Russian Journal of Coordination Chemistry最新文献

To complete the studies of double complex compounds, (N-thiocyanato)chromates(III) of lanthanide complexes with pyridine-3-carboxylic acid, new compounds of the compositions [LnL₃(H₂O)₂][Cr(NCS)₆]·nH₂O were synthesized from aqueous solutions (Ln = Pr (I), n = 1.5; Sm (II), Gd (III), Tb (IV), n = 2; L = C₆H₅NO₂). The substances were studied by chemical analysis, IR spectroscopy, and PXRD (CCDC nos. 2427051–2427054). In the crystal structures of complexes I–IV, the cation has a chain structure due to the bidentate-bridging function of pyridine-3-carboxylic (nicotinic) acid molecules. The coordination environment of the lanthanide atoms consists of eight oxygen atoms belonging to six nicotinic acid molecules and two coordinated H₂O molecules, located at the vertices of a distorted square antiprism. In the isolated [Cr(NCS)₆]^3– anions, the Cr coordination polyhedron consists of the N atoms of six thiocyanate ions and is close to a regular octahedron. In the structures of complexes I–IV, the space between polymeric cations is filled with complex anions and crystallization water molecules. Additionally, the structure is stabilized by intermolecular hydrogen bonds.

In order to study the effect of bulky terminal substituents in the β-diketonate ligand on the structure and properties of volatile magnesium compounds, complexes with 2,2,6,6-tetramethylheptane-3,5-dione (HThd) and, for the first time, with 2-methoxy-2,6,6-trimethylheptane-3,5-dione (HZis) were obtained. The complexes [Mg₂(L)₄] (L = Thd (I), Zis (II)), the synthesis intermediates [Mg(H₂O)₂(L)₂] (L = Thd (III), Zis (IV)), and aqua derivative [Mg₂(H₂O)(Zis)₄] (V) were characterized by elemental analysis and IR spectroscopy. The structures of binuclear complexes and the synthesis by-product [Mg₇(Zis)₆(μ-OH)₆]Cl₂·5CHCl₃ (VI) were established by X-ray diffraction (CCDC nos. 2424128 (Ia, a new polymorph), 2424130 (II), 2424129 (V), 2424126 (V·1/2CHCl₃), 2424127 (VI) ). Both [Mg₂(L)₄] molecules are characterized by asymmetric environment of metal centers (the Mg coordination number (C.N.) is 5, 6), but in I, three μ,κ²:¹-ligands occupy bridging positions, while in II, two ligands have different coordinations (μ,κ²:κ¹ and μ,κ²(O,O'):κ²(O',O_OMe)). The inclusion of water in II to give V is not associated with any significant structural rearrangement, but C.N. of the unsaturated metal center changes from 5 to 6. Thermogravimetric analysis showed that complex I is more volatile and low-melting than II.

Four cobalt complexes with cucurbit[6]uril (CB[6]), [Co(H₂O)₆](Bdc)·CB[6]·14.5H₂O (I), 2(H₂NMe₂)₂[CoCl₄]·CB[6]·12H₂O (II), [{Co(H₂O)₄Cl}₄(CB[6])]Cl₄·9H₂O (III), and [Co(H₂O)₆]-[Co(H₂O)₅(Dmf)][CoCl₄]₂·CB[6]·6H₂O (IV), were prepared by evaporation of the reaction solution containing cobalt chloride and cucurbit[6]uril (CB[6]). According to X-ray diffraction data, compound I is formed by packing of cationic cobalt aqua complexes, terephthalate anions, and CB[6] molecules linked together by hydrogen bonds with crystallization water molecules into a supramolecular cage. The structure of compound II represents a packing of CB[6] molecules, dimethylammonium cations, and anionic cobalt chloro complexes. Compound III contains tetranuclear cationic cobalt chloro aqua complexes with CB[6], with chloride anions acting as counter-ions. The crystal structure of IV is a packing of cationic cobalt aqua complexes, anionic cobalt chloro complexes, and CB[6] molecules linked by hydrogen bonds with crystallization water molecules into a supramolecular cage. The resulting compounds are characterized by IR spectra and elemental analysis data.

This study investigates α‑ketoamines from α‑diketones and arylamines using palladium and rhodium catalyst with chiral ligands. Among the catalysts tested, Pd(Tfa)₂/Dppf and Rh(Acac)(CO)₂/BINAP proved to be effective in facilitating the synthesis of α‑ketoamines. While high chemoselectivity and good yields were obtained, low enantioselectivity was observed, which may be attributed to the presence of multiple rhodium hydride species identified by NMR analysis. These findings highlight the chemoselectivity of this reaction, enabling the continuous production of high‑value products and synthetic intermediates.

A novel series of similar cationic complexes of the lanthanides containing cymantrenecarboxylate and 1,1'-bis(diphenylphosphine oxide)ferrocene ligands, [Ln(CymCO₂)₂(DppfO₂)₂]NO₃·Solv (Cym = (η⁵-C₅H₄)Mn(CO)₃); DppfO₂ = Fe(η⁵-C₅H₄P(O)Ph₂)₂; Solv are the lattice solvent molecules; Ln = Tb (I), Dy (II), Ho (III), Er (IV), Yb (V)), was prepared and characterized by X-ray analysis. The Ln³⁺ ions encapsulated in the unique bulky [Ln(CymCO₂)₂(DppfO₂)₂]⁺ cations are eight-coordinate; both kinds of the shell-forming organometallic ligands are bidentate. Magnetic properties of complexes I–V were studied in dc and ac modes; the derivatives of Er and Yb reveal the properties of single-molecule magnets.

Based on a series of substituted o-iminobenzoquinones (6-((2,6-di-iso-propylphenyl)imino)-2,4-bis(2,4,4-trimethylpentan-2-yl)cyclohexa-2,4-dien-1-one (L¹), 4-(tert-butyl)-6-((2,6-di-iso-propylphenyl)imino)-3-methoxycyclohexa-2,4-dien-1-one (L²), and 6-((2,6-di-iso-propylphenyl)imino)-3-methoxy-4-(2,4,4-trimethylpentan-2-yl)cyclohexa-2,4-dien-1-one (L³)), indium(III) iodide complexes were synthesized containing a redox-active ligand in the neutral form. The o-iminobenzoquinone L¹ was synthesized for the first time. It was found that the structure of the obtained complexes depends on the degree of shielding of the carbonyl oxygen atom in the starting o-iminobenzoquinone. The sterically hindered L¹ forms a 1 : 1 adduct with InI₃ (complex (L¹)InI₃ (I)). The absence of a substituent at position 2 of the o-iminobenzoquinone ring promotes the formation of bisligand ionic derivatives {[(L²)₂InI₂]InI₄} (II) and {[(L³)₂InI₂]InI₄} (III). The molecular structure of L¹ and complexes I·0.5 toluene, II·toluene·0.5 hexane was established by X-ray diffraction analysis (CCDC nos. 2440874 (L¹), 2440875 (I·0.5 toluene), 2440876 (II·toluene·0.5 hexane)). The optical and electrochemical properties of the starting o-iminobenzoquinones and their indium(III) complexes were studied. It was shown that complexation significantly enhances the oxidative properties of L¹, L², and L³.

The carbonyl isonitrile complex [Re(CO)₃(L)(m-XylylNC)]OTf (m-XylylNC is 2,6-dimethylphenyl isocyanide) based on the 1,10-phenanthroline ligand (L) containing the menthol fragment (MtO^–) in position 2 is synthesized. In the cationic moiety of the complex, the Re(I) atom has a distorted octahedral environment formed by N,N'-chelate ligand L and one isonitrile and three CO ligands. At ambient temperature the synthesized compound exhibits bright green phosphorescence in the solid state and in the solution with quantum yields of 15 and 10%, respectively.

Two new iridium(III) complexes with benzimidazole ligands differing in the size of the aromatic system and an auxiliary N-donor ligand with an extended conjugated system were synthesized and studied by structural and spectroscopic methods. A comparison of the results of crystal packing analysis with the data of electronic absorption spectroscopy, diffuse reflectance spectroscopy, and luminescence spectroscopy shows that intermolecular π–π interactions between the benzimidazole ligands have little effect on the optical characteristics of the complexes. Both compounds exhibit light absorption in the 250–550 nm range (ε = 58 000–1000 M^–1 cm^–1) in solution and in the solid state (E_g = 2.14–2.16 eV) and emit in the orange region (λ_max = 558–585 nm), with the maxima of solid-state emission systematically red-shifted by approximately 25 nm compared to emission in solution. The results of this work provide a better understanding of the extent to which crystal packing affects the optical properties of iridium(III) complexes and will be used in further development of crystal engineering approaches for designing iridium-based luminescent compounds in the long-wavelength region.

New cobalt(II) complex [Co(L)₂](ClO₄)₂ is synthesized by the reaction of 2,6-bis(pyrazol-3-yl)pyridine (L) containing capable of deprotonating hydroxy groups with cobalt(II) perchlorate hexahydrate in deuterated methanol in a tube for NMR spectroscopy. A possibility of the new complex to undergo in situ reversible deprotonation under the action of 1,8-diazabicyclo[5.4.0]undec-7-ene is demonstrated. As found by the approach based on an analysis of changing chemical shifts in the ¹H NMR spectra with temperature, the synthesized complex exists in the high-spin state both before and after complete deprotonation in a temperature range of 200–325 K. The X-ray diffraction (XRD) data of the completely deprotonated complex [Co(L-2H)₂](DBU+H)₂ (CIF file CCDC no. 2448321) indicate that the high-spin state of the complex is retained in the crystal as well.