Imino Nitrogen Atoms Research Articles

Behavior of Trapped Molecules in Lantern-Like Carcerand Superphanes.

Superphanes are a group of organic molecules from the cyclophane family. They are characterized by the presence of two parallel benzene rings joined together by six bridges. If these bridges are sufficiently long, the superphane cavity can be large enough to trap small molecules or ions. Using ab initio (time scale of 80 ps) and classical (up to 200 ns) molecular dynamics (MD) methods, we study the behavior of five fundamental molecules (M = H2O, NH3, HF, HCN, MeOH) encapsulated inside the experimentally reported lantern-like superphane and its two derivatives featuring slightly modified side bridges. The main focus is studying the dynamics of hydrogen bonds between the trapped M molecule and the imino nitrogen atoms of the side chains of the host superphane. The length of the N···H hydrogen bond increases in the following order: HF < HCN < H2O < MeOH < NH3. The mobility of the trapped molecule and its preferred position inside the superphane cage depend not only on the type of this molecule but also largely on the in/out conformational arrangement of the imino nitrogens in the side chains of the superphane. Their inward-pointing positions allow the formation of strong N···H hydrogen bonds. For this reason, these nitrogens are the preferred sites of interaction. The mobility of the molecules and their residence times on each side of the superphane have been explained by referring to the symmetry and conformation of the given superphane cage. All force field MD simulations have shown that the encapsulated molecule remained inside the superphane cage for 200 ns without any escape event to the outside. Moreover, our simulations based on some endohedral complexes in the water box also showed no exchange event. Thus, the superphanes we study are true carcerand molecules. We attribute this property to the hydrophobic side chains and their pinwheel arrangement, which makes the side walls of the studied superphanes fairly impenetrable to small molecules.

Evaluation of Concomitant Halogen and Pnictogen Bonds in Cocrystals of Imines Derived from 2-Nitrobenzaldehyde and 4-Haloaniline.

Three imines have been prepared by condensation of 2-nitrobenzaldehyde and 4-haloanilines (halo = Cl, Br, and I) with functionalities that enabled them to act as both halogen and pnictogen bond donors; however, both interactions were found to be absent in the solid state. The prepared imines were further cocrystallized with 1,3-diiodotetrafluorobenzene and 1,3,5-triiodotetrafluorobenzene as halogen bond donors. Six novel cocrystals were prepared by means of liquid-assisted mechanochemical synthesis and by crystallization from solution. All six cocrystals were of 1:1 stoichiometry and comprised a N···I halogen bond between an iodine atom of the perhalogenated halogen bond donor and the imino nitrogen atom of the imine acting as an acceptor. Additionally, in all six cocrystals, the imine molecules were interconnected by NO2···NO2 pnictogen bonding interactions. Computational analysis has shown that the NO2···NO2 exhibits bond critical point electron densities in the region (4.897-8.306) × 10-3 e Å-3 and interaction energies of 23.6-27.7 kJ mol-1, whereas the N···I halogen bonds generally have higher critical point electron densities ((1.795-1.937) × 10-2 e Å-3), but the corresponding total interaction energies are lower (19.4-20.4 kJ mol-1). Statistical analysis of the appearance of NO2···NO2 contacts concomitantly with halogen or hydrogen bonds seems to indicate that there is a positive correlation between the presence of NO2···NO2 pnictogen bonding interactions and other directional interactions in crystal structures.

Syntheses, Crystal Structures and Antimicrobial Activity of Zinc(II) Complexes Derived from 5-Bromo-2- (((2-piperazin-1-yl)ethyl)imino)methyl)phenol

Three new zinc(II) complexes, [ZnCl2L]·CH3OH (1), [ZnClL(NCS)]·2CH3OH·0.5H2O (2), and [ZnL(NCS)2]·CH3OH·H2O (3), where L is the zwitterionic form of 5-bromo-2-(((2-piperazin-1-yl)ethyl)imino)methyl)phenol, NCS is thiocyanate anion, were facile prepared by reaction of different molar ratio of L, zinc chloride and ammonium thiocyanate in methanol. The complexes were characterized by IR and UV-Vis spectroscopy. Detailed structures of the three complexes were confirmed by single crystal X-ray determination. The Zn atoms in the complexes are in tetrahedral coordination. The Schiff base ligand coordinates to Zn atom through phenolate oxygen atom and amino and imino nitrogen atoms. The remaining two sites are occupied by two Cl for 1, one Cl and one NCS for 2, and two NCS for 3. The compounds show significant antimicrobial activities.

Characteristics of Intermolecular Interactions between Encapsulated Molecules and the Lantern-Like Carcerand Superphanes

The main topic of the article is to provide the characteristics of individual intermolecular interactions present between three lantern-like superphanes and the H2O, NH3, HF, HCN, and MeOH molecules trapped inside them. Despite the large cavity, the freedom of the trapped molecules is significantly limited by the presence of numerous interaction sites on the side chains of the superphane molecule. It is shown that the molecule trapped inside the superphane is stabilized mainly by only one or, less often, two strong hydrogen bonds involving the imino nitrogen atom, but QTAIM calculations also suggest the presence of many other intermolecular interactions, mainly hydrogen bonds involving imino or central hydrogen atoms from the side chains of the superphane molecule. Moreover, it is also shown that the structural simplification of the side chains does not significantly affect both the size of the superphane molecule and the obtained encapsulation energies, which is important in modeling this type of carceplexes. Noticeably, the parent superphane considered here was previously synthesized by the group of Qing He, so the results obtained will help in understanding this type and similar systems.

Unusual reaction of (E)-2-[(benzo[d]thia-zol-2-yl-imino)-meth-yl]-5-(di-ethyl-amino)-phenol with tri-phenyl-borane: crystal structures and optical properties.

The mol-ecular and crystal structure of (E)-2-[(benzo[d]thia-zol-2-yl-imino)-meth-yl]-5-(di-ethyl-amino)-phenol (C18H19N3O2S, Et2N-Bz) and its unexpected reaction product with tri-phenyl-borane, 2,2-diphenyl-1,3-dioxa-2-borata-1,2-di-hydro-naphthalene [systematic name: N,N-diethyl-2,2-diphenyl-2H-1,3λ3,2λ4-ben-zodioxaborinin-7-amine, C23H24BNO2, (I)] are described. For Et2N-Bz, the hydroxyl group is involved in an intra-molecular hydrogen bond with the imino nitro-gen atom and the C=N bond displays an E configuration. The crystal packing is characterized by layers of inversion dimers parallel to the (10) plane and chains of mol-ecule in the a-axis direction formed through C-H⋯O inter-actions. Complex (I) crystallizes with two mol-ecules (A and B) in the asymmetric unit, which differ in the orientation of the ethyl groups. The 1,3-dioxa-2-borata-1,2,3,4-tetra-hydro-naphthalene ring displays a slight envelope conformation with the boron atom as the flap. In the crystal packing, chains of alternating A and B mol-ecules formed by C-H⋯O hydrogen bonds run in the b-axis direction. The UV-vis absorption and emission properties of the compounds are discussed and their aggregation-induced emission properties are further investigated.

Iminopyridine Copper Complex‐Based Catalysts for 1,3‐Dienes Stereospecific Polymerization

AbstractSome novel copper complexes are synthesized by reacting copper(II) dichloride and copper(II) dibromide with a series of pyridyl‐imine ligands differing in the nature of the substituents at the iminic carbon and at the imino nitrogen atom. All the complexes are characterized by analytical and infrared data: for some of them single crystals are obtained, and their molecular structure is determined by X‐ray diffraction. The complexes are combined with methylaluminoxane (MAO) for the polymerization of 1,3‐dienes (i.e., 1,3‐butadiene and isoprene) obtaining active and selective catalysts and, in case of isoprene, polymers with quite unusual structures, i.e., predominantly alternating cis‐1,4‐alt‐3,4 structures containing cis‐1,4 units sequences within the polymer chain.

Luminescent La3+, Eu3+ and Tb3+ mononuclear complexes with a Schiff base tripodal ligand derived from 9-anthracenecarboxaldehyde

Tripodal ligands represent a category of molecules able to offer a good containment to the metal ions. The N-donor tripodal ligand derived from tris(2-aminoethyl)amine and 9-anthracenecarboxaldehyde (L) was employed for synthesis of three mononuclear complexes: [La(L)(hfac)3], [Eu(L)(hfac)3] and [Tb(L)(hfac)3] where hfac is the hexafluoroacetylacetonate anion. The complexes were structurally characterized by single-crystal X-ray diffraction. The Schiff base tripodal ligand behaves as tridentate ligand coordinating through the amino and two (out of the three) imino nitrogen atoms. Luminescent properties of the ligand L and the complexes were investigated in solid-state.

Synthesis, Spectroscopic Characterization, and X-ray Structure of the Co-crystal Copper(II) Complex of the Dissymmetrical 1-(2 hydroxy-3-methoxybenzylidene)-5-(pyridin-2 ylmethylene) Carbnohydrazide Ligand

In the pentanuclear title complex, bis{<i>μ</i>₂-1-(2-oxido-3-methoxybenzylidene)-5-(pyridin-2-ylmethylene)carbonohydrazide}-1<i>κ</i>⁴<I>O</I>,<I>N</I>,<I>N</I>’,<I>N</I>’’:2<i>κ</i>²<I>O</I>,<I>N</I>;2<i>κ</i>²<I>O</I>,<I>N</I>:3<i>κ</i>⁴<I>O</I>,<I>N</I>,<I>N</I>’,<I>N</I>’’-1,2,3-tricopper(II) bis{[1-(2-oxido-3-methoxybenzylidene)-5-(pyridin-2-ylmethylene)carbonohydrazide]-<i>κ</i>⁴<I>O</I>,<I>N</I>,<I>N</I>’,<I>N</I>’’-copper(II)} tetraperchlorate tetrahydrate (1), two monocationic mononuclear units and one dianionic trinuclear unit co-exist. The Cu<SUP>II</SUP> centers in the mononuclear units as well as the two terminal Cu<SUP>II</SUP> centers in the trinuclear unit are located in the N₃O cavity of the ligand and are coordinated to a phenolate oxygen atom, to a pyridine nitrogen atom, to an imino nitrogen atom and to a hydrazinyl nitrogen atom. The third central Cu(II) atom in the trinuclear unit, which is hexacoordinated, is located in N₂O₄. The metal center is coordinated to two ligand molecule through one imino nitrogen atom one oxygen atom of a carbonyl moiety per ligand and two oxygen atom of water molecules. The tetracoordinated copper(II) ions are situated in distorted square planar environments, while the hexacoordinated copper(II) is located in octahedral geometry. In the mononuclear units, as well as in the trinuclear units, the methoxy oxygen atoms remain uncoordinated. Each atom of the uncoordinated perchlorate anions is disordered over two sets of sites in a 0.5 ratio. Four free water molecules are also present. In the crystal, the trinuclear cationic unit and the mononuclear cationic units are assembled into infinite layers. These layers are held together via electrostatic interactions, forming a three-dimensional structure.

Interesting chemical and physical features of the products of the reactions between trivalent lanthanoids and a tetradentate Schiff base derived from cyclohexane-1,2-diamine.

The initial use of a tetradentate Schiff base (LH2) derived from the 2 : 1 condensation between 2-hydroxyacetophenone and cyclohexane-1,2-diamine in 4f-metal chemistry is described. The 1 : 2 reaction of Ln(NO3)3·xH2O (Ln = lanthanoid or yttrium) and LH2 in MeOH/CH2Cl2 has provided access to isostructural complexes [Ln(NO3)3(L'H2)(MeOH)] in moderate to good yields. Surprisingly, the products contain the corresponding Schiff base ligand L'H2 possessing six aliphatic -CH2- groups instead of the -CH-(CH2)4-CH- unit of the cyclohexane ring, i.e. an unusual ring-opening of the latter has occurred. A mechanism for this LnIII-assisted/promoted LH2 → L'H2 transformation has been proposed assuming transient LnII species and a second LH2 molecule as the H2 source for the reduction of the cyclohexane moiety. DFT calculations provide strong evidence for the great thermodynamic stability of the products in comparison with analogous complexes containing the original intact ligand. The structures of the PrIII, SmIII, GdIII, TbIII, and HoIII complexes have been determined by single-crystal X-ray crystallography. The 9-coordinate LnIII centre in the molecules is bound to six oxygen atoms from the three bidentate chelating nitrato groups, two oxygen atoms that belong to the bidentate chelating organic ligand, and one oxygen atom from the coordinated MeOH group. In the overall neutral bis(zwitterionic) L'H2 ligand, the acidic H atoms are clearly located on the imino nitrogen atoms and this results in the formation of an unusual 16-membered chelating ring. The coordination polyhedra defined by the nine donor atoms around the 4f-metal-ion centres can be best described as distorted, spherical capped square antiprisms. The EuIII, TbIII, and DyIII complexes exhibit LnIII-based luminescence in the visible region, with the coordinated L'H2 molecule acting as the antenna. Ac magnetometry experiments show that the DyIII member of the family behaves as an SIM at zero field and under external dc fields of 0.1 and 0.2 T without the enhancement of the peaks' maxima, suggesting that QTM is not the relaxation path. The GdIII complex behaves, rather unexpectedly, as a SIM with two different magnetic relaxation paths occurring at very close temperatures; this behaviour is tentatively attributed to a very small axial zero-field splitting (D ∼ 0.1 cm-1), which cannot be detected by magnetization or susceptibility experiments. The prospects of the present, first results in the lanthanoid(III)-LH2 chemistry are discussed.

Synthesis and crystal structures of copper, nickel and zinc complexes derived from 2-((2-(pyrrolidin-1-yl)ethylimino)methyl)phenol with antimicrobial activity

Five new copper(II), nickel(II) and zinc(II) complexes, [Cu4Cl2(μ1,1-N3)4(DMF)2] (1), [Cu4Br2(μ1,1-N3)4(DMF)2] (2), [Ni3L2(CH3COO)4]CH3OH (3), [Ni3L2(CH3COO)2(μ1,1-N3)2(CH3OH)2] (4) and [Zn(LH)I2]CH3OH (5), were designed and successfully synthesized using the Schiff base ligand 2-((2-(pyrrolidin-1-yl)ethylimino)methyl)phenol (HL). All the synthesized complexes were characterized using different physico-chemical and spectroscopic methods, like elemental analysis, infrared spectra and single crystal X-ray diffraction. The X-ray structural analysis showed that the Cu atoms in the tetranuclear complexes 1 and 2 are in a square pyramidal coordination, the Ni atoms in the trinuclear complexes 3 and 4 are in an octahedral coordination and the Zn atom in the mononuclear complex 5 is in a tetrahedral coordination. The Schiff base ligand was coordinated to the metal atoms through the phenolate oxygen, imino nitrogen and/or pyrrolidine nitrogen atoms. The biological study indicated that the copper and zinc complexes have interesting antimicrobial activity against B. subtilis, S. aureus, E. coli and P. fluorescens, with MIC values of 0.6–2.3 μmol/L.

Adsorption behavior and mechanism for Pb(II) and Cd(II) by silica anchored salicylaldehyde modified polyamidoamine dendrimers

BackgroundWater pollution caused by Pb(II) and Cd(II) poses severe threat to human beings. Construction of adsorbent for efficient adsorption of these ions is of vital importance. Polyamidoamine (PAMAM) dendrimers based adsorbents displayed excellent binding ability for metal ion. MethodsSilica anchored salicylaldehyde modified polyamidoamine dendrimer (G0-S, G1-S, and G2-S) have been prepared for removing these ions. The adsorption behavior and mechanism was systematically reveled via batch experiments and theoretical calculation. Significant findingsG1-S is the most efficient adsorbent that exhibits highest adsorption at pH 6.0 for these ions. Kinetic adsorption is dominated by film diffusion and fitted by pseudo-second-order model. The adsorption of these ions can be enhanced by elevating temperature and concentration. Adsorption isotherm process fits Langmuir model and is spontaneous, endothermic and randomness increased in nature. Adsorption mechanism indicates imino and tertiary amine nitrogen, hydroxyl and carbonyl oxygen participate in the adsorption, and imino nitrogen atoms dominate the coordination.

Syntheses, Characterization, and X-Ray Crystal Structure of a 1:1 Co-Crystal of bis{bis[((2-(1H-imidazol-2-yl)methylidene)amino)phenolato-κ3N,N’,O]nickel(II)} and bis{bis[((2-(1H-imidazol-2-yl)methylidene) amino)phenol-κ3N,N’,O]nickel(II)} tetra(chloride)

The present investigation describes the synthesis and structural study of the ligand 2-((1H-imidazol-2-yl)methyleneamino)phenol, which was used to generate three dimensio-nal supramolecular complex formulated as {[Ni(HL)2]2.[Ni(H2L)2]2.(Cl)4.(H2O)5}. The title compound crystallizes in the orthorhombic space group Fddd with the following unit cell parameters: a = 13.9269(4) Å, b = 29.5295(16) Å, c = 43.1739(15) Å, V = 17755.5(12) Å3, Z = 8, R1 = 0.043 and wR2 = 0.129. For this compound, the structure reveals that one neutral mononuclear unit [Ni(HL)2] and one cationic mononuclear unit [Ni(H2L)2]2+. In the neutral unit, the organic molecule acts as a tridentate through one imino nitrogen atom, one nitrogen atom from the imidazole ring and one phenolate oxygen atom. In the cationic unit, it acts as tridentate through one imino nitrogen atom, one nitrogen atom from the imidazole ring and one oxygen atom of non-deprotonated phenol group. In both units the nickel(II) ion is hexacoordinated and the coordination environment can be described as distorted octahedral geometry. Numerous hydrogen bonds link the molecules into three dimensional network.

Synthesis, chemical and physical properties of lanthanide(III) (Nd, Gd, Tb) complexes derived from (E)-ethyl 4-(2-hydroxybenzylideneamino)benzoate

The 1:2 reaction between Ln(NO3)3·6H2O (1) (Ln = Nd (a), Gd (b) or Tb (c)) and ((E)-ethyl 4-((2-hydroxybenzylidene)amino)benzoate) (LN,OH) in ethanol has provided access to the complexes [LnIII(LNH,O)2(NO3)3(H2O)] (2a–c) in good yield. The isomorphous structures of 2a–c have been determined by single-crystal X-ray crystallography. The LnIII ions in 2a–c are coordinated by 9 oxygen atoms: two from the phenolate oxygen atoms of the Schiff bases, six from three chelating nitrato groups and one aqua ligand. The ligands LN,OH behave as monodentate phenolate O–donors, whereby an additional hydrogen atom is bonded to the imino nitrogen atom, resulting in a formally neutral ligand that adopts an exceptionally unusual coordination mode engaging in the zwitterionic form. The nine donor atoms that define the coordination polyhedra surrounding the LnIII ion are best described as capped square antiprisms. The crystal structures are based on a variety of intermolecular interactions. Hirshfeld surface analysis was used to assess the degree of interactions between the molecules. Susceptibility measurements on 2a–2c confirm the occurrence of the free ion ground 2S+1LJ state at room temperature. However, the magnetization measurements at 2 K revealed a lack of saturation at the highest applied field of 70,000 Oe for both 2a and 2c, indicating the presence of substantial magnetic anisotropy in these compounds. On the other hand, 2b exhibits perfect paramagnetic behavior with magnetic saturation at high fields, indicating the absence of significant magnetic anisotropy in this compound. Solid-state IR and UV/VIS data are discussed in terms of the structural features. Solid 2a–c emit in the visible region upon UV-Excitation with the emission exhibiting dopant characteristics.

A cross-linked tin oxide/polymer composite gel electrolyte with adjustable porosity for enhanced sodium ion batteries

Solid electrolytes have a great potential to replace traditional flammable liquid electrolytes for lithium/sodium ion batteries. However, the solid electrolytes have a low ionic conductivity and poor interface properties, so it is difficult for them to reach the level of conventional liquid electrolyte systems. We have now built an adjustable porous 3D network structure by contacting PVDF-HFP and SnO2, and optimized the ion conductive path in the gel polymer electrolyte by adding 1-(4-cyanophenyl)-guanidine. PVDF-HFP with a 3D network structure provides a channel for storing and transporting sodium ions, and the imino nitrogen atom of 1-(4-cyanophenyl)guanidine can form a ligand with sodium ions to enhance the conduction of Na+. The gel polymer electrolyte (PSGGSE) thus obtained has an ion conductivity of 0.232 mS cm−1 at 70 °C, and is easy to form a stable interface layer with the anode. Further experiments showed that compared with liquid electrolytes, a more stable interface was formed between PSGGSE and the anode. Cycling tests of Na/PSGGSE/Na symmetric batteries under different current densities showed that no short circuit occurred after 400 h, indicating that the battery could not be short-circuited, and PSGGSE can effectively inhibit the growth of Na dendrites. In addition, the Na/PSGGSE/NiMoO4 battery has an excellent cycling stability at the current density of 100 mA g−1, and still maintains a high capacity of 150 mAh g−1 after 200 cycles, which is much higher than that of liquid electrolytes.

Synthesis and characterization of cobalt(II) complexes with bidentate Schiff base ligand

The coordination complexes of Co(II) have been prepared from bidentate Schiff base. The Schiff base ligand was synthesized by the condensation of 4- hydroxy-3-methoxybenzaldehyde and 2-aminobenzhydroxamic acid in an alcoholic medium at room temperature. The ligand and cobalt (II) complexes were characterized by elemental analysis, molar conductance, electronic spectra, IR spectra, NMR spectra, electrical conductivity and magnetic susceptibility. The cobalt (II) complexes are colored and stable in air. In the metal complexes, the metal -ligand ratio was found to be 1:2. A sharp band at 1630 cm-1 is characteristics of the azomethine group present in the Schiff base ligand. This band was shifted to lower frequency (1605 – 1620 cm-1) in all the cobalt complexes, indicating the coordination of the azomethine nitrogen to the metal ion in complexes. The ν(N-OH) stretching vibration of the ligand obtained at 1080 cm-1 was raised up by 10-40 cm-1 in the complexes suggesting the deportation of (N-OH) hydrogen and coordination of hydroxy imino nitrogen atom in the bond formation with the Co(II) ions. The molar conductivity data of the complexes in DMF solution indicates that they are of non-electrolytic nature. On the basis of elemental analysis, magnetic susceptibility and electronic spectral data, geometry of complexes was proposed to be octahedral.

Synthesis of Open‐Cage Fullerenes with Pyrrole, Pyrrolone, Pyridinone, Iminofuran, and Pyranone Fragments Embedded on the Rim of the Orifice

AbstractAn open‐cage fullerene derivative with a pyranone and a diiminopentanone moiety was prepared. Further reaction with aniline could convert the pyranone moiety into a pyrrole moiety through the pyridinone moiety as an intermediate. During the process, decarboxylation and dehydroxylation aromatization reactions also took place on the diiminopentanone moiety and the two adjacent hydroxyl groups, thus forming iminofuran or pyrrolone moiety on the rim of the open‐cage fullerene. Protonation experiment showed that the imino nitrogen atom on the rim of the orifice is more basic than the pyrrole nitrogen atom. The lone pair of the pyrrole nitrogen is partially conjugated with the π system of the fullerene cage as shown by single crystal X‐ray structures.

Crystal structures of bis-{N-[1-(pyridin-2-yl-κN)ethylidene]nicotine hydrazide-κ2N’,O}cobalt(II)bis(perchlorate) dihydrate and bis-{N'-[1-(pyridin-2-yl-κN)ethylidene]nicotinohydrazide-κ2N',O}copper(II) perchlorate

Complexes of Co(II), [Co(C26H24N8O2)]·(ClO4)2·(H2O)2 (1), and Cu(II), [Cu(C26H23N8O2)]·(ClO4) (2), have been synthesized. The prepared two compounds were characterized by elemental analysis, infrared and their structures were determined by single-crystal X-ray diffraction. The compound 1 crystallizes in the triclinic space group P-1 with the following unit cell parameters: a = 8.880 (5) Å, b = 10.529 (5) Å, c = 18.430 (5) Å, α = 99.407 (5)°, β = 102.174 (5)°, γ = 100.652 (5)°, V = 1618.2 (13) Å3, Z = 2, T = 293(2), μ(MoKα) = 0.77 mm-1, Dcalc = 1.582 g/cm3, 16135 reflections measured (5.050° ≤ 2q ≤ 59.152°), 7648 unique, Rint = 0.034 which were used in all calculations. The final R1 was 0.066 (I ≥ 2σ(I)) and wR2 was 0.22 (all data). The compound 2 crystallizes in the monoclinic space group P21/c with the following unit cell parameters : a = 11.652 (5) Å, b = 16.540 (5) Å, c = 14.512 (5) Å, β = 93.495 (5)°, V = 2791.6 (18) Å3, Z = 4, T = 293(2), μ(MoKα) = 1.05 mm-1, Dcalc = 1.768 g/cm3, 15592 reflections measured (5.624° ≤ 2θ ≤ 58.804°), 6630 unique, Rint = 0.025 which were used in all calculations. The final R1 was 0.050 (I ≥ 2σ(I)) and wR2 was 0.144 (all data). In both complexes, the ligand acts in a tridentate fashion. In the structure of the mononuclear complex 1, the Co(II) cation is coordinated by two ligand molecules. The basal plane around the Co(II) cation is occupied by two pyridine nitrogen atoms and two carbonyl oxygen atoms. Two imino nitrogen atoms occupy the apical positions of the distorted square-pyramidal geometry. The mononuclear 2 consists of a Cu(II) coordinated by one ligand and one monodeprotonated ligand molecule. The metal center lies in a distorted square bipyramidal environment. The basal plane around the Cu(II) is occupied by two pyridine nitrogen atoms and two carbonyl oxygen atoms, the apical position being occupied by the two imino nitrogen atoms.

Heterometallic supramolecular architectures constructed from cyanido-based [CoIII(AA)(CN)4]- building-blocks (AA = 1,10-phenantroline and 2,2’-bipyridine)

A neutral, mixed-valence cyanido-bridged {Co2IICo2III} complex, with formula {[CoII2(L)(MeOH)2][CoIII(phen)(CN)4]2}·2H2O·0.5MeOH (1), and a cyanido-based ionic compound, with formula [MnII(MAC)(H2O)2][CoIII(bipy)(CN)4]2·3H2O (2) were obtained by reacting the heteroleptic Ph4P[CoIII(AA)(CN)4] building-block [AA = 1,10-phenanthroline, phen, (1) and 2,2’-bipyridine, bipy, (2)] with the dinuclear {Co2IIL}2+ (1) and mononuclear {MnII(MAC)}2+ (2) precursors, respectively [H2L = macrocyclic Schiff-base obtained by condensation of 2,6-diformyl-p-cresol with 1,3-diaminopropane and MAC = 2,13-dimethyl-3,6,9,12,18-pentaazabicyclo-[12.3.1]octadeca-(18),2,12,14,16-pentaene]. The structures of 1 and 2 were determined by X-ray diffraction on single crystals. 1 is a neutral tetranuclear homometallic compound where two peripheral [CoIII(phen)(CN)4]- entities which act as end-cap ligands through one of its four cyanide groups towards the inner double phenoxido-bridged [Co2II(L)(MeOH)2]2+ dinuclear unit. Both cobalt(III) and cobalt(II) ions are six-coordinate with two phenanthroline-nitrogen and four cyanide-carbon atoms (at CoIII) and two phenoxido-oxygens and two imino-nitrogen atoms from the Schiff-base ligand plus a methanol molecule and a cyanide-nitrogen atom (at CoII) building somewhat distorted octahedral surroundings. The value of the cobalt(II)×××cobalt(II) separation is 3.11 Å and that of the angle at the phenoxo bridge is 99.4°. Compound 2 is a heterobimetallic ionic salt which is made up of [CoIII(bipy)(CN)4]- anions and [Mn(MAC)(H2O)2]2+ cations. Each cobalt(II) in 1 is six-coordinated, in a distorted octahedral environment built by a bidentate bipy ligand and four monodentate cyanide groups whereas the manganese(II) ion is seven-coordinated with five nitrogen atoms of the MAC ligand and two water molecules describing a distorted pentagonal bipyramid surrounding. The cryomagnetic investigation of 1 in the temperature range 1.9-300 K reveals the occurrence of strong spin-orbit coupling effects and a relatively weak antiferromagnetic interaction between the high-spin cobalt(II) ions linked by the double phenoxido bridge . The nature and magnitude of the magnetic coupling in 1 compares well with those from previous magneto-structural studies on the CoII2O2 motifs where antiferromagnetic interactions result in the examples having values at the phenoxido angle larger than 99.7º with dihedral angles smaller than 35.3°.

Synthesis, characterization, and density functional theory studies of hydrazone–oxime ligand derived from 2,4,6‐trichlorophenyl hydrazine and its metal complexes searching for new antimicrobial drugs

Novel 13 mononuclear complexes derived from 3‐(2‐(2,4,6‐trichlorophenyl) hydrazono) butan‐2‐one oxime with various molar ratio, geometry and different mode of interaction were prepared using transition metal Cd2+, Zn2+, Cu2+, Ni2+, Co2+, Fe3+, Mn2+, and VO2+. The structure of these compounds was investigated physically, analytically, and spectrophotometrically. The ligation sites of the free 3‐(2‐(2,4,6‐trichlorophenyl) hydrazono) butan‐2‐one oxime were designated via molecular modeling calculations. Furthermore, quantum chemical parameters for the ligand and its complexes were calculated. The analytical and spectral data revealed that the complexes (2–13) were formed with molar ratio of (1 M:1 L) or (1 M:2 L) in which hydrazone oxime adhered with the metal ion as a univalent or neutral bidentate chelator, via the imino nitrogen atom of hydrazone moiety and oximato nitrogen atom of deprotonated/protonated oxime moiety adopting different geometrical structures. The electron spin resonance (ESR) spectra of Cu2+complexes (7–8) and (10–11) were referred to axial symmetry with g||&gt; g┴&gt; ge, which indicated that unpaired electron is localized in a d(x2 − y2)orbital with notable bonding covalency nature. The thermo analysis (thermogravimetry [TG]) confirmed that the complexes were decayed in one, two, three, or four steps starting with dehydration process, elimination of coordination water molecules, or removal of anions and completed with the whole decomposition of the complexes with the formation of metal oxide. The ligand did not exhibit antimicrobial activities, but its complexes showed variable activities.

Di-aqua-bis-{μ-1,5-bis-[(pyridin-2-yl)methyl-idene]carbonohydrazide(1-)}di-μ-chlorido-tetra-chlorido-tetra-zinc(II).

A tetra-nuclear ZnII complex, [Zn4(C13H11N6O)2Cl6(H2O)2] or {[Zn2(HL)(H2O)(Cl2)](μCl)2[Zn2(HL)(H2O)(Cl)]}2, was synthesized by mixing an equimolar amount of a methanol solution containing ZnCl2 and a methanol solution containing the ligand H2 L [1,5-bis-(pyridin-2-yl-methyl-ene)carbono-hydrazide]. In the tetra-nuclear complex, each of the two ligand mol-ecules forms a dinuclear unit that is connected to another dinuclear unit by two bridging chloride anions. In each dinuclear unit, one ZnII cation is penta-coordinated in a N2OCl2 in a distorted square-pyramidal geometry, while the other ZnII cation is hexa-coordinated in a N3OCl2 environment with a distorted octa-hedral geometry. The basal plane around the penta-coordinated ZnII cation is formed by one chloride anion, one oxygen atom, one imino nitro-gen atom and one pyridine nitro-gen atom with the apical position occupied by a chloride anion. The basal plane of the hexa-coordinated ZnII cation is formed by one chloride anion, one hydrazinyl nitro-gen atom, one imino nitro-gen atom and one pyridine nitro-gen atom with the apical positions occupied by a water oxygen atom and a bridged chloro anion from another dinuclear unit, leading to a tetra-nuclear complex. A series of intra-molecular C-H⋯Cl hydrogen bonds is observed in each tetra-nuclear unit. In the crystal, the tetra-nuclear units are connected by inter-molecular C-H⋯Cl, C-H⋯O and N-H⋯O hydrogen bonds, forming a planar two-dimensional structure in the ac plane.