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Cationic Mn(III) complexes with 3,5‐Hal‐sal2323 (Hal=diCl, diBr, BrCl) ligands containing electroactive TCNQ anions as counterions have been synthesized: [Mn(3,5‐diCl‐sal2323)](TCNQ)2 (1), [Mn(3,5‐diBr‐sal2323)]2(TCNQ)3⋅6CH3CN (2), and [Mn(3,5‐Br,Cl‐sal2323)]2(TCNQ)3⋅6CH3CN (3). The crystal structures, magnetic and conducting properties of the obtained compounds have been investigated. In 1, an incomplete spin transition from the low‐spin (LS) state at 100 K to the high‐spin (HS) state upon heating to 400 K is observed. Isostructural complexes 2 and 3 contain 6 molecules of solvated acetonitrile, which is lost upon heating, accompanied by the crystal structure transformation. As a result, desolvated complexes jump to the HS state. The temperature dependences of resistivity 2 and 3 show resistivity jumps associated with the loss of lattice solvent. [ABSTRACT FROM AUTHOR]

As a result of the electrochemical oxidation process, the [FeIII(5Cl‐thsa)2]− spin‐crossover (SCO) anion with N2S2O2 coordination sphere transforms into N4O2‐coordinated FeIII SCO neutral binuclear complex 2 with twist of two disulfide bridges. Each dimeric complex is a binuclear double‐stranded helicate with similar chirality of both Fe centers. The crystal structure of the complex 2 ⋅ 3H2O at 100 K has a monoclinic C2/c space group and contains large cavities (about 21.5 % of the unit cell volume) half‐filled by 3 water molecules per one dimer. The N4O2 coordination of iron(III) with two oxygen atoms (−O−) of phenoxy groups, two imine‐type (−Nim=) nitrogen atoms of azomethine groups, one amidrazone‐type (=NamidH) nitrogen atom and one ionized terminal group (−NionizH) of nitrogen has not been observed in CCDC so far. The oxidation state of the iron atoms in the dimeric complex was confirmed by 57Fe Mössbauer spectroscopy on 90 % enriched 57Fe sample. Mössbauer spectra and dc magnetic measurements demonstrated the partial HS‐HS→LS‐LS SCO in the 185–225 K temperature range. The details of the structure of complex 2 and the features of its magnetic properties were refined by theoretical analysis based on DFT calculations. The B3LYP* functional correctly predicting the energy of the spin‐crossover process was revealed. [ABSTRACT FROM AUTHOR]

The first mononuclear anionic erbium complex [Er(hfac)4]− (hfac = hexafluoroacetylacetone) with an organic ammonium cation [(CH3)4N+] as the counterion was synthesized and structurally and magnetically characterized. The coordination geometries around the Er ions are square antiprisms with pseudo-D4d symmetry. The complex shows distinct field-induced slow magnetization relaxation, which is described by a combination of Orbach (Ueff/kB~28.54(8) K.) and direct mechanisms. Quantum chemical calculations were performed to analyze the magnetic properties of the complex under consideration. [ABSTRACT FROM AUTHOR]

Four new heterometallic complexes combining [MII(H2dapsc)]2+ cations with the chelating H2dapsc {2,6-diacetylpyridine-bis(semicarbazone)} Schiff base ligand and [Cr(CN)6]3− anion were synthesized: {[MII(H2dapsc)]CrIII(CN)6K(H2O)2.5(EtOH)0.5}n·1.2n(H2O), M = Mn (1) and Co (2), {[Mn(H2dapsc)]2Cr(CN)6(H2O)2}Cl·H2O (3) and {[Co(H2dapsc)]2Cr(CN)6(H2O)2}Cl·2EtOH·3H2O (4). In all the compounds, M(II) centers are seven-coordinated by N3O2 atoms of H2dapsc in the equatorial plane and N or O atoms of two apical –CN/water ligands. Crystals 1 and 2 are isostructural and contain infinite negatively charged chains of alternating [MII(H2dapsc)]2+ and [CrIII(CN)6]3− units linked by CN-bridges. Compounds 3 and 4 consist of centrosymmetric positively charged trimers in which two [MII(H2dapsc)]2+ cations are bound through one [CrIII(CN)6]3− anion. All structures are regulated by π-stacking of coplanar H2dapsc moieties as well as by an extensive net of hydrogen bonding. Adjacent chains in 1 and 2 interact also by coordination bonds via a pair of K+ ions. The compounds containing MnII (1, 3) and CoII (2, 4) show a significant difference in magnetic properties. The ac magnetic measurements revealed that complexes 1 and 3 behave as a spin glass and a field-induced single-molecule magnet, respectively, while 2 and 4 do not exhibit slow magnetic relaxation in zero and non-zero dc fields. The relationship between magnetic properties and non-covalent interactions in the structures 1–4 was traced. [ABSTRACT FROM AUTHOR]

The cationic complexes of Mn(III) with the 5-Hal-sal2323 (Hal = Cl, Br) ligands and a paramagnetic doubly charged counterion [ReCl6]2− have been synthesized: [Mn(5-Cl-sal2323)]2[ReCl6] (1) and [Mn(5-Br-sal2323)]2[ReCl6] (2). Their crystal structures and magnetic properties have been studied. These isostructural two-component ionic compounds show a thermally induced spin transition at high temperature associated with the cationic subsystem and a field-induced slow magnetic relaxation of magnetization at cryogenic temperature, associated with the anionic subsystem. The compounds are the first examples of the coexistence of spin crossover and field-induced slow magnetic relaxation in the family of known [MnIII(sal2323)] cationic complexes with various counterions. [ABSTRACT FROM AUTHOR]

We report the synthesis, crystal structure and magnetic properties of the new heptacoordinated mononuclear erbium(III) complex (Et3NH)[Er(H2DAPS)Cl2] (H4DAPS = 2,6-diacetylpyridine bis-(salicylhydrazone)) (1). The coordination polyhedron around the Er(III) ion features a slightly distorted pentagonal bipyramid formed by the pentagonal N3O2 chelate ring of the H2DAPS ligand in the equatorial plane and two apical chloride ligands. Detailed high-frequency/high-field electron paramagnetic resonance (HF-EPR) studies of 1 result in the precise determination of the crystal field (CF) splitting energies (0, 290 and 460 GHz) and effective g-values of the three lowest Kramers doublets (KDs) of the Er(III) ion. The obtained HF-EPR data are in good agreement with the results from CF analysis for the Er(III) ion based on the simulation of the dc magnetic data of 1. The results from dynamic susceptibility measurements indicate that there is no slow relaxation of magnetisation behaviour. This observation is discussed in terms of the electronic structure of 1 obtained from experimental and theoretical results. [ABSTRACT FROM AUTHOR]

Three tetraphenylborates of mononuclear Mn(III) cation complexes with hexadentate ligands, the products of the reaction between a N,N′‐bis(3‐aminopropyl)ethylenediamine and salicylaldehydes with the different haloid substitutions at the 5 or 3,5 positions, have been synthesized: [Mn(5‐F‐sal‐N‐1,5,8,12)]BPh4 (1), [Mn(3,5‐diCl‐sal‐N‐1,5,8,12)]BPh4 (2) and [Mn(3,5‐Br,Cl‐sal‐N‐1,5,8,12)]BPh4 (3). Their crystal structure, dielectric constant (ϵ) and magnetic properties have been studied. Ligand substituents have a dramatic effect on the structure and magnetic properties of the complexes. With decreasing temperature, the complex (1) shows a gradual spin crossover from the high‐spin state (HS) to the HS:LS intermediate phase, followed by an abrupt transition to the low‐spin state (LS) without changing the crystal symmetry. The complexes 2 and 3 are isostructural, but have fundamentally different properties. Complex 2 demonstrates two structural phase transitions related to sharp spin crossovers from the HS to the HS:LS intermediate phase at 137 K and from the intermediate phase to the LS at 87 K, while complex 3 exhibits only one spin transition from the HS to the HS:LS intermediate phase at 83 K. [ABSTRACT FROM AUTHOR]

New organic (super)conductors of the β''-(BEDT-TTF)4A+[M3+(C2O4)3]G family, where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene; M is Fe; A is the monovalent cation NH4+; G is 2-fluoropyridine (2-FPy) (1); 2,3-difluoropyridine (2,3-DFPy) (2); 2-chloro-3-fluoropyridine (2-Cl-3-FPy) (3); 2,6-dichloropyridine (2,6-DClPy) (4); 2,6-difluoropyridine (2,6-DFPy) (5), have been prepared and their crystal structure and transport properties were studied. All crystals have a layered structure in which the conducting layers of BEDT-TTF radical cations alternate with paramagnetic supramolecular anionic layers {A+[Fe3+(C2O4)3]³-G0}2-.Crystals 1 undergo a structural phase transition from the monoclinic (C2/c) to the triclinic (P1) symmetry in the range 100-150 K, whereas crystals 2-5 have a monoclinic symmetry in the entire range of the X-ray experiment (100-300 K). The alternating current (ac) conductivity of salts 1-4 exhibits metallic behavior down to 1.4 K, whereas the salt 5 demonstrates the onset of a superconducting transition at 3.1 K. The structures and conducting properties of 1-5 are compared with those of the known monoclinic phases of the family containing different monohalopyridines as "guest" solvent molecules G. [ABSTRACT FROM AUTHOR]

A pi-donor molecule, 4,5;4',5'-bis(1,4-dioxanediyl-2,3-dithio)tetrathiafulvalene (BDDT-TTF), identical to bis(ethylenedithio)tetrathiafulvalene (ET) is synthesized. BDDT-TTF has its central region identical to ET but has additional oxygen heteroatoms due to dioxane ring substitution to terminal ethylene bridges of ET. Cyclic voltammetric data show no significant alterations in the electronic structure due to addition of dioxane rings to the ET structure. New conductive radical cation salts with inorganic anions are prepared by donor BDDT-TTF.

Heptacoordinated metal complexes with a pentadentate ligand 2,6-diacetylpyridine-bis(thiosemicarbazone) (H2daptsc) were used for the first time ever as building blocks to create polynuclear multifunctional molecular materials. Reactions of the paramagnetic [Mn(II)(H2daptsc)(H2O)2](ClO4)2 and [Mn(II)(H2daptsc)Cl2] complexes with photochromic sodium nitroprusside Na2[Fe(II)(CN)5NO].2H2O were studied. As a result, six polynuclear phases were obtained: {Mn(H2daptsc)Fe(CN)5NO}n·0.5n(MeOH)·0.5n(H2O) (1), {Mn(H2daptsc)Fe(CN)5NO}3n·8n(MeOH) (2), {Mn(H2daptsc)Fe(CN)5NO}2n·n(MeOH)·n(H2O) (3), [Mn(H2daptsc)Cl]2[Fe(CN)5NO] (4), {Mn(H2daptsc)Fe(CN)5NO}n·2n(H2O) (5) and {Mn(H2daptsc)Fe(CN)5NO}n·n(EtOH) (6). The crystal structures of the phases as well as the magnetic and photochromic properties of 1 and 4 were studied. [ABSTRACT FROM AUTHOR]

Three radical cation salts of BDH-TTP with the paramagnetic [ReF6]2- and diamagnetic [ReO4]- anions have been synthesized: K-(BDH-TTP)4ReF6 (1), κ-(BDH-TTP)4ReF6⋅4.8H2O (2) and pseudo-κ"-(BDH-TTP)3(ReO4)2 (3). The crystal and band structures, as well as the conducting properties of the salts, have been studied. The structures of the three salts are layered and characterized by alternating κ-(1, 2) and κ"-(3) type organic radical cation layers with inorganic anion sheets. Similar to other κ-salts, the conducting layers in the crystals of 1 and 2 are formed by BDH-TTP dimers. The partial population of positions of Re atoms and disorder in the anionic layers of 1-3 are their distinctive features. Compounds 1 and 2 show the metallic character of conductivity down to low temperatures, while 3 is a semiconductor. The ac susceptibility of crystals 1 was investigated in order to test the possible slow relaxation of magnetization associated with the [ReF6]2- anion. [ABSTRACT FROM AUTHOR]

A series of five neutral mononuclear lanthanide complexes [Ln(HL)(L)] (Ln = Dy3+, Ho3+ Er3+ and Tb3+) with rigid pentadentate N3O2-type Schiff base ligands, H2LH (1-Dy, 3-Ho, 4-Er and 6-Tb complexes) or H2LOCH3, (2-Dy complex) has been synthesized by reaction of two equivalents of 1,1'-(pyridine-2,6-diyl)bis(ethan-1-yl-1-ylidene))dibenzohydrazine (H2LH, [H2DAPBH]) or 1,1'-(pyridine-2,6-diyl)bis(ethan-1-yl-1-ylidene))di-4-methoxybenzohydrazine (H2LOCH3, [H2DAPMBH]) with common lanthanide salts. The terbium complex [Tb(LH)(NO3)(H2O)2](DME)2 (5-Tb) with one ligand H2LH was also obtained and characterized. Single crystal X-ray analysis shows that complexes 1-4 have the composition {[Ln3+(HL)-(L)2-] solv} and similar molecular structures. In all the compounds, the central Ln3+ ion is chelated by two interlocked pentadentate ligands resulting in the coordination number of ten. Each lanthanide ion is coordinated by six nitrogen atoms and four oxygen atoms of the two N3O2 chelating groups forming together a distorted bicapped square antiprismatic polyhedron N6O4 with two capping pyridyl N atoms in the apical positions. The ac magnetic measurements reveal field-induced single-molecule magnet (SMM) behavior of the two dysprosium complexes (with barriers of Ueff = 29 K at 800 Oe in 1-Dy and Ueff = 70 K at 300 Oe in 2-Dy) and erbium complex (Ueff = 87 K at 1500 Oe in 4-Er); complex 3-Ho with a non-Kramers Ho3+ ion is SMM-silent. Although 2-Dy differs from 1-Dy only by a distant methoxy-group in the phenyl ring of the ligand, their dynamic magnetic properties are markedly different. This feature can be due to the difference in long-range contributions (beyond the first coordination sphere) to the crystal-field (CF) potential of 4f electrons of Dy3+ ion that affects magnetic characteristics of the ground and excited CF states. Magnetic behavior and the electronic structure of Ln3+ ions of 1-4 complexes are analyzed in terms of CF calculations. [ABSTRACT FROM AUTHOR]

A series of three mononuclear pentagonal-bipyramidal V(III) complexes with the equatorial pentadentate N3O2 ligand (2,6-diacethylpyridinebis(benzoylhydrazone), H2DAPBH) in the different charge states (H2DAPBH0, HDAPBH1−, DAPBH2−) and various apical ligands (Cl−, CH3OH, SCN−) were synthesized and characterized structurally and magnetically: [V(H2DAPBH)Cl2]Cl·C2H5OH (1), [V(HDAPBH)(NCS)2]·0.5CH3CN·0.5CH3OH (2) and [V(DAPBH)(CH3OH)2]Cl·CH3OH (3). All three complexes reveal paramagnetic behavior, resulting from isolated S = 1 spins with positive zero-field splitting energy expected for the high-spin ground state of the V3+ (3d2) ion in a PBP coordination. Detailed high-field EPR measurements for compound 3 show that its magnetic properties are best described by using the spin Hamiltonian with the positive ZFS energy (D = +4.1 cm−1) and pronounced dimer-like antiferromagnetic spin coupling (J = −1.1 cm−1). Theoretical analysis based on superexchange calculations reveals that the long-range spin coupling between distant V3+ ions (8.65 Å) is mediated through π-stacking contacts between the planar DAPBH2− ligands of two neighboring [V(DAPBH)(CH3OH)2]+ complexes. [ABSTRACT FROM AUTHOR]