Macrocyclic Ligand

In the title binuclear copper(II) complex, [Cu2(ClO4)2(OH)2(C10H8N2)2], the CuIIion is coordinated in the form of a Jahn–Teller distorted octahedron by two bipyridine N atoms, two perchlorate O atoms and two hydroxide O atoms, and displays a distorted octahedral geometry. The molecule belongs to the symmetry point groupC2h. The CuIIion is located on a twofold rotation axis and the hydroxide and perchlorate ligands are located on a mirror plane. Within the dinuclear molecule, the Cu...Cu separation is 2.8614 (7) Å. The crystal structure exhibits O—H...O, C—H...O and π–π [centroid–centroid distance = 3.5374 (13) Å] interactions.

The asymmetric unit of the title compound, [Cr(C 2 O 4 )(C 10 H 24 N 4 )] 2 [Cr 2 O 7 ]Á-8H 2 O (C 10 H 24 N 4 = 1,4,8,11-tetraazacyclotetradecane, cyclam; C 2 O 4 = oxalate, ox) contains one [Cr(ox)(cyclam)] + cation, one half of a dichromate anion that lies about an inversion centre so that the bridging O atom is equally disordered over two positions, and four water molecules. The terminal O atoms of the dichromate anion are also disordered over two positions with a refined occupancy ratio 0.586 (6):0.414 (6). The Cr III ion is coordinated by the four N atoms of the cyclam ligand and one bidentate oxalato ligand in a cis arrangement, resulting in a distorted octahedral geometry. The Cr-N(cyclam) bond lengths are in the range 2.069 (2)-2.086 (2) A ˚, while the average Cr-O(ox) bond length is 1.936 A ˚. The macrocyclic cyclam moiety adopts the cis-V conformation. The dichromate anion has a staggered conformation. The crystal structure is stabilized by intermolecular hydrogen bonds involving the cyclam N-H groups and water O-H groups as donors, and the O atoms of oxalate ligand, water molecules and the Cr 2 O 7 2À anion as acceptors, giving rise to a three-dimensional network.

The title compound, C10H13N3O2S, was prepared by condensation
of 3,4-dihydroxybenzaldehyde with 4-ethyl-3-thiosemicarbazide.
The molecule adopts an E configuration with
respect to the C N bond. One of the OH substituents on the
dihydroxybenzene ring is disordered over the two possible 3-
positions on either side of the ordered 4-hydroxy group. The
occupancy of the major disorder component refined to
0.633 (7). The molecule is essentially planar, with an r.m.s.
deviation through all non-H atoms of 0.0862 A ° . An intramolecular
N—H     N hydrogen bond forms between the outer
amine residue and the imine N atom, generating an S(5) ring
motif and contributing to the planarity of the molecule. In the
crystal structure, an extensive network of classical O—H     O,
O—H     S and N—H     S hydrogen bonds and weak C—
H     O and S     O [3.301 (3) A ° ] interactions link molecules
into sheets running approximately parallel to the ab plane.

Figure S1. Cyclic voltammograms of 1 at pH 2 and scan rates 10, 25, 50, 75, 100 and 150 mV s - 1 . The inset shows the anodic and cathodic peak currents vs the square root of the scan rate. Conditions: 1 (2 × 10 -3 M), 0.1 M NaClO 4 adjusted to pH 2 with HClO 4 , 25°C, glassy carbon working electrode.

In the Ba complex (IV), crystallizing in P1 with Z=4, the novel macrocycle is folded so that all the oxygen atoms are coordinated to Ba. In the eleventh position one triflate anion is bound. In (VI) the geometry around Ba is similar, additionally one mole of H2O is coordinated. (VIa) crystallizes in Pbca with Z = 8. In the complexes (VI) the "soft" metal centers are different from other known dicopper compounds. The electrochemical properties of the trinuclear complexes (VI) are investigated by polarography and cyclovoltammetry. For (VIa) two one-electron reductions, corresponding to the Cu(II)/Cu(I) and Cu(I)/Cu(I) oxidation states, are observed. This process is chemically reversible. For (VIb) the reduced Ni complex is to be regarded as a Ni(II) complex of a radical anion ligand. The reduction/oxidation of (VIb) is also chemically reversible.

Novel copper(II) X-salicylate complexes with N,N-diethylnicotinamide (dena) of the formula [Cu(R-COO) 2 (dena) 2 (H 2 O) 2 ] (RCOO = 3-methylsalicylate anion (3-Mesal, 1), 4-methylsalicylate anion (4-Mesal, 2), 5-methylsalicylate anion (5-Mesal, 3), 5-methoxysalicylate anion (5-MeOsal, 4) or 4-methoxysalicylate anion (4-MeOsal, 5)), and complex )) have been prepared in the crystalline forms and characterized by spectroscopic methods (IR, Vis-UV, EPR). All the compounds according to their composition (1-5) seem to possess octahedral copper(II) stereochemistry. The complex 1 has been prepared in two different forms. X-ray analyses of the complexes 1, 4, and 5 were carried out and they featured a tetragonal-bipyramidal geometry around the copper atoms. The tetragonal planes are created by X-salicylate anions bonded to the copper(II) atoms via unidentate carboxylate oxygen atoms and the pyridine ring nitrogen atoms of the neutral ligand N,N-diethylnicotinamide, while in axial positions are water molecules. The two forms of complex 1 present conformation polymorphs and supramolecular isomers.

The magnetization of a series of Al 2 O 3 with different particle sizes and their 27 Al NMR spectra have been studied at room temperature. The field dependence of the magnetization demonstrated the existence of a long-range ferromagnetic order in a small part of the sample at room temperature; however, the relative volume of this contribution was very small (less than 1%), and this seems likely due to an impurity phase. The NMR spectra did not contain any lines of metallic aluminum the existence of which in these nanooxides was assumed before in a surface layer of the nanoparticles, according to the data of other techniques. The data on the phase composition and the charge distribution in different phases of the Al 2 O 3 nanoparticles have been obtained. The change in the mean particle size (by a factor of almost three) only insignificantly changed their phase composition.

The solid-state structures of the four homodinuclear chelate ligand system with that of the parent amine and its dinuclear copper complex. NMR investigations of the diamagnetic complexes, Na 2 (Eu 2 OHEC)-complex 1 indicate a very similar environment of the lanthanide cations in solution and in the solid state. Low-(H 2 O) 2 ] • 11 H 2 O (3), and [Cs 2 (La 2 OHEC)(H 2 O) 2 ] • 14 H 2 O (4) (H 8 OHEC = 1,4,7,10,14,17,20,23-octaazacyclohexacosane-temperature and variable-temperature 1 H-NMR measurements prove the existence of two isomers of 1 (3.5:1 1 ,4,7,10,14,17,20,23-octaacetic acid), were determined by Xray crystal structure analysis. Each lanthanide(III) ion is ratio) which undergo conformational processes. The rate constants of these processes were deduced from a complete ninefold coordinated by eight donor atoms of the ligand system and the oxygen atom of one water molecule. The line shape analysis and were used to determine the activation parameters. structures are compared with those of DOTA-and TETAcoordinated complexes and the conformation of the OHEC mational and coordination equilibria in aqueous solution [a] Institut für Anorganische und Analytische Chemie, Technische Universität Berlin, dinuclear lanthanide(III) chelate complexes, [9] among them Strasse des 17. Juni

Herein, we report the metal complexation properties of a macrocyclic ligand (L) that contains three pyridines as well as three urea groups. Linear and strand like ligands are typically used to afford helical coordination polymer. Our reported macrocyclic ligand (L) has remarkable flexibility and can twist upon dative bond formation. Two macrocyclic ligands complex with three cadmium atoms to form a helicate monomeric structure [Cd 3 L 2 (H 2 O) 6 (CH 3 CN) 2 ] 6+ , which extends to a 1D polymeric structure via hydrogenbonding. We also investigated the binding property of this new ligand in solution by NMR and UV-Vis spectroscopy. These results together with diffusion NMR studies suggest that in solution this ligand also forms an oligomeric complex with cadmium.

Complexos de cobre(II) (3d 9 , S = 1/2) são estáveis e amplamente investigados por espectroscopia de ressonância paramagnética eletrônica (EPR). Já o isoeletrônico níquel(I) é muito menos comum e muito menos estudado. No entanto, níquel(I) tem interesse biológico, uma vez que o sítio ativo da metil coenzima M redutase (MCR) contém um ligante macrocíclico, F 430 , que coordena o Ni I na sua forma ativa, MCR red1. Assim, o comportamento redox e espectroscópico de complexos tetraazamacrocíclicos de níquel tem importância na química biomimética. O estudo desses complexos é complicado pela dificuldade na obtenção de Ni I a partir dos precursores estáveis de Ni II. A redução de complexos macrocíclicos de Ni II pode gerar Ni I em certos casos, mas em muitos outros leva à redução do macrociclo, gerando um ânion radical orgânico. Estudos anteriores da formação de complexos tetraazamacrocíclicos de Ni I são aqui discutidos em termos da competição entre a redução centrada no metal e a centrada no ligante. Resultados de EPR são particularmente importantes para distinguir esses dois processos de redução, já que a formação de Ni I produz espectros de EPR característicos, similares aos de Cu II , enquanto a redução centrada no ligante gera espectros de EPR agudos, centrados em g = 2,00 e típicos de radicais orgânicos. Mesmo que uma redução centrada no metal ocorra, a geometria do complexo macrocíclico de Ni I resultante é amplanente variável e, consequentemente, o espectro de EPR também será. Nesse caso, a comparação é entre os extremos dos espectros típicos de complexos tetragonais distorcidos (estado fundamental dx2-y2 1 , que inclui as geometrias octaédrica tetragonalmente distorcida, piramidal de base quadrada e quadrado-planar) e dos complexos bipiramidais de base trigonal (estado fundamental dz2 1). Trabalhos anteriores realizados com Cu II foram relacionados com a situação para Ni I. Os diferentes tipos de espectros de EPR desses sistemas são discutidos especificamente usando exemplos inéditos de vários complexos tatraazamacrocíclicos de níquel, incluindo F 430 e a própria MCR. Copper(II) (3d 9 , S = 1/2) complexes are stable and widely investigated by electron paramagnetic resonance (EPR) spectroscopy. In contrast, isoelectronic nickel(I) is much less common and much less investigated. Nickel(I), however, is of biological interest as the active site of methyl coenzyme M reductase (MCR) contains a tetraaza macrocyclic ligand, F 430 , which coordinates Ni I in its active form, MCR red1. As result, the redox behavior and spectroscopy of tetraaza macrocyclic complexes of nickel is of importance in biomimetic chemistry. Such efforts are complicated by the difficulty in generating Ni I from their stable, Ni II , precursors. Reduction of Ni II macrocyclic complexes can afford Ni I in certain cases, but in many other cases can lead instead to reduction of the macrocycle to generate an organic radical anion. Previous studies on the formation of tetraaza macrocyclic complexes of Ni I are discussed in terms of the competition between metal-centered and ligandcentered reduction. EPR results are particularly important in making the distinction between these two reduction processes, as formation of Ni I gives characteristic EPR spectra similar to those for Cu II , while ligand-centered reduction gives narrow EPR spectra at g = 2.00, typical of organic radicals. Even if metal-centered reduction occurs, the geometry of the resulting Ni I macrocyclic complex is highly variable and, as a result, the EPR spectral appearance is highly variable. In this case, the comparison is between the extremes of spectra typical for tetragonally distorted complexes (dx2-y2 1 ground state, which includes tetragonally distorted octahedral, square pyramidal and square planar geometries) and those for trigonal bipyramidal complexes (dz2 1 ground state). Previous work on Cu II was related to the situation for Ni I. The different types of EPR spectra for such systems are specifically discussed using previously unpublished examples of several tetraaza macrocyclic complexes of nickel, including F 430 and MCR itself.

Background The hypothetical concept of ‘macrocyclic cavity’ is largely employed as useful model to interpret the affinity of metal ions for the macrocyclic chelating ligand 2,2′,2′′,2′′′-(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetraacetic acid (H4DOTA). It Is hypothesized that a close matching between the size of the macrocyclic cavity and that of the metallic ion is a key parameter to ensure the high-yield formation of stable coordination metal-DOTA complex. This approach has become popular in the design of radiopharmaceuticals containing radiometals and H4DOTA as chelating group. Results Based on X-ray structural data of metallic complexes formed by the ligand H4DOTA upon coordination with a variety of metals, an elementary argument based on Euclidean geometry is presented here that questions the existence of the hypothetical ‘macrocyclic cavity’ within the chelator macrocycle. The geometrical analysis was applied to the complex formed by a Ga3+ ion coordinated to H4DOTA ...

The hypothetical concept of 'macrocyclic cavity' is largely employed as useful model to interpret the affinity of metal ions for the macrocyclic chelating ligand 2,2′,2′′,2′′′- (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetraacetic acid (H 4 DOTA). It Is hypothesized that a close matching between the size of the macrocyclic cavity and that of the metallic ion is a key parameter to ensure the high-yield formation of stable coordination metal-DOTA complex. This approach has become popular in the design of radiopharmaceuticals containing radiometals and H 4 DOTA as chelating group. Results: Based on X-ray structural data of metallic complexes formed by the ligand H 4 DOTA upon coordination with a variety of metals, an elementary argument based on Euclidean geometry is presented here that questions the existence of the hypothetical 'macrocyclic cavity' within the chelator macrocycle. The geometrical analysis was applied to the complex formed by a Ga 3+ ion coordinated to H 4 DOTA as model compound. Conclusions: Application of Euclidean geometry to calculate bond angles in the coordination complex of the ligand H 4 DOTA with the Ga +3 ion, supposed to incorporate a hypothetical 'macrocyclic cavity' , revealed that this conceptual entity has no physical reality and, therefore, cannot be considered a meaningful description of a stable structural arrangement for metallic radiopharmaceuticals.

A hybrid, macrocyclic structure based on o-phenylenediamine and a crown ether promotes an intimate mutual interaction with a bound potassium ion in the form of chelation by the redox-active moiety. A general synthetic method and properties are described for the first member of a new class of redox-active, lariat-type macrocycles called the "o-Wurster's crowns".

The reaction between K 3 [Fe(CN) 6 ] and [Mn(MAC)(H 2 O) 2 ]Cl 2 ×/4H 2 O (MAC0/2, 13-dimethyl-3,6,9,12,18-pentaazabicyclo-[12.3.1]octadeca-1(18),2,12,14,16-pentaene) in a water/methanol mixture affords a pentanuclear complex with the formula [{Mn 3 (MAC) 3 (H 2 O) 2 }{Fe(CN) 6 } 2 ] ×/6H 2 O ×/2CH 3 OH (1), whose crystal structure has been solved. It consists of discrete [Mn II Fe III Mn II Fe III Mn II ] entities. The three {Mn(MAC} 2' moieties are connected by two [Fe(CN) 6 ] 3( anions, each one involving two cis cyano bridging groups. The manganese ions display a distorted pentagonal Á/bipyramidal geometry, with the macrocyclic ligand forming the equatorial plane. The axial positions are occupied by two nitrogen atoms arising from the cyano bridges, for the central manganese atom, and by one aqua ligand and one nitrogen atom from the cyano bridge, for the terminal manganese atoms. The cryomagnetic properties of 1 have been investigated and reveal a new case of irregular spin-state structure.

Large uniaxial magnetic anisotropy, expressed by a negative value of the axial zero-field splitting parameter D, has been achieved in a series of trigonal prismatic Co(II) complexes with the general formula [Co (L)X]Y, where L = 1,5,13,17,22-pentaazatricyclo[15.2.2.17,11]docosa-7,9,11(22)-triene, X = Cl − (1a,b), Br − (2), N 3 − (3), NCO − (4), NCS − (5), NCSe − (6), and Y = Cl − (1), Br − (2), NCS − (4), NCSe − (5), ClO 4 − (3,6). Complexes 1-6 are six-coordinate with the distorted trigonal prismatic geometry imparted by the pentadentate pyridine-/piperazine-based macrocyclic ligand L and by one monovalent coligand X −. Based on magnetic studies, all complexes 1-6 exhibit strong magnetic anisotropy with negative D-values ranging from about −20 to −41 cm −1. This variation in D (i.e. the increase of magnetic anisotropy) parallels the trend obtained by theoretical calculations and the lesser distortion of the coordination sphere with respect to the trigonal prismatic reference geometry. AC magnetic susceptibility investigations revealed field-induced singlemolecule magnet behaviour for all complexes except Cl − derivative 1. The series investigated represents a rare example of Co(II) complexes with a robust trigonal prismatic geometry.

Using as precursor the mononuclear lanthanide (Ln) macrocyclic complex, based on the 15-crown-5 ether (C) ligand and coordinated water (W) molecules, [LnCW 4 ] 3 þ , four novel analogous complexes for each of the three Ln(III) ions (Ln¼Eu, Tb and Gd) were synthesized through systematic substitution of water molecules by the antenna-type ligands: 2,2′-dipyridyl (D), 1,10-phenanthroline (P) and 2,2′;6',2′′-terpyridine (T). The corresponding formulae of the complexes, obtained in a trichloride salt form, were the following: [LnCW 4 ] 3 þ , [LnCP 2 ] 3 þ , [LnCDW] 3 þ , [LnCDP] 3 þ , and [LnCT] 3 þ. The compounds were characterized by elemental analysis, UV and infrared spectroscopy and investigated through luminescence spectroscopy. For the Eu(III) and Tb(III) complex series, the most luminescent ones were [EuCDP] 3 þ and [TbCT] 3 þ , respectively. Motivated by this fact, two dinuclear analogous Eu(III) and Tb(III) complexes, based on the two-site coordinating macrocyclic ligand lariat-silacrown ether (S), as well as analogous Gd(III) complexes, were obtained as hexachloride salts with the following formulae: [Eu 2 SD 2 P 2 ] 6 þ , [Gd 2 SD 2 P 2 ] 6 þ , [Tb 2 ST 2 ] 6 þ and [Gd 2 ST 2 ] 6 þ. Also, [Eu 2 SW 8 ] 6 þ , [Tb 2 SW 8 ] 6 þ and [Gd 2 SW 8 ] 6 þ complexes were prepared and used as reference non-antenna type dinuclear compounds. Comparing the luminescence between the antenna mononuclear complexes with the analogous dinuclear ones, for Eu(III) and Tb(III) ions, almost no change was observed. On the other hand, in the particular case of Eu (III), comparing the mono-and dinuclear non-antenna reference complexes [EuCW 4 ] 3 þ and [Eu 2 SW 8 ] 6 þ , a surprisingly much higher luminescence intensity was observed for the dinuclear complex ($ one order of magnitude). The proposed cause for this behavior is the peculiar electronic properties of the siloxane group, which has a partial character of (p-d)π hyperconjugation. Results of quantum chemical theoretical calculations of molecular and electronic structures, using DFT methods, reinforce such special properties of the siloxane and also show that its presence is responsible for considerable differences in the coordination sphere between the mono-and dinuclear species, such as in the coordination number, which decreases from nine to seven. Furthermore, particularly in the dinuclear [Eu 2 SW 8 ] 6 þ complex, one water molecule per coordination center suffers a hydrolysis, donating a proton to the near NH 2 of an amino-propyl function, present in the siloxane group bridging the two mononuclear moieties, and this event could also be related with the observed enhanced luminescence.

The preparation of complexes M2L(NO3)4-2CH3OH-nH20 (4a-d) (M=Mn, Co, Ni, Cu; L=C18H22N604 (3); n =0.5 or 1) from pyridine-l-oxide-2,6-dialdehyde, 1,2-diaminoethane and the metal(II) nitrate is reported. The complex [Ni2L(H20)4](NO3) 4. 2H20 (5) was also prepared and its crystal structure determined. 5 is monoclinic, space group P21/n, a = 11.831(8), b = 12.168(8), c = 12.329(7)/~,/3= 114.26(5) °, Z =2. In the cyclic ligand 3, the pyridine-l-oxide rings are linked by CH(OH).NH.(CH2)2.N:CH groups, showing that partial hydrolysis of the expected Schiff-base ligand has occurred during synthesis of the complex. In the centrosymmetric complex 5, the Ni 2÷ ions are bridged in a planar Ni202 unit by the N-oxide oxygen atoms, the iigand adopting a non-planar 'stepped' conformation with pyramidal stereochemistry at the bridging O atoms. Six-fold coordination of each Ni 2÷ ion is completed by two N atoms and two c/s water molecules. The magnetic susceptibilities of 4a-d were measured between 5 and 300 K and analysed to obtain values of the parameter J in the exchange Hamiltonian-2JS~.$2: J=-1.15,-5.0,-15.5 and + 3.3 cm-~, respectively. These values are discussed in terms of the contributing orbital pathways.

The synthesis and characterization of an imino-pyridyl ligand N,N'-(butane-1,4-diyl)bis(1-(pyridin-2-yl)methanimine) (L) and its Ag(I)ClO4 complex (I) by various spectroscopic techniques and elemental analyses is presented in this study. X-ray single crystal structure of complex I revealed that in complex I, each Ag(I) ion is tetra coordinated with two pyridine N-atoms and two imine N-atoms of the ligand L, forming a macrocyclic dimeric Ag(I) grid. In the macrocyclic dimer complex I, Ag-Ag separation along the chain is 5.318 Å. The Ag-Npy average distance is 2.396 Å and that of the Ag-Nim is 2.257 Å. The macrocyclic dimer complex I is supramolecularly arranged by π-stacking interactions. Computational, Hirshfeld surface analysis and photophysical studies on ligand L and complex I have also been performed. Crystal data for C32H36Ag2Cl2N8O8 (M =947.33 g/mol): Triclinic, space group P-1 (no. 2), a = 9.1714(12) Å, b = 10.4373(14) Å, c = 10.8297(14) Å, α = 112.317(3)°, β = 91.391(3)°, γ = 92.353(3)°, V = 957.3(2) Å 3 , Z = 1, T = 293.15 K, μ(MoKα) = 1.220 mm-1 , Dcalc = 1.643 g/cm 3 , 10248 reflections measured (4.07° ≤ 2Θ ≤ 53.098°), 3966 unique (Rint = 0.0280, Rsigma = 0.0331) which were used in all calculations. The final R1 was 0.0722 (I > 2σ(I)) and wR2 was 0.2229 (all data). DFT Ag(I) dimer Photophysics Imino-pyridyl ligand X-ray crystal structure Hirshfeld surface studies

В ходе выполнения данной работы были рассмотрены виды конструкций шагающих роботов, формы корпусов и типы движителей. После обзора, в данной работе, было решено использовать гексапедальную конструкцию с продолговатой формой корпуса и дуговыми движителями. Спроектированы структурная и функциональная схемы, дерево вызова процедур мобильного робота повышенной проходимости, помимо этого, был разработан алгоритм движения робота. Произведён расчёт и выбор элементов системы. В месте с этим, был разработан и изготовлен физический макет проектируемого робота. Проведены испытания макета и сделаны заключения, о том, что при использовании шаговых приводов, необходимо применение датчика положения, в связи с пропуском шагов привода, либо применение редуктора, который бы предотвратил пропуск шагов.In the course of this work, the types of walking robot structures, the shapes of the body, and the types of propulsors were considered. After the literature review, it was decided to use a hexapedal cons...

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Объектом исследования являются алгоритмы распознавания рукописных символов на изображении. Цель работы – разработка алгоритмов и библиотеки распознавания машиночитаемых бланков на основе сверточных нейронных сетей. Реализованная библиотека используется в модуле верификации системы для проведения диагностических работ ЕГЭ в РЦОИ Томской области.The object of research is handwriting recognition algorithms in the image. The purpose of the work is to develop algorithms and a library for recognizing machine-readable forms based on a convolutional neural networks. The implemented library is used in the verification module of system for conducting diagnostic works of the Unified State Examination in in DPC of the Tomsk region

View related articles Citing articles: 3 View citing articles Experimental Chemistry All the reported macrocyclic complexes were prepared by both template and microwave methods. Conventional method To a hot, well stirred MeOH solution (∼50 cm 3) of ethylenediamine (10 mmol) was added trivalent chromium or iron salt (5 mmol) dissolved in a minimum quantity of MeOH (20 cm 3). The resulting solution was refluxed for 0.5 h. After

Preliminary kinetic studies on the binding of CO 2 A series of preliminary studies were performed in order to follow the binding of CO 2 to the Cu(II) complexes by UV-vis spectrophotometry. The experiments were performed under the conditions employed for the synthesis of the isolated complexes. Solutions consisting of ACN and between 5 and 20 % water were saturated with CO 2 (g) prior to the reactions with the complexes 1(CF 3 SO 3) 2 and 2(CF 3 SO 3) 2. In general the observed reactions were kinetically not clean reactions and depended strongly on the composition of the solvent. The interpretation of the observed kinetic trends was not fully done because it turned out that dissolved CO 2 is not the actual reactive species, but rather HCO 3 formed through the hydration of CO 2. A few examples are given in support of this statement. The reaction of 1(CF 3 SO 3) 2 with a CO 2 saturated ACN solution containing 5 % water clearly exhibits two reaction steps and the kinetic traces shown in Figure S7 were fitted with a twoexponential function. The faster reaction step shows an almost linear dependence on the CO 2 concentration, whereas the slower step shows almost no concentration dependence. The latter

The synthesis and characterization of an imino-pyridyl ligand N,N'-(butane-1,4-diyl)bis(1-(pyridin-2-yl)methanimine) (L) and its Ag(I)ClO4 complex (I) by various spectroscopic techniques and elemental analyses is presented in this study. X-ray single crystal structure of complex I revealed that in complex I, each Ag(I) ion is tetra coordinated with two pyridine N-atoms and two imine N-atoms of the ligand L, forming a macrocyclic dimeric Ag(I) grid. In the macrocyclic dimer complex I, Ag-Ag separation along the chain is 5.318 Å. The Ag-Npy average distance is 2.396 Å and that of the Ag-Nim is 2.257 Å. The macrocyclic dimer complex I is supramolecularly arranged by π-stacking interactions. Computational, Hirshfeld surface analysis and photophysical studies on ligand L and complex I have also been performed. Crystal data for C32H36Ag2Cl2N8O8 (M =947.33 g/mol): Triclinic, space group P-1 (no. 2), a = 9.1714(12) Å, b = 10.4373(14) Å, c = 10.8297(14) Å, α = 112.317(3)°, β = 91.391(3)°, γ = 92.353(3)°, V = 957.3(2) Å 3 , Z = 1, T = 293.15 K, μ(MoKα) = 1.220 mm-1 , Dcalc = 1.643 g/cm 3 , 10248 reflections measured (4.07° ≤ 2Θ ≤ 53.098°), 3966 unique (Rint = 0.0280, Rsigma = 0.0331) which were used in all calculations. The final R1 was 0.0722 (I > 2σ(I)) and wR2 was 0.2229 (all data). DFT Ag(I) dimer Photophysics Imino-pyridyl ligand X-ray crystal structure Hirshfeld surface studies

The conductometric study of ligand structure influence on the Pb(II) complexation with crown ethers in different solvents has been investigated. In this paper, the complexation reaction of macrocyclic ligand, 18-crown-6 (18C6), dibenzo-18-crown-6 (DB18C6), and Pb(II) cation was studied in different solvents: dichloromethane (DCM) and 1,2dichloroethane (1,2-DCE). The effects of surfactant structure (Triton X-100 and Triton X-45) on the conductivity of the Pb(II) complex with 18-crown-6 and dibenzo-18-crown-6 ether have been investigated. The conductance data showed that the stoichiometry of the complexes in most cases is 1:1(ML). It is also demonstrated that the influence of crown ethers is deeply affected by the organic solvent used. In the solvents studied, the stability of the resulting complexes showed higher stability in dichloromethane comparing with 1,2-dichloroethane. Macrocyclic ligand 18-crown-6 showed more suitable for complexation of Pb(II) ions compared to dibenzo-18-crown-6. Adding a surfactant affected the higher absolute values of the conductivity of systems, but not the change in the stoichiometric ratio between a metal ion and macrocyclic ligand.

The reaction of acetone-2-thenoylhydrazone (ath) with LnCl 3 .nH 2 0 yields compounds of the composition [Ln(athhCI 2 ]Cl while complexes of the type lLn(thdth)2CI2]Cl [where thdth = 2,2,6,6-tetramethyl-3,5-heptanedione-2-thenoylhydrazone; Ln = La(III), Pr(lII), Nd(III), Sm(III), EU(lII), Gd(III), Tb(lII) and Dy(UI)] have been synthesized through the metal template effect. The complexes have been characterized by elemental analysis, magnetic, IR, electronic and emission spectral studies. The unit lattice of l fb(thdthhCI2]CI belongs to tetragonal crystal lattice having one molecule per unit lattice.

Supporting information: this article has supporting information at journals.iucr.org/c Synthesis, structural characterization, EPR spectroscopy and Hirshfeld surface analysis of a novel Cu 2+doped 3,14-diethyl-2,13-diaza-6,17-diazoniatricyclo[16.4.0.0 7,12 ]docosane bis(perchlorate)

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The title ferrocene derivative, [Fe(C5H5)2(C8NO2)], including an alkyne bonded to a para-nitrophenyl substituent, which was synthesized from a copper-free Sonogashira cross-coupling reaction between ethynylferrocene and 4-bromo-1-nitrobenzene, crystallizes in the P21/n space group. In the ferrocene unit, the pentadienyl (Cps) rings are in an eclipsed conformation. The angle of rotation between the substituted cyclopentadienyl ring and the p-nitrophenyl group is 6.19 (10)°, yielding a quasi-linear extension of the ferrocenyl substitution. Important intermolecular interactions arise from π–π stacking between the Cp rings and the p-nitrophenyl, from corners of the Cp rings that are perpendicularly aligned, and between the O atoms from the nitro substituent and carbons at the corners of the Cp rings, propagating along all three crystallographic axes.

The structure of the title compound (systematic name: N-{[(2-hydroxyphenyl)methylidene]amino}morpholine-4-carbothioamide), C12H15N3O2S, was previously determined (Koo et al., 1977) using multiple-film equi-inclination Weissenberg data, but has been redetermined with higher precision to explore its conformation and the hydrogen-bonding patterns and supramolecular interactions. The molecular structure shows intramolecular O—H...N and C—H...S interactions. The configuration of the C=N bond is E. The molecule is slightly twisted about the central N—N bond. The best planes through the phenyl ring and the morpholino ring make an angle of 43.44 (17)°. In the crystal, the molecules are connected into chains by N—H...O and C—H...O hydrogen bonds, which combine to generate sheets lying parallel to (002). The most prominent contribution to the surface contacts are H...H contacts (51.6%), as concluded from a Hirshfeld surface analysis.

Density functional theory calculations at M052X/6-311??G** level were performed to understand the structure and stability of Ni(II) tetraaza macrocyclic dicarbinolamine complex 1. The preferential stability of 1 over the hitherto unknown Ni(II) complex having fully conjugated macrocyclic ligand 2, is examined by analyzing geometric and electronic structures and energy considerations. The present calculations predict that in the trans (C 2) structure, 1 is 102 kcal/mol more stable than its components 2 and 2(OH) at M062X-D3/def2-QZVP//M052X/6-311??G** level. This significant stabilization explains the formation of 1 as experimentally observed. The calculations support a distorted square planar environment for Ni in 1, in agreement with the observed spectral and magnetic properties. In order to understand the stability of 1, we examined the second-order stabilizing interactions in natural bond orbital (NBO) basis, the role of the noncovalent dispersion energy, macrocyclic cavity size, Ni-ligand covalent bond strength, natural electronic population on the atomic centers and the nature of the frontier molecular orbitals in the complexes. The present study reveals that the higher stability of 1 over 2 is primarily due to the stronger covalent bonds between the Ni(II) centre, and two of the coordinating nitrogen atoms in 1 than in 2 and significant secondorder stabilizing interactions originating from the NBOs involving the oxygen atoms.

The effects of N-alkylation on the redox potential of the couples NiU 2 +/NiL i 4, L = tetraaza-14-membered-macrocyclic ligands, and on the properties of the monovalent nickel complexes in aqueous solutions are reported for 14 complexes. The spectra and lifetimes of the NiU + complexes are reported. The self-exchange rates for the couples NiU 24/NiL i + were determined. Two of the ligands were synthesized for the first time for this study. Cyclic voltammetry and pulse radiolysis were used. The results point out that: (i) N-alkylation always shifts the redox potential to a less cathodic one; this effect stems to a large degree from the decrease in the solvation energy of the complex caused by the N-alkylation of the ligand. (ii) The lifetime of the monovalent complexes is not linearly related to the redox potential of the NiU 24 / NiU 4 couples. (iii) The NiU 4 complexes exist in several isomeric forms; the rate of the isomerization depends on the structure of the ligand. (iv) Different isomers of NiU + may be formed when the complex NiU 24 is reduced by different reagents; therefore, the pulseradiolytically formed NiU ÷ complexes might have different properties than those formed electrochemically.

The non-H atoms of the title compound, C 10 H 12 N 2 O 2 , are approximately coplanar with the exception of those at the ends: the terminal allyl carbon atom and terminal hydrazide nitrogen atom are displaced from the mean plane by 0.67 (2) and 0.20 (2) Å , respectively. In the crystal, the molecules are linked by N-HÁ Á ÁO and N-HÁ Á ÁN hydrogen bonds, which give rise a two-dimensional network propagating in the (001) plane. Structure description Hydrazides containing an R-C(O)-NH-NH 2 functional group may act as a pharmacophore and present biological activity (see, for example, Joshi et al. 2008). Hydrazidecontaining molecules are effective ligands in coordination chemistry (see, for example, Saygıdeg er Demir et al., 2021). As part of our studies in this area, we now describe the synthesis and structure of the title compound (Fig. 1). The X-ray diffraction analysis revealed that the non-hydrogen atoms are approximately coplanar with the exception of the terminal atoms, which deviate by 0.67 (2) Å for C10 and 0.20 (2) Å for N2. In the crystal, the molecules are connected by N-HÁ Á ÁO and N-HÁ Á ÁN hydrogen bonds involving the carbohydrazide moieties of symmetry-related molecules (Fig. 2 and Table 1) that form a two-dimensional network propagating in the ab plane. This arrangement favours weak aromatic-stacking interactions of the phenyl rings [centroid-to-centroid distance of 4.092 (3) Å , see Fig. 2].

Co(II), Ni(II), and Cu(II) complexes with a tetradentate nitrogen donor [N4] macrocyclic ligand, viz 1,5,8,13-tetraaza-2,9-dimethyl-4,11- diphenylcyclotetradeca-2,4,4,11-tetraene were synthesized. Their structures were determined based on elemental analyses; molar conductance and magnetic susceptibility measurements; and IR, 1H-NMR (ligand), and electronic spectral studies. Based on analytical and molar conductance data, the complexes may be formulated as [M(L)Cl2] and [M?(L)]Cl2 [where M = Co(II) and Cu(II), and M? = Ni(II)] due to their non-electrolytic and 1:2 electrolytic nature. Based on spectral studies, an octahedral geometry was assigned for the Co(II) complex, whereas square-planar and tetragonal geometry were proposed for the Ni(II) and Cu(II) complexes, respectively. The synthesized ligand and its complexes were screened for fungicidal activity against two pathogenic fungi (i.e., Fusarium. moniliformae and Rhizoctonia solani) to assess their growth inhibiting potential.

Acta Cryst. (2008). E64, m912-m913 Eltayeb et al. [Zn 8 (C 20 H 12 N 2 O 4) 4 (H 2 O) 4 ]Á4C 2 H 6 OSÁ2H 2 O m913 supporting information sup-11 Acta Cryst. (2008). E64, m912-m913 C3-H3A•••O3 iii 0.93 2.57 3.271 (5) 132 C21-H21C•••O4 iv 0.96 2.52 3.454 (7) 165 C21-H21B•••Cg1 v 0.96 2.81 3.475 (6) 127 Symmetry codes: (i) y, −x+1/2, −z+1/2; (iii) −x+1/2, −y+1/2, z; (iv) −y+1, x+1/2, z−1/2; (v) −x+1, −y+1, −z.