Crystal Structures and Characterizations of Bis(pyrrolidinedithiocarbamato)Cu（Ⅱ） and Zn(Ⅱ） Complexes

The structures of [Cu (S₂CN (CH₂)₄)₂] (1) and [Zn₂(S₂CN‐(CH₂)₄)₄] (2) have been determined by X‐ray crystallography analysis. They are all isomorphous and triclinic, space group of P1^?, with Z = 1. The lattice parameters of compound 1 is: a = 0.63483(2) nm, b = 0.74972(3) nm, c=0.78390(1) mn, α = 75.912(2)°, β = 78.634(2)° and γ = 86.845(2)°; compound 2: a = 0.78707(6) nm, b=0.79823(6) nm, c = 1.23246(9) nm, α = 74.813(2)°, β = 73.048(2)° and γ = 88.036(2)°. The copper atom is located on a crystallographic inversion center and zinc atom lies across centers of symmetry. The Cu(II) ion has a square‐planar geometry while Zn(II) has a distorted tetrahedral geometry. The thermal gravity (TG) data indicate that no structural transitions in the two compounds were abserved and the decomposition products can adsorb gas. Also they all have a high thermal stability.     

Structure and Reactivity of a Unique Y‐Shaped Tricoordinate Bis(silyl)platinum(II)–NHC Complex

Y not? A unique, three‐coordinate Y‐shaped bis(silyl)platinum(II) complex was isolated and characterized (see structure; C light gray, N blue, Si pink, Pt dark gray). DFT studies on a model system shed light on the nature of this unusual coordination mode for platinum(II).

     

Synthesis and Characterization of Diorganotin(IV) Complexes Bearing Binary Schiff‐Bases and Crystal Structure of nBu2SnL1

Four novel diorganotin(IV) complexes with general formula R₂SnL (R = nBu, PhCH₂) were synthesized from diorganotin dichlorides and binary Schiff‐bases (H₂L) containing N₂O₂ donor atoms in the presence of sodium ethoxide. The Schiff bases were prepared by reactions of o‐phenylenediamine with 3‐tert‐butyl‐2‐hydroxy‐5‐methylbenzaldehyde (H₂L¹) and salicylaldehyde (H₂L²) respectively. The compounds were characterized by elemental analyses, IR, and NMR spectroscopy. The solid‐state crystal structure of the compound nBu₂SnL¹ was determined by single‐crystal structural analysis.     

2,6‐Bis(pyrazol‐3‐yl)pyridine as Meridional Capping Ligand: Synthesis,Characterization, and Crystal Structure of the First Corresponding Hexanuclear Iron(III) Complex

Based on the 2,6‐bis(pyrazol‐3‐yl)pyridine ligand (H₂bpp) the hexanuclear iron(III) complex [Fe₆(bpp)₄(μ₃‐O)₂(μ‐OMe)₃(μ‐OH)Cl₂] ( 1 ) was synthesized. The reaction with iron(II) chloride and additional pyridine leads to the exclusive formation of the complex through self‐assembly process. Six octahedrally coordinated iron atoms are linked through the pyrazolido groups of four H₂bpp ligands. These are further linked through bridging hydroxido, methoxido, and oxido groups. The complex has been characterized by IR spectroscopy, ESI mass spectrometry, elemental analysis and X‐ray crystallography. Temperature‐dependent magnetic measurements indicate strong antiferromagnetic exchange interaction between the high‐spin iron(III) ions within the complex, which leads to an S = 0 spin ground state. As a result of the two Fe3(μ₃‐O) fragments two frustrated exchange pathways are present. In addition the properties of H₂bpp as a potential capping ligand for the synthesis of heteroleptic trinuclear complexes based on the triaminoguanidine core is investigated.     

Pd(II) complexes of N(4)‐substituted phenylaminoacetohydrazone and biacetylmonooxime: synthesis,characterization, structures and catalytic behaviour towards Suzuki–Miyaura coupling reactions

The reaction of [PdCl₂(CH₃CN)₂] and N(4)‐substituted phenylaminoacetohydrazone ligands (LH) in methanol at room temperature afforded air‐ and moisture‐stable palladium(II) complexes of two types with general formulae [Pd(LH)Cl] and [Pd₂(LH)(L)]Cl. An unusual coordination mode of ligand LH is observed, in which the ligand coordinates through N(4)H nitrogen and without enolization of the carbonyl group of the hydrazone moiety in both mono‐ and bimetallic complexes. The crystal structure of the complexes reveals that the oxime LH reacts with [PdCl₂(CH₃CN)₂] presumably via the elimination of HCl from hydrazine NH. All the synthesized Pd(II) complexes were evaluated as catalysts in the Suzuki cross‐coupling reaction of aryl halides, activated 4‐bromoacetophenone and non‐activated bromobenzene, with phenylboronic acid in aqueous medium. In both cases, i.e. with activated and non‐activated aryl halides, all the complexes show moderate conversion leading to biaryls with yields in the range 50–65%. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis,Characterization, and Structural Comparisons of the First Neodymium(III) Sulfite‐Acetate Crystal Structure

The first lanthanide sulfite compound with a secondary ligand, Nd(SO₃)(C₂H₃O₂), was hydrothermally synthesized and solved with single‐crystal X‐ray diffraction. In order to prevent the facile oxidation of the sulfite to sulfate, careful control of both pH and reaction temperature were required for successful synthesis of the title compound; even slight changes in conditions allow for the facile oxidation of sulfite to sulfate and yields the known [Nd(C₂H₃O₂)(SO₄)(H₂O)₂] structure. This two‐dimensional sheet topology further expands the chemistry of lanthanide sulfite extended structures and also allows for easy structural comparisons to other lanthanide sulfite compounds and the above mentioned neodymium sulfate‐acetate compound.     

Crystal Structures and Characterizations of Bis(pyrrolidinedithiocarbamato) Cu(II) and Zn(II) Complexes

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Crystal Structure of Iron(II) Acetate

In this paper the X‐ray structure and magnetic properties of iron(II) acetate – starting material for the synthesis of a wide range of iron complexes – are presented. The compound crystallises in the space group Pbcn and was identified as 2D coordination polymer consisting of iron atoms and acetate moieties with all the iron atoms hexacoordinate and different coordination modes for the acetate moieties. Additional hydrogen bond contacts lead to a porous coordination polymer with 1D channels in the size of mesopores. Temperature dependent magnetic measurements confirm that the complex is a high‐spin compound in the entire temperature range investigated with a room temperature magnetic moment of 5.4 μ_B. Field‐dependent magnetisation measurements reveal a slightly sigmoidal curve progression typical for metamagnetism.     

Crystal Structure and Spectroscopic Properties of Bis[trans‐dichlorobis(2,2‐dimethylpropane‐1,3‐diamine)chromium(III)] Tetrachlorozincate

The structure of trans‐[Cr(Me₂tn)₂Cl₂]₂ZnCl₄ (Me₂tn = 2,2‐dimethylpropane‐1,3‐diamine) was determined by a single‐crystal X‐ray diffraction study at 173 K. The analysis reveals that there are three crystallographically independent chromium(III) complex cations in the title compound. The chromium(III) atoms are coordinated by four nitrogen atoms of Me₂tn and two chlorine atoms in a trans arrangement, displaying a distorted octahedral geometry. The two six‐membered chelate rings in three complex cations are oriented in an anti chair–chair conformation with respect to each other. The Cr–N and Cr–Cl bond lengths average 2.0862(2) and 2.3112(6) Å, respectively. The ZnCl₄^2– have slightly distorted tetrahedral arrangement with Zn–Cl lengths and the Cl–Zn–Cl angles are influenced by hydrogen bonding. The resolved absorption maxima in the electronic d–d spectrum were fitted with a secular determinant for a quartet energy state of the d³ configuration in a tetragonal field. It is confirmed that the nitrogen atoms of the Me₂tn ligand are strong σ donors, but the chloro ligands have weak σ‐ and π donor properties toward the chromium(III) ion.     

Crystal Structure and Magnetic Properties of Copper(II) and Nickel(II) Binuclear Complexes with Bisacylhydrazones Based on 2,6‐Diformyl‐4‐methylphenol

The series of binuclear Cu(II) and Ni(II) complexes with an asymmetrical exchange fragment based on 2,6‐diformyl‐4‐methylphenol bishydrazone has been synthesized for the first time. The compositions and structures of both ligands and its complexes have been established with the data of IR, ¹H NMR, and extended X‐ray absorption fine structure (EXAFS) spectroscopical studies as well as magnetic measurements. The structure of [Ni₂L₃(μ‐Pz)] · 2CH₃OH (L = triply deprotonated form of bishydrazone, Pz = pyrazol) was confirmed by X‐ray crystallographic analysis. In this complex, the coordination environment of two nickel ions is quite different, one nickel atom is square‐planar and the other is distorted octahedral coordinated. The values of exchange parameter calculated in terms of HDVV theory have been compared with the features of an asymmetrical exchange fragment's electronic and geometrical structure.     

Photomagnetism of a sym‐cis‐Dithiocyanato Iron(II) Complex with a Tetradentate N,N′‐Bis(2‐pyridylmethyl)1,2‐ethanediamine Ligand

A comprehensive study of the magnetic and photomagnetic behaviors of cis‐[Fe(picen)(NCS)₂] (picen=N,N′‐bis(2‐pyridylmethyl)1,2‐ethanediamine) was carried out. The spin‐equilibration was extremely slow in the vicinity of the thermal spin‐transition. When the cooling speed was slower than 0.1 K min^?1, this complex was characterized by an abrupt thermal spin‐transition at about 70 K. Measurement of the kinetics in the range 60–70 K was performed to approach the quasi‐static hysteresis loop. At low temperatures, the metastable HS state was quenched by a rapid freezing process and the critical T(TIESST) temperature, which was associated with the thermally induced excited spin‐state‐trapping (TIESST) effect, was measured. At 10 K, this complex also exhibited the well‐known light‐induced excited spin‐state‐trapping (LIESST) effect and the T(LIESST) temperature was determined. The kinetics of the metastable HS states, which were generated from the freezing effect and from the light‐induced excitation, was studied. Single‐crystal X‐ray diffraction as a function of speed‐cooling and light conditions at 30 K revealed the mechanism of the spin‐crossover in this complex as well as some direct relationships between its structural properties and its spin state. This spin‐crossover (SCO) material represents a fascinating example in which the metastability of the HS state is in close vicinity to the thermal spin‐transition region. Moreover, it is a beautiful example of a complex in which the metastable HS states can be generated, and then compared, either by the freezing effect or by the LIESST effect.     

Synthesis and Crystal Structure of Mercury(II) Metal Crown Ether with N‐Heterocyclic Carbene Linkage

The mercury(II) metal crown ether ( 2a ) was obtained in high yield by reaction of the carbene precursor 1,2‐bis[N‐(1‐naphthylmethylene)imidazoliumethoxy]benzene dihexafluorophosphate ( 1 ) and Hg(OAc)₂. Addition of NaI to the acetone solution of 2a resulted in precipitation of pale yellow solid 2b . The structures of 2a and 2b were determined by single‐crystal X‐ray diffractometry. Both molecules display a helical conformation with a torsional cycle. The mercury atom in complex 2a is tricoordinated by two intramolecular carbene carbon atoms and an acetate oxygen atom. The mercury atom in complex 2b is tetracoordinated by two intramolecular carbene carbon atoms and two cis‐iodine atoms.     

Photomagnetic Switching of the Complex [Nd(dmf)4(H2O)3(μ‐CN)Fe(CN)5]⋅H2O Analyzed by Single‐Crystal X‐Ray Diffraction

X‐ray vision : Single‐crystal XRD experiments (see picture) reveal the excited‐state structure of the photomagnetic heterobimetallic title complex. The system shows a decrease in all the iron–ligand bond lengths, suggesting that photoexcitation involves a ligand‐to‐metal charge transfer or a change in the superexchange coupling between the metal centers.

     

Revealing the Dynamic Structure of Complex Solid Catalysts Using Modulated Excitation X‐ray Diffraction

X‐ray diffraction (XRD) is typically silent towards information on low loadings of precious metals on solid catalysts because of their finely dispersed nature. When combined with a concentration modulation approach, time‐resolved high‐energy XRD is able to provide the detailed redox dynamics of palladium nanoparticles with a diameter of 2 nm in 2 wt % Pd/CZ (CZ=ceria–zirconia), which is a difficult sample for extended X‐ray absorption fine structure (EXAFS) measurements because of the cerium component. The temporal evolution of the Pd(111) and Ce(111) reflections together with surface information from synchronous diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) measurements reveals that Ce maintains Pd oxidized in the CO pulse, whereas reduction is detected at the beginning of the O₂ pulse. Oxygen is likely transferred from Pd to Ce³⁺ before the onset of Pd re‐oxidation. In this context, adsorbed carbonates appear to be the rate‐limiting species for re‐oxidation.     

Crystallographic report: Crystal structure of tetra(4‐methyl‐5‐imidazole‐carboxyaldehyde)zinc(II) diperchlorate

The central zinc(II) atom in the title complex is tetrahedrally coordinated by four nitrogen atoms derived from 4‐methyl‐5‐imidazolecarboxyaldehyde ligands with Zn? N in the range 2.007(3) to 2.026(4) Å. Copyright © 2003 John Wiley & Sons, Ltd.     

A Novel Organosulfonate Cadmium(II) Complex with Graphite‐like 2D Layer Linked by Hydrogen Bonds

A novel mixed‐ligand complex, [Cd(im)₆][Cd(im)₃(H₂O)₃]₂(ans)₆ · 8H₂O ( 1 ), was obtained from the reaction ofCd(OAc)₂ · 2H₂O, imidazole (im) and sodium 4‐aminonaphthalene‐1‐sulfonate tetrahydrate (Na‐ans) in a mixed solvent at 25 °C. The complex was characterized by elemental analysis, IR spectroscopy, and X‐ray single crystal diffraction. There are two kinds of cations constructed by Cd^II atoms with a octahedral coordination arrangement in 1 . The Cd^II atom is bonded by six nitrogen atoms from six im ligands in the first cation, and the second central Cd^II atom is bonded by three nitrogen atoms of im molecules and three oxygen atoms belonging to water molecules. The ans anion acts as a counterion to balance the charge, and the adjacent anions are reversed but non‐parallel interlinked by N–H ··· O(S) hydrogen bonds into graphite‐like 2D sheet viewed from the c axis. The anionic channels along the [110] direction are filled with the cations, and the two kinds of cations are alternatingly arranged in the channels. The hydrogen‐bonding interactions together with the ionic bonds stabilize the crystal structure. The thermostability of the complex was investigated by TG and DSC.     

Synthesis,Characterization, and Antimicrobial Activity oF The Ligand 3-Methylpyrazole- 4-Carboxaldehyde Thiosemicarbazone and Its Pd(II) Complex

Abstract

The synthesis and characterization of a new palladium(II) complex [Pd(MePhPzTSC)₂] and its corresponding ligand 3-methylpyrazole-4-carboxaldehyde thiosemicarbazone (MePhPzTSC) are described. The bidentate ligand is coordinated to Pd(II) through the azomethine nitrogen atoms and sulfur in the form of thiol by deprotonation of the NH-C = S. The antimicrobial activity of these new compounds was evaluated against gram-negative (Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa) and gram-positive (Staphylococcus aureus and Bacillus thuringiensis) bacteria and two yeast strains (Candida albicans and Saccharomyces cerevisiae). Coordination of the ligand to the metallic ion showed improved antimicrobial activity compared to the free ligand. For the gram-positive bacteria the antimicrobial activity of the complex was higher than that of the positive control used.

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