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Vol 51, No 4 (2025)
Articles
Manganese(II) complexes based on sterically hindered {N,O,O} tridentate Schiff bases: synthesis, structures, and properties
Abstract
Manganese(II) complexes (DMSO){(DMSO)2bis[5,7-di-tert-butyl-2-(2-hydroxyphenolato)-1,3-benzoxazol-4-ol]}manganese(II) (Ia) and (DMSO)2{bis[5,7-di-tert-butyl-2-(2-hydroxyphenolato)-5-nitro-1,3-benzoxazol-4-ol]}manganese(II) (Ib) are synthesized from the tridentate sterically hindered Schiff bases: condensation products of 4,6-di-tert-butyl-2-aminophenol with salicylaldehyde derivatives N-(3,5-di-tert-butyl-2-oxyphenyl)salicylaldimine and N-(3,5-di-tert-butyl-2-oxyphenyl-5-nitro)salicylaldimine. The structures and compositions of the synthesized metal chelates are characterized by C, H, and N elemental analysis, IR spectroscopy, and magnetochemical measurement data. The EPR data in DMF and toluene are presented for complex Ia. The molecular structures of complexes Ia and Ib are proved by X-ray diffraction (XRD) results (CIF files CCDC nos. 2325776 (Ia) and 2325777 (Ib), respectively). In both complexes, the manganese ion exists in the octahedral {N2O4} ligand environment in which the coordination occurs due to two nitrogen atoms of the benzoxazole cycle and two oxygen atoms of the o-hydroxyphenol group and the apical positions are occupied by the oxygen atoms of two DMSO molecules.
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Quantum-chemical calculations of direct spin–spin coupling constants 195Pt–13C in the platinum complexes: possibilities and restraints
Abstract
Calculational protocols are proposed for the estimation of direct spin–spin coupling constants 1JPtC in the platinum complexes with practically significant accuracy. To attain a good accuracy, calculations are required within the framework of a fully relativistic four-component level of the theory (RMSE = 24.7 Hz (2%)). A scalar relativistic approximation can be used as an alternative, but the accuracy will appreciably be lower (RMSE = 50.5 Hz (5%)).
222-228
Synthesis of carbonylchromium complexes of benzimidazole and quinoxaline derivatives
Abstract
Two approaches to the preparation of chromium complexes of condensed heterocyclic compounds bearing two nitrogen atoms are approved. The reactions of benzimidazole (L1) and 2-methylbenzimidazole (L2) with triammine(tricarbonyl)chromium (I) give the corresponding pentacarbonylchromium derivatives [(η1-C7H6N2)]Cr(CO)5 (II) and [2-Me-(η1-C7H5N2)]Cr(CO)5 (III) characterized by the nitrogen–chromium σ-bond, and ammine(pentacarbonyl)chromium (Cr(NH3)(CO)5, IV) is formed as a by-product. Analogous reactions involving 1,2,3,4-tetrahydroquinoxaline (L3) and 3-phenyl-1,2-dihydroquinoxaline (L4) afford tricarbonylchromium π-complexes [(η6-C6H4)C2H6N2)]Cr(CO)3 (V) and [3-Ph-(η6-C6H4)C2H3N2)]Cr(CO)3 (VI), respectively. The condensations of (η6-ortho-phenylenediamine)tricarbonylchromium (VII) with benzaldehyde and of ortho- phenylenediamine with (η6-benzaldehyde)tricarbonylchromium (VIII) afford acyclic compounds (azomethines [PhCH=N(η6-C6H4)NH2]Cr(CO)3 (IX) and [(η6-Ph)CH=NC6H4NH2]Cr(CO)3 (X), respectively), whereas the reaction of acetaldehyde with complex VII gives a mixture of heterocyclic products: exo-[1,3-bis-(C2H4OEt)-2-Me-(η6-C6H4)CHN2]Cr(CO)3 (XI) and endo-[1,3-bis-(C2H4OEt)-2-Me-(η6-C6H4)CHN2]Cr(CO)3 (XII). The spectral characteristics of the synthesized compounds are studied, and their purity and individual character are proved. The molecular structures of complexes III and XI are determined by XRD (CIF files CCDC nos. 2245463 (III) and 2362231 (XI)).
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The tetranuclear macrocyclic mercury(II) complex of [Hg4{S2CN(CH3)2}4Cl4]: preparation, molecular and supramolecular structures, and thermal behavior
Abstract
The tetranuclear mercury(II) dithiocarbamato-chlorido complex [Hg4(S2CNMe2)4Cl4] (I), the molecule of which includes a centrosymmetric 16-membered metallacycle [Hg4S8C4], was prepared by the reaction of solutions of HgCl2 and sodium dimethyldithiocarbamate (Me2Dtc). The crystal, molecular, and supramolecular structures of I were established by direct single crystal X-ray diffraction (CCDC no. 2364847). In complex I, the non-equivalent μ2-bridging dithiocarbamate ligands join neighboring mercury atoms in pairs, thus forming a tetranuclear macrocyclic molecule. The intramolecular Hg···S and Hg···Cl secondary bonds stabilize the spatial configuration of this macrometallacycle. The supramolecular self-organization of the complex is due to the relatively weak, pairwise S···Cl and Hg···Cl secondary interactions, which combine the tetranuclear molecules of I into 2D pseudo-polymer layers; numerous non-classical C–H···Cl and C–H···S hydrogen bonds connect these layers to form a 3D framework. According to simultaneous thermal analysis data, the thermal decomposition of I is accompanied by the formation of HgS and release of HgCl2.
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Heterometallic manganese(III) coordination polymers with Schiff bases (H2Salpn) and dicyanometallates
Abstract
Single crystals of the Mn(III) complexes with tetradentate (N2O2) Schiff bases (L) and dicyanometallates [Mn(L)M(CN)2]n, where L = Salpn2– = N,N’-bis(salicylidene)-1,3-diaminopropane, M = M = Ag+ (I), Au+ (II) were obtained for the first time. The molecular structures of I and II were determined by X-ray diffraction (CCDC no. 2351118 (I), 2351119 (II)). It was found that the dicyanometallate anion [M(CN)2]ˉ in the crystal structure of these compounds acts as a bridge binding the Mn(III) moieties with the Schiff base into 1D. Using quantum chemical calculations, the (3, –1) type critical points were found near the C‒H…Ag/Au contact; this attests to the existence of weak hydrogen bonds between these atoms.
255-264
Synthesis of neutral binuclear two-chain helicate from the anionic Fe(III) complex of 5-chlorosalicylaldehyde thiosemicarbazone by electrocrystallization
Abstract
The electrocrystallization of salts of the anionic spin-variable complex [FeIII(L)2]‒ (L is 5-chlorosalicylaldehyde thiosemicarbazone (Н25Cl-thsa)) with cations Cat+ = K+ (I), Me4N+ (II), and Et4N+ (III) affords crystals of the neutral binuclear two-chain helicate [FeIII2(L1)2]0 (IV) (L1 = (L‒2)‒(L‒) are transformed monoanionic and dianionic fragments of L, respectively, linked with each other by the disulfide S–S bridge), which are identified by XRD at 100 and 293 K as the same phase IV · n(H2O) (n ≤ 6) with close lattice parameters. “Fresh” crystals of the complex obtained from salt I correspond to the composition IV · 6(H2O) at 293 K, rapidly lose 50% water molecules, and decrepitate to fine crystalline fragments IV · 3(H2O). The structure of crystals IV · 6(H2O) is monoclinic (space group С2/c) and characterized by cavities filled with disordered water molecules, which amount to more than 20% of the total unit cell volume. Complex IV has the point symmetry group С2 and high-spin geometry of coordination nodes N4O2. As found by cyclic voltammetry, electrochemically inactive complex IV is formed by the two-electron oxidation of the [FeIII(5Cl-thsa)2]– anion via the EEC mechanism.
265-276
Reactivity of monovalent thulium
Abstract
It was found that monovalent thulium iodide TmI in the TmIx mixture reacts with hydrogen at 200°C and atmospheric pressure, forming a hydrogenation product [TmIxH], which is confirmed by the reaction with (C6F5)3GeBr, leading to the formation of (C6F5)3GeН. In the reaction with nitrogen at 450°C, a mixture is formed containing diiodide TmI2 and a product of the composition [Tm4IN], containing a Tm–N valence bond. TmI in the TmIx mixture also reacts with phenol and phenylacetylene. In the first case, a difficult-to-separate mixture of iodide phenolates TmIx(OPh)y is formed. The reaction with PhC≡CH leads to the formation of styrene, diphenylbenzene and a mixture of triphenylbenzenes. In the reaction of TmIx with СО2, trivalent thulium iodioxalate (C2O4)TmI(DМЕ).was isolated with a high yield.
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Academician Vladimir Isaakovich Minkin is 90 years old!
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