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The one-pot self-assembly of Mn

Herein we report a series of CuI complexes supported by tetradentate RN4 pyridinophane ligands that coordinate to ethylene forming either mononuclear complexes with ethylene coordinated in an η2-mode or a binuclear complex where ethylene binds to two Cu atoms in a μ-η2-η2-mode, depending on the steric effects of the RN4 ligand and the reaction conditions. In the binuclear complex with bridging ethylene, the C[double bond, length as m-dash]C bond is significantly elongated, with a bond length of 1.444(8) Å according to X-ray diffraction analysis. This complex represents the only examination a μ-η2-η2-coordinated Cu–olefin complex reported to date, featuring one of the longest reported C[double bond, length as m-dash]C bonds. The spectroscopic characterization, structure, electrochemical properties and solution behavior are analyzed in this study. Coordination of ethylene was found to be reversible in these complexes and more favored in less sterically hindered RN4 ligands, so that ethylene binding is observed in a coordinating solvent (MeCN) environment. In the case of the MeN4 ligand, the ethylene complex is photoluminescent in the solid state. The ethylene binding modes in mono- and binuclear complexes are elucidated through Natural Bond Orbital and QTAIM analyses.

Single and double deprotonation of the N,S-donor macrocyclic pyridinophane ligand in structurally characterized Ru complexes results in the dearomatization of one or two pyridine rings.

The coordination diversity of a novel N4-ligand and its sodium complex toward cobalt(ii) ions was studied.

The crystal and electronic structure of an isocyanuric acid derivative was studied by high-resolution single-crystal X-ray diffraction within the Hansen–Coppens multipole formalism. The observed deformation electron density shows signs of thermal smearing. The experimental picture meaningfully assigned to the consequences of unmodelled anharmonic atomic motion. Straightforward simultaneous refinement of all parameters, including Gram–Charlier coefficients, resulted in more significant distortion of apparent static electron density, even though the residual density became significantly flatter and more featureless. Further, the method of transferring multipole parameters from the model refined against theoretical structure factors as an initial guess was employed, followed by the subsequent block refinement of Gram–Charlier coefficients and the other parameters. This procedure allowed us to appropriately distinguish static electron density from the contaminant smearing effects of insufficiently accounted atomic motion. In particular, some covalent bonds and the weak π...π interaction between isocyanurate moieties were studied via the mutual penetration of atomic-like kinetic and electrostatic potential φ-basins with complementary atomic ρ-basins. Further, local electronic temperature was applied as an advanced descriptor for both covalent bonds and noncovalent interactions. Total probability density function (PDF) of nuclear displacement showed virtually no negative regions close to and around the atomic nuclei. The distribution of anharmonic PDF to a certain extent matched the residual electron density from the multipole model before anharmonic refinement. No signs of disordering of the sulfonyl group hidden in the modelled anharmonic motion were found in the PDF.

The present work demonstrates the optimization of the ligand structure in the series of bis(phosphine oxide) and β-ketophosphine oxide representatives for efficient coordination of Tb3+ and Eu3+ ions with the formation of the complexes exhibiting high Tb3+- and Eu3+-centered luminescence. The analysis of the stoichiometry and structure of the lanthanide complexes obtained using the XRD method reveals the great impact of the bridging group nature between two phosphine oxide moieties on the coordination mode of the ligands with Tb3+ and Eu3+ ions. The bridging imido-group facilitates the deprotonation of the imido- bis(phosphine oxide) ligand followed by the formation of tris-complexes. The spectral and PXRD analysis of the separated colloids indicates that the high stability of the tris-complexes provides their safe conversion into polystyrenesulfonate-stabilized colloids using the solvent exchange method. The red Eu3+-centered luminescence of the tris-complex exhibits the same specificity in the solutions and the colloids. The pronounced luminescent response on the antibiotic ceftriaxone allows for sensing the latter in aqueous solutions with an LOD value equal to 0.974 μM.

Two crystalline diastereomorphs of rac-1-benzyl-3-bromo-5-hydroxy-4-[(4-methylphenyl)sulfanyl]-1,5-dihydro-2Н-pyrrole-2-one are obtained and characterized: the racemic compound (P21/c) and the normal conglomerate (P65, P61). The conglomerate is shown to be more thermodynamically preferred while the racemic compound is a metastable form in the entire temperature range studied. These two modifications are formed as a mixture during routine crystallization from a solution and characterized by a similar density, however, their structures significantly differ in the parameters of hydrogen bonds. A small difference in the free energies of two phases at room temperature, which is found by differential scanning calorimetry, explains the experimental availability of both forms during crystallization from the solution. The formation of a stronger hydrogen bond in the conglomerate crystals, which is detected by X-ray diffraction and solid-state vibrational spectroscopy, may be explained by a more favorable arrangement of donor and acceptor groups of the neighboring molecules in a homochiral helix of the conglomerate as compared with a heterochiral dimer, which is the main motif in crystals of the racemic compound.

A detailed analysis of a complete set of the local potentials that appear in the Euler equation for electron density is carried out for noncovalent interactions in the crystal of a uracil derivative using experimental X-ray charge density. The interplay between the quantum theory of atoms in molecules and crystals and the local potentials and corresponding inner-crystal electronic forces of electrostatic and kinetic origin is explored. Partitioning of crystal space into atomic basins and atomic-like potential basins led us to the definite description of interatomic interaction and charge transfer. Novel physically grounded bonding descriptors derived within the orbital-free quantum crystallography provided the detailed examination of π-stacking and intricate C=O⋅⋅⋅π interactions and nonclassical hydrogen bonds present in the crystal. The donor-acceptor character of these interactions is revealed by analysis of Pauli and von Weizsäcker potentials together with well-known functions, e. g., deformation electron density and electron localization function. In this way, our analysis throws light on aspects of these closed-shell interactions hitherto hidden from the description.

Manganese complexes have been considered as a cheap and readily available alternative to commonly used precious metal catalysts in C–C bond coupling reactions. Although high-valent Mn aryl intermediates have been proposed in such reactions, a mechanistic understanding of possible organometallic intermediates in Mn-mediated C–C coupling is still lacking due to their high reactivity. We report the synthesis of stable, isolable Mn(III) aryl complexes obtained by oxidative addition of aryl bromide or aryl chloride. These complexes react with a range of organometallic alkylating or arylating reagents (alkyl and aryl Grignard reagents, MeLi, ZnMe2) to undergo C(sp2)–C(sp3) or C(sp2)–C(sp2) bond coupling, and a preliminary catalytic system could be demonstrated. The reagent scope and yield of the C(sp2)–C(sp3) coupled product can further be increased by addition of TEMPO as an oxidant, generating alkyl radicals.

Redox properties of monoiminoacenaphthenes (MIANs) were studied using various electrochemical techniques. The potential values obtained were used for calculating the electrochemical gap value and corresponding frontier orbital difference energy. The first-peak-potential reduction of the MIANs was performed. As a result of controlled potential electrolysis, two-electron one-proton addition products were obtained. Additionally, the MIANs were exposed to one-electron chemical reduction by sodium and NaBH4. Structures of three new sodium complexes, three products of electrochemical reduction, and one product of the reduction by NaBH4 were studied using single-crystal X-ray diffraction. The MIANs reduced electrochemically by NaBH4 represent salts, in which the protonated MIAN skeleton acts as an anion and Bu4N+ or Na+ as a cation. In the case of sodium complexes, the anion radicals of MIANs are coordinated with sodium cations into tetranuclear complexes. The photophysical and electrochemical properties of all reduced MIAN products, as well as neutral forms, were studied both experimentally and quantum-chemically.

The row of metallocyclic dinuclear gold(I) complexes with cyclic diphosphines, namely, P-pyridylethyl-substituted 1,5-diaza-3,7-diphosphacyclooctanes, has been obtained. Further interaction of the dinuclear gold(I) complexes with copper(I) iodide gave the first examples of hexanuclear AuI/CuI complexes containing two unusual trinuclear AuICu2I2 fragments. The structures of di- and hexanuclear complexes were confirmed by NMR spectroscopy, ESI mass spectrometry, elemental analysis, and single-crystal X-ray diffraction. All of the obtained complexes are moderate emitters in the solid state. Dinuclear gold(I) complexes displayed a greenish emission with the maxima in the emission spectra at ca. 550 nm. The obtained hexanuclear heterobimetallic AuI/CuI complexes are triplet solid-state blue emitters with the maximum in the emission spectra at 463 and 484 nm. According to the TD-DFT calculations, the observed emission of all studied complexes had a triplet origin and was caused by the 3CC or 3(MLCT) T1 → S0 transitions for dinuclear and hexanuclear complexes, respectively.

The presence of Pd⋯Cu and Pd⋯Pd interactions as well as the order of metal atoms in a chain held by a modular polynucleating ligand is controlled by the coordinating ability of the anions, leading to selective formation of bi- and tetranuclear Pd/Cu and Pd4 chains. Metal–metal cooperative reactivity in these complexes was tested in Ar–O bond formation and alkyne activation.

Herein we have found a second example of doubly enantiophobic behavior during the crystallization of rac-1-benzyl-3-chloro-4-[(4-chlorophenyl)sulfanyl]-5-hydroxy-1,5-dihydro-2H-pyrrol-2-one, i.e., the formation of two conglomerates with different crystal structures in the absence of any racemic compounds. In both polymorphic modifications, the main supramolecular motif is appeared to be a hydrogen-bonded chain or helix of different symmetry, which is related to an α-hydroxyamide chain synthon. Additional crosslinking of the homochiral chains in the crystals of both crystalline forms, which is realized through weak, noncovalent interactions, can be a probable reason for the reproducibility and stability of the α-hydroxyamide chain synthon and polymorphic diversity registered. It was shown that each of the conglomerates is thermodynamically stable in certain temperature ranges. For the first time, a binary phase diagram for the chiral system complicated by an enantiotropic phase transition is reconstructed based on experimental data, which is characterized by the presence of a thermodynamic stability permutation line between the two racemic conglomerates.

We report a series of heterobimetallic Pt/Zn and Pt/Ca complexes to study the effect of proximity of a dicationic base metal on the organometallic Pt species. Varying degrees of Pt⋅⋅⋅Zn and Zn interaction with the bridging Me group are achieved, showcasing snapshots of a hypothetical process of retrotransmetalation from Pt to Zn. In contrast, only weak interactions were observed for Ca with a Pt-bound Me group. Activation of H2, B−H and Si−H bonds leads to the formation of hydride-bridged Pt−H−Zn complexes, which is not observed in the absence of Zn, pointing out the importance of metal-metal cooperation. Reactivity of PtMe2/M2+ with terminal acetylene, water and methanol is also studied, leading to facile protonation of one of the Me groups at the Pt center only when Zn is present. This study sheds light on various ways in which the presence of a 2+ metal cation significantly affects the reactivity of a common organoplatinum complex.

Bond homolysis is one of the most fundamental bond cleavage mechanisms. Thus, understanding of bond homolysis influences the development of a wide range of chemistry. Photolytic bond homolysis and its reverse process have been observed directly using time-resolved spectroscopy. However, direct observation of reversible bond homolysis remains elusive. Here, we report the direct observation of reversible Co–Co bond homolysis using two-dimensional nuclear magnetic resonance exchange spectroscopy (2D EXSY NMR). The characterization of species involved in this homolysis is firmly supported by diffusion ordered NMR spectroscopy (DOSY NMR). The unambiguous characterization of the Co–Co bond homolysis process enabled us to study ligand steric and electronic factors that influence the strength of the Co–Co bond. Understanding of these factors will contribute to rational design of multimetallic complexes with desired physical properties or catalytic activity.

We report a series of heterobimetallic Pt/Zn and Pt/Ca complexes to study the effect of proximity of a dicationic base metal on the organometallic Pt species. Varying degrees of Pt⋅⋅⋅Zn and Zn interaction with the bridging Me group are achieved, showcasing snapshots of a hypothetical process of retrotransmetalation from Pt to Zn. In contrast, only weak interactions were observed for Ca with a Pt-bound Me group. Activation of H

Hydrogenation of substituted styrenes and unactivated aliphatic alkenes by molecular hydrogen has been achieved using a Mn catalyst with a non‐pincer, picolylphosphine ligand. This is the second reported example of alkene hydrogenation catalyzed by a Mn complex. Mechanistic studies showed that a Mn hydride formed by H2 activation in the presence of a base is the catalytically active species. Based on experimental and DFT studies, H2 splitting is proposed to occur via a metal‐ligand cooperative pathway involving deprotonation of the CH2 arm of the ligand, leading to pyridine dearomatization.

Cooperation between two different metals plays a crucial role in many synergistic catalytic reactions, such as the Sonogashira C-C cross-coupling reaction, where an interaction between the Pd and Cu centers is proposed in the transmetalation step. Although several heterobimetallic Pd/Cu complexes were proposed as structural models of the active species in Sonogashira coupling, the detailed understanding of the metal-metal cooperation in transmetalation is still lacking in current systems. In this work, we report a stepwise and systematic approach to building heteromultimetallic Pd/Cu assemblies as a tool to study metal-metal cooperativity. We obtained fully characterized Pd/Cu multimetallic assemblies that show reactivity in alkyne activation, formation of catalytically relevant aryl/acetylide species, and C-C elimination, serving as functional models for Sonogashira reaction intermediates. The combined experimental and DFT studies highlight the importance of ligand-controlled coordination geometry, metal-metal distances and dynamics of the multimetallic assembly for transmetalation step.

The crystal structures of new salt forms of the known nitrogen-containing pharmaceuticals (dacarbazine, metoclopramide, and acetylcholine) in which 1,1,2,3,3-pentacyanopropenide anion acts as a counterion are analyzed by X-ray diffraction. It is found that in the crystals of studied salts with dacarbazine (in the form of a monohydrate) and metoclopramide, the mentioned anion plays the role of a structure-forming spacer, linking with more than one cation by classical hydrogen bonds. The types of cation and anion localization in the studied salts are revealed. They are: layered in the crystals with dacarbazine, stacked with the cation and anion alternation in the crystals with metoclopramide, and anion columns surrounded by cations in the crystals with acetylcholine. The tendency of the pentacyanopropenide anion to disordering in the crystals of metoclopramide and acetylcholine salts is detected.

We report the selective formation of heterobimetallic PtII/CuI complexes that demonstrate how facile bond activation processes can be achieved by altering the reactivity of common organoplatinum compounds through their interaction with another metal center. The interaction of the Cu center with the Pt center and with a Pt-bound alkyl group increases the stability of PtMe2 towards undesired rollover cyclometalation. The presence of the CuI center also enables facile transmetalation from an electron-deficient tetraarylborate [B(ArF)4]− anion and mild C–H bond cleavage of a terminal alkyne, which was not observed in the absence of an electrophilic Cu center. The DFT study indicates that the Cu center acts as a binding site for the alkyne substrate, while activating its terminal C–H bond., The selective formation of heterobimetallic PtII/CuI complexes demonstrates how facile bond activation processes can be achieved by altering the reactivity of common organoplatinum compounds through their interaction with another metal center.

Two packing polymorphs of 5-hydroxy-1-(4-methylbenzyl)-3-chloro-4-[(4-chlorophenyl)sulfanyl]-1,5-dihydro-2H-pyrrol-2-one are studied by single-crystal and powder X-ray diffraction, IR spectroscopy, and differential scanning calorimetry. Classical hydrogen bonds and CL…O interactions have the fundamental importance for the formation of the supramolecular motif that is identical in both modifications. The difference relates to the packing of 2D layers which is “parallel” in the triclinic modification and of the “herringbone” type in the monoclinic modification. It is shown that close similarity between structural organizations of crystal lattices, which is typical of packing polymorphs, can be accompanied by significant differences between their energies as well as by a high potential barrier upon the transition from the metastable polymorph to its stable form.

Herein we present a detailed experimental charge-density study for the low-temperature polymorph of antithyroid drug methimazole crystallized with two crystallographically independent molecules lacking conformational freedom. Quantum-topological analysis of experimental electron density allowed us to detect the distinctive differences in the electron distribution within their thiourea groups, arising primarily from crystal packing effects. Sulfur atom S(1a) features two separate regions of positive deformation density, whilst the other atom S(1b) is found to be more diffuse with positive density taking a toroidal form. In contrast to S(1a), the couple of the lone pairs of S(1b) derived by non-bonding charge concentrations takes a more significant turn relative to the molecular plane and proves to be distorted. We also report an ambiguous electronic structure of the heteroatoms, i.e. appearance of “false” Laplacian CPs (3, +3) or splitting of true ones, which is caused by neglecting or excessive use of Gra...