Afaf K. Hafez

Two new polymeric cadmium(II) complexes containing end-to-end bridging azido or thiocyanato ligands with different topologies

Abstract Two new polymeric cadmium(II) complexes; [Cd(3,5-DMP)2(N3)2] (1) and [Cd(4-Brpy)2(NCS)2] (2), where 3,5-DMP=3,5-dimethylpyridine and 4-Brpy=4-bromopyridine, have been synthesized and characterized. IR spectral data suggest end-to-end bridging azido and thiocyanato ligands. X-ray crystal structure determination has shown the 1-D complex 1 to contain each cadmium octahedrally coordinated by two double μ(1,3)-bridging azides and the other two sites are occupied by two pyridine ligands in a cis-arrangement. The CdCd distances in the Cd2(N3)2 eight membered rings are 5.142(2) and 5.152(2) A, the azide ligands are almost symmetrical and linear [NN distances: 1.167(5)–1.182(5) A; ∠NNN=176.7(4)° and 177.6(4)°]. In complex 2 each octahedrally cadmium atom is coordinated by two trans pyridine ligands and two trans nitrogen or sulfur atoms from four μ(N,S) bridging thiocyanato groups. The other end atoms of these four thiocyanato ligands bind four different cadmium atoms giving a 2-D layer structure.

Synthesis and crystal structure of three new 2D polymeric cadmium(II) complexes of some pyridine derivatives with different cadmium(II)–azide topologies

Three new polymeric complexes [Cd(2-Acpy)(N3)2]n1, [Cd(4-Acpy)2(N3)2]n2 and [Cd3(4-Brpy)4(N3)6]n3 (2-Acpy = 2-acetylpyridine, 4-Acpy = 4-acetylpyridine, and 4-Brpy = 4-bromopyridine) have been synthesized and characterized by single crystal X-ray diffraction. The coordination environment of the cadmium atom in all the complexes is distorted octahedral with two-dimensional polynuclear layers. The cadmium atoms are linked by both μ-1,1 and μ-1,3 in 1, by only μ-1,3 in 2 and by μ-1,1 and μ-1,1,3 azide bridges in 3 giving different cadmium(II)–azide topologies.

Structural characterization of one-, two-, and three-dimensional polymeric complexes assembled by cadmium(II) pseudohalides and some pyridine ligands via covalent bonds and hydrogen bonds

Three new cadmium(II) complexes: [Cd(4-Clpy)2(NCS)2]n (1), [Cd(3-aldpy)(H2O)(N3)2]n (2) and [Cd(3-CNpy)(N3)2]n (3) (4Clpy ¼ 4-chloropyridine, 3-aldpy ¼ 3-aldehyde-pyridine, and 3-CNpy ¼ 3-cyanopyridine) have been synthesized and structurally characterized. The IR spectra of the complexes are measured and discussed. The single crystal X-ray diffraction revealed that the structure of 1 features l-1,3-thiocyanate bridges and 1D chains. It consists of alternate octahedrally coordinated Cd atoms. Both Cd(1) and Cd(2) are surrounded by pairs of 4-Clpy, S atoms and N atoms of two di-l-1,3 thiocyanato bridges in trans and cis arrangements, respectively. In complex 2 each octahedrally coordinated Cd binds two di-l-1,1 azide bridges in a zigzag 1D chain and the other two positions are occupied by O and N atoms from aqua and 3-aldpy molecules, respectively. Hydrogen bonds of the types O–H ��� O and O–H �� � N are formed between aqua molecules and end nitrogen atoms of the l-1,1 azide bridges generating 3D framework structure of 2. The structure of 3 consists of [Cd(N3)2]n chains in which each octahedrally coordinated Cd atom is linked by two di-l-1,1 azide bridges. These chains are cross-linked by l-N ; N 0 -3-CNpy bridges generating 2D systems for this complex.

SYNTHESIS AND SPECTRAL AND STRUCTURAL CHARACTERIZATION OF A BRIDGING CHLOROPICOLINATOCOPPER(II) COMPLEX, CU(C5H4NCOO)CL

SummaryThe title complex of copper(II) chloride with picolinic acid was prepared and characterized by spectroscopic and X-ray crystallographic methods. The complex, Cu(C5H4NCOO)Cl, crystallizes tetragonal, space group P42/n (No. 86),a=976.4(1),c=1499.6(4) pm,N=8;Rw=0.048 for 543 observed MoKα diffractometer data. In the structure of the complex two μ-chloro bridges form only slightly bent Cu2Cl2 rings [Cu-Cl=224.2(4) and 275.6(4) pm] with Cu...Cu separation of 359.4(2) pm and Cl...Cl separation of 348.7(5) pm. These edge-sharing copper coordination polyhedra are further linked via the N and O donor atoms of the picolinato anions at Cu-N distances of 199.6(12) pm and Cu-O bond lengths of 195.7(8) and 200.6(10) pm, to form a two-dimensional layer structure in which these layers are arranged along theab plane. Each picolinate anion functions as a tetra-dentate ligand: N(1) and O(2) are coordinated to the same Cu(II) center whereas O(1) is bonded to a neighbouring Cu(II) center. O(2) is further bonded to the latter Cu(II) center at a long Cu-O distance of 256.5(8) pm. The electronic, infrared and Raman spectra of the solid complex are reported and discussed.ZusammenfassungDer Titelkomplex aus Kupfer(II)chlorid und Picolinsäure wurde dargestellt und mit spektroskopischen und Röntgen-Einkristall-Methoden charakterisiert. Cu(C5H4NCOO)Cl kristallisiert tetragonal, Raumgruppe P42/n (No. 86),a=976.4(1),c=1499.6(4) pm,N=8;Rw=0.048 für 543 beobachtete Mokα-Diffraktometerdaten. In der Kristallstruktur bilden zwei μ-chloro-Brücken nur wenig gewinkelte Cu2Cl2-Ringe aus [Cu-Cl=224.2(4) und 275.6(4) pm], mit Cu...Cu Abständen von 359.4(2) pm und Cl...Cl Abständen von 348.7(5) pm. Die kantenverknüpften Koordinationspolyeder der Kupferatome sind in Richtung derab-Ebene über die N- und O-Donoratome der Picolinat-Anionen [mit Cu-N Abständen von 199.6(12) pm und Cu-O Abständen von 195.7(8) und 200.6(10) pm] zu einer zweidimensionalen Schichtstruktur verknüpft. Jedes Picolinat-Anion fungiert als vierzähniger Ligand: N(1) und O(2) sind zum selben Cu(II)-Zentrum gebunden; O(1) ist zum benachbarten Cu(II)-Zentrum koordiniert, zu dem O(2) einen langen Cu-O-Abstand von 256.5(8) pm ausbildet. Die elektronischen, Infrarot- und Raman-Spektren des Festkörper-Komplexes werden berichtet und diskutiert.

A copper(I) complex containing a new structure of the [Cu2I3]− anion. Reaction of CuI with quinaldic acid and the crystal structure of tris-(2-carboxyquinoline)triiododicopper(I) monohydrate

Abstract The reaction between copper(I) iodide dissolved in excess NaI and quinaldic acid (H-Quild) afforded two compounds: tris-(2-carboxy quinoline)triiodocopper(I) monohydrate (1) and [(H-Quild)2H]+I−·2H2O (2). Both compounds are characterised by elemental analysis, electronic, IR and Raman spectra. They exhibit charge transfer transitions in the visible region. The crystal structure of complex 1 shows that it consists of the polymeric [Cu2I3]− anion, three H-Quild molecules in zwitterionic form (two of them are linked by a hydrogen bond between the two carboxy groups) and a lattice water molecule. The infinite anionic chain [Cu2I3]− is composed of a fusion of three kinds of rings: rhombus-likeCu2I2, folded Cu2I2, and Cu4I4 in a twisted-chair conformation, in which the Cu(1) atom is tetrahedral whereas the Cu(2) atom is trigonal planar. The thermal decomposition of complex 1 is investigated in nitrogen atmosphere.

Synthesis and characterization of copper(I) complexes of 4-methylquinoline, and x-ray crystal structure of a discrete, centrosymmetric [Cu2Cl2(4-methylquinoline)3]2 complex with a Cu4Cl4 core of ‘step’ geometry

Copper(I) complexes of the general formula (CuX)nLm, where L = 4-methylquinoline, n = 1, m = 1 for X = Cl, Br, I, SCN and N3, n = 1, m = 2 for X = NO3 and ClO4, and n = 2, m = 3 for X = Cl and Br were prepared and characterized. Excepting the perchlorate complex all other complexes are colored and exhibit strong CT bands in the visible region. The infrared spectral data suggest the presence of bridging halide and pseudohalide, monodentate nitrate, and bidentate perchlorate groups in the respective complexes. The structure of the 2:3 chloro complex was determined by X-ray crystallography. The crystals are triclinic, space group P1, with a = 10.587(1), b = 11.321(3), c = 11.329(3) A, α = 85.17(2), β = 89.67(2), γ = 80.88(2)° and Z = 1. The structure was refined to RF = 0.053 for 3174 observed Mo Kα diffractometer data. The discrete [Cu2Cl2(4-methylquinoline)3]2 molecule is centrosymmetric with a short Cu(1)…Cu(2′) contact of 2.777(1) A, and has the ‘step’ structure well known for Cu4X4L4 species; however, the copper atoms at the periphery of the ‘step’ are coordinated by a pair of nitrogen ligands.

Synthesis, spectra, crystal structure and thermal properties of a polymeric 1-D cobalt(II) cyanato complex with hexamethylenetetramine

A new cobalt(II) cyanato complex, [Co(NCO)2(H2O)2(hmt)] (I) where hmt is hexamethylenetetramine, has been synthesized and structurally characterized. The electronic spectra of the solid compound suggest octahedral cobalt and IR spectra revealed monodentate N-cyanato groups and aqua ligands, while hmt is a bridging N, N′-bidentate leading to a 1-D infinite polymeric chain. The structure has been confirmed from single crystal X-ray diffraction. Crystal data for I : Fw 319.20, a = 9.234(2), b = 11.252(2), c = 12.576(3) Å, β = 107.75(3)°, V = 1244.5(4) Å3, Z = 4, T = 100 K. Crystal system : monoclinic, space group : C2/c. Hydrogen bonds of the type O–H ··· O and O–H ··· N between aqua molecules and O atom of the terminal N-cyanato groups or an N atom of hmt ligands consolidate and extend the structure to a 3-D network. The thermal properties of I are reported. 1Deceased.

Preparation and X-ray structure of [(methyl quinaldate)2H]+ [AuBr4]−

The crystal structure of the title complex (RF=0.051 for 2384 observed MoKα data) consists of a packing of tetrabromoaurate(III) anions and [(methyl quinaldate)2H]+ cations in which the two planar heterocyclic ring moieties are interlinked by a proton to form a N⋯H⋯N hydrogen bond of length 2.88(1) Å; the dihedral angle of the planes is 79.5°. The infrared spectrum of the compound is also discussed.

Gold(III) Halide Complexes of 3- and 4- Quinolinecarboxylic Acids

Abstract Gold(III) halides form with 3- and 4-quinolinecarboxylic acids complexes of the types [(H3o)(HQA)2][AuX4] for X = Cl or Br and AuX3(HQA)n, where n = 1 for X = Cl or Br and n = 2 for X = I. The complexes were isolated and characterized by elemental analysis, conductivity and spectra. In the solid state the gold atom is in an elongated octahedral coordination environment in [(H3o)(HQA)2][AuX4]. The stereochemistries of the other complexes are discussed in relation to the number of their gold-halogen frequencies observed in the far infrared region.