Bromide Complexes Research Articles

Interaction with Simple Monopyridinecarboxylic Ligands Revealing Unexpected Structural Types of Uranyl Halides.

The inclusion of monopyridinecarboxylic acids into the structures of uranyl halides results in the formation of unexpected structural units. Molecules of picolinic and nicotinic acids acting as bridging ligands favor the formation of unprecedented dinuclear units in two uranyl bromide complexes, which comprise two metal centers in different, tetragonal- and pentagonal-bipyramidal, coordination geometries. Moreover, the different positions of the nitrogen atom in the molecule of nicotinic acid induce significant bending of the heterodimer. The uranyl chloride complex with isonicotinic acid also exhibits a structure containing metal atoms in two unique geometries. The structure consists of cationic and anionic isolated fragments. The anionic part is unprecedented and represents the first example of a 1:3 uranyl halide unit with a tetragonal bipyramid surrounding the central atom.

Mononuclear silver(I)-N-heterocyclic carbene complexes with benzimidazole-2-ylidene ligands: synthesis, crystal structure analyses and comparative antibacterial studies

The synthesis, characterization and antibacterial studies of N-heterocyclic carbene (NHC) precursors and their respective silver(I)-NHC complexes are reported. Five non-symmetric benzimidazolium bromide salts were synthesized through the addition of N-alkylbenzimidazole and various alkylbromides. These n-butyl-n’-alkylbenzimidazolium bromide salts (alkyl = methyl, ethyl, pentyl, hexyl, heptyl) 1, 2 and 4–6 were further used as precursors to synthesize silver(I)-NHC complexes, 8, 9 and 11–13, respectively, via in situ deprotonation. In addition, 14 was synthesized from its reported precursor salt, 1-benzyl-3-butylbenzimidazolium bromide (7) through the same procedure. Complex 8 is present as monomeric cation in the form of [NHC-Ag-NHC]PF6, as illustrated by single crystal X-ray crystallography analyses. In order for a full series of antibacterial studies, 1-butyl-3-propylbenzimidazolium bromide, 3, and respective complex, 9, were synthesized according to the reported procedure. All benzimidazolium salts (1–7) and silver(I)-NHC complexes (8–14) were evaluated for antibacterial activities. All benzimidazolium salts show no antibacterial activities while all silver(I)-NHC complexes show lower activities against Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 12600) compared to the standard antibiotic drug Amoxicillin. Nevertheless, these mononuclear silver(I)-NHC complexes show lower antibacterial activities compared to the reported dinuclear silver(I)-NHC complexes with the same substituents in the ligands.

Synthesis, characterization, antifungal and antibacterial activities evaluation of copper (II), zinc (II) and cadmium (II) chloride and bromide complexes with new (E)‐1‐(3,4‐dimethoxybenzylidene)‐4‐methylthiosemicarbazone ligand

The reactions of Cu (II), Zn (II) and Cd (II) chloride or bromide with (E)‐1‐(3,4‐dimethoxybenzylidene)‐4‐methylthiosemicarbazone (MTSVT) lead to the formation of new complexes. They were characterized by spectroscopic studies: IR, 1H and 13C NMR. The crystal structures of the compounds [MTSVT] (L), [ZnBr2(MTSVT)2] (2), [CdCl2(MTSVT)2] (3) and [CdBr2(MTSVT)2.H2O] (4) were determined by X‐ray diffraction. For complexes 2–4, the ion is coordinated through the sulfur atom. All compounds were tested for their antifungal activity against human pathogenic fungi Candida albicans and Aspergillus fumigatus, and for their antibacterial activity against Gram (+) Bacillus subtilis and Enterococcus faecalis as well as against Gram (−) bacteria such as Paracoccus yeei and Acinetobacter baumanii. The results indicated that the metal complexes exhibited a marked enhancement in antibacterial activity compared with the parent Schiff base.

Perovskite-Inspired High Stability Organometal Antimony(V) Halide Thin Films by Post-Deposition Bromination

Metal–organic or all-inorganic Sb(V) bromide complexes are a novel class of semiconductor materials with potential use in optoelectronic devices. The implementation of these materials for optoelect...

Hydrogen and Halogen Bond Mediated Coordination Polymers of Chloro-Substituted Pyrazin-2-Amine Copper(I) Bromide Complexes

A new class of six mono- (1; 3-Cl-, 2; 5-Cl-, 3; 6-Cl-) and di-(4; 3,6-Cl, 5; 5,6-Cl-, 6; 3,5-Cl-) chloro-substituted pyrazin-2-amine ligands (1–6) form complexes with copper (I) bromide, to give 1D and 2D coordination polymers through a combination of halogen and hydrogen bonding that were characterized by X-ray diffraction analysis. These Cu(I) complexes were prepared indirectly from the ligands and CuBr2 via an in situ redox process in moderate to high yields. Four of the pyrazine ligands, 1, 4–6 were found to favor a monodentate mode of coordination to one CuI ion. The absence of a C6-chloro substituent in ligands 1, 2 and 6 supported N1–Cu coordination over the alternative N4–Cu coordination mode evidenced for ligands 4 and 5. These monodentate systems afforded predominantly hydrogen bond (HB) networks containing a catenated (μ3-bromo)-CuI ‘staircase’ motif, with a network of ‘cooperative’ halogen bonds (XB), leading to infinite polymeric structures. Alternatively, ligands 2 and 3 preferred a μ2-N,N’ bridging mode leading to three different polymeric structures. These adopt the (μ3-bromo)-CuI ‘staircase’ motif observed in the monodentate ligands, a unique single (μ2-bromo)-CuI chain, or a discrete Cu2Br2 rhomboid (μ2-bromo)-CuI dimer. Two main HB patterns afforded by self-complimentary dimerization of the amino pyrazines described by the graph set notation R22(8) and non-cyclic intermolecular N–H∙∙∙N’ or N–H∙∙∙Br–Cu leading to infinite polymeric structures are discussed. The cooperative halogen bonding between C–Cl∙∙∙Cl–C and the C–Cl∙∙∙Br–Cu XB contacts are less than the sum of the van der Waals radii of participating atoms, with the latter ranging from 3.4178(14) to 3.582(15) Å. In all cases, the mode of coordination and pyrazine ring substituents affect the pattern of HBs and XBs in these supramolecular structures.

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.

Asymmetric halogen dioxides: High level calculations and anion photoelectron spectroscopy

Gas phase complexes formed between bromide and iodide anions and molecular oxygen are investigated via high level CCSD(T) calculations and experimental anion photoelectron spectroscopy. Experimental electron binding energies of the 2P3/2 and 2P1/2 states are determined to be 3.43 and 3.90 eV, and 3.12 and 4.06 eV for the bromide and iodide complexes respectively. Calculations predict one minimum for each of the halide-oxygen complexes corresponding to a bent Cs geometry, while for the analogous neutral (radical) complexes two stationary points were located; one linear (C∞v) and another T-shaped (C2v). These lie close in energy to one another (Δ E < 1 kJ mol−1) suggesting that internal rotation of the oxygen molecule is highly likely.

Luminescent properties of a polymeric copper(I)-bromide complex in a PMMA film

The [Cu2Br2(DIB)2(PPh2)2]n complex, obtained by the reaction between [Cu4Br4(PPh3)4] and 1,4-diisocyanobenzene (DIB), was found to have a bridged polymeric structure with a planar {Cu2Br2} core. The compound exhibited bluish-green (λmax = 498 nm) and green (λmax = 515 nm) luminescence at 295 and 77 K, respectively, corresponding to the emissions from XLCT (HE band) and (X + M)LCT (LE band), respectively. The dual emission, which is attributed to the luminescence from both bands, was observed at around 178 K. The complex also displayed a change in luminescence color from bluish-green to yellow (λmax = 529 nm) upon applying external mechanical stimuli. The film containing [Cu2Br2(DIB)2(PPh2)2]n was prepared by a cast method using polymethyl methacrylate as a binding agent. The rubbed part of the film turned yellow and the other parts maintained bluish-green luminescence. Restoration of the initial color was feasible by annealing, even in film state.

Hybrid photocatalytic systems comprising a manganese complex anchored on g-C3N4 for efficient visible-light photoreduction of CO2

Inorganic–organic composites are triggering an increasing interest in the photocatalytic reduction of CO2 due to its stability and high efficiency. In this study, the reflux condensation method was used to synthesize 2,2-bipyridine-4,4-bisphosphonic acid tricarbonyl manganese bromide complex (MnP), which was then anchored onto g-C3N4 via a facile self-assembly method. The resulting g-C3N4/MnP composites catalysts exhibited efficient photocatalytic reduction of CO2 under visible light irradiation. Moreover, the yield of CO of g-C3N4/MnP catalyst was 5 times more compared with pure g-C3N4 catalyst. Additionally, the only product of catalytic reduction of CO2 was CO. These results were attributed to that the Mn complex played important role in the photocatalytic reduction of CO2 to CO by the composite catalyst. An integrated “Z-scheme” mechanism was proposed for CO2 reduction using the g-C3N4/MnP system. This hybrid photocatalyst system has good application prospects in the field of photocatalysis owing to its environmental friendliness and strong visible- light absorption.

Mechanism of CO oxidation by oxygen in the presence of palladium(ii) bromide complexes: a quantum chemical modeling

Mechanisms of CO oxidation by oxygen in the PdBr2-LiBr-MeCN-H2O system in the absence and in the presence of iron(ii) phthalocyaninate (PcFe) as co-catalyst were studied within the framework of the density functional theory with the PBE functional. According to calculations, palladium(ii) bromide complexes most likely occur as Pd(AN)(CO)Br2 (AN is acetonitrile), Pd(CO)2Br2, and [Pd(CO)Br3]−. From the results of calculations it follows that neutral complexes Pd(AN)(CO)Br2 and Pd(CO)2Br2 can be highly catalytically active in the CO oxidation. Insertion of O2 into the Pd-H bond in the hydride complexes is the rate-limiting step of the CO oxidation reaction proceeding in the absence of PcFe as co-catalyst. Iron(ii) phthalocyaninate present in the reaction system causes a noticeable decrease in the activation energy of regeneration of the PdII complexes due to more efficient activation of O2. The oxidation of palladium hydride complexes by iron superoxophthalocyaninate can follow two routes that differ in the fashion of hydride transfer.

Manganese tetraphenylporphyrin bromide and iodide. Studies of structures and magnetic properties

Manganese tetraphenylporphyrin bromide and iodide Mn(TPP)X (X = Br, 2; I, 3; TPP2− = meso-tetraphenylporphyrinate) are synthetic analogs of Mn(III) geoporphyrins. Crystal structures of 2 and 3 with chloroform in the lattices, Mn(TPP)Br·CHCl3 (2·CHCl3), Mn(TPP)I·CHCl3 (3·CHCl3), Mn(TPP)I·CDCl3 (3·CDCl3 in a different space group from 3·CHCl3), Mn(TPP)I·1.5CHCl3 (3·1.5CHCl3), and 2 with dichloromethane in the lattice, Mn(TPP)Br·CH2Cl2 (2·CH2Cl2), have been determined by single-crystal X-ray diffraction at 100 K or 298 K. Hirshfeld surface analyses of the crystal structures of 2·CHCl3, 2·CH2Cl2, 3·CHCl3, 3·CDCl3 and 3·1.5CHCl3 have been performed. Surprisingly the Mn(III)–Br and Mn(III)–I bonds in Mn(TPP)X (2–3) are about 0.2 Å (8%) longer than Fe(III)–Br and Fe(III)–I bonds in S = 5/2 Fe(TPP)X (X = Br, 4; I, 5), although both Mn(III) and Fe(III) ions have the same radii. Magnetic properties of 2 and 3 have been studied by direct current (DC) and alternating current (AC) susceptibility measurements, high-field electron paramagnetic resonance (HFEPR), and inelastic neutron scattering (INS). With four unpaired electrons in Mn(TPP)X (X = Br, 2; I, 3), the bromide complex 2 in 2·CDCl3 possesses easy-axis anisotropy, as does the chloride analog Mn(TPP)Cl (1), with the axial (D) and rhombic (E) zero-field splitting parameters of D = –1.091(3) cm−1 and |E| = 0.087(2) cm−1. The iodide complex 3 in 3·CDCl3 becomes easy-plane with D = +1.30(1) cm−1 and |E| = 0.010(5) cm−1. Axial ZFS parameters D change from −2.290(5) cm−1 in 1, reported earlier, to −1.091(3) cm−1 in 2 and +1.30(1) cm−1 in 3.

Phase Transitions and Crystal Structures of Ni(II) Complexes Determined with X-ray Powder Diffraction Data

Structural changes of chloride and bromide complexes, [Ni(Et2en)2(H2O)2]Cl2 (designated as 1a) and [Ni(Et2en)2]Br2 (2a), have been investigated by using simultaneous measurements of powder X-ray diffraction (XRD) and differential scanning calorimetry data under the temperature and humidity controls. The hydrate form of chloride complex 1a was transformed into an anhydrate form (1b) by heating at a temperature of 361 K. Then the 1b was reversibly returned to the original 1a by humidification at 25% relative humidity (RH) and temperature of 300 K. On the other hand, the anhydrate form of the bromide complex 2a was first transformed into a hydrate form (2b) at 30% RH and 300 K. On heating, the 2b turned to a new anhydrate form (2c) at 344 K, and then it returned to the original form 2a on further heating. In the present experiments, a series of reactions of 2a proceeded via 2c, which was newly found with the benefit of differential scanning calorimetry (DSC) measurements performed in parallel to the XRD measurements. Crystal structures of new crystalline forms of 1b, 2b, and 2c were determined from the powder XRD data.

Carbon monoxide oxidation by oxygen in water-acetonitrile solutions of palladium(II) bromide complexes in the presence of Co(II), Fe(II) and Mn(III) phthalocyaninates

Objectives. The objective of this paper was to compare acetylene oxidative dicarbonylation that leads to maleic anhydride with a side reaction of CO oxidation by oxygen in a PdBr 2 -LiBr-H 2 C-CH 3 CN system and in the presence of insoluble (Co) and soluble (Co, Fe, and Mn) phthalocyaninates (PcM). Methods. To study the oxidation of CO to CO 2 , a kinetics method was used; UV and IR spectroscopy was used to determine the concentrations of initial and intermediate compounds. Results . The knetics of CO to CO 2 oxidation were investigated and the reactivity series of PcM in CO oxidation and maleic anhydride synthesis was characterized. A satisfactory correlation was observed between reaction rates and PcM concentration, as well as the nature of metal, in both processes. The IR measurements of concentrations of Pd(II) and Pd(I) intermediate carbonyl complexes, and CO 2 concentrations, have made it possible to hypothesize the mechanism of CO 2 generation. The effect of PcM concentration on the concentrations of Pd(II)(CO) in CO oxidation has been shown. Conclusions. Based on the data regarding CO oxidation and acetylene oxidative dicarbonylation, certain conditions have been proposed to effectively produce double-labeled maleic anhydride with 13 C (from 13 CO).

A bis(arylphosphinito)amide pincer ligand that binds nickel forming six-membered metallacycles

The synthesis of a bis(arylphosphinito)amide pincer ligand P2ONO− designed to form two six-membered rings upon metallation is reported. Phosphination of a known bis(phenolato)amide ONO3− scaffold led to isolation of two isomers: the intended H(P2ONO) preligand with an amine moiety is formed as a kinetic product, which isomerizes via net oxidative addition of the amine N−H to phosphorous to yield a benzoxazaphosphole-containing thermodynamic product. Both isomers undergo productive metallation with NiBr2(dimethoxyethane) to produce the same complex, (P2ONO)NiBr. Treatment with triethylborohydride furnished the terminal hydride complex (P2ONO)NiH. The bromide and hydride complexes enabled comparisons of the steric and electronic properties of the P2ONO− ligand with other amide-based pincers.

Crystal structure of metal (I) bromide complexes containing 1-(4-nitrophenyl)thiourea and triphenylphosphine ligands

Crystal structure of metal (I) bromide complexes containing 1-(4-nitrophenyl)thiourea and triphenylphosphine ligands

Spin-crossover in iron(ii) coordination compounds with 2,6-bis(benzimidazol-2-yl)pyridine

Novel iron(ii) bromide, nitrate and dicyanamide complexes with 2,6-bis(benzimidazol-2-yl)pyridine possessing high-temperature 1A1 ↔ 5T2 spin crossover were obtained.

Structural investigation of bromide complexation with bipodal, tripodal and tetrapodal cationic molecules

Various multipodal molecules comprising dicationic bipodal molecules, tricationic tripodal molecules and tetracationic tetrapodal molecules with adaptable functional groups have been synthesized and characterised.

Tunable luminescent lead bromide complexes

Efficient emission from lead bromide in polyethylene glycol is tuned from orange to green by alkylammonium salts, which influence the particular lead bromide complex formation.

Synthesis and reactivity of cyclobutadiene nickel bromide.

NiBr2 reacts with 3-hexyne in the presence of Mg and EtOH to give the cyclobutadiene bromide complex [(C4Et4)NiBr2]2, which serves as a general precursor for various cyclobutadiene nickel compounds. In particular, complexes with 2-electron ligands (C4Et4)Ni(L)Br2 (L = PPh3, P(OMe)3, pyridine), complexes with bidentate ligands [(C4Et4)Ni(L2)Br]PF6 (L2 = bipyridine, phenanthroline), and nickelacarborane (C4Et4)NiC2B9H11 were obtained from [(C4Et4)NiBr2]2 in 70-95% yields. The reactions of [(C4Et4)NiBr2]2 with an excess of strong ligands, such as tBuNC or dppe, led to the displacement of cyclobutadiene. The structures of the five compounds have been established by X-ray diffraction analysis. The previously reported data on cyclobutadiene nickel complexes have been also reviewed.

A copper(i) bromide organic–inorganic zwitterionic coordination compound with a new type of core: structure, luminescence properties, and DFT calculations

A new organic–inorganic Cu(i) bromide complex based on protonated tris(2-pyridyl)phosphine, [(HPy)3PCu2Br5], has been synthesized by a straightforward reaction in solution or by modification of the [Cu2Br2(Py3P)2] complex using hydrobromic acid.