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Novel bis-o-semiquinonato nickel complexes (2,2′-bpy)Ni(3,6-DBSQ)2 (1) and (1,10-phen)Ni(3,6-DBSQ)2 (2) was synthesized (2,2′-bpy - 2,2′-dipyridine; 1,10-phen - 1,10-phenanthroline; 3,6-DBSQ-anion-radical of 3,6-tert-butyl-o-benzoquinone). Single crystal X-ray diffraction study indicated distorted octahedral environment of nickel atom in both complexes. Variable temperature magnetic susceptibility measurement detected predomination of ferromagnetic exchange interactions between high spin nickel ion and anion-radicals of o-semiquinones. DFT calculations are in a good agreement with experimental structural and magnetic results.

Complexes of Cu(II), Ni(II), Co(II) and Fe(II) ions with N-[2-[(hydroxyalkylimino)methyl]phenyl]-4-methylbenzenesulfonamides containing the (CH2)n-spacer of a variable length (n = 2–6) were synthesized by chemical and electrochemical methods. All the compounds were characterized by C, H and N elemental analysis, IR, EPR and X-ray absorption spectroscopy data. The dimeric structures of the copper complexes with (CH2)n-spacers (n = 2, 3) were determined by the magnetochemical method and by X-ray diffraction analysis for the copper complex with the (CH2)3-spacer.

Complexes [Cu2L2Cl4], [NiL2Cl2], [PdLCl2], and [PtLCl2], where L is a novel ligand from the series of 2-subsituted 5-(α-aminoalkyl)tetrazoles, namely 5-(N,N-dimethylaminomethyl)-2-tert-butyltetrazole, have been synthesized and characterized by IR spectroscopy, thermal analysis and single crystal X-ray analysis. The complexes reported show different coordination geometries of the metals, viz. octahedral for Ni, square pyramidal for Cu, and square planar for Pt and Pd complexes. At the same time, the ligand L demonstrates the same coordination mode in all the complexes. It acts as a chelating ligand coordinated to the metal via two nitrogen atoms, namely the tetrazole ring N4 and the dimethylamino N atoms. Complex [PtLCl2] was found to have promising antiproliferative activity against human cervical carcinoma cells, with IC50 value being average between those of cisplatin and carboplatin. The temperature-dependent magnetic susceptibility measurements of complex [Cu2L2Cl4] revealed that the copper(II) ions were weakly antiferromagnetically coupled showing a coupling constant J of −2 cm−1.

Regioselective activation of dioxolene coordination site was observed in reactions of Ni(CO)4 and bifunctional o-quinone, annulated with dithiete cycle (ditQ). Novel hexacoordinated bis(o-semiquinonato) nickel complexes Ni(ditSQ)2(THF)2 (1), Ni(ditSQ)2(Py)2 (2), Ni(ditSQ)2(2,2′-bpy) (3) and Ni(ditSQ)2(4-NIT-Py)2 (4) (4-NIT-Py = 2-(4-pyridinyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) were obtained. X-ray diffractometry study revealed a distorted octahedral geometry with trans-arrangement of neutral monodentate ligands for Ni ion. Ferromagnetic metal–ligand and antiferromagnetic ligand–ligand exchange interactions were observed in obtained heterospin systems.

Bis-o-semiquinonato cobalt complex (2,2′-bpy)Co(3,6-DBSQ)2 (1) is known to be redox-isomeric (valence tautomeric), i. e. undergo reversible ligand–metal electron transfer accompanied with spin crossover of metal ion under external excitation (2,2′-bpy – 2,2′-bipyridine; 3,6-DBSQ – 3,6-di-tert-butyl-o-benzosemiquinone). The using of one pot reaction allowed us to obtain the number of solid solutions of cobalt complex 1 with similar complexes (2,2′-bpy)M(dioxolene)2 of M = zinc (2), M = nickel (3) and M = manganese (4) in the ratios 1:1 and 1:5 (dioxolene = redox forms of 3,6-di-tert-butyl-o-benzosemiquinone). Composition of solid solutions was established by X-ray spectral microanalysis and confirmed by magnetic measurements. The metals ratio taken into reaction is well reproduced in solid solution. Crystal structures of solid solutions were established by single crystal X-ray diffraction study. X-ray diffraction pattern allows to observe the superpositions of two structures. Variable temperature magnetic susceptibility measurements show that magnetizations of solid solutions are additive and are composed of magnetizations of both complexes. Redox-isomeric transformation occurs in all solid solutions independently of their compositions. The dilution of redox-isomeric compound 1 by inert components 2 and 3 (with zinc and nickel complexes) results in diminishing of transition temperature whereas the dilution by manganese compound does not affect the transition temperature. The reason of this result is proposed to be the maximal difference in molecules volumes (which is determined by ionic radii and charge distributions between metal and ligands) in cobalt/zinc and cobalt/nickel pairs being compared to cobalt/manganese one.

The reaction of (NBu4)2Me2Mal (where Me2Mal2− is dimethylmalonate dianion) with cobalt(II) or nickel(II) acetates M(OAc)2·4H2O (M = CoII or NiII) gave (NBu4)6[Co36(H2O-κO)12(μ3-OH)20(μ4-HMe2Mal-κ2O,O′)2(μ4-Me2Mal-κ2O,O′)22(μ4-Me2Mal)6]·3EtOH (1) and (NBu4)8[Ni36(H2O-κO)12(μ3-OH)20(μ4-Me2Mal-κ2O,O′)24(μ4-Me2Mal)6]·6H2O·2EtOH (2), respectively. Replacement of the aqueous NBu4OH solution by a methanolic solution allowed us to isolate the 36-nuclear complex (NBu4)8[Co36(H2O-κO)12(μ3-OH)20(μ4-Me2Mal-κ2O,O′)24(μ4-Me2Mal)6]·2.5H2O·CH3OH (3). Complexes 1–3 were characterized by IR spectroscopy, single crystal X-ray diffraction analysis, and magnetochemical studies.

The V(III) complex [V(TptBu2)Cl2] (1, TptBu2 = hydrotris(3,5-di-tert-butylpyrazolyl)borate) was synthesized by the reaction of [VCl3(THF)3] (prepared in situ) and K(TptBu2). Reduction of 1 with potassium mirror afforded the V(II) complex [V(TptBu2)Cl] (2). Both complexes were characterized by means of a single crystal X-ray diffraction. 1 represents the first example of pentacoordinated vanadium tris(pyrazolyl)borate (Tp) complexes. The V(III) ion environment is a distorted trigonal bipyramid. 2 is the first V(II) Tp-complex. The V(II) ion has tetrahedral environment, and the Cl atom is deviated from the B–V axis (∠B(1)–V(1)–Cl(1) = 157.8°). Magnetic susceptibility measurements showed reasonable µeff values at 300 K: 2.80 (1) and 3.78 (2) µB, those prove the oxidation states of V: +3 (1) and +2 (2).

Two novel dicarbonyl-semiquinonato rhodium complexes were synthesized and studied. Complexes are analogues of (CO)2Rh(3,6-DBSQ) (3,6-DBSQ-3,6-di-tert-butyl-o-benzosemiquinone) which thread-like crystals can bend reversibly under light or heat activation (G.A. Abakumov, V.I. Nevodchikov, Dokl. Acad. Nauk SSSR 1982, 266, 1407–1410). Complexes differ from (CO)2Rh(3,6-DBSQ) by substituents in 3,6-positions of quinonato ring (cyclohexyl (1) and isopropyl (2) instead of tert-butyl). Single crystal structural study indicates that both complexes are the derivatives of Rh(I) with o-semiquinonato anion-radical. Molecules form pairs due the short contacts in contrast to (CO)2Rh(3,6-DBSQ) and other similar compounds which form the endless alternated chains with direct Rh-Rh bond. At that, complex 1 molecules form isolated pairs, whereas molecules of 2 can be united in the chain. Both compounds 1 and 2 have the array of intensive bands in IR spectrum in the region 1350 cm−1 which is closer to bond stretch vibrations of C–O ordinary bond but not sesquilateral. EPR of solutions of complexes indicates presence of monomeric complex molecules where the single unpaired electron is localized in o-semiquinonato ligand. The drop of EPR signal intensity with cooling of solutions of 1 and 2 evidence that the association process takes place.

Hitherto unknown 4-substituted TEMPO derivatives bearing β-(oxy)acrylate moiety have been synthesized via nucleophilic addition of 4-hydroxy-TEMPO to methyl and ethyl propiolate, respectively. The reaction of these radicals (L) with Cu(hfac)2 produces heterospin chain-polymers [Cu(hfac)2L]n, which contain alternating { N – · O–Cu–O – · N } and { C O–Cu–O C } fragments. The magnetic behavior of these coordination polymers have been studied using SQUID magnetometry to reveal that the complex based on 4-[E-(3-methoxy-3-oxoprop-1-en-1-yl)oxy]-TEMPO does not show significant exchange interactions between the spins of the Cu2+ ion and the nitroxides. By contrast, complex with 4-[E-(3-ethoxy-3-oxoprop-1-en-1-yl)oxy]-TEMPO features ferromagnetic exchange interaction between the paramagnetic centers.

Three new polymeric compounds with general formula {[Gd(phen)(H2O)3Gd(phen)(H2O)2(μ-OH)2][Re4Q4(CN)12]}·nH2O (Q = S0.84Te0.16, n = 0.25 for compound 1; Q = Se, Te, n = 1 for compounds 2, 3, respectively) were obtained by self-assembly reaction of [Re4Q4(CN)12]4− cluster anions, Gd3+ cation and 1,10-phenthroline (phen) in a solvothermal conditions. Compounds were investigated by single-crystal X-ray diffraction, magnetic measurements and thermogravimetric analysis. Structure of compounds consist of non-charged ladder chains formed by alternating [Re4Q4(CN)12]4− cluster anions and dimeric cationic complex [{Gd(phen)(H2O)3Gd(phen)(H2O)2(μ-OH)2}]4+ connected through –C N–Gd–N C– covalent bonds. Chains are packed parallel and linked with each other by a system of hydrogen bonds. The magnetic susceptibility of compounds is determined by spins of Gd3+ ions that weakly antiferromagnetic coupled in dimeric cationic fragments.

Coordination compounds of cobalt(II), nickel(II), and copper(II) with a poly nitrogen-containing heterocyclic ligand 1-(pyrid-2-yl)-1H-tetrazole (1-Pytz) such as [Cu(1-Pytz)2Cl2]n, [M(1-Pytz)2(H2O)Cl2] (M = Co, Ni), [M(1-Pytz)2(C2N3)2]n (M = Co , Ni) have been synthesized. The compounds have been studied by means of infrared diffuse reflectance spectroscopy, single-crystal and powder X-ray diffraction, and static magnetic susceptibility. The studies on the µeff(T) for the [Cu(1-Pytz)2Cl2]n, [Co(1-Pytz)2(C2N3)2]n and [Ni(1-Pytz)2(C2N3)2]n polynuclear complexes in the temperature range of 2–300 K have shown that exchange interactions between spins of metal ions are weak.

New bis-o-iminobenzosemiquinonato derivatives of nickel (imSQC(O)Ph)2Ni (1) and (imSQPh)2Ni (2) that are ligated by functionalized o-aminophenols H2LC(O)Ph and H2LPh, respectively, were synthesized. Complex 1 is distinguished by a square-planar geometry of N2O2 coordination core while the bis-o-iminobenzosemiquinonate 2 demonstrates a slight deviation from planarity. Both complexes 1 and 2 show the strong antiferromagnetic interactions between radical anion ligands as established by variable-temperature magnetic susceptibility measurements. Electrochemical behavior of 1 and 2 is represented by ligand-centered redox transitions: two quasi-reversible one-electron reduction processes and two-electron oxidation one. The salient peculiarity of cyclic voltammogram for 1 is an increase in number of redox waves owing to the quasi-reversible reduction of benzophenone fragments in ligands. Six-coordinated NiII derivative [(imQC(O)Ph)2Ni(H2O)2](OSO2CF3)2 (3) with two o-iminobenzoquinones as well as four-coordinated NiII species [(imSQC(O)Ph)Ni(APC(O)Ph)]CoCp2∙2.1toluene (4∙2.1toluene) including radical-anion and o-amidophenolate forms of redox-active ligand were prepared as products of oxidation and reduction of the initial 1, respectively, in accordance with the CV data. The value of effective magnetic moment (μeff) unambiguously indicates the high-spin state for nodal NiII ion in 3. Low-temperature EPR signal demonstrates rather the ligand-centered nature of unpaired electron in 4 that corresponds to the total doublet ground spin state (S = 1/2) for compound and diamagnetic low-spin (SNi = 0) configuration of the metal center.

New bis-o-benzosemiquinonato complexes of zinc (3,6-SQ)2Zn(Phen) (1), (3,6-SQ)2Zn(MePhen) (2), (3,6-SQ)2Zn(Dipy) (3) based on sterically hindered 3,6-di-tert-butyl-o-benzoquinone (3,6-Q) were synthesized. The crystal structures of compounds 1, 2 were investigated using X-ray diffraction. The coordination polyhedron of both complexes is distorted octahedron. The magnetic properties of solid bis-o-semiquinonates were found to be complicated by intermolecular interaction between diradical molecules. The combination of the magnetic susceptibilities measurements and quantum chemical calculations has established that the weak intramolecular ferromagnetic interaction between o-semiquinone radicals is accompanied by the comparable in magnitude intermolecular antiferromagnetic exchange.

New nitronyl nitroxides LMe and LMe-CP containing a 4-methylpyridin-3-yl substituent were synthesized. It was found that the interaction of Сu(hfac)2 with LMe and LMe-CP gave binuclear [Cu(hfac)2LMe]2 and [Cu(hfac)2LMe-CP]2·Solv (Solv = n-C6H14, n-C10H22, n-C16H34) and chain polymer {[[Cu(hfac)2]2LMe2][Cu(hfac)2]}∞ heterospin complexes. An important structural peculiarity of LMe and LMe-CP is a large dihedral angle between the planes of the O –N−C N → O paramagnetic fragment and the pyridine ring: 55.2 and 56.1°, respectively. The presence of a methyl group in the pyridine ring of the nitroxide molecule in {[[Cu(hfac)2]2LMe2][Cu(hfac)2]}∞ proved favorable for spin transition at nearly room temperature.

New coordination compounds of copper(II) chloride with 2-(N-acetylamino)-6-methylpyridine (L) of the compositions [Cu2L2Cl4] (1), [CuL(H2O)Cl2]·L (1a), and [CuL2Cl][CuLCl3]·C2H5OH (2) have been prepared by the reactions between ethanol solutions of L and ethanol solutions of CuCl2·2H2O at different Cu:L ratios. The compounds have been characterized by a set of methods including elemental analysis, IR-spectroscopy, single-crystal X-ray diffraction analysis, and magnetic susceptibility measurements in the range 5–300 K (for 1). The crystal structures of 1 and 1a revealed distorted square-pyramidal geometry around Cu(II) centers, while in 2 both distorted square-pyramidal and trigonal–bipyramidal coordinations are present. L acts as a bidentate chelate ligand bound to the metal center through the pyridine N atom and the acetyl O atom. The results of the study demonstrate that the presence of 6-methyl substituent in L provides a high steric hindrance, precluding the formation of complexes with a distorted octahedral coordination of Cu(II).

The main goal of this work was to obtain VIV–BaII and VIV–MnII heterometallic dycarboxylates, to characterize their structures, magnetic properties and to investigate the possibility of using obtained compounds in composite paste electrodes. The reactions of vanadyl sulfate VOSO4·3H2O with barium salts of dimethylmalonic (H2Me2mal = C3H6(COOH)2) and butylmalonic (H2Bumal = C4H10(COOH)2) acids taken in a ratio of 1:2 in aqueous solution gave crystals of the coordination polymers {[Ba(VO)(Me2mal)2(H2O)]·H2O}n (1) and {[Ba3(VO)3(Bumal)6(H2O)13]·4H2O}n (2), respectively. The crystal structures of the compounds are built of mononuclear bis-chelate metal fragments containing vanadium(IV), which are bridged to barium ions by carboxylate groups. The reactions of the synthesized compounds with manganese(II) sulfate in aqueous solutions were found to give new heterometallic polymers 3 and 4 {[Mn(VO)(L)2(H2O)5]·H2O}n (L = Me2mal in 3 and L = Bumal in 4), which retain the bis-chelate vanadyl moiety formally acting as a vanadium-containing O-donor ligand. Compounds 1–4 were studied by cyclic voltammetry in solution and as composites in paste electrodes; the potential values as well as localization sites of oxidation and reduction processes were determined.

(6H-1,2,3-Benzodithiazol-6-ylidene)malononitrile (4) was electrochemically and chemically reduced with tetrakis(dimethylamino)ethylene (TDAE) and CrTol2 into the title radical anion (5). The electrochemically generated 5 and its salts [TDAE]2+[5]2 (7) and [CrTol2]+ [5] (8) were characterized by solution EPR in combination with UV–Vis spectroscopy. Salts 7 and 8 were isolated and characterized by elemental analysis and solid-state EPR, and 8 by magnetic measurements in the temperature range 2–300 K. The value of the effective magnetic moment of the salt 8 at 300 K, μeff = 1.64 μB, indicates π-dimerization of 5 in the solid state. For the molar magnetic susceptibility χ of 8, the temperature dependences of χT and 1/χ in the range 2–300 K can be approximated by the Curie–Weiss law with the Curie–Weiss constant C and temperature Tc equal to 0.33 ± 0.01 cm3 K mol−1 and −1.0 ± 0.1 K, respectively. In the mean-field approximation, the effective value of the exchange interaction of [CrTol2]+ with its neighboring cations can be estimated as zJ = −1.4 сm−1. All the experimental results were supported by DFT calculations.

The high-temperature solid-state desolvation under an inert atmosphere was studied for two new polymorphic complexes of the same composition (bath)2Sm2(piv)6·2EtOH (piv = (CH3)3CCO2−, bath = 4,7-diphenyl-1,10-phenanthroline), which differ in the structural functions of the bridging carboxylate anions. This resulted in the synthesis of new non-solvated pivalate (bath)2Sm2(piv)6. The complexes (bath)2Sm2(piv)6·2EtOH (two polymorphic modifications) and (bath)2Sm2(piv)6 were characterized by X-ray diffraction. The solid-state thermal decomposition of binuclear Sm(III) pivalates with heterocyclic chelating N-donors, such as 2,2′-bipyridyl (bpy), 1,10-phenanthroline (phen), and bath, was studied, the composition of the complexes in the gas phase was determined, and the magnetic and luminescent properties were analyzed.

New heterodinuclear pivalates (HPiv)6EuTb(Piv)6 (5) and (Phen)2EuTb(Piv)6 (6), where Piv = (CH3)3CCO2−, the 2,2-dimethylpropanoate anion, and Phen = 1,10-phenanthroline, were synthesized. The structures and compositions of the heterodinuclear molecules were determined by X-ray diffraction and based on magnetic measurements, inductively coupled plasma atomic emission spectrometry (ICP-AES) and the results of the research on the thermal decomposition and vaporization of the complexes. Under UV excitation, complex 6 exhibits luminescence and complete intramolecular excitation energy transfer to the Eu3+ ions involving singlet levels of the Phen ligand and f–f levels of the Tb3+ ions.

New cobalt(II) (1), iron(II) (2) and manganese(II) (3) complexes of M(3,6-SQ)2L type containing 3,6-di-tert-butyl-o-benzosemiquinonato ligands (3,6-SQ) and 5,7-di-tert-butyl-2-(pyridine-2-yl)benzoxazole (L) were synthesized and characterized in details. Magnetic susceptibility measurements and spectroscopic studies have shown that all complexes include metal(II) in the high-spin state and two radical-anionic o-semiquinonato ligands. The antiferromagnetic ligand–ligand coupling in cobalt(II) and iron(II) complexes takes place, while manganese(II) complex demonstrates metal–ligand antiferromagnetic interactions. Molecular structure of Co(3,6-SQ)2L was determined by X-ray analysis. Cobalt(II) atom has a distorted trigonal prismatic environment.

New isostructural lanthanide cymantrenecarboxylates [Ln2(μ-О,η2-OOCCym)2(μ2-OOCCym)2(η2-ООССym)2(py)4]·2py, where Ln = Pr (1), Sm (2), Eu (3), Gd (4) and Cym = (η5-C5H4)Mn(CO)3, were synthesized and characterized by X-ray diffraction. The crystals of 1–4 are built of discrete binuclear molecules; the Ln atoms are nine-coordinate. The phases produced by thermal elimination of pyridine from complexes 3 and 4 are identical to the phases formed by elimination of THF from the THF-containing cymantrenecarboxylates prepared earlier. The magnetic properties of complex 4 indicate an enhancement of antiferromagnetic interactions between Gd3+ ions due to the substitution of THF for pyridine; in the product of ligand elimination from 4, ferromagnetic interactions were found. It was shown that the lanthanide cymantrenecarboxylates are virtually nonvolatile. The thermal decomposition of the complexes was studied by differential scanning calorimetry (DSC) and thermogravimetry (TGA). Thermolysis of 1–4 in air affords mixtures of LnMn2O5 and Mn2O3. For the earlier prepared complex [Nd2(μ2-OOCCym)4(OOCCym)2(THF)4] (5), standard thermodynamic functions were calculated from adiabatic calorimetry data. Cymantrenecarboxylate ligands appreciably suppress Eu3+ luminescence and determine the spectral and the fluorescent properties of the lanthanide cymantrenecarboxylates.

New polynuclear heteroligand complexes [(η-HPiv)2(μ2-Hmhp)4Na6Co5(μ6,η2-O3PPh)2(μ3,η2-Piv)2(μ3-Piv)3(μ-Piv)7]·2C10H22 (1·2C10H22) and [(η-H2O)4Na12Co12(μ5,η2-O3PPh)4(μ6-O3PPh)4(μ3,η2-mhp)8(μ2-Piv)4(μ3-Piv)8]·1.25C10H22 (2·1.25C10H22), where Hmhp is 6-methyl-2-pyridone, mhp is the 6-methyl-2-piridonate, and Piv is the pivalate anion, were obtained by the self-assembly of {Co(Piv)2}n, Na2O3PPh, and Hmhp in boiling decane (174 °C). The structures of compounds 1·2C10H22 and 2·1.25C10H22 were determined by single-crystal X-ray diffraction. The magnetic properties of these compounds and their thermal decomposition were investigated. The removal of coordinated water molecules from complex 2·1.25C10H22 begins at 470 °С.

An approach to the synthesis of nitronyl nitroxide 2,2′-(buta-1,3-diyne-1,4-diyl)bis(4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole 3-oxide 1-oxyl) (4) was developed. Compound 4 is the first diradical with nitronyl nitroxide groups directly linked through a diacetylene fragment. In solid phase the diradicals are arranged in stacks with parallel C C fragments, with the distances between the terminal carbon atoms of the neighboring diacetylene groups (T and d) being 6.170 and 4.466 A, respectively, and the angle between the translation vector and the median line passing through the C C C C fragment of 45.9°. The values of T and d are outside the range of structural criteria allowing a topochemical reaction. Thus UV irradiation does not initiate solid phase polymerization of 4. After exposure at 373 K for 1 h the crystals of 4 turn dark-brown, become X-ray amorphous and lose the majority of their paramagnetic centers without significantly changing their mass. Upon further heating up to 400–420 K the product explodes, releasing about 360 kJ/mol of heat. A diluted solution of 4 in 1,4-dioxane produces an EPR spectrum typical of a strong exchange (a multiplet of nine broadened lines with A4N = 0.35 mT), indicating the efficiency of the C C C C fragment as an exchange channel. The character of the experimental μeff(T) dependence for 4 indicates a strong intramolecular antiferromagnetic-type exchange interaction (J/kB ∼ −104 K) and the dominating weak intermolecular ferromagnetic exchange.

New dodecanuclear phenylphosphonate-bridged Co(II) complexes [(μ2-THF)5(η-HPiv)Co12(μ3-OH)4(μ6-O3PPh)4(μ-Piv)12]·THF·2С6Н6 (1·THF·2С6Н6), [(μ2-THF)6Co12(μ3-OH)4(μ6-O3PPh)4(μ-Piv)12]·3THF (2·3THF) and [(μ2-Hmhp)6Co12(μ3-OH)4(μ6-O3PPh)4(μ-Piv)12]·6.5MeCN (3·6.5MeCN) have been synthesized by the reaction of the cobalt(II) pivalate polymer {Co(Piv)2}n (Piv is the pivalate anion), as a source of metal fragments containing cobalt(II) atoms, with potassium phenylphosphonate (K2PO3Ph) in the presence of neutral O-donor additional ligands like molecules of THF or 6-methyl-2-pyridone (Hmhp). The structures of the dodecanuclear complexes 1–3 were determined by using single-crystal X-ray diffraction data. The magnetic properties of the compounds showed that complexes 1 and 3 exhibit antiferromagnetic exchange interactions between the magnetic centers. The stability of compounds 1 and 3 were studied using thermogravimetric analysis.

Solid heterospin compounds based on Cu(hfac)2 complexes with a new group of nitronyl nitroxides bearing different azine-N-oxide substituents at position 2 of the 2-imidazoline ring (Ln) were studied. The major factor responsible for the change in the magnetic characteristics of the [Cu(hfac)2L1] complex with triazine nitronyl nitroxide with temperature was shown to be the specific pairwise packing of heterospin molecules with the dominant antiferromagnetic exchange between the radical fragments of adjacent molecules. For complexes of Cu(hfac)2 with 1-oxoazin-2-yl-substituted nitronyl nitroxides L2 and L4, 7-membered metallocycles were obtained, although they form rarely. It was shown that polymer chains formed in the solid complex with spin-labeled pyrazine-N-oxide [(Cu(hfac)2)3(L3)2] due to the cross-linking of {(Cu(hfac)2)2(L3)2} binuclear fragments via the bridging [Cu(hfac)2].

Lithium-containing heterometallic complexes with cobalt (Li2Co2(Piv)6(2,4-Lut)2 (2, Piv is the pivalate anion) and Li2Co2(O2CCH2But)6(2,4-Lut)2 (3)) and with nickel (Li2Ni2(Piv)6(DME)2 (4) and Li2Ni2(Piv)6(2,2′-bpy)2 (5)) were synthesized. The structures of the complexes were established by X-ray diffraction. The magnetic properties of complexes 2 and 4 were studied. The thermal behavior of compounds 2, 3, and 5 was investigated. It was shown that the compounds under study can be used as molecular precursors for the synthesis of lithium cobaltate and nickelate.

Tetrabridged dinuclear complexes ((2-NH2)C5H4N)2Cu2(μ2-OOCCMe3)4 (2·С6Н6) and ((3-NH2)C5H4N)2Cu2(μ2-OOCCMe3)4 (3) and the cocrystallization product ((4-NMe2)C5H4N)2Cu(η2–OOCCMe3)2·2((4-NMe2)C5H4N)2Cu2(μ2-OOCCMe3)4 (4) were synthesized by the reaction of the polymer [Cu(OOCCMe3)2]n (1) with aminopyridine ligands (L) of different nature (Cu: L = 1:1) in С6Н6. The solid-state thermal decomposition of these compounds was studied by differential scanning calorimetry and thermogravimetry, and their electrochemical behavior was investigated by cyclic voltammetry. All newly synthesized complexes were studied by X-ray diffraction, the magnetic properties of the complexes were investigated, and ESR measurements were performed.

The solid-state thermolysis (420–450 °С) of the new heterometallic coordination polymer [Li2Co2(Piv)6(μ-L)2]n (1, Piv is the anion of pivalic acid, L is 2-amino-5-methylpyridine) followed by annealing of the decomposition products at 500 °С was shown to afford LiCoO2 in quantitative yield. Compound 1 was characterized by X-ray diffraction and magnetic measurements.

The reaction of the polymer {Co(Piv)2}n (Piv is the pivalic acid anion) with triethylenetetramine (L1) (M:L1 = 2:1) in MeCN affords the polymeric compound [Co2L1(η2-Piv)2(μ-Piv)2]n (1) containing asymmetric dicobalt units coordinated by one chelate ligand L1. The reaction of 1 with an additional amount of L1 (M:L1 = 1:1) in MeCN gives rise to the binuclear molecule Co2 L 1 2 (Piv)4 (2), where L1 acts as a chelate-bridging ligand. Compounds analogous to 2 with M = Fe (3) were prepared by the reaction of the polymer {Fe(Piv)2}n with L1 in MeCN using the reagent ratio M:L1 = 1:1. The reaction of the compound Co L 1 2 (Piv)4 (2) with isophthalaldehyde (L2) produces the binuclear complex Co2L3(Piv)4 (4) containing the new [2 + 2] macrocyclic ligand L3 as a result of condensation of L1 with L2. All newly synthesized compounds were characterized by X-ray diffraction and magnetic measurements.

It was established that the reactions of pyrazol-3-yl-substituted nitronyl nitroxide (HL1) and pyrazol-3-yl-substituted imino nitroxide (HL3) with Cu(II) acetate lead to self-assembly of the Cu4(OH)2(OAc)4(DMF)2(L1)2 tetranuclear and Cu2(OAc)2(H2O)2(L3)2 dinuclear complexes, respectively. The reaction of Cu(II) acetate with 5-ethoxycarbonyl-pyrazol-3-yl-substituted nitronyl nitroxide (HL2) gave unexpected solid Cu2(H2O)2(L6)2 · 2DMF, in which L6 is a deprotonated 5-carboxy-pyrazol-3-yl-substituted nitronyl nitroxide, formed as a result of cleavage of an ester bond in the starting HL2. A similar transformation of the paramagnetic ligand was observed in the reaction of Cu(II) acetate with 5-ethoxycarbonyl-pyrazol-3-yl-substituted imino nitroxide (HL4). It led to the formation of Cu2(DMF)2(L7)2, where L7 is deprotonated 2-(5-carboxy-1H-pyrazol-3-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole 3-oxide. An X-ray diffraction study indicated that in Cu4(OH)2(OAc)4(DMF)2(L1)2 and Cu2(OAc)2(H2O)2(L3)2, the L1 and L3 paramagnetic ligands perform the bridging cyclic tridentate function, while in Cu2(H2O)2(L6)2 · 2DMF and Cu2(DMF)2(L7)2, the paramagnetic L6 and diamagnetic L7 are bridging bicyclic tetradentate ligands. The magnetic behavior of complexes with coordinated nitronyl nitroxide – Cu4(OH)2(OAc)4(DMF)2(L1)2 and Cu2(H2O)2(L6)2 · 2DMF is dictated by the dominant antiferromagnetic exchange interactions, which is confirmed by quantum-chemical data. The magnetic susceptibility of Cu2(OAc)2(H2O)2(L3)2 reflects the competition between the antiferromagnetic and ferromagnetic components, of which the latter is due to electron coupling in the Cu(II) ← N=C–N ∸ O exchange channels. EPR data confirm the results received from static magnetic measurements for multispin solids.