E. Yu. Fursova

Structure of the complex of hexanuclear manganese pivalate with isonicotinamide

The structure of the [Mn6(O)2(Piv)10L2]∞ compound, where Piv is the pivalate anion and L is isonicotinamide, is investigated. Its solid phase is found to be formed by polymeric layers within which hexanuclear fragments {Mn6(O)2(Piv)10} are bound by bidentate bridging L. The molecules of the solvent (Me2CO or EtOAc) in which the synthesis was performed are incorporated into the inter-layer space of the crystal.

Interpretation of X-ray photoelectron spectra of free nitroxyl radicals

N1s and O1s X-ray photoelectron spectra of stable nitroxyl radicals (substituted piperidine-1-oxyl, 2-imidazoline-1-oxyl, and 2-imidazoline-3-oxide-1-oxyl) and also diamagnetic derivatives with a {ONCNO} fragment are measured. It is shown that the structure of N1s and O1s X-ray photoelectron spectra of nitroxyls is determined by charge transfer processes between different parts of the molecule to screen the X-ray hole and the spin-spin interaction of unpaired electrons on the HOMO and 1s level.

XPS spectra of free nitroxyl radicals and their electronic structure

The N(1s) and O(1s) XPS spectra of stable nitroxyl radicals and molecules with a related heterocycle structure: 4,4,5,5-tetramethyl-2-phenyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl, 4,4,5,5-tetramethyl-2-(3-nitrophenyl)-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl, 4,4,5,5-tetramethyl-2-(2-hydroxyphenyl)-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl, 4,4,5,5-tetramethyl-2-(2-hydroxy-3-nitrophenyl)-4,5-dihydro-1Himidazole-3-oxide-1-oxyl, and 4,4,5,5-tetramethyl-2-phenyl-4,5-dihydro-1H-imidazole-3-oxide were studied. The possibility to apply X-ray electron spectra for investigation of the charge electron and spin density distribution on free radical atoms and at their coordination by a metal is considered.

New heterospin complexes: The multinuclear compounds of transition metals with nitroxyl radicals

Synthesis and properties of the complex heterospin systems based on polynuclear transition metal compounds with stable nitroxides are reviewed. The appearance of the new synthetic approaches in the molecular magnetism area presents infinite possibilities in the chemical design of magnetically active

Structure and Magnetic Properties of Mn(II) Complexes with Enaminoketone Derivatives of 3-Imidazoline Nitroxide

The crystal structures of two manganese complexes with the enaminoketone derivatives of 3-imidazoline nitroxide: MnL2COOMe (layered polymeric) and MnL2CF3(DMF)2 (molecular) have been determined. The polymer structure of MnL2COOMe is the result of direct coordination of the nitroxyl O atoms of the neighboring bischelate fragments by the Mn atoms. This forms heterospin exchange clusters >N⋅-O–Mn(II)–O-N< with strong antiferromagnetic interactions between the odd electrons of the paramagnetic centers. The structure of MnL2CF3(DMF)2 is characterized by ligand cis-coordination in the octahedral coordination polyhedron. Due to the molecular nature of the complex, the solid compound has only weak ferromagnetic intramolecular indirect exchange interactions. The charge states of atoms in coordination units was confirmed by X-ray photoelectron data.

X-ray photoelectron and X-ray emission study of the electronic structure of hexanuclear Mn(II,III) pivalate complexes

The electronic structure of hexanuclear Mn(II,III) pivalate complexes with tetrahydrofuran and isonicotinamide are studied by X-ray photoelectron spectroscopy and X-ray emission spectroscopy. It is shown that when isonicotinamide substitutes for tetrahydrofuran the spin state of manganese ions is retained; the electron density increases on the manganese and oxygen atoms of the [Mn6(O)2Piv10] core.

Crystal structure of polynuclear pivalate Ni(II) complexes with butanediol

Using single crystal X-ray diffraction the structure of polynuclear [Ni6(OH)4(Piv)7(HOC4H8O)(HPiv)4], {K4[Ni12(CO3)2(Piv)16(OH)8(HOC4H8OH)2]}HPiv, {[Ni6(OH)4(Piv)6(HOC4H8O)(Me2CO)(HOC4H8OH)2]4×(Piv)4}, and {K[Ni2L2(Piv)3]}∞ complexes, where HOC4H8OH is 1,4-butanediol, HPiv is pivalic acid, and L is the anion of nitroxyl radical 2,2,5,5-tetramethyl-4-(3′,3′,3′-trifluoro-2′-oxy-1′-propenyl)-3-imidazolin-1-oxyl is determined.

Crystals of the CuII complex with nitronyl nitroxide and imino nitroxide exhibiting mechanical activity

As part of continuing studies of multispin compounds capable of exhibiting chemomechanical activity, a series of heterospin solids of the composition [Cu(hfac)2LxL′2−x], [Cu(hfac)2L′], [Cu2(Piv)4L′2]·0.5C6H14, and [Cu2(hfac)2(Piv)2L′2], where hfac is the hexafluoroacetylacetonate anion, L is 4,4,5,5-tetramethyl-2-(1-methyl-1H-imidazol-5-yl)-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl, L′ is the imino nitroxide analog of L, viz., 4,4,5,5-tetramethyl-2-(1-methyl-1H-imidazol-5-yl)-4,5-dihydro-1H-imidazole-1-oxyl, and Piv is the 2,2-dimethylpropionate anion, were synthesized and characterized. The packing of the synthesized crystals of the solid solutions [Cu(hfac)2LxL′2-x], where L predominates, is similar to that for [Cu(hfac)2L2], and these crystals are able to undergo chemomechanical motion. On the contrary, the crystals of [Cu(hfac)2LxL′2−x], where L′ predominates, have structural parameters similar to those of [Cu(hfac)2L′2] and do not exhibit thermally activated or photoactivated chemomechanical activity.

Structure and Magnetic Properties of Solid Solutions of Molecular Magnetics Based on Ni(II) and Co(II) Complexes with Nitroxyl Radicals

Ni(II) and Co(II) complexes with deprotonated paramagnetic enaminoketones 4‐(3′,3′,3′‐trifluorine‐2′‐oxopropylidene)‐ 2,2,5,5‐tetramethyl‐3‐imidazolidine‐1‐oxyl (L) and 4‐(3′,3′,3′‐trifluorine‐1′‐chlorine‐2′‐oxopropylidene)‐2,2,5,5‐tetramethyl‐3‐imidazolidine‐1‐oxy‐l (L1) and alcohols are shown to form continuous solid solutions NixCo1-xL2(C2H5OH)2 and NixCo1-xL21(CH3OH)2. Single crystal X‐ray diffraction analysis showed that concentration variation practically does not affect the structural characteristics of the solid solutions. Distinguishing features if the magnetic behavior of NixCo1-xL2 · (C2H5OH)2 and NixCo1-xL21(CH3OH)2 are the antiferromagnetic interaction of the moments of the nickel and cobalt sublattices inside the polymeric layers and the antiferromagnetic nature of interlayer interaction of the magnetic moments.

Crystal structure of cobalt(II) complexes with imidazoline nitroxide

The crystal structures of Co(II) coordination compounds CoL2-α modification (I), CoL2(CH3OH)2 (II), and CoL2Py2(III) — where L is a stable nitroxide 4-(3′,3′,3′-trifluoro-2′-oxypropylene)-2,2,5,5-tetramethyl-3-imidazoline-l-oxyl (L), were determined. It was found that the tetrahedral surroundings of cobalt in I consist of the O and N donor atoms of the deprotonated enaminoketone groups of L. In II and III, the same atoms form the equatorial plane of the centrosymmetric octahedral environment of the central atom in which the axial positions are occupied by the methanol O atoms or the pyridine N donor atoms. In the octahedral coordination centers of II and III, the Co-O and Co-N distances exceed analogous distances in the tetrahedral coordination center of I, substantially increasing the chelate angle in I compared to II and III. In I, the Co-O and Co-N bond lengths and the OCoN chelate angles are, respectively, 1.921(4), 2.006(4) Å, 93.6(2)° in II, 2.014(4), 2.177(4), Co-OOH 2.146(4) Å, 86.9(2)° in the two crystallographically independent molecules of III, 2.031(2) and 2.022(2), 2.170(2) and 2.193(2), Co-NPy 2.213(2) and 2.219(2)Å, 87.04(7) and 87.20(7)°. Compounds I and III are molecular. Compound II in the solid state has a layered polymer structure due to hydrogen bonding between the O atoms of the nitroxyl groups of L and the O atoms of the coordinated alcohol molecules.