganic Chemistry, Slovak Technical University, Radlinského 9, SK-812 37 Bratislava, Slovakia.
Acta Crystallogr Sect E Struct Rep Online. 2008 Apr 16;64(Pt 5):m665-6. doi: 10.1107/S1600536808009756.
The dinuclear mol-ecule of the title compound, [Cd(2)(C(6)H(4)NO(2))(4)(C(2)H(8)N(2))(2)(H(2)O)(2)]·2H(2)O, lies on an inversion centre and forms 12-membered (CdNC(3)O)(2) metallacycles with the two Cd(2+) ions bridged by two nicotinate ligands. Both Cd(2+) ions display coordination polyhedra with a distorted octa-hedral geometry that includes two pyridine N atoms from bridging and terminal nicotinate anions, two amine N atoms from chelating ethylene-diamine ligands, carboxylate O atoms from bridging nicotinate anions and water O atoms. Inter-molecular O-H⋯O and N-H⋯O hydrogen bonds result in the formation of a three-dimensional network, and π-π stacking inter-actions are observed between symmetry-related pyridine rings of bridging as well as terminal nicotinate anions (the centroid-centroid distances are 3.59 and 3.69 Å, respectively, and the distances between parallel planes of the stacked pyridine rings are 3.53 and 3.43 Å, respectively). The two methylene groups of the ethylene-diamine ligand are disordered over two positions; the site occupancy factors are ca 0.8 and 0.2.
标题化合物[Cd₂(C₆H₄NO₂)₄(C₂H₈N₂)₂(H₂O)₂]·2H₂O的双核分子位于一个对称中心上，由两个烟酸酯配体桥连两个Cd²⁺离子形成12元(CdNC₃O)₂金属环。两个Cd²⁺离子均呈现出扭曲八面体几何构型的配位多面体，其中包括来自桥连和端基烟酸酯阴离子的两个吡啶N原子、来自螯合乙二胺配体的两个胺N原子、来自桥连烟酸酯阴离子的羧酸根O原子和水分子O原子。分子间的O—H⋯O和N—H⋯O氢键导致形成三维网络，并且在桥连以及端基烟酸酯阴离子的对称相关吡啶环之间观察到π–π堆积相互作用（质心间距分别为3.59和3.69 Å，堆叠吡啶环的平行平面之间的距离分别为3.53和3.43 Å）。乙二胺配体的两个亚甲基在两个位置上无序；占据因子约为0.8和0.2。
