Novel Coordination Polymer of Cadmium (II) with L-Tryptophan

A new cadmium (II) polymeric coordination compound with tryptophan (Trp) of general formula {[Cd(L-Trp)2(H2O)Cl]∙(Trp)∙(H2O)}n was synthesized. The monocrystals of the investigated complex were obtained using the method of slow evaporation. The crystal and molecular structure was determined. The compound was crystallized in the orthorhombic P212121 space group. The cadmium atom was seven coordinates by two oxygen atoms from one bidentate-chelating carboxylate group of bridging Trp, two oxygen atoms from one bidentate-chelating carboxylate group from a monodentate organic ligand, one oxygen atom of water molecule, one nitrogen atom of the amino group from bridging Trp and one chlorine atom, which means that every tridentate Trp substituent was bridging towards one cadmium atom and bidentate chelating towards one another. The monodentate Trp is a zwitterionic molecule. The coordination led to the formation of 1D supramolecular chains entrapping water and Trp molecules.

The crystal structures and Hirshfeld surface analyses of a cadmium(II) and a zinc(II) mononuclear complex of the new tetrakis-substituted pyrazine ligand N,N′,N′′,N′′′-[pyrazine-2,3,5,6-tetrayltetrakis(methylene)]tetrakis(N-methylaniline)

The whole molecule of the cadmium(II) complex, diiodido{N,N′,N′′,N′′′-[pyrazine-2,3,5,6-tetrayltetrakis(methylene)]tetrakis(N-methylaniline)-κ3 N 2,N 1,N 6}cadmium(II), [CdI2(C36H40N6)], (I), of the ligand N,N′,N′′,N′′′-[pyrazine-2,3,5,6-tetrayltetrakis(methylene)]tetrakis(N-methylaniline) (L), is generated by a twofold rotation symmetry; the twofold axis bisects the cadmium atom and the nitrogen atoms of the pyrazine ring. The ligand coordinates in a mono-tridentate manner and the cadmium atom has a fivefold CdN3I2 coordination environment with a distorted shape. In the zinc(II) complex, dichlorido{N,N′,N′′,N′′′-[pyrazine-2,3,5,6-tetrayltetrakis(methylene)]tetrakis(N-methylaniline)-κ3 N 2,N 1,N 6}zinc(II) dichloromethane 0.6-solvate, [ZnCl2(C36H40N6)]·0.6CH2Cl2, (II), ligand L also coordinates in a mono-tridentate manner and the zinc atom has a fivefold ZnN3Cl2 coordination environment with a distorted shape. It crystallized as a partial dichloromethane solvate. In the crystal of I, the complex molecules are linked by weak C—H...I contacts, forming ribbons propagating along [100]. In the crystal of II, the complex molecules are linked by a series of C—H...π interactions, forming layers lying parallel to the (1\overline{1}1) plane. In the crystals of both compounds there are metal–halide...π(pyrazine) contacts present. The Hirshfeld analyses confirm the importance of the C—H...halide contacts in the crystal packing of both compounds.

Structural study of the coordination behavior of a tetradentate NO3-donor amino alcohol ligand toward a CdII:HgII mixture

In this work, the reaction of 2,2′,2″-nitrilotriethanol (NTE) with a 1:1 mixture of CdI2and HgI2is investigated. The complex [Cd(NTE)2][Hg2(μ-I)2I4] was synthesized and identified by elemental analysis, FT-IR,1H NMR spectroscopy and single-crystal X-ray diffraction. The structure of the [HNTE]Cl salt is also presented. In the crystal structure of the complex, the cadmium atom has a CdN2O6environment in a slightly distorted cube geometry. This geometry is one of the rare cube geometries with a minimum distortion among the Cambridge Structural Database structures for cadmium complexes. The anionic moiety has a binuclear structure with the mercury atoms being in tetrahedral environments. In the network of the complex, in addition to O−H · · · I hydrogen bonds, there are I · · · I interactions which lead to ten-membered rings.

Synthesis and Crystal Structure of Cadmium(II) Dichloroaquasalicylidenesemicarbazone

Cadmium(II) complex with salicyl aldehyde semicarbozone (Н2L) has been synthesized. Based on elemental analysis and IR spectroscopy its composition – [Cd∙Н2L∙H2O∙Cl2] – has been established. The complex crystal structure has been examined using XRD analysis. The coordination polyhedron of cadmium atom is a distorted octahedron, where two cis-positions are occupied by oxygen atoms of water molecule and carbamide fragment of H2L molecule, other positions are occupied by chlorine atoms. At the same time two edges of octahedron are combined with adjoined octahedrons and form endless zigzag chains of octahedrons in the structure along the crystallographic axis. H2L molecule is a planar one due to the presence of intramolecular hydrogen bond.

A two-dimensional CdIIcoordination polymer: poly[diaqua[μ3-5,6-bis(pyridin-2-yl)pyrazine-2,3-dicarboxylato-κ5O2:O3:O3,N4,N5]cadmium]

The reaction of 5,6-bis(pyridin-2-yl)pyrazine-2,3-dicarboxylic acid with cadmium dichloride leads to the formation of the title two-dimensional coordination polymer, [Cd(C16H8N4O4)(H2O)2]n. The metal atom is sevenfold coordinated by one pyrazine and one pyridine N atom, two water O atoms, and by two carboxylate O atoms, one of which bridges two CdIIatoms to form a Cd2O2unit situated about a centre of inversion. Hence, the ligand coordinates to the cadmium atom in anN,N′,O-tridentate and anO-monodentate manner. Within the polymer network, there are a number of O—H...O hydrogen bonds present, involving the water molecules and the carboxylate O atoms. There are also C—H...N and C—H...O hydrogen bonds present. In the crystal, the polymer networks lie parallel to thebcplane. They are aligned back-to-back along theaaxis with the non-coordinating pyridine rings directed into the space between the networks.

Perturbed Angular Correlation Study of the Static and Dynamic Aspects of Cadmium and Mercury Atoms Inside and Attached to a C60 Fullerene Cage

Abstract30 keV 111mCd and 50 keV 199mHg beams from ISOLDE were used to implant on preformed targets of C60 with a thickness of 1 mg cm-2. Endofullerene compounds, viz. 111mCd@C60 and 199mHg@C60 formed during implantation were separated by filtration through micropore filter paper followed by solvent extraction. Dried samples of the endofullerene compounds were counted for the time differential perturbed angular correlation (TDPAC) measurement using the coincidence of the 151 - 245 keV cascade of 111mCd and the 374 - 158 keV cascade of 199mHg on a six LaBr3(Ce) detector system coupled with digital electronics. The results for 111mCd@C60 indicate a single static component (27%) and a fast relaxing component (73%), the latter implying that the cadmium atom moves rapidly inside the cage at room temperature. The quadrupole interaction frequency and asymmetry parameter of the cadmium atom occupying the static site in C60 are wQ=8.21(36) Mrad s-1 and η = 0.41(9), respectively. The fast relaxation constant is 0.0031(4) ns-1. Similarly, mercury atoms also exhibit a single static and a fast component. The static site has a quadrupole frequency wQ=283.0(12.4) Mrad s-1 and η =0 with a fraction of 30%. The fast relaxation constant is 0.045(8) ns-1 with a fraction of 70%, very similar to that of cadmium.

Synthesis and Structural Study of the Bis(ethylenediamine)CdFe(CO)4 Monomer

The new (en)2CdFe(CO)4 complex has been isolated from the crystallization of [(en)CdFe(CO)4]x from ethylenediamine (en). The cadmium center bears square-pyramidal coordination, with the iron atom occupying the apical position. The iron coordination may be described either as trigonal bipyramidal, with the cadmium atom being in an axial position, or as monocapped (by cadmium) tetrahedral. The Cd-Fe distance was found to be 2.6250(2) Å. The complex crystallizes in the monoclinic space group P21/a with a=14.4137(3) Å, b=7.65740(10) Å, c=14.5465(2) Å, and β=119.4972(9)° at 150(1) K.

catena-Poly[[bis(μ2-1,4,7,10,13,16-hexaoxacyclooctadecane)dipotassium]-μ2-iodido-(iodidocadmium)-di-μ2-iodido-(iodidocadmium)-μ2-iodido]

The reaction of CdCl2, 18-crown-6 and KI in water yields the title coordination polymer, [{K(C12H24O6)}2Cd2I6]n. The potassium ion lies approximately in the plane of the crown ether, coordinated by all six crown ether O atoms and also by an iodide anion bound to a cadmium atom. A C atom of the crown ether is disordered over two positions with site occupancies of 0.77 (2) and 0.23 (2). Two K(18-crown-6)+units are linked by inversion symmetry, forming a [bis(μ2-18-crown-6)dipottasium] system with approximately square-planar K2O2units. Inversion symmetry also generates the Cd2I6fragment and the polymeric system is extended along thecaxis by the formation of K—I—Cd bridges.

Experimental and computational investigations of a cadmium(II) mononuclear complex with 2,6-Bis(3,5-dimethyl-N-pyrazolyl)pyridine (bdmpp) and selenocyanate as ligands

A new cadmium (II) complex, [Cd(bdmpp)(SeCN)2(H2O)] (1) (where bdmpp = 2,6-bis(3,5-dimethyl-N-pyrazolyl)pyridine), has been synthesized and characterized by elemental and spectral (IR, 1H-NMR and 13C-NMR, UV-Vis) analyses, differential scanning calorimetry, and single crystal X-ray diffraction studies. X-ray analysis showed that the structure was crystallized in the monoclinic space group Cc with a = 9.031(2), b = 13.884(3), c = 16.910(3) Å, and Z = 4. The geometry around the cadmium atom is distorted octahedral with a CdN3Se2O setup. The N atoms of the SeCN are engaged in two strong intermolecular H-bonding interactions forming a 3D supramolecular polymeric network. The geometry and vibrational frequencies of complex 1 computed with the DFT methods (BLYP, B3LYP, B3PW91, MPW1PW91) are in better agreement with experiment than those obtained with the ab-initio method except for the bond angles. The molecular orbital diagram has been also calculated and visualized at the B3LYP/LanL2DZ level of theory.