Seven-coordinated Cadmium Research Articles

Zn(tp)(RdmB)(H2O)] and [Cd(tp)(RdmB)]: Two Unusual One-Dimensional Rhodamine B Coordination Polymeric Ribbons as Luminescent Sensors for Small Molecules and Metal Cations

Two new complexes, [Zn(tp)(RdmB)(H2O)] (I) and [Cd(tp)(RdmB)] (II) (tp = terephthalate, RdmB = rhodamine B), are obtained by similar hydrothermal synthesis reactions. X-ray crystallography reveals that both compounds are one-dimensional (1D) polymeric solids, in which I (C36H36N2O8Zn) ascribes to monoclinic C2/m space group, Z = 4 (a = 18.834(5) A, b = 16.859(5) A, c = 10.111(3) A, β = 97.638(4)°), while II (C108H102N6O21Cd3) crystallizes in monoclinic P21/n, 4 (a = 12.2309(1) A, b = 61.5661(7) A, c = 12.5852(1) A, β = 93.951(1)°). Owing to the difference in the coordination sphere around the metal center, four-coordinated zinc centers for I bridged by linear tp molecules associated with RdmB ligands result in an interesting 1D infinite zigzag tape-like structure, whereas six-/seven-coordinated cadmium centers for II bridged by the same ligands generate a novel 1D infinite biserrated edge ribbon structure with a 2,3,3-linked {62.10}{63}{6} network or a simplified 2,4-linked {43.62.8}{4} topological networ...

Construction of mononuclear macrocyclic and dinuclear acyclic Schiff base complexes via cadmium(II)–ion template: Synthesis, characterisation, and crystal structures

Abstract Using a metal template approach a series of mono and dinuclear cadmium(II) were synthesized by Schiff base condensation of a pendant armed dialdehyde, i.e. 2-[3-(2-formylphenoxy)-2-hydroxypropoxy] benzaldehyde (PL) with selection of different diamines, diethylenetriamine, dipropylenetriamine, 1,2-diaminopropane and 1,2-diaminoethane. Depending on the nature of the diaminoalkane spacers and metal ion, 1:1 (metal:ligand) macrocyclic (L1OH and L2OH) or 2:1 (metal:ligand) acylic (L3O− and L4O−) complexes of cadmium(II) were obtained. With the longer spacers diethylenetriamine and dipropylenetriamine ring closure around the cadmium ion was observed and [1+1] macrocyclic Schiff base ligands (L1OH and L2OH) were formed. With the shorter spacers 1,2-diaminopropane and 1,2-diaminoethane ring closure was not observed. Interestingly, the dialdehyde PL reacted with two molecules of diamine, forming intermediate product acyclic Schiff base [1+2] ligands (L3O− and L4O−) that are coordinated to two cadmium ions to form dinuclear complexes. Crystal structures indicated that the complex [CdL1(NO3)]. NO3 contains a hexadentate macrocyclic ligand and a bidentate NO3− anion with an eight-coordinated cadmium in distorted dodecahedron geometry. The molecular structures of the complexes [Cd2(L3O)(NO3)3(H2O)] and [Cd2(L4O)(NO3)3], on the other hand, exhibit of two seven-coordinated cadmium centers, which are bridged by the deprotonated hydroxyl group. The coordination geometries of the cadmium ions can be described as a capped trigonal prism and/or capped octahedron.

Preparation, Structural and Thermal Studies of a Seven-Coordinated Cadmium(II) Complex Containing 2-Aminopyrimidine with an Elaborate Network of Hydrogen Bonding and π Stacking

A cadmium(II) complex formulated as, [Cd(amp)2(O2NO)(ONO2) (OH2)2]·H2O (1), (amp = 2-aminopyrimidine) has been synthesized and characterized by elemental analysis and IR spectroscopy as well as by X-ray crystal structure analysis. Its thermal stability by TGA/DTA methods. Each cadmium(II) ion is seven coordinated in adistorted pentagonal bipyramidal geometry. A wide range of hydrogen bandings (of the O–H…O, N–H…O, and N–H…N types) and π-π stacking interactions are also present in the crystal structure. This arrangement leads to the formation of a 3D supramolecular structure.

Synthesis, characterization and X-ray crystal structures of seven-coordinate pentagonal-bipyramidal zinc(II), cadmium(II) and tin(IV) complexes of a pentadentate N3S2 thiosemicarbazone

New complexes of the general formula, [M(H2dap4NMetsc)(H2O)2](NO3)2·H2O (M=Zn2+, Cd2+; H2dap4NMetsc=2,6-diacetylpyridinebis(4N-methylthiosemicarbazone) and [Sn((dap4NMetsc)X2] (X=Ph, Cl and I) (dap4NMetsc=the doubly deprotonated form of 2,6-diacetylpyridine bis(4N-methylthiosemicarbazone) have been synthesized and structurally characterized by a variety of physico-chemical techniques. X-ray crystallographic structure determination shows that in the zinc and cadmium complexes, the bis(thiosemicarbazone) ligand coordinates as a neutral N3S2 pentadentate chelating agent through the two azomethine nitrogen atoms, the pyridine nitrogen atom and the two thione sulfur atoms. The N3S2 donors of the ligand occupy the equatorial plane and the two aqua ligands occupy the sixth and seventh axial positions of the seven-coordinated cadmium(II) and zinc(II) ions. In the tin(IV) complexes, however, the thiosemicarbazone is coordinated to the tin(IV) ion as a dinegatively charged pentadentate chelating agent via the pyridine nitrogen atom, the two azomethine nitrogen atoms and the two thiolate sulfur atoms. The two apical positions of the seven-coordinate tin(IV) ion are occupied by either phenyl, chlorido or iodido ligands. In each of the complexes, the overall geometry adopted by the metal ion may be considered as a distorted pentagonal-bipyramid.

Bis(2,2′-bipyridyl-κ2N,N′)bis(2-hydroxybenzoato)-κO1;κ2O1,O1′-cadmium(II) methanol solvate

The title compound, [Cd(C7H5O3)2(C10H8N2)2]·CH3OH, contains one monomeric seven-coordinate cadmium complex and one methanol solvate mol­ecule. The CdII atom is coordinated to two 2,2′-bipyridyl ligands via the N atoms and to two salicylate anions (Hsal−) via the carboxyl­ate O atoms, which act as monodentate ligand for the one and bidentate ligand for the second. The CdII atom exhibits a {6 + 1} environment, approximately described as a distorted capped octa­hedron with the apical positions occupied by one of the two N atoms belonging to one bipyridyl ligand and one of the two carboxyl­ate O atoms from the monodentate Hsal− ligand. Two intra­molecular six-membered hydrogen-bonded rings are present, generated from inter­actions between the carboxyl­ate and hydr­oxy groups of the salicylate ligands. There is one inter­molecular hydrogen-bonding inter­action involving the methanol solvent mol­ecule and the carboxyl­ate group from the monodentate Hsal− ligand. The crystal packing is governed by π–π stacking inter­actions [centroid–centroid distance = 3.783 (4) Å] which occur between bipyridyl ligands, by C—H⋯O and C—H⋯π inter­actions and by numerous van der Waals contacts.

Self-assembled coordination polymers of V-shaped bis(pyridyl)thiadiazole dependent upon the spacer length and flexibility of aliphatic dicarboxylate ligands

An investigation into 2,5-bis(4-pyridyl)-1,3,4-thiadiazole (bpt) and cupric or cadmium complexes with a large variety of aliphatic α,ω-dicarboxylic acids HOOC-X-COOH (X = (CH2)n, n = 0–4 corresponding to oxalic acid (H2ox), malonic acid (H2mal), succinic acid (H2suc), glutaric acid (H2glu) and adipic acid (H2adi); CHCH, maleic acid (H2male) and fumaric acid (H2fum)) is performed. Ten novel metal–organic architectures, [Cu2(bpt)(ox)2]n·2.92nH2O (1), [Cu(bpt)(mal)(H2O)]n·2nH2O (2), [Cu(bpt)(glu)]n (3), [Cu(bpt)(adi)]n (4), [Cu2(bpt)2(fum)2]n·3nH2O (5), [Cd(bpt)(mal)(H2O)]n (6), [Cd(bpt)(suc)]n (7), [Cd(bpt)(glu)]n·nH2O (8), [Cd2(bpt)2(male)2]n·2nH2O (9), and [Cd(bpt)(fum)(H2O)]n·nH2O (10) were successfully synthesized through varying the organic acid linkers. The molecule 1 is a 3D pillared-layer framework with the open channels encapsulating infinite 1D water chains. Complex 2 shows the contorted 2D layer, which is extended to a 2-fold interpenetrated 3D supramolecular net by antidromic R24(8) hydrogen-bonding pattern. Compound 3 is a grid-like layer motif with the terminal bpt ligands as pendants. The MOFs 4 and 5 present two-fold interpenetrating primitive cubic (α-Po) coordination networks. Interestingly, discrete tetrameric water clusters exist in the micropores of the MOF 5. For the cadmium complex 6, six-coordinated metal centers link malonate and bpt to form interdigitated layers through edge-to-face π–π stacking interactions. Coordination polymer 7 can be considered as six-connected self-penetrated topological 3D network, in which the right- and left-handed helices are alternately arranged into a wavy Cd/succinate layer. Flexible glutarate with cadmium atoms produces a 1D ribbon, and is further linked by bpt ligands to produce the 2D double-layered motif 8. Incorporating with rigid butenedioic acid, the reaction of seven-coordinated cadmium and bpt leads to two distinct 2D (4,4) layered frameworks 9 and 10, with a one-dimensional Cd–O chain observed in the former framework. A systematic structural comparison of these ten complexes indicates that the final polymeric structures could be tuned through the introduction of the different backbone length and flexibility of the aliphatic dicarboxylates. In addition, host–guest chemistry of MOFs 1 and 5, and the luminescent properties of cadmium compounds were discussed.

Reactivity and solid-state photo-luminescence of cadmium compounds constructed from 4′-Ph-terpy and cadmium salts

Three cadmium compounds, [Cd2L2Cl(C6H5O7)] n (1), [CdLCl2] (2), and [CdL2(NO3)](NO3) · 2H2O (3) (L = 4′-Ph-terpy), were synthesized by hydrothermal methods from 4′-Ph-terpy and cadmium salts. The structure of 1 consists of a helical structure with cadmiums coordinated by 4′-Ph-terpy ligands and chloride and bridged by citrate, constructing a chiral 1-D polymeric compound. The cadmium in 2 is five-coordinate, bound to one tridentate terpyridine ligand and two chlorides, exhibiting a neutral mononuclear unit with an irregular CdN3Cl2 polyhedron. Compound 3 shows a seven-coordinate cadmium bound to two tridentate terpy ligands and one oxygen from nitrate in a mer configuration. The reactions producing these compounds are temperature dependent. The compounds show photo-luminescence in the solid state.

Conformation preference of a flexible cyclohexanetetracarboxylate ligand in three new metal-organic frameworks: structures, magnetic and luminescent properties.

Three novel complexes of formula [Co(5)(OH)(2)(cht)(2)(H(2)O)(10)](n) x 2nH(2)O (1) (H(4)cht = cyclohexane-1,2,4,5-tetracarboxylic acid), [Zn(2)(cht)(H(2)O)(3)](n) x nH(2)O (2), and [Cd(2)(cht)(H(2)O)(5)](n) x 2nH(2)O (3) were synthesized by a hydrothermal reaction of cyclohexane-1,2,4,5-tetracarboxylic acid in the presence of sodium hydroxide with Co(NO(3))(2) x 6H(2)O, Zn(NO(3))(2) x 6H(2)O, and Cd(NO(3))(2) x 4H(2)O, respectively. These complexes were obtained by controlling the molar ratios of starting materials and the pH values of reaction mixtures with an initial pH of 5.87 for 1, 5.50 for 2, and 5.57 for 3, respectively. The single-crystal X-ray investigations reveal that the cht ligands change their conformations exclusively to the a,e,e,a form in all three complexes. Complex 1 features a two-dimensional (2D) metal-organic framework (MOF) with an axis surrounded by two zigzag structures, a rectangular channel surrounded by two a-carboxylate-metal-a-carboxlate and two e-carboxylate-metal-e-carboxylate chains, and two smaller distorted square-pyramidal channels surrounded by hydroxyl oxygen, cyclohexane, and its two a-carboxylates. Each cht ligand connects five cobalt atoms and each cobalt atom is six-coordinated with carboxylate-oxygen, hydroxyl, and water molecules. Complex 2 possesses a three-dimensional (3D) MOF structure that consists of the cht ligands and two types of cobalt; one is four-coordinated with carboxylate-oxygens and the other is six-coordinated with carboxylate-oxygens and water molecules. Each cht ligand is bonded to seven zinc atoms. Complex 3 is also a 2D MOF structure constructed by seven-coordinated cadmium atoms and the cht ligands. The e-carboxylates of two parallel cht ligands are connected to a type of cadmium atoms to form 1D chains, and these chains are further connected through a-carboxylates of the ligands and another type of cadmium atoms to give the 2D structure. Extensive hydrogen bonding interactions involving carboxylate-oxygen atoms and crystallization water molecules afford 3D supramolecular networks in complexes 1 and 2. Magnetic susceptibility measurement of 1 confirmed a six-coordinated high-spin cobalt(II) ion and the presence of magnetic exchange coupling among the three hydroxyl-oxygen bridged cobalt ions. Fluorescent spectra of complexes 2 and 3 show strong fluorescent emissions in the blue region.

Di-μ-acetato-κ3O,O′:O;κ3O:O,O′-bis[(acetato-κ2O,O′)(1,10-phenanthroline-κ2N,N′)cadmium(II)

The title compound, [Cd2(C2H3O2)4(C12H8N2)2], consists of dimeric units built up around a crystallographic symmetry centre. Each cadmium(II) unit is chelated by a 1,10-phenanthroline (phen) group and two acetate ligands, one of which also acts as a bridge, linking both seven-coordinated cadmium(II) centres. The crystal structure is governed by a single π–π inter­action between stacked phen groups [centroid–centroid distance 3.5209 (11) Å], leading to a planar structure parallel to (010).

Solid-state 111Cd NMR studies on cadmium(II)-2, x-pyridinedicarboxylates. Crystal structure of 2,4-pyridinedicarboxylato triaqua cadmium(II) hemihydrate: [Cd(II)(2,4-pydc)(H 2O) 3] · 1/2H 2O

The synthesis and characterisation by solid-state 111Cd NMR of Cd(2,3-), Cd(2,4-), Cd(2,5-) and Cd(2,6-pyridinedicarboxylato) · xH 2O is reported. Results indicate that the 111Cd NMR signal is very sensitive to the relative position of both carboxylates. Similar shifts (at 54.0 and 55.4 ppm) are found for the 2,4- and the 2,6-isomers where the carboxylates groups are meta to each other. For the 2,3- and 2,5-derivatives (carboxylates in ortho and para positions), the signals are detected at 119.6 and 84.2 ppm. The crystal and molecular structure of the seven-coordinated cadmium complex, [Cd(2,4-pyridinedicarboxylato)(H 2O) 3] · 1/2H 2O is also reported. This data allows a correlation between Cd–O and Cd–N coordination and geometry with 111Cd chemical shifts. Additional coupling between 111Cd and 14N in 2,3- (also found in 2,4-pydc) suggests only one N is coordinated to Cd. The anisotropy magnitude, Δ σ, and the asymmetry parameter, η, are also analysed.

Novel heterometallic Cu/Cd complex containing a unique polymeric ladder-like anion [Cd 2(O 2CMe) 6] 2−n derived from elemental copper and cadmium oxide

Copper powder reacts with cadmium oxide and ammonia acetate in methanol solution of ethylenediamine affording {[Cu(en) 2][Cd 2(O 2CMe) 6]} n in which seven-coordinated cadmium atoms are ligated by three bonding modes of acetate groups forming ladder-like anions [Cd 2(O 2CMe) 6] 2− n . The cations [Cu(en) 2] 2+ are located in the lattice and serve as bridges to connect separate anionic polymer chains into a two- dimensional network via hydrogen bonds.

Preparation and characterization of the seven coordinate cadmium(II) complex [Cd(3,4-H 2dhb) 2(H 2O) 3] · HCl · (3,4-H 3dhb) · 2.5H 2O; the first structural determination of a complex containing the 3,4-dihydroxybenzoato(−1)(3,4-H 2dhb −) ligand

The 1:2:1 reaction of CdCl 2·2.5H 2O with 3,4-dihydroxybenzoic acid (3,4-H 3dhb) and KOH in Pr nOHH 2O gave the unique, seven-coordinate cadmium(II) complex [Cd(3,4-H 2dhb) 2(H 2O) 3]·HCl·(3,4-H 3dhb)·2.5H 2O as one of the products. Crystal structure and 13Cd NMR studies showed that 3,4-H 2dhb − behaves as a bidentate chelate with ligated atoms being the carboxylate oxygens, but the seven-coordination is not retained in aqueous solution.

Electrospray mass spectrometry and X-ray crystallography studies of divalent metal ion complexes of tris (2-pyridylmethyl) amine

Coordination complexes of tris(2-pyridylmethyl)amine (TPA) were prepared and characterized including [Zn(TPA)X]ClO 4 (X = Cl, Br, I), [Cu(TPA)Br]ClO 4, [Cd(TPA)Br 2], [Cd(TPA) (H 2O) (NO 3]NO 3, [Cd(TPA)I 2], [Co9TPA)Cl 2], [Fe(TPA)Cl 2] and [Mn(TPA) Cl 2] The solid-state structures of Zn(TPA)ClClO 4 (monoclinic space group, P2 1/c; a = 14.733(3), b = 9.408(2), c = 29.722(4) A ̊ , β=90.65(1)°; V=4119(1) A ̊ 3 ; Z=8, Zn(TPA)IClO 4 (triclinic space group, P1; a = 14.435(3), b = 17.69(4), c = 9.745(2) A ̊ , α=100.36(2), β=91.40(2), γ=114.62(1)°; V=2134(2) A ̊ 3 ; Z=4) and Cu(TPA)BrClO 4 (monoclinic space group, P2 1/ c; a=14.555(3), b=9.519(2), c=30.024(3) A ̊ , β=91.66(1)°; V=4158(1) A ̊ 3 ; Z=8), contain trigonal bypyramidal metal ions with halide coordinated in an apical position. The X-ray structure of [Cd(TPA)(H 2O)(NO 3)]NO 3 (monoclinic space group, P2 1/ n; a=15.415(4), b=9.333(2), c=17.429(4) a ̊ , β=99.39(2)° ; V=2474(2) A ̊ 3 ; Z=4) contains a seven-coordinate cadmium ion including a bidentate nitrate anion and a water molecule as ligands. The X-ray structure of [Cd(TPA)I 2] (monoclinic space group, P2 1/ n; a=10.383(2), b=13.813(2), c=15.391(1) A ̊ , β=106.07(1)° ; V=2121.1(5) A ̊ 3 ; Z=4) contains a cadmium ion with an approximately octahedral geometry. In this structure, the TPA ligand is conformationally distorted in order to accomodate the octahedral coordination geometry. The convenient new technique, electrospray mass spectrometry (ESI-MS), provided mass spectra consistent with X-ray and spectroscopic data. Mass analysis of solutions containing added competing anions was also consistent with solution data.

Synthesis and complexation studies of mesocyclic and macrocyclic polythioethers. 9. Crystal and molecular structure of (1,4,7,10,13-pentathiacyclopentadecane)cadmium(II) perchlorate hydrate: a seven-coordinate cadmium

Synthesis and complexation studies of mesocyclic and macrocyclic polythioethers. 9. Crystal and molecular structure of (1,4,7,10,13-pentathiacyclopentadecane)cadmium(II) perchlorate hydrate: a seven-coordinate cadmium