Dimeric Cadmium Research Articles

Structural Diversity of Cadmium Complexes with N‐Heterocyclic Carbene‐Isothiocyanate Zwitterionic Ligand

In this study, we discuss the synthesis and structural characterization of three N‐heterocyclic carbene isothiocyanate zwitterionic ligands, 1,3‐bis(2,6‐diisopropylphenyl)‐2‐N‐phenyl‐thiocarbamoyl imidazolium (ImDipp ‐CSNPh, L1), 1,3‐bis(tert‐butyl)‐2‐N‐phenylthiocarbamoyl imidazolium (ImtBu‐CSNPh, L2) and 1,3‐bis(2,4,6‐trimethylphenyl)‐2‐N‐phenylthiocarbamoyl imidazolium (ImMes‐CSNPh, L3) and their cadmium complexes, [(ImDipp‐CSNPh)2CdCl][CdCl3] (1) and [(ImtBu‐CSNPh)2Cd2Cl6] (2). Both bench‐stable cadmium complexes were synthesized by directly reacting the corresponding NHC‐CSNPh adducts with anhydrous cadmium chloride. The solid‐state structures of zwitterionic NHC‐isothiocyanate betaine adducts (L1‐L3) and cadmium complexes (1 and 2) were investigated with the assistance of single crystal X‐ray diffraction analysis. A steric modification of N‐substituent on NHC governs a unique structural change from betaine ImDipp‐CSNPh coordinated cationic cadmium complex to neutral dimeric cadmium complex with ImtBu‐CSNPh.

Monomeric and dimeric cadmium(II) complexes of N4-phenyl semicarbazones: Spectral features, thermogravimetric analysis, DFT study and crystal structure of a bromido bridged complex

Seven cadmium(II) complexes ([Cd(HPySc)Br2] (1), [Cd(HPySc)(OAc)2]·3H2O (2), [Cd(HPySc)Cl2] (3), [Cd(PySc)N3] (4), [Cd(BpSc)(OAc)] (5), [Cd(HBpSc)Cl2] (6), and [Cd2(BpSc)2Br4]) (7) were synthesized using two semicarbazone ligands (HPySc and HBpSc) and characterized by elemental analyses, IR, UV–Vis, thermogravimetric analyses, conductance and single crystal XRD studies. It is found that all the complexes are non-electrolytes in nature and one of the compounds has three molecules of lattice water in the complex. Single crystal study of the complex 7 exhibits a binuclear centrosymmetric structure with a distorted octahedron arrangement around the cadmium(II) centre with Cd⋯Cd non-bonding distance of 4.0809(14) Å. A two-dimensional supramolecular hydrogen bonding network with a zig-zag arrangement is found in the crystal system supported by means of a non-classical hydrogen bonding. DFT calculations reveal that the dimeric complex is the softest and having high chemical reactivity, low stability and high polarizability compared to the other complexes. The NPA and charge distribution analysis indicate that the complexes have significant coordinating sites and potential preferred electron donor sites to metal centers.

Synthesis, structural, spectral studies, and DFT calculations of a series of mixed ligand complexes of a tridentate N, N, S pyrazole based aldimine and 2,2′-bipyridine. The first example of structurally characterized dimeric cadmium(II) adduct with unusual μ2-Osulfonamido bridges

Refluxing of equimolar amounts of 2,2′-bipyridine (bipy) and N, N, S-tridentate basic form of the Schiff base N-[2-[[3-methyl-1-phenyl-5-thioxo-pyrazole-4-ylidenemethyl]amino]phenyl]-4-methylbenzenesulfonamide (H2L) with corresponding metal acetate hydrate (Cu, Ni, Zn, Cd) in acetonitrile-methanol solution (1:1) give rise to the formation of mononuclear mixed ligand complexes with a common formula [M(L)bipy]·(CH3CN) (M=Cu(II), Ni(II), Zn(II)) (1–3) and binuclear cadmium(II) heteroleptic compound with the composition [Cd2(L)2(bipy)2]·(CH3CN)2(CH3OH)2 (4). All compounds were characterized by C, H, N elemental analysis, FT-IR, 1H NMR, and magnetic measurements. The structures of the ligand H2L and complexes 1, 3 and 4 were determined by X-ray single-crystal diffraction. The metal center in 1, 3 is surrounded with imine and amide nitrogen, sulfur of thiol group of H2L and two nitrogen of 2,2′-bipy employing as the auxiliary ligand. The crystal structure of binuclear cadmium complex reveals unexpected μ2-O sulfonamido bridges. The time-dependent density functional theory (TD-DFT) calculations have been performed to explore the assignment and the nature of the bands in experimental UV–vis absorption spectra of adducts 1–4.

Monomeric and dimeric cadmium(II) complexes of S-alkyl/aryl dithiocarbazate as single-source precursors for cadmium sulfide nanoparticles: An experimental, theoretical interpretation in the stability of precursor and visible light dye degradation study

The reaction of S-alkyl/aryl dithiocarbazate functionalized with 2-acetyl pyridine ligands and cadmium chloride in ethanol leads to the formation of a mono nuclear cadmium(II) complex, [Cd(L1)2] (SP1), (HL1 is S-methyl-2-(1-(pyridine-2-yl)ethylidene)hydrazine-1-carbodithioate) and a dinuclear dichloro bridged complex, [(L2)Cd(μ-Cl)2Cd(L2)] (SP2), (L2 is S-benzyl-2-(1-(pyridine-2-yl)ethylidene)hydrazine-1-carbodithioate). The complexes are characterized by FTIR, single X-ray crystallography and thermogravimetry analysis. Density functional calculations indicate that different coordination patterns of the complexes with HL1 and HL2 ligands relate with the available space of the dissociation of CdCl2 in their solutions. Thermochemical destruction of the precursor complexes at the molecular level fabricated hexagonal CdS nanoparticles where the morphology is guided by the precursor. In situ generated thiols e.g., CH3SH in case of SP1, and PhCH2SH in case of SP2, internally stabilized the flower-like and rod shaped CdS structures, respectively. The synthesized nanoparticles were characterized by powder X-ray diffraction (XRD), scanning electronic microscope (SEM) and energy-dispersive X-ray spectroscopy (EDAX). The UV–Vis spectroscopic study shows a prominent quantum confinement effect in CdS with a band gap energy of 2.4 eV and 2.5 eV for SP1 and SP2, respectively. The CdS nanocrystals under investigation degrade Rose Bengal (RB) dye (96%) under visible light irradiation. A reusability study shows that the CdC nanoparticles retain their catalytic activity (86%).

Homochiral, Supramolecular Frameworks Built from a Zinc(II) Tetramer or Cadmium(II) Dimer Containing Enantiopure Carboxylate Ligands Functionalized with a Strong π···π Stacking Synthon

AbstractThe enantiopure ligand (S)‐2‐(1,8‐naphthalimido)propanoate (Lala–) forms a tetrameric zinc(II) complex [Zn4(Lala)6(OH)2(MeOH)4]·3(CH2Cl2)·2(MeOH) (1) and a dimeric cadmium(II) complex [Cd2(Lala)4(DMF)3(MeOH)] (2). Bridging κ2‐carboxylate and hydroxide ligands link the four zinc centers in 1. The strong π···π‐stacking 1,8‐naphthalimide supramolecular synthons organize the tetramers into a 3D architecture that contains linked, homochiral helical chains. In the structure, each chain is connected to four other chains by the π···π‐stacking interactions of the naphthalimide rings. The structure is open with two types of channels filled with ordered and disordered solvent molecules. The two cadmium centers in 2 are linked by two κ2‐carboxylate ligands. The π···π‐stacking interactions of the naphthalimide rings organize the structure into 2D sheets, which lack complex chiral features. The naphthalimide rings in these d10 metal complexes promote blue (1) and green (2) emission in the solid state.

High-yield synthesis of quantum-confined CdS nanorods using a new dimeric cadmium(II) complex of S-benzyldithiocarbazate as single-source molecular precursor

A convenient solvothermal single-source route has been developed for the bulk synthesis of CdS nanorods using new air stable dimeric cadmium(II) complex of S-benzyldithiocarbazate, [Cd(PhCH 2SC( S)NHNH 2)Cl 2] 2, at a relatively low temperature. The decomposition of the precursor was made by heating at 160 °C in hexamethylenediamine (HMDA) to give amine capped CdS nanocrystals having yield ca. 90%; nano-dimensional rods are clearly visible in transmission electron microscope (TEM). The nanorods have been further characterized by X-ray diffraction (XRD), energy dispersed X-ray spectroscopy (EDX), FTIR and optical measurements. The structure of precursor was also established by single crystal X-ray crystallography.

Synthesis, Crystal Structure, and Spectrothermal Characterization of a Novel Dimeric Cadmium(II) Azobispyridine Complex, [(μ–abpy){CdCl2(abpy)}2]·0.86H2O

AbstractThe novel complex μ–2,2′–azobispyridine–bis[2,2′‐azobispyridinedichlorocadmium(II)]·0.86 hydrate (1) was synthesized and characterized by elemental analysis, IR and UV–Vis spectroscopy, thermal analysis and X–ray diffraction techniques. The crystal structure analysis indicates that the Cd2+ ions have a distorted octahedral coordination with CdII–CdII distance of 5.929(7) Å. One of the azobispyridine (abpy) ligands acts as a 's–frame' bridging ligand which adopts an s–cis/E/s–cis conformation, while the others adopt an s‐cis/E/s‐trans conformation, coordinated to Cd2+ ions in a trans position. π–π and π–ring interactions are responsible for crystal packing. The decomposition reaction takes place in the temperature range of 20–1000 °C in the static air atmosphere. Thermal decomposition of the title complex proceeds in five stages.

Synthesis and crystal structure of two dimeric cadmium(II) complexes bonded with pseudohalides, 1.1 and 1.3 bonding

Abstract Two different complexes were obtained from (dmpp) and Cd(II) ions with the aid of pseudohalide ions in non-aqueous solvents. The dinuclear complex formed with thiocyanate ions show, using XRD, to posses two 1.3 bond μ bridges [CdL(SCN)2]2. The other dinuclear complex was also seen to form with cyanate ions but with the μ-bridge in a 1.1 position [CdL(OCN)2]. All Cd atoms are located in a distorted octahedral environment in 1 and 2 complexes. The Cd…Cda distances are 6.032(4) Å in 1 and 3.704(3) Å in 2, respectively. The N—C—S and O—C—N angles are approximately linear as 178.1(3) and 178.6(3)° in 1 and 177.2(5) and 176.9(7)° in 2, respectively. The Cd—(μ N,S-NCS)2—Cda bonds form a zig-zag structure in 1 and the Cd—(μ O,N-OCN)2—Cda bonds form a distorted square planar in 2.

Structural and dielectric characterization of cadmium tartrate

Polycrystalline samples of dimeric cadmium tartrate, [(Cd,C4H4O6)2H2O)]3H2O [labeled CdT(I)], were studied using impedance measurements and x-ray powder diffraction. The dependence of the real part of the dielectric constant on temperature showed a sharp peak at about 65 °C, revealing a structural phase transition, while the other broad peak in the temperature range (70<T<85 °C) was due to the loss of water molecules. The x-ray powder diffraction patterns at three temperatures (25, 60, and 70 °C) are consistent with three nonequivalent space groups. According to these results, it seems that this compound undergoes two successive phase transitions: P212121→P21→Pnmn, suggesting an intermediate ferroelectric behavior, labeled CdT(II) between a paraelectric CdT(I) and an anhydrous phase, labeled CdT(III).

Contributions to the chemistry of silicon-sulphur compounds—LX. Synthesis, molecular structure and properties of the dimeric cadmium(II) bis(tri-tert-butoxysilanethiolate) (t-C 4H 9O) 3SiS 2Cd 2

The preparation and X-ray crystal structure of cadmium(II) bis(tri-tert-butoxysilanethiolate) from tri-tert-butoxysilanethiol and cadmium acetate are described. The compound forms a dimeric molecule (t-C 4H 9O) 3SiS 2Cd 2 with a central four-membered Cd 2S 2 ring. According to the mass spectra the dimeric molecule is not preserved in the vapour phase. The compound is also characterized by 1H, 13C, 29Si NMR and UV spectra. Reactions with 1,10-phenanthroline and 2,2′-bipyridine afforded adducts with formal (RS) 2,Cd(NN) stoichiometry. The central Cd 2S 2 kernel is folded with an angle of 150.6° at the CdCd diagonal. The cadmium atoms are three-fold bonded to thiolate sulphur atoms and the plane coordination is Cd(μ-SR) 2(SR) with the mean distances of d(Cdμ-S) 256.0 pm and d(CdS) 240.8 pm. Additionally, there are weaker interactions with two oxygen atoms of two different tri-tert-butoxysilanethiolate ligands [d(CdO) 268 and 289 pm]. The comparison with the corresponding lead compound clearly shows the influence of the stereochemically active lone electron pair at lead(II).