Two isostructural uranyl complexes have been crystallized with different bipyridyl cations to yield the compounds hemi(4,4'-bipyridinium) tris(5-chlorothiophene-2-carboxylato)dioxidouranate(VI) monohydrate, (C(10)H(10)N(2))(0.5)[U(C(5)H(2)ClO(2)S)(3)O(2)]·H(2)O, (I), and hemi[4,4'-(ethane-1,2-diyl)dipyridinium] tris(5-chlorothiophene-2-carboxylato)dioxidouranate(VI) monohydrate, (C(12)H(14)N(2))(0.5)[U(C(5)H(2)ClO(2)S)(3)O(2)]·H(2)O, (II). In the [UO(2)X(3)](-) complexes (X is 5-chlorothiophene-2-carboxylate), the uranyl O atoms occupy the two axial positions and the equatorial positions are occupied by six O atoms of the three X ions so that each U atom is eight coordinated in a puckered hexagonal-bipyramidal structure. In both compounds, the metal centres are linked by classical O-H...O and N-H...O hydrogen bonds involving the coordinated ligands, the diprotonated organic linker cation (which rests on a centre of inversion at the mid-point of the central C-C bond) and water molecules. The crystal structures are further stabilized by weak C-H...O and π-π stacking interactions, forming similar three-dimensional supramolecular architectures, forming a two-dimensional network parallel to the (100) plane in (I) and a three-dimensional network in (II).
BackgroundVarious dinuclear copper (II) complexes with octahedral geometry have been reported. The majority of these complexes contain N containing aromatic rings as axial ligands. There are also a few cases where the solvent used in the reaction occupies the axial position of the dinuclear copper (II) complex. This may occur by planned synthesis or some times by serendipity. Here we report some four copper (II) complexes containing solvent and or N containing heterocyclic ring as the axial ligand.ResultsFour compounds, each containing dinuclear Copper (II) units (with the most robust, frequently occurring paddle wheel structures) were synthesized and characterised by single crystal X-ray diffraction and by IR spectroscopy. The compounds 1 & 2 have the general formula Cu2(RCOO) 4(L)2 [(for (1) RCOO= 4-Chloro Benzoate, L= Isopropanol; for 2 RCOO= Benzoate, L= 2-Amino-4,6-dimethyl pyrimidine )] while 3 & 4 have the general formula, Cu2(RCOO) 4(S)2 Cu2(RCOO) 4(L)2 [RCOO=5-Chloro-thiophene-2-carboxylate L= 2-Amino-4,6-dimethyl pyrimidine, for 3 S= ethanol; for 4 S= methanol ]. A wide range of hydrogen bonds (of the O-H…O, N-H…O and N-H…N type) and π-π stacking interactions are present in the crystal structures.ConclusionsAll compounds contain the dinuclear units, in which two Cu (II) ions are bridged by four syn, syn-η1:η1:μ carboxylates, showing a paddle-wheel cage type with a distorted octahedral geometry. The compounds 1 &2 contain a single dimeric unit while 3 &4 contain two dimeric units. The structures 3 and 4 are very interesting co-crystals of two paddle wheel molecules. Also it is interesting to note that the compounds 3 &4 are isostructural with similar cell parameters. Both the compounds 3 &4 differ in the solvent molecule coordinated to copper in one of the dimeric units. In all the four compounds, each of the copper dimers has an inversion centre. Every copper has a distorted octahedral centre, formed by four oxygen atoms (from different carboxylate) in the equatorial sites. The two axial positions are occupied by copper and the corresponding ligand.
Two Pb(II) complexes with 8-quinolinol (8-Quin), 5-chloro thiophene-2-carboxylic acid, and (5-CTPC)/5-bromo thiophene-2-carboxylic acid (5-BTPC) have been synthesized and characterized by IR, 13 C NMR, and solid state photoluminescence spectra. The structures of [Pb(8-Quin) 4 ](5-CTPC) 2 (1) and have been confirmed by X-ray crystallography. Both complexes crystallize in the triclinic crystal system with a space group P 1. In 1, Pb(II) is eight coordinate by four bidentate 8-quinolinol groups, while in 2 it is six coordinate by two bidentate 8-quinolinol groups and one bidentate 8-quinolinolate group. This leads to square antiprismatic and pentagonal pyramidal geometries around Pb(II) in 1 and 2, respectively. Two of the 5-CTPC ligands in 1 and a 5-BTPC in 2 are involved in strong O-HÁ Á ÁO hydrogen bonding in the lattice. ClÁ Á Á interactions are found in 1. The crystal structures are stabilized by weak C-HÁ Á ÁO and -stacking interactions.
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