Zinc Halide Complexes Research Articles

Zinc(II) and copper(II) halide complexes of 2-(aminomethyl)aniline

The syntheses and structures of 2-(aminomethyl)aniline (2-AMAn) complexes of CuX2 and ZnX2 (X = Cl, Br) are reported: [(2-AMAn)ZnCl2] (1), [(2-AMAn)ZnBr2] (2), [(2-AMAn)2ZnCl2] (3), [(2-AMAn)2ZnBr2] (4), [(2-AMAn)2CuCl]Cl (5) and [(2-AMAn)2Cu(H2O)2]Br2 (6). Compounds 1 and 2 are isomorphous and crystallize in the monoclinic space group Ia with two coordinated halide ions and one chelating 2-AMAn ligand. Compounds 3 and 4 are also isomorphous and crystallize in the monoclinic space group P21/n with two monodentate 2-AMAn ligands and two coordinated halide ions. All four Zn(II) complexes are slightly distorted tetrahedral in geometry. The Cu(II) complexes are structurally distinct from the Zn(II) complexes. 5 crystallizes in the monoclinic space group P21/n and is strongly distorted square pyramidal in geometry with two chelating 2-AMAn ligands, one coordinated chloride ion and one dissociated chloride ion. The bromide compound, 6, crystallizes in the monoclinic space group P21/c, also with two chelating 2-AMAn ligands, but with two coordinated water molecules and both bromide ions dissociated in the lattice.

2,1,3-Benzoselenadiazole-containing zinc(II) halide complexes: Chalcogen bonding in the solid state and catalytic activity in the Schiff condensation

XRD study of crystals of zinc(II) halide complexes featuring 2,1,3-benzoselenadiazole (L) ligands [ZnL2X2] (X = Cl, Br, I) indicated availability of intramolecular chalcogen bonds between the Se atom and the halide ligands, which affect a rotation barrier around the Zn–N bonds and thus control a geometry of these species. In the solid state, the Se atom additionally forms intermolecular chalcogen bonds with the N atom of the 2,1,3-benzoselenadiazole ligands, which results in formation of infinite 1D chains. Theoretical calculations and experimental kinetic study indicated that although the Se atom serves as a Lewis acid, coordination of the organic ligand to the zinc(II) center does not provide enhanced catalytic activity of the latter in the model reaction of the Schiff condensation.

Synthesis, crystal structures and luminescent properties of three layered zinc complexes: Zn(1,10-phen)mI2 (m = 1, 2) and Zn2(1,10-phen)2C2O4Br2 (phen = phenanthroline)

Three 1,10-phenantroline zinc halide complexes were successfully synthesized under solvothermal method and structurally characterized by single-crystal X-ray diffraction analysis. The three title complexes Zn(1,10-phen)I2 (1), Zn(1,10-phen)2I2 (2) and Zn2(1,10-phen)2C2O4Br2 (3), crystallize in the triclinic space group P1¯(No.2) with different unit cell parameters, are isolated neutral molecules. The extra stretching force from another 1,10-phen ligand in 2 lead to the Zn−N bond lengths longer than the corresponding in 1. Meanwhile, the molecules of Zn(1,10-phen)I2 and Zn(1,10-phen)2I2 further connect each other via the π-π interactions between the adjacent phenanthrolines to form a pseudo-two-dimensional layer which parallel to b-axis. Their face-to-face distance of π-π stacking interactions between the adjoining 1,10-phen rings is 3.7264 Å and 3.4435 Å, respectively. The zinc bromide complex 3 contains C−H···O intramolecular and C−H···Br (2-D) interlayer hydrogen bonding, which contributed to the connection between the parallel zig-zag molecules. The distance of phenanthroline rings in intramolecular and interlayer is 2.6071 Å and 3.8125 Å.The luminescent emissions of free ligand 1,10-phen and its zinc halide complexes were measured in various solvents. These zinc halide complexes show the obvious luminescent phenomenon with grass-green, yellow-green and light yellow in Dimethyl sulfoxide (DMSO), respectively (the maximum emission wavelength is 530 nm, 539 nm and 496 nm). The maximum emission wavelength for 2 has a little red-shifted compared with 1. It can be concluded that the number of ligand and the electron density on coordinated Zn atoms influence the emission wavelength through charge transfer from ligand to the metal. The emission wavelengths of 3 are also slightly red-shifted compared with the free 1,10-phen ligand, which is attributed to the coordination effects of the 1,10-phen ligands to the Zn cations and [C2O4]2− group.

Complexes of zinc halides with amide ligands having a high dipole moment

Complexes [Zn(C6H5CONH2)2Br2] and [Zn((NH2)2CO)2Br2] were synthesized and characterized by elemental analysis, IR spectroscopy, and X-ray diffraction and compared to other complexes of zinc halides with benzamide and urea. In all complexes, the zinc ion has a tetrahedral coordination environment of two halide ligands and two oxygen atoms of two amide ligands. The structure of [Zn(C6H5CONH2)2Br2] (orthorhombic, Pna21, a = 29.207(6), b = 7.5826(14), c = 14.753(3) Å, Z = 8) is not isostructural to the chloride and iodide compounds. The [Zn((NH2)2CO)2Br2] complex (triclinic, P-1, a = 6.4435(9), b = 7.096(1), c = 11.7079(18) Å, α = 88.119(9)°, β = 77.005(9)°, γ = 66.320(8)°, Z = 2) is isostructural to [Zn((NH2)2CO)2Cl2], and they both differ from [Zn((NH2)2CO)2I2]. Dipole moments of complexes of various zinc halides with benzamide, urea, and dimethylformamide were calculated; they vary in the 9–13 D range. Complexes of zinc halides with amides were used to prepare films with the use of cellulose diacetate as a polymer matrix. Dielectric measurements showed the presence of a pronounced electret effect.

Chemical Speciation of Zinc–Halide Complexes in Zinc/Bromine Flow Battery Electrolytes

Zinc/bromine flow batteries are a promising solution for utility-scale electrical energy storage. The behavior of complex Zn–halogen species in the electrolyte during charge and discharge is currently not well-understood, and is an important aspect to be addressed in order to facilitate future electrolyte formulations. The speciation of the primary zinc bromide electrolyte with and without a secondary zinc chloride electrolyte is studied in the present work. Raman spectroscopy was carried out on aqueous solutions of zinc bromide at 5 concentrations (2–4 M) to account for the initial and later stages of charging, with 3 concentrations (1–2 M) of zinc chloride. Mixed solutions containing various combinations of each primary and secondary electrolyte concentrations were also studied. Semi-quantitative analysis of peaks after Gaussian and Lorentzian peak deconvolution showed that the proportion of four-ligand coordinated Zn–halides (i.e. [ZnBr4]2− and [ZnCl4]2−) increases with higher salt concentration, as compared to complexes with lower halide coordination numbers. The presence of a previously unassigned peak was observed at the 220 cm−1 band in the Raman spectra of mixed electrolytes. Results from ab-initio molecular modeling using the GAUSSIAN 16 software package suggests this peak is due to the presence of the hybrid-halide anionic complex [ZnBr2Cl(H2O)]–. Increasing the Cl:Br ratio in electrolytes promotes hybridization and subsequently decreasing the proportion of single-halide Zn–Br complexes. While this speciation study is focused on Zn/Br batteries, the findings are also potentially applicable to other energy storage and electrochemical systems containing zinc halide electrolytes.

Zinc Hydride-Catalyzed Hydrofuntionalization of Ketones.

Three new dimeric bis-guanidinate zinc(II) alkyl, halide, and hydride complexes [LZnEt]2 (1), [LZnI]2 (2) and [LZnH]2 (3) were prepared. Compound 3 was successfully employed for the hydrosilylation and hydroboration of a vast number of ketones. The catalytic performance of 3 in the hydroboration of acetophenone exhibits a turnover frequency, reaching up to 5800 h-1, outperforming that of reported zinc hydride catalysts. Notably, both intra- and intermolecular chemoselective hydrosilylation and hydroboration reactions have been investigated.

Zinc(II) halide and copper(II) bromide complexes with caffeine: structures, physicochemical properties, and biological activity

This study provides a comparative characterization of the structural parameters and cytotoxicity of zinc halide and copper(II) bromide complexes with caffeine (caf) of the composition [Zn(caf)(H2O)X2] (X = Cl, Br, I) and [Cu(caf)2Br2] (1). The cytotoxicity of the complexes is dose-dependent in all cell lines. The concentrations of the complexes, at which they are more cytotoxic against cancer cells (MCF-7) than against stem cells (DPSC), were determined. The synthesized complexes exhibited synergism of cytotoxicity.

Cobalt and zinc halide complexes of 4-chloro and 4-methylaniline: Syntheses, structures and magnetic behavior

A family of cobalt(II) and zinc(II) compounds with the general formula (4-subC6H4NH2)2MX2, (M = Co, Zn; X = Cl, Br; sub = CH3, Cl) has been prepared and the compounds characterized by single-crystal X-ray diffraction. The eight compounds crystallize in the monoclinic space group I2/a and are isocoordinate, but show different crystal packing for the 4-methyl and 4-chloroaniline complexes as a result of halogen bonding in the 4-chloroaniline family. The cobalt complexes have also been studied via variable temperature magnetic susceptibility measurements. All four Co(II) compounds exhibit antiferromagnetic exchange (maxima in χ are observed) and have been fitted with a 1D-chain model (cobalt chloride complexes, J ∼ −3 K) or a 2D-model (cobalt bromide complexes, J ∼ −4 K). Analysis of potential superexchange pathways is provided.

Mono- and Hexanuclear Zinc Halide Complexes with Soft Thiopyridazine Based Scorpionate Ligands

Scorpionate ligands with three soft sulfur donor sites have become very important in coordination chemistry. Despite its ability to form highly electrophilic species, electron-deficient thiopyridazines have rarely been used, whereas the chemistry of electron-rich thioheterocycles has been explored rather intensively. Here, the unusual chemical behavior of a thiopyridazine (6-tert-butylpyridazine-3-thione, HtBuPn) based scorpionate ligand towards zinc is reported. Thus, the reaction of zinc halides with tris(6-tert-butyl-3-thiopyridazinyl)borate Na[TntBu] leads to the formation of discrete torus-shaped hexameric zinc complexes [TntBuZnX]6 (X = Br, I) with uncommonly long zinc halide bonds. In contrast, reaction of the sterically more demanding ligand K[TnMe,tBu] leads to decomposition, forming Zn(HPnMe,tBu)2X2 (X = Br, I). The latter can be prepared independently by reaction of the respective zinc halides and two equiv of HPnMe,tBu. The bromide compound was used as precursor which further reacts with K[TnMe,tBu] forming the mononuclear complex [TnMe,tBu]ZnBr(HPnMe,tBu). The molecular structures of all compounds were elucidated by single-crystal X-ray diffraction analysis. Characterization in solution was performed by means of 1H, 13C and DOSY NMR spectroscopy which revealed the hexameric constitution of [TntBuZnBr]6 to be predominant. In contrast, [TnMe,tBu]ZnBr(HPnMe,tBu) was found to be dynamic in solution.

Zinc(II) and cadmium(II) halide complexes with caffeine: Synthesis, X-ray crystal structure, cytotoxicity and genotoxicity studies

Molecular complexes [Zn(caf)(H2O)I2] (I), [Zn(caf)(H2O)Cl2] (IV), and the polymeric ones {[Cd(H2O)2I2](caf).2H2O}n (II) and {[Cd(H2O)2Br2](caf).2H2O}n (III) consisting of infinite Cd-containing chains with bridging halide ions and water molecules in trans-position and connected with each other due to hydrogen bonding with participation of caffeine (caf) and water molecules, were prepared and characterized by the powder and single crystal X-ray diffraction, IR vibrational spectroscopy, 1H NMR, ESI-MS spectroscopy, thermal analysis and DFT calculations. It was found that the complexes (I) and (IV) are characterized by tetrahedral geometry, the caffeine molecule being coordinated by the central atom via its N9 atom. The preferability of complex formation was evaluated by quantum-chemical calculations. Cyto- and genotoxicity of the compounds have been investigated and discussed in comparison with that of [Zn(AP)2I2] (1) and [Cd(AP)6][Cd(AP)I3]2 (2). It was demonstrated that the prepared complexes, primarily that of cadmium iodide with caffeine (II), are the promising ones for further studies both in vitro and in vivo.

Experimental and Theoretical Study on New Zn(II) Halide Complexes of 3,5-Diazaindole

3,5-Diazaindole — zinc(II) halide complexes (halogen: Cl, Br, I) are synthesized for the first time. Experimental mid-IR spectra of the compounds were recorded in the range 4000–550 cm–1, and far-IR spectrum of the zinc(II) chloride complex is recorded in range 700–40 cm–1. The structural features of the zinc(II) halide complexes of 3,5-diazaindole (ICPY) are studied by quantum chemical methods. The optimized geometry and vibrational frequencies of the ICPY — zinc(II) halide complexes are calculated using the B3LYP/DFT method with the LANL2DZ basis set in the ground state. Vibrational assignments of the most important bands are made with the help of the vibrational energy distribution analysis. The frontier molecular orbital energies, NBO charges, and dipole moments are presented. 1H and 13C NMR spectra of the zinc(II) chloride complex is also given.

Synthesis and characterization of phenoxo-bridged dinuclear zinc(II) halide complexes: Role of electron withdrawing group on phosphatase activity

Three phenoxo-bridged dinuclear zinc(II) halide complexes $$[\hbox {Zn}(\mathbf{L2})(\hbox {X})]_{2}$$ (X = Cl, Br, I) were isolated from a reduced Schiff base [HL2 = 2-(((2-(dimethylamino)ethyl)amino)methyl)-4-nitrophenol]. Ligand and complexes were characterized using different physico-chemical and spectroscopic methods. Structural study confirms that $$[\hbox {Zn}(\mathbf{L2})(\hbox {Cl})]_{2}$$ contains a discrete dinuclear unit where two zinc(II) ions are bridged by the two phenoxo oxygen atoms of the deprotonated ligand (L2). The complex adopts a rare cis-orientation with respect to chloride ions. The rate of hydrolysis of 4-NPP ((4-nitrophenyl)phosphatehexahydrate) in the presence of zinc(II) complexes was measured by initial rate method giving $$\hbox {k}_{\mathrm{cat}}$$ values in the order $$\hbox {I}>\hbox {Cl}>\hbox {Br}$$ and mechanistic pathway was monitored using ESI-mass spectroscopy. It is worth mentioning that presence of an electron withdrawing $$-\hbox {NO}_{2}$$ group in HL2 eventually increases the Lewis acidity of zinc(II) which in turn reduces the nucleophilic character of metal bound water molecule in the intermediate state causing an overall decrease in the rate of hydrolysis of 4-NPP as compared to our previous work with HL1 (2-((2-(dimethylamino)ethylamino)methyl)phenol). Three new dinuclear zinc(II) halide complexes were synthesized using a tridentate N,N,O-donor ligand and characterized using spectroscopic methods. Structural study of a representative complex reveals phenoxo-bridged dinuclear nature with cis-halide orientation. Complexes show good phosphatase mimicking behaviour in aqueous-DMF. The role of electron withdrawing $$-\hbox {NO}_{2}$$ on phosphatase activity is highlighted.

Structure of Hybrid Interpolymeric Complexes of Zinc Halides with Polyvinyl Alcohol

Structure of Hybrid Interpolymeric Complexes of Zinc Halides with Polyvinyl Alcohol

Reactivity of Zinc Halide Complexes Containing Camphor-Derived Guanidine Ligands with Technical rac-Lactide

Three new zinc complexes with monoamine–guanidine hybridligands have been prepared, characterized by X-ray crystallography and NMR spectroscopy, and tested in the solvent-free ring-opening polymerization of rac-lactide. Initially the ligands were synthesized from camphoric acid to obtain TMGca and DMEGca and then reacted with zinc(II) halides to form zinc complexes. All complexes have a distorted tetrahedral coordination. They were utilized as catalysts in the solvent-free polymerization of technical rac-lactide at 150 °C. Colorless polylactide (PLA) can be produced and after 2 h conversion up to 60% was reached. Furthermore, one zinc chlorido complex was tested with different qualities of lactide (technical and recrystallized) and with/without the addition of benzyl alcohol as a co-initiator. The kinetics were monitored by in situ FT-IR or 1H NMR spectroscopy. All kinetic measurements show first-order behavior with respect to lactide. The influence of the chiral complexes on the stereocontrol of PLA was examined. Moreover, with MALDI-ToF measurements the end-group of the obtained polymer was determined. DFT and NBO calculations give further insight into the coordination properties. All in all, these systems are robust against impurities and water in the lactide monomer and show great catalytic activity in the ROP of lactide.

New tetrahedral zinc halide Schiff base complexes: Synthesis, crystal structure, theoretical, 3D Hirshfeld surface analyses, antimicrobial and thermal studies

A new bidentate Schiff base ligand named as N,N′-bis((E)-3-phenylallylidene)butane-1,4-diamine (L) and three its zinc halide complexes were synthesized and characterized by FT-IR, 1H NMR, 13C NMR and UV–Vis spectroscopy. The crystal structure of zinc bromide and iodide complexes were characterized using single crystal X-ray diffraction. The two structures are isomorphous, crystallizing in the monoclinic crystal system with space group C2/c with closely similar unit cell dimensions. In these complexes, the Zn(II) ion is in the center of a distorted tetrahedral environment completed by two iminic nitrogen atoms of Schiff base ligand and two halide anions. The analysis of crystal structures shows that intermolecular interactions such as CH⋯halogen, π⋯π and CH⋯π interactions have effective role in stabilization of complexes structure. Intermolecular interactions were more analyzed using 3D Hirshfeld surface analysis and corresponding 2D fingerprint plots. Furthermore, structural optimization by DFT calculations at the B3LYP/LANL2DZ level have been performed and then compared with the experimental data. Time-dependent density functional theory (TDDFT) has been also used to calculate the electronic transitions of molecules at B3LYP/LANL2DZ level using the optimized ground-state geometries. NBO analysis was applied for investigation of intra and inter-molecular bonding and conjugative interaction in molecular systems. Schiff base ligand and their zinc complexes have been screened for their antibacterial and antifungal activities by disc diffusion method. Thermal behaviors of all compounds were studied by TG/DTG analysis data. Also, nanostructures of zinc complexes were synthesized by sonochemical method and characterized by FT-IR spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). ZnO nanoparticles were simply prepared by calcination of zinc iodide complex as new precursor at 600°C.

Zinc halide complexes of thionicotinamide; crystal structure of dichlorido bis(thionicotinamide-κN)zinc(II)

Zinc halide complexes of thionicotinamide (TNA) having the general formula [Zn(TNA)2X2] (X = Cl–, Br–, I–) are prepared and characterized by thermal analysis, IR and NMR spectroscopy. The crystal structure of one of them, dichloridobis(thionicotinamide-κN)zinc(II), [Zn(TNA)2Cl2] (1), is determined using X-ray crystallography. In 1, the zinc atom is coordinated by two thionicotinamide ligands through nitrogen atoms and two chloride ions in a distorted tetrahedral coordination environment. The molecular structure of the complex is stabilized through intermolecular hydrogen bonding.

Synthesis, crystal structures and blue emission of zinc(II) halide complexes of 1-alkyl-imidazole and (–)-nicotine

Abstract Zn(II) halide complexes of the form L2ZnX2 (X=Cl, Br, I) containing bio-relevant or bio-related ligands like 1-alkyl-imidazoles (alkyl=methyl, ethyl and iso-propyl) or (–)-nicotine are presented. All complexes were characterized by 1H NMR spectroscopy, mass spectrometry and elemental analysis. The molecular structures of the majority of complexes were determined by single crystal X-ray diffraction. The zinc ion exists in a tetrahedral environment coordinated by two halide anions and two nitrogen atoms of the N-heterocycles. Upon photoexcitation the nicotine complexes feature a blue emission which we tentatively assign to phosphorescence.

Thiophene-based terpyridine and its zinc halide complexes: third-order nonlinear optical properties in the near-infrared region.

A novel 4'-(4-(diphenylamino)thienyl)-2,2':6',2''-terpyridine ligand () based on thiophene and its complexes (X = Cl, Br, I, SCN) was designed, synthesized and characterized by elemental analysis, far-IR, MALDI-TOF-MS, and single crystal X-ray diffraction analysis. Structural studies revealed that the central zinc(ii) atom adopted a distorted trigonal bipyramidal coordination model. However, there were different hydrogen bonds and stacking models with different counter anions in the crystals. The absorption properties of the compounds were investigated with the aid of TD-DFT computational methods. Furthermore, the third-order nonlinear optical (NLO) properties were systematically studied via open-aperture Z-scan methods using a tunable wavelength femtosecond laser. The results from photophysical property investigations suggested that the complexation of the thiophene-based terpyridine ligand with zinc halides resulted in strong ICT/LLCT bands of about 450 nm, and the complexes exhibited strong nonlinear optical response in the near-infrared range around 850 nm. Above all, the two-photon absorption (2PA) cross-section values (σ) were enhanced by coordination with zinc and influenced by halide ions, reaching up to 2583 GM (X = Br).

Experimental and theoretical study on free 5-nitroquinoline, 5-nitroisoquinoline, and their zinc(II) halide complexes

In this study where the interpretations of the experimental IR and Raman spectra recorded at room temperature for the ligands 5-nitroquinoline (5NQ) and 5-nitroisoquinoline (5NIQ) and also for their Zn(II) halide (halogen: chlorine, bromine, iodine) complexes were first reported, the assignments of the observed fundamental bands were achieved in the light of the vibrational spectral data and total energy distribution (TED) values calculated at B3LYP/6–311++G(d,p) and B3LYP/LANL2DZ levels of theory. The equilibrium geometrical parameters, Natural Bond Orbital (NBO) charges and frontier orbital (HOMO, LUMO) energies of these molecular structures were also calculated at the same level of theory. Comparisons over the corresponding experimental and theoretical data obtained for the title ligands and their complexes revealed that in complex form both ligands bond to Zn(II) ion through their ring nitrogen atoms and NO2 groups at the same time.

Vibrational and electronic structural study of dinuclear Zn(II) halide complexes with 4-azabenzimidazole

Two zinc(II) halide complexes of 4-azabenzimidazole (4AB), [Zn2(4AB)4Cl2]Cl2 and [Zn2(4AB)4Br2]Br2, have been synthesized for the first time and characterized by elemental analysis, FT-IR (mid IR, far IR), Raman spectra, and DFT calculations. For the zinc chloride complex, 1H and 13C NMR spectra are also presented. The DFT calculations have been carried out at the B3LYP/6-31G(d) level. The optimized structures were resulted in dinuclear paddlewheel-like geometries around the zinc atoms. The ligands are coordinated to the metal centers in bidentate fashion.