Structural Aspects of Cadmium(II) Complexes - Isomers (original) (raw)
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Inorganica Chimica Acta, 1999
Note Cadmium(II) complexes with [(4-methylphenyl)sulfonyl]-2-pyridyl-amine: crystal structures of bis{[(4-methylphenyl)sulfonyl]-2-pyridyl-amide}cadmium(II); aquobis(pyridine) bis{[(4-methylphenyl)sulfonyl]-2-pyridyl-amide}cadmium(II) and 1,10-phenanthroline bis{[(4-methylphenyl)sulfonyl]-2-pyridyl-amide}cadmium(II) Abstract Electrochemical oxidation of cadmium in a solution of [(4-methylphenyl)sulfonyl]-2-pyridyl-amine (HL) in acetonitrile/ dichloromethane afforded the compound [CdL 2 ]. When pyridine (py), 2,2%-bipyridine (bipy) or 1,10-phenanthroline (phen) was added to the electrolytic phase, [CdL 2 py 2 (H 2 O)], [CdL 2 bipy] and [CdL 2 phen] were obtained. The crystal structures of [CdL 2 ] (1), [CdL 2 py 2 (H 2 O)] (2) and [CdL 2 phen] (3) have been determined by X-ray diffraction techniques. The complex [CdL 2 ] is best described in terms of a linear polymer with the metal atom in a [CdN 4 O 2 ] distorted octahedral environment. The [CdL 2 py 2 (H 2 O)] and [CdL 2 phen] complexes are monomeric, with the cadmium atoms in [CdN 6 O] distorted pentagonal bipyramid and [CdN 6 ] trigonal prismatic environments, respectively. (J. Castro), qiansoal@usc.es (A. Sousa)
Polyhedron, 1997
Complexes formed by Zn", Cd" and Hg" in the presence of the octadentate ligand 1,4,7,10tetrakis(pyrazol-1-ylmethyl)-1,4,7,10tetraazacyclododecane. X-ray structure of the cadmium complex
Polyhedron, 2005
Chelation of the tetradentate pyridyl di-Schiff-base ligands, N,N 0 -bis-(1-pyridin-2-yl-ethylidene)-propane-1,3-diamine (L 1 ) or N,N 0 -bis-(1-pyridin-2-yl-ethylidene)-ethane-1,2-diamine (L 2 ) to a cadmium(II) centre reveals interesting structural deviations from regular octahedral geometry in the resulting hexacoordinated complexes [Cd(L 1 )(NCS) 2 ] (1) and [Cd(L 2 )(NCS) 2 ] (2), respectively. The two tetradentate ligands L 1 and L 2 differ only in the polymethylene chain -(CH 2 ) 3 and (CH 2 ) 2 , respectively, which connects the two halves of the symmetric ligands. Complex 1 assumes a trigonal prismatic (TP) geometry. The structure of 2 reveals a severely distorted octahedral geometry. The structural differences between [Cd(L1)(NCS) 2 ] (1) and [Cd(L 2 )(NCS) 2 ] (2) can be traced to the length of the polymethylene spacers and the formation of a six-versus a five-membered metal-chelate ring together with the pyramidal Cd(L 1 ) and planar Cd(L 2 ) arrangement.
Taylor & Francis Group, 2012
"By Mohammad Hakimi (a), Zahra Mardani (a), Keyvan Moeini (a) and Manuel A. Fernandes (b) (a) Department of Chemistry, Payame Noor University, Tehran, I. R. Iran (b) Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Private Bag 3, Wits, Johannesburg 2050, South Africa The new ligand 2-(2-(2-hydroxyethylamino)ethylamino)cyclohexanol, (HEAC), was prepared under microwave conditions through ring opening of cyclohexene oxide with 2-(2-aminoethylamino) ethanol. Its cadmium(II) complexes [Cd2(HEAC)2(-Cl)2Cl2] (1) and [Cd(HEAC)2][CdI4] (2) were identified by elemental analysis, FT-IR, Raman, 1H NMR spectroscopies, and single-crystal X-ray diffraction. HEAC formed 1 : 1 M: L complexes with cadmium chloride and cadmium iodide. Complex 1 crystallized as a dimer with two asymmetrically bound bridging Cl and a terminally coordinated Cl on each metal. The geometry around the cadmiums in 1 with four five-membered chelate rings and four Cl ligands is distorted octahedral for each Cd(II). The cyclohexanol OH of each ligand forms intramolecular hydrogen bonds. In 2, the coordination numbers for cadmium in [Cd(HEAC)2]2þ and [CdI4]2 moieties are six and four, respectively. In [Cd(HEAC)2]2þ each ligand coordinates through two N- and one O-donors, leading to a distorted octahedral geometry. The geometry of [CdI4]2 in 2 is slightly distorted tetrahedral. The protonation equilibrium constants of the two secondary amino groups in HEAC, determined by pHpotentiometry, were 6.26 and 9.26, respectively, at 25C. Stability constants for this ligand with Ni(II), Cu(II), and Zn(II) (1 : 1 M: L), determined by glass-electrode potentiometry, were 7.13, 10.50, and 5.42, respectively. CCDC 850085 and 869839 for 1 and 2, respectively, contain the supplementary crystallographic data for this article. These data can be obtained free of charge via www.ccdc.cam.ac.uk/conts/retrieving.html [or from the Cambridge Crystallographic Data Centre (CCDC), 12 Union Road, Cambridge CB21EZ, UK; Fax: þ44(0)1223-336033; E-mail: deposit@ccdc.cam.ac.uk]. Structure factor table is available from the authors. Keywords: Amino alcohol; Cadmium; X-ray structure; Dimer; Stability constant DOI: 10.1080/00958972.2012.690145"
Preparation and structural characterisation of a Cd(II) complex with unusual geometry
Inorganic Chemistry Communications, 2007
Reaction of Cd(NO 3) 2 AE 4H 2 O with ethyl-2-pyridinecarboxylate yields [Cd(NO 3) 2 (C 5 H 4 NCOOEt) 2 ]. Elemental analyses, conductivity measurements, infrared, 1 H and 13 C{ 1 H} NMR spectroscopies and single-crystal X-ray diffraction enabled us to characterise this complex. The crystal structure consists of monomeric units in which the cadmium atom is eight-coordinated.
Physico-chemical studies of a novel cadmium(II) coordination compound[(C6H9N2)2CdCl4]0.305H2O
European Chemical Bulletin, 2014
The crystal structure of the title organic-inorganic hybrid material, [(C 6 H 9 N 2 ) 2 CdCl 4 ]0.305H 2 O, contains two crystallographically independent but chemically equivalent cadmium complexes with essentially the same geometry (rms deviation of all atoms: 0.152 A). The metal centers have a 6-coordinated octahedral geometry and both Cd atoms exhibit exact crystallographic inversion symmetry. Crystal packing is stabilized by intermolecular N-H...Cl hydrogen bonds that connect individual zwitter-ionic complexes into a three dimensional lattice, which is further stabilized through p-p stacking interactions between aromatic rings of neighboring complexes, with centroid to centroid distances of 3.4406(14) and 3.7022(13) A and interplanar separations of 3.299(1) and 3.302(1) A. Interstitial space is partially filled with water molecules which are connected to the network through O-H...Cl and C-H...O hydrogen bonds. The 13 C and 15 N CP-MAS NMR spectra are in agreement with the X-ray...
Inorganica Chimica Acta, 1995
The complexation of Cd(II) by a series of triazacycloalkanes, ([x]aneN3, x= 9-12), has been studied in 0.10 mol dm-3 KNO3 aqueous solution at 298.2-1-0.1 K. Stability constants (/3CdL) for the complexes decrease in magnitude with increasing number of atoms in the ligand ring, and are several orders of magnitude smaller than corresponding /3Z, L values. Two complexes [Cd2([9]aneN3)2(/.~-Cl)2Cl2] (1) and [Cd2([11]aneN3)2(/~-Cl)2Br2] (2) were synthesized, and the structures determined by X-ray crystallography. Complex I crystallizes in the triclinic space group P1, with a = 7.657(2), b = 7.741(2), c = 17.750(2)/~, a = 90.13(3), /3=94.65(3), y=90.76(3) ° and V=1048.5(5) A3 for Z=2. Complex 2 crystallizes in the monoclinic space group P21/c with a =8.144(2), b = 8.469(2), c = 18.480(4) /k, /3 =97.62(3) ° and V= 1263.3(6) /~3 for Z = 2. Both structures contain bridging di-/.~chloro groups separating six-coordinate Cd(II). Each Cd(II) is also bonded to a tridentate ligand and Cl (structure 1) or Br (structure 2).
Journal of Molecular Structure, 2009
A novel compound with formula unit (pipzH 2 )[Cd(pydc) 2 ]Á6H 2 O, was synthesized and characterized by IR, 1 H NMR and 13 C NMR spectroscopy, elemental analysis, single crystal X-ray diffractometry. Moreover, the solution behavior was studied, and ab initio HF, DFT calculations were carried out. The compound belongs to a great family of supramolecular metal complexes derived from a proton transfer ion pair i.e. (pip-zH 2 )(pydc), where pipz is piperazine and pydcH 2 is pyridine-2,6-dicarboxylic acid. The compound shows a distorted octahedral geometry around the six-coordinated Cd II atom. A variety of intermolecular OAHÁÁÁO, NAHÁÁÁO and CAHÁÁÁO hydrogen bonds are responsible to extend the supramolecular network of the compound. The geometry parameters of [Cd(pydc) 2 ] 2À complex and free (pydc) 2À ligand have been optimized with the B3LYP method of density functional theory (DFT) and ab initio Hartree-Fock (HF) methods for comparison. The effect of basis sets has been investigated using four combination basis sets. The electronic properties of the Cd II compound and free (pydc) 2À ligand have been investigated based on the natural bond orbital (NBO) analysis at the B3LYP/A level of theory which verifies that the synergistic effect have been occurred in the compound. In solution study, the protonation constants of pipz and pydc, the equilibrium constants for pydc/pipz proton transfer system and the stoichiometry and stability of the system with Cd 2+ ion in aqueous solution were investigated by potentiometric pH titrations. The stoichiometry of one of the most abundant complexed species in solution was found to be the same as that of the crystalline cadmium complex.
Solid State Structures of Cadmium Complexes with Relevance for Biological Systems
Metal Ions in Life Sciences, 2012
This chapter reviews the literature on structural information from crystal structures determined by Xray diffractometry of cadmium(II) complexes containing ligands of potential biological interest. These ligands fall into three broad classes, (i) those containing N-donors such as purine or pyrimidine bases and derivatives of adenine, guanine or cytosine, (ii) those containing carboxylate groups such as αamino acids, in particular the twenty essential ones, the water soluble vitamins (B-complex) or the polycarboxylates of EDTA-like ligands, (iii) and those S-donors such as thiols/thiolates or dithiocarbamates. For some representative complexes of these ligands, a crystal and molecular structural analysis has been made, specifically addressing the coordination mode of ligands, the coordination environment of cadmium and, in some significant cases, the intermolecular interactions.
STRUCTURAL CHARACTERIZATION OF TETRAKIS(1,3-DIAZINANE-2-THIONE)CADMIUM(II) SULFATE
A cadmium(II) complex tetrakis(1,3-diazinane-2-thione)cadmium(II) sulfate [Cd(Diaz) 4 ]SO 4 (1) is prepared and its crystal structure is determined by X-ray crystallography. The crystal structure of 1 consists of [Cd(Diaz) 4 ] 2+ and 2 4 SO ions. In the complex ion, the central cadmium atom is coordinated by four Diaz molecules through sulfur atoms adopting a distorted tetrahedral geometry. The molecular structure is stabilized by N–H…O and N–H…S hydrogen bonding interactions. The complex is also characterized by IR and NMR spectroscopy and the spectroscopic data are discussed in terms of the nature of bonding. In recent years, considerable research efforts have been devoted to the structural characterization of cadmium(II) complexes of thioamides [1-22] because of their applications in biological systems [23, 24], in analytical chemistry [25, 26], in environmental toxicology [27], and as precursors for the preparation of CdS nanoparticles [28-30]. These structural reports describe that in most of the cases, cadmium(II) complexes exist as neutral monomeric [3-16] or polymeric [17-19] molecules of the general formula [CdL 2 X 2 ] with the cadmium atom possessing a tetrahedral or distorted octahedral coordination environment respectively. In some cases, ionic complexes of the type [CdL 4 ]X 2 (X = nitrate or sulfonate) are also formed [21, 22]. Recently, we have reported the crystal structures of two new complexes [Cd(Detu) 4 (SO 4)] (Detu = N,N-diethylthiourea) [1] and [Cd(Diaz) 2 (CH 3 COO) 2 ] (Diaz = 1,3-diazinane-2-thione) [2] in which cadmium(II) shows severe distortions from the octahedral geometry. In view of our continued interest in the structural chemistry of cadmium(II) complexes with thiones [1-10], we report here the synthesis and crystal structure of a cadmium(II) complex of the heterocyclic ligand 1,3-diazinane-2-thione (3,4,5,6-tetrahydropyrimidine) [Cd(Diaz) 4 ]SO 4. Experimental. Materials. Cadmium sulfate (CdSO 4 8/3H 2 O) was obtained from Merck Chemical Company, Germany. Diazinane-2-thione (Diaz) was prepared according to the procedure published in the literature [31]. Synthesis of [Cd(Diaz) 4 ]SO 4 (1). The title complex was prepared by adding 0.24 g (2.0 mmol) of Diaz in 15 ml of methanol to an aqueous solution (5 ml) of cadmium sulfate (1.0 mmol, 0.26 g) and stirring the mixture for 30 min. The very light yellow cloudy solution was filtered and the filtrate was kept at room temperature for crystallization. As a result, the off-white crystalline product was obtained, which was washed with methanol and dried.