Vanadium Complexes with Thioanilide Derivatives of Amino Acids: Inhibition of Human Phosphatases and Specificity in Various Cell Models of Metabolic Disturbances

In the text, the synthesis and characteristics of the novel ONS-type vanadium (V) complexes with thioanilide derivatives of amino acids are described. They showed the inhibition of human protein tyrosine phosphatases (PTP1B, LAR, SHP1, and SHP2) in the submicromolar range, as well as the inhibition of non-tyrosine phosphatases (CDC25A and PPA2) similar to bis(maltolato)oxidovanadium(IV) (BMOV). The ONS complexes increased [14C]-deoxy-D-glucose transport into C2C12 myocytes, and one of them, VC070, also enhanced this transport in 3T3-L1 adipocytes. These complexes inhibited gluconeogenesis in hepatocytes HepG2, but none of them decreased lipid accumulation in the non-alcoholic fatty liver disease model using the same cells. Compared to the tested ONO-type vanadium complexes with 5-bromosalicylaldehyde and substituted benzhydrazides as Schiff base ligand components, the ONS complexes revealed stronger inhibition of protein tyrosine phosphatases, but the ONO complexes showed greater activity in the cell models in general. Moreover, the majority of the active complexes from both groups showed better effects than VOSO4 and BMOV. Complexes from both groups activated AKT and ERK signaling pathways in hepatocytes to a comparable extent. One of the ONO complexes, VC068, showed activity in all of the above models, including also glucose utilizatiand ONO Complexes are Inhibitors ofon in the myocytes and glucose transport in insulin-resistant hepatocytes. The discussion section explicates the results within the wider scope of the knowledge about vanadium complexes.

Dimethyl Derivatives of 2,2'-Bipyridine as Ligands in [W(CN)6(bpy)]2--Type Complexes

The thermal decomposition of (XMebpyH)3(H3O)[W(CN)8]·3H2O (where XMebpy denotes 4Mebpy 4,4'-dimethyl-2,2'-bipyridine or 5Mebpy 5,5'-dimethyl-2,2'-bipyridine) in glycerol results in the coordination of XMebpy. Salts of the anion formula [W(CN)6(XMebpy)]2- were isolated for PPh4+ and/or AsPh4+ cations as well as for K+, Rb+, and Cs+ ones. X-ray single-crystal analyses for tetraphenyl-phosphonium and tetraphenyl-arsonium cations are described. IR, UV-Vis, and cyclic voltammetry data are presented. The results were compared with those for [W(CN)6(bpy)]2- (bpy = 2,2'-bipyridine) ion salts.

The High-Temperature Soft Ferromagnetic Molecular Materials Based on [W(CN)6(bpy)]2-/- System

The synthesis of molecular materials with magnetic properties, in particular ferromagnetic properties, has been the subject of interest in coordination chemistry for decades. In the last three decades, research has accelerated, as it has emerged that creating bridging systems based on cyanido ligands is a good and relatively simple way to create complex polymer structures exhibiting magnetic properties. Based on many years of personal experience in the field of the synthesis of polycyanido systems, supported by comprehensive structural analysis, a simple method of transforming cyanido complexes into soft ferromagnetic materials with a Curie temperature (T_C) higher than the thermal decomposition temperature, usually above 150 °C has been developed. Two soft ferromagnetic materials based on zinc and cadmium hexacyanido salts in the system with [W(CN)₆(bpy)]^2−/− anions are presented. The crystal structures (X-ray single crystal as well as XRD) of the precursors and the properties of the ferromagnetic materials are discussed. Most importantly, a patented method of synthesizing this type of material, based on which we obtain more than 80 soft, high-temperature ferromagnetic compounds, which proves the wide spectrum of this method, is also presented.

Anion-cation interactions in a series of salts with substituted Hphen, Hbpy and H2bpy cations and [W(CN)8]4- anion: polymer with "super-short" N-H⋯N hydrogen bridges containing exclusively anions and H. Dalton Trans 2021;50:17981-17987. [PMID: 34842868 DOI: 10.1039/d1dt03224k]

The 10 ion-pairs of [W(CN)₈]^4- with substituted Hphen and H_nbpyⁿ⁺ (where phen = 1,10-phenantroline, bpy = 2,2'-bipyridine, n = 1 or 2) were isolated and the spectroscopic properties of these salts are discussed. Three salts with dimethyl-substituted H_nbpyⁿ⁺ cation were structurally characterized. In the structure of the salt with H₂bpy, one of the cyanido ligands of the anion is in the CNH form. This situation is very unique, as well as the formation of two water double bridges by water molecules in [W(CN)₈]^4-. The formulas of other compounds were determined based on the IR spectra, thermogravimetry, and elemental analyses. The ion-pair formation was accompanied not only by anion-cation charge-transfer bands in the visible part of the electronic spectra, but also low-energy bands above 1000 nm were found and are related to the thermal electron transfer; the amount of the paramagnetic W^V was determined by EPR measurement. The thermal excitation of electrons may indicate the possibility of using these compounds as semiconductors. Finally, the improved method of K₄[W(CN)₈]·2H₂O synthesis is also described.

A Vanadium-Catalyzed Synthesis of Fully Substituted Pyrroles

We present a straightforward, fast, inexpensive, and environmentally friendly synthesis of 1,2,3,4,5-pentasubstituted derivatives of pyrrole, which were produced in one-pot reactions of 3-oxoanilides with hydrazides of carboxylic acids, catalyzed by 10 mol % VOSO₄·H₂O. The reactions were carried out in ethanol in contact with air as the oxidant. The 19 pyrroles obtained were usually crystalline and did not require purification. The reaction tolerates various substituents in both substrates. All products were characterized by infrared, nuclear magnetic resonance, and ultraviolet-visible spectroscopy and elemental analysis. The molecular structures of the products and the intermediates were unambiguously determined by X-ray single-crystal analysis.

Unusual structural changes going from Li+ to Cs+ in [W(CN)6(bpy)]2− ion salts: the Na+ case

Two sodium salts with the [W(CN)₆(bpy)]²⁻ ion were synthesized and compared to Li⁺, K⁺, Rb⁺ and Cs⁺ structures. The comparison of molecular packing, inter- and intra-molecular interactions and cation properties is discussed.

Spin-state energetics of metallocenes: How do best wave function and density functional theory results compare with the experimental data?

We benchmark the accuracy of quantum-chemical methods, including wave function theory methods [coupled cluster theory at the CCSD(T) level, multiconfigurational perturbation-theory (CASPT2, NEVPT2) and internally contracted multireference configuration interaction (MRCI)] and 30 density functional theory (DFT) approximations, in reproducing the spin-state splittings of metallocenes. The reference values of the electronic energy differences are derived from the experimental spin-crossover enthalpy for manganocene and the spectral data of singlet-triplet transitions for ruthenocene, ferrocene, and cobaltocenium. For ferrocene and cobaltocenium we revise the previous experimental interpretations regarding the lowest triplet energy; our argument is based on the comparison with the lowest singlet excitation energy and herein reported, carefully determined absorption spectrum of ferrocene. When deriving vertical energies from the experimental band maxima, we go beyond the routine vertical energy approximation by introducing vibronic corrections based on simulated vibrational envelopes. The benchmarking result confirms the high accuracy of the CCSD(T) method (in particular, for UCCSD(T) based on Hartree-Fock orbitals we find for our dataset: maximum error 0.12 eV, weighted mean absolute error 0.07 eV, weighted mean signed error 0.01 eV). The high accuracy of the single-reference method is corroborated by the analysis of a multiconfigurational character of the complete active space wave function for the triplet state of ferrocene. On the DFT side, our results confirm the non-universality problem with approximate functionals. The present study is an important step toward establishing an extensive and representative benchmark set of experiment-derived spin-state energetics for transition metal complexes.

X-ray crystal structures of K+ and Rb+ salts of [W(CN)6(bpy)]2− ion. The unusual cation–anion interactions and structure changes going from Li+ to Cs+ salts

The K⁺ and Rb⁺ salts of [W(CN)₆(bpy)]²⁻ ion were compared to the Li⁺ and Cs⁺ ones. The layered structure is independent on cation radii and decreasing strength of the cation–anion interactions on going from Li⁺ to Cs⁺.

The versatility of lithium cation coordination modes in salts with [W(CN)6(bpy)]2− anions

Effect of the cation size (compared to Cs⁺) in Li₂[W(CN)₆(bpy)] salts on the nature of the interaction with cyanide ligands and on the crystal structure is discussed, unusual decrease of the W–W distance and increase of cell volume are observed.

Templated metalophilicity: synthesis of halometallic double salts directed by a dicopper(i) hydrazinyl-tetraimine nanocation

The solvothermal synthesis and crystal structures of a new class of luminescent inclusion double salts, exhibiting d¹⁰–d¹⁰ and d¹⁰–d⁵ metallophilicity, of the formula [Cu₂(dih)₂]₂[Cu_(4−y)M^yCl₈], where M is either Cu⁺ or heterometal of valency y (in this paper Mn²⁺ or La³⁺), are reported.

5-(2-Pyridil)-1H-tetrazole complexes with Mo(iv) and W(iv) cyanides

The reactions of tetrazole ligand derived from 2-cyanopyridine with K₃Na[Mo(CN)₄O₂]·6H₂O and K₃Na[W(CN)₄O₂]·6H₂O in water–ethanol solution result in isolation of two new complexes with the following formulae: (PPh₄)₂[Mo(CN)₃O(pdt)]·2H₂O (1) (Hpdt = 5-(2-pyridil)-1H-tetrazole) and (PPh₄)₂[W(CN)₃O(pdt)]·3H₂O (2).

How can [Mo(IV)(CN)6](2-), an apparently octahedral (d)(2) complex, be diamagnetic? Insights from quantum chemical calculations and magnetic susceptibility measurements

Quantum chemical calculations are employed to elucidate the origin of a puzzling diamagnetism for a hexacyanomolybdate(IV) anion, [Mo(CN)6](2-), which was previously reported by Szklarzewicz et al. [Inorg. Chem., 2007, 46, 9531-9533]. The diamagnetism is surprising because for the octahedral (d)(2) complex one would rather expect a (paramagnetic) triplet ground state, clearly favored over a (diamagnetic) singlet state by an exchange interaction between two d electrons in the t2g orbitals. Nevertheless, the present calculations reveal that the minimum energy structure of isolated [Mo(CN)6](2-) is not an octahedron, but a trigonal prism; the latter geometry allows maximization of a σ-donation from the cyanides to the electron-deficient Mo(iv) center. Unlike for the octahedron, for the trigonal prism structure the singlet and triplet spin states are close in energy to within a few kcal mol(-1). Although the actual relative energy of the two spin states turns out to be method-dependent, the complete active space calculations (CASPT2; with the appropriate choice of the IPEA shift parameter) can reproduce the singlet ground state, in agreement with the experimentally observed diamagnetism. Moreover, magnetic measurements reveal a slight increase of the magnetic susceptibility with the increase of temperature from 100 to 300 K, suggesting an admixture of a thermally induced paramagnetism (possibly due to Boltzmann population of the low-energy triplet state) on top of the dominant diamagnetism. Our prediction that the geometry of [Mo(CN)6](2-) should significantly deviate from the ideal octahedron, not only in the gas phase, but also in a periodic DFT model of the crystalline phase, as well as the experimentally confirmed diamagnetic properties, does not agree with the previously reported ideal octahedral structure. We suggest that this crystal structure might have been determined incorrectly (e.g., due to overlooked merohedral twinning or superstructure properties) and it should be re-investigated.

Disentangling steric and electronic factors in monomeric bis(2-bromo-4-chloro-6-{[(2-hydroxyethyl)imino]methyl}phenolato-κ2N,O)copper(II)

The title compound, [Cu(C9H8BrClNO2)2], is a square-planar complex. The potentially tridentate dibasic 2-bromo-4-chloro-6-{[(2-hydroxyethyl)imino]methyl}phenolate ligand coordinates in atrans-bis fashion to the CuIIcentreviathe imine N and phenolate O atoms. The CuIIatom lies on the centre of inversion of the molecule. The potentially coordinating hydroxyethyl group remains protonated and uncoordinated, taking part in intermolecular hydrogen bonds with vicinal groups, leading to the formation of a two-dimensional hydrogen-bond network with sheets parallel to the (10\overline{1}) plane. Substituent effects on the crystal packing and coordination modes of the ligand are discussed.

Assemblies of salen-type oxidovanadium(iv) complexes: substituent effects and in vitro protein tyrosine phosphatase inhibition

A systematic study of 5,5′-disubstituted oxidovanadium(iv) complexes with a chiral salen type ligand showed variable assemblies of complex molecules dependent on steric and electronic factors of the substituents.

A simple and safe method for the preparation of bis[2-(2H-tetrazol-5-yl)pyridinium] tetrachloridozincate(II)

In the title complex salt, (C6H6N5)2[ZnCl4], the Zn(II) cation is coordinated by four chloride ligands in a distorted tetrahedral geometry. The organic cations and complex anions are connected by N-H···Cl hydrogen bonds, leading to the formation of a three-dimensional network. The title complex salt was synthesized by the reaction of sodium azide, pyridine-2-carbonitrile and ZnCl2 in aqueous solution. The salt was characterized by elemental analysis and IR and UV-Vis spectroscopy.

Iron(III) Complexes with a Biologically Relevant Aroylhydrazone: Crystallographic Evidence for Coordination Versatility

Complexation of iron(III) with the heterodonor chelating agent 3,5-di-tert-butylsalicylidene benzoylhydrazine, H2(3,5-tBu2)salbh, in the absence or presence of a base affords the complex cation [Fe{H(3,5-tBu2)salbh}2]+ or the neutral compound [Fe{H(3,5-tBu2)salbh}{(3,5-tBu2)salbh}], respectively, as revealed by single-crystal X-ray analyses. Such a synthetic and crystallographic demonstration of the coordination versatility of an aroylhydrazone toward iron is uncommon. The oxidation and spin states of the iron have been verified with magnetic and spectroscopic measurements.