Structure and magnetic properties of Ln2[Cu(opba)]3(DMSO)6(H2O) · (H2O) compounds with LnLa-Lu exhibiting ladder-like molecular motifs

The reaction of Ln(III) ions with the precursor [Cu(opba)]²⁻ in DMSO has afforded a series of isostructural compounds of general chemical formula Ln₂[Cu(opba)]₃(DMSO)₆(H₂O) · (H₂O), where Ln(III) stands for a lanthanide ion and opba stands for ortho-phenylenebis(oxamato). The crystal structure has been solved for the Gd(III) containing compound. It crystallizes in the orthorhombic system, space group Pbn2₁ (No. 33) with a = 9.4183(2) Å, b = 21.2326(4) Å, c = 37.9387(8) Å and Z = 4. The structure consists of ladder-like molecular motifs parallel to each other. To the best of our knowledge, this is the first Ln(III)Cu(II) coordination polymer family exhibiting the same crystal structure over the whole lanthanide series. The magnetic properties of the compounds have been investigated and the magnetic behavior of the Gd(III) containing compound was studied in more detail.     

Transition metal complexes of 2-amino-3,5-dihalopyridines: Synthesis, structures and magnetic properties of Cu(3,5-diCAP)2X2 and Cu(3,5-diBAP)2X2

A family of bis(2-amino-3,5-dihalopyridine)dihalocopper(II) compounds has been synthesized, including (3,5-diCAP)₂CuCl₂ (1), (3,5-diCAP)₂CuBr₂ (2), (3,5-diBAP)₂CuCl₂ (3), and (3,5-diBAP)₂CuBr₂ (4) [3,5-diCAP = 2-amino-3,5-dichloropyridine; 3,5-diBAP = 2-amino-3,5-dibromopyridine]. These complexes have been analyzed through single crystal X-ray diffraction and temperature dependant magnetic susceptibility. The compounds are all isostructural, forming bi-bridged chains with long Cu-X?Cu bridges in the crystal lattice. The two copper chloride compounds (1 and 3) exhibit weak antiferromagnetic interactions along these chains.     

Study of the magnetic properties of the mixed oxide Fe2O3-Fe2(MoO4)3 in the temperature range 2-300 K with different compositions

Powdered Fe₂O₃-Fe₂(MoO₄)₃ with different amounts of iron and molybdate precursors was prepared by a solvothermal route, followed by a supercritical drying and oxidation at 500 °C. The possibility to arrange Fe or Mo precursors in excess into a methanol solution makes one accessible to the preparation of iron(III) molybdate samples with different composition. The structural parameters and relationship between different phases in the composition are obtained from Rietveld profile refinement. Our intention was to modify the magnetic properties of Fe₂(MoO₄)₃ by adding the crystalline phase of Fe₂O₃, which carries a Fe-O magnetic component. A possible contribution to the magnetization and the magnetic susceptibility by this magnetic component is analyzed in the temperature range 2-300 K. The observed higher magnetic susceptibilities are compared to those reported.     

Ln2(O2CCH2PO3)2(H2O)3 · H2O (Ln = La, Pr, Nd, Sm): Layered lanthanide phosphonoacetates containing two-dimensional -Ln-O- linkages

Four novel isostructural lanthanide phosphonate compounds with formula Ln₂(O₂CCH₂PO₃)₂(H₂O)₃ · H₂O [Ln = La (1), Pr (2), Nd (3), Sm (4)] have been prepared through hydrothermal reactions of phosphonoacetate acid and lanthanide nitrates. All show layered structures made up of {LnO₉} polyhedra and {CPO₃} tetrahedra with the lattice water molecules locating between the layers. Within the layer, chains of edge-sharing {LnO₉} polyhedra are connected via corner-sharing by phosphonate oxygens forming a two-dimensional -Ln-O- linkage. Thermal analyses and XRD measurements reveal that the framework structures can be maintained up to 400 °C.     

A hexanuclear iron(III) complex [Fe6O2(OH)2(PhCOO)10(hedmp)2]·3CH3CN assembled from 2-hydroxyethyl-3,5-dimethyl pyrazole

In order to assemble polynuclear iron(III) complexes, the coordination chemistry of the 2-hydroxyethyl-3,5-dimethylpyrazole (hedmp-H) ligand has been investigated. Reaction of hedmp-H with trinuclear iron carboxylate precursor [Fe₃O(PhCOO)₆(H₂O)₃]Cl in acetonitrile yielded the hexanuclear Fe(III) complex [Fe₆O₂(OH)₂(PhCOO)₁₀(hedmp)₂]·3CH₃CN (1). This aggregate has been characterized by employing various analytical techniques, spectroscopic studies and single crystal X-ray diffraction. Detailed magnetic susceptibility measurements revealed that 1 displays an S_T = 5 ground state.     

Nature of the Ln-Co magnetic interactions in compounds [Ln2Co3(C5H4NPO3)6] · 4H2O with open-framework structures

The reactions of Ln(NO₃)₃ · xH₂O, CoSO₄ · 7H₂O or ZnSO₄ · 6H₂O and 2-pyridylphosphonic acid under hydrothermal conditions result in heterometallic phosphonate compounds with formula [Ln₂M₃(C₅H₄NPO₃)₆] · 4H₂O (Ln₂M₃; M = Co^II or Zn^II; Ln = La^III, Ce^III, Pr^III, Nd^III, Sm^III, Eu^III, Gd^III, Tb^III, Dy^III). These compounds are isostructural and crystallize in a chiral cubic space group I2₁3. Each structure contains the {LnO₉} polyhedra and {MN₂O₄} octahedra which are connected by edge-sharing to form an inorganic open-framework structure with a 3-connected 10-gon (10, 3) topology. The nature of Ln^III-Co^II magnetic interactions in Ln₂Co₃ is investigated by a comparison with their Ln^III-Zn^II analogues. It is found that the Ln^III-Co^II interaction is weak antiferromagnetic for Ln = Ce and ferromagnetic for Ln = Sm, Gd, Tb and Dy. In the cases of Ln = Pr, Nd and Eu, no significant magnetic interaction is observed.     

Synthesis, magnetism and X-ray structures of [Cu(2-aminopyrimidine)2(μ-OH)(CF3SO3)]2(2-aminopyrimidine)2, a new hydroxo-bridged dinuclear Cu(II) compound generating extremely small antiferromagnetism

The synthesis, optical and magnetic properties and X-ray crystal structure of [Cu(2-aminopyrimidine)₂(OH)(CF₃SO₃)]₂(2-aminopyrimidine)₂, a new dinuclear hydroxo-bridged copper(II) compound with a CuOCu angle of 97.96° and a very small antiferromagnetic interaction for which the singlet-triplet exchange parameter J, is described. The magnetic exchange coupling is almost negligible and, depending on the actual sample, varies from −1.8 to −7.2 cm⁻¹.     

Long-range superexchanged magnetic interaction observed in heterometallic complex: {[Fe(Tpms)(CN)3][Mn(H2O)2(DMF)2]} · DMF

A new tri-cyanometalate building block for heterometallic complexes, [PPh₄]₂[Fe^II(Tpms)(CN)₃] (2) (PPh₄ = tetraphenylphosphonium; Tpms = tris(pyrazolyl) methanesulfonate), has been prepared. Using it as a building block, a one-dimensional chain compound, {[Fe^II(Tpms)(CN)₃][Mn^II(H₂O)₂( DMF)₂]} · DMF (3), has been synthesized and structurally characterized. The magnetic properties of 3 correspond to a ferromagnetic chain with weak long-range superexchanged magnetic interaction between the high-spin manganese(II) ions.     

Synthesis, spectroscopy and magnetism of novel metal complexes of 3-aminoflavone (3-af). X-ray crystal structure of 3-af and [Cu(3-af)2(NO3)2]

The synthesis and characterization of four new complexes with the bioactive ligand 3-aminoflavone (3-af) are reported. The complexes of general formula [M(3-af)₂(H₂O)₂](NO₃)₂ · nH₂O], where M = Co(II), Ni(II), and Zn(II), and n = 0, 2, 0, respectively, and [Cu(3-af)₂(NO₃)₂] compound were prepared and studied. In particular, to investigate the binding in detail, the crystal structures of the free ligand (3-af) and [Cu(3-af)₂(NO₃)₂] (1) were determined. The new coordination compounds were identified and characterized by elemental analysis, magnetic measurements, and infrared and ligand-field spectra. The crystal structure of the Cu(II) complex reveals that the ligand acts as a N,O-bidentate chelate ligand forming a five-membered ring with the copper(II) ion. The copper(II) ion is octahedrally surrounded by the two amino nitrogens and two carbonyl oxygens from two chelating organic ligands in trans arrangement. Two molecules of coordinated nitrate anions occupy axial positions. The spectral and magnetic properties are in accordance with the structural data of the copper(II) compound. From X-ray powder-diffraction patterns and IR spectra, the complexes of nickel(II) (2) and cobalt(II) (3) were found to be mutually isomorphous. The results of the spectroscopic studies suggest a mononuclear structure of 2 and 3 complexes. The variable-temperature (1.8-300 K) magnetic susceptibility data of 2 indicate a weak ferromagnetic interaction. The magnetic behavior of complex 3 is characteristic of cobalt(II) systems with an important orbital contribution via spin-orbit-coupling and also suggests a weak ferromagnetic interaction.     

Comparative reactivity of triorganosilanes, HSi(OEt)3 and HSiEt3, with IrCl(CO)(PPh3)2. Formation of IrCl(H)2(CO)(PPh3)2 or Ir(H)2(SiEt3)(CO)(PPh3)2 depending on the substituents at Si

Reaction of HSi(OEt)₃ with IrCl(CO)(PPh₃)₂ (5:1 molar ratio) at room temperature for 1 h gives IrCl(H){Si(OEt)₃}(CO)(PPh₃)₂ (1), which is observed by the ¹H and ³¹P{¹H} NMR spectra of the reaction mixture. The same reaction, but in 20:1 molar ratio at 50 °C for 24 h produces IrCl(H)₂(CO)(PPh₃)₂ (2) rather than the expected product Ir(H)₂{Si(OEt)₃}(CO)(PPh₃)₂ (3) that was previously reported to be formed by this reaction. Accompanying formation of Si(OEt)₄, (EtO)₃SiOSi(OEt)₃, and (EtO)₂HSiOSi(OEt)₃ is observed. On the other hand, trialkylhydrosilane HSiEt₃ reacts with IrCl(CO)(PPh₃)₂ (10:1 molar ratio) at 80 °C for 84 h to give Ir(H)₂(SiEt₃)(CO)(PPh₃)₂ (4) in a high yield, accompanying with a release of ClSiEt₃.     

Reduction of acetonitrile by neodymium diiodide: Molecular structure of [{(HNCMe)2MeCNH2}NdI(MeCN)5]I2 and [{(HNCMe)2MeCNH2}Nd(MeCN)6]I3

The reaction of neodymium diiodide NdI₂ (1) with acetonitrile is accompanied by C-C coupling and formation of bis(ethylimine)ethylamine/acetonitrile complexes {[(MeCNH)₂CMeNH₂]NdI(MeCN)₅}I₂ (2) and {[(MeCNH)₂CMeNH₂]Nd(MeCN)₆}I₃ (3). Yields of the products are 9% and 50%, respectively. Probable scheme of the complexes formation is discussed. Treatment of 3 with 2 equiv. of 1 in THF affords NdI₃(THF)₃, hydrogen and monoiodide complex containing presumably bis(imide)amine ligand, NdI[(MeCN)₂CMeNH₂]. The X-ray analysis revealed that in the molecule of 2 one I⁻ anion is directly bonded to Nd³⁺ cation while two other I⁻anions are not in contact to the metal centre. The molecule of 3 is isostructural to previously obtained Dy and Tm analogues. All three I⁻ anions in it are located away from Nd³⁺ cation.     

1D chain coordination assembly of [Mn4(hmp)6(NO3)2] single-molecule magnets linked by the photochromic [FeNO(CN)5] precursor

The first heterometallic chain cluster {[Mn₄(hmp)₆(NO₃)₂FeNO(CN)₅·4CH₃CN}_n (1) based on the [Mn₄(hmp)₆] SMM has been synthesized. 1 has one-dimensional chain structure: the [Mn₄(hmp)₆] units are linked via CN-groups of nitroprusside anions. Its magnetic and relaxation properties and low temperature IR spectra under light irradiation have been investigated. The ferromagnetic exchange constants have been calculated.     

Synthesis, spectral and magnetical characterization of monomeric [Cu(2-NO2bz)2(nia)2(H2O)2] and structural analysis of similar [Cu(RCOO)2(L-N)2(H2O)2] complexes

A new complex of composition [Cu(2-NO₂bz)₂(nia)₂(H₂O)₂] (1) (nia = nicotinamide, 2-NO₂bz = 2-nitrobenzoate) has been prepared and its composition and stereochemistry as well as coordination mode have been determined by elemental analysis, electronic, infrared and EPR spectroscopy, magnetization measurements over the temperature range 1.8-300 K, and its structure has been solved, as well. The complex structure consists of the centrosymmetric molecules with Cu(II) atom monodentately coordinated by the pair of 2-nitrobenzoato anions and by the pair of nicotinamide molecules, forming nearly tetragonal basal plane, and by a pair of water molecules that complete tetragonal-bipyramidal coordination polyhedron about the copper atom. The complex 1 exhibits magnetic moment μ_eff = 1.86 B.M. at 300 K which decreases to μ_eff = 1.83 B.M. at 1.8 K. The magnetic susceptibility temperature dependence obeys Curie-Weiss law with Curie constant of 0.442 cm³ K mol⁻¹ and with Weiss constant of −1.0 K. EPR spectra at room temperature as well as at 77 K are of axial type with g_⊥ = 2.065 and g_∥ = 2.280 and exhibit clearly, but partially resolved parallel hyperfine splitting with A_II = 160 G, that is consistent with the determined molecular structure of 1. In order to analyze the factors influencing the degree of tetragonal distortion of coordination polyhedron, the dataset of 72 structures similar to that of 1 was extracted from CCD and analyzed. A significant correlation between the average Cu-O_ax bond length and tetragonality parameter τ which was found as a consequence of the Jahn-Teller effect.     

Rb2[B12(OH)12]·2H2O and Rb2[B12(OH)12]·2H2O2: Hydrate and perhydrolate of rubidium dodecahydroxo-closo-dodecaborate

The orthorhombically crystallizing salts Rb₂[B₁₂(OH)₁₂]·2H₂O (a = 1576.81(9), b = 813.08(5), c = 1245.32(7) pm) and Rb₂[B₁₂(OH)₁₂]·2H₂O₂ (a = 1616.54(9), b = 814.29(5), c = 1260.12(7) pm) could be prepared from Rb₂[B₁₂H₁₂] and hydrogen peroxide. Both crystal structures were determined by X-ray single crystal diffraction and refined in the space group Cmce. They are not isostructural to the other compounds containing icosahedral dodecahydroxo-closo-dodecaborate dianions [B₁₂(OH)₁₂]²⁻ and potassium, rubidium or cesium cations already known to literature, but both title compounds crystallize quasi-isotypically exhibiting Rb⁺ cations in 10-fold oxygen coordination. The hydrogen peroxide adduct (Rb₂[B₁₂(OH)₁₂]·2H₂O₂) is explosive on shock and heat, while the hydrate (Rb₂[B₁₂(OH)₁₂]·2H₂O) is not.     

Pressure-tuning infrared spectra of the three Magnus’ Green salts, [Pt(NH3)4][PtCl4], [Pt(ND3)4][PtCl4] and [Pt(NH3)4][PtBr4]

Pressure-tuning infrared spectra (up to ca. 40 kbar) are reported for Magnus’ Green salt, [Pt(NH₃)₄][PtCl₄] and two of its derivatives, [Pt(ND₃)₄][PtCl₄] and [Pt(NH₃)₄][PtBr₄]. The spectroscopic data indicate that there is restricted rotation of the coordinated ammonia groups about the Pt-N bonds in the complexes. It is possible that this restricted rotation is due to the presence of weak hydrogen bonding to the halogens, i.e., N-H?X (X = Cl, Br) interactions.     

A new example of a tetranuclear iron(III) cluster containing the [Fe4O2] core: preparation, X-ray crystal structure, magnetochemistry and Mössbauer study of [Fe4O2(O2CMe)6(N3)2(phen)2]

Two synthetic procedures have been employed that allow access to the new tetranuclear cluster [Fe₄O₂(O₂CMe)₆(N₃)₂(phen)₂] (1), where phen is 1,10-phenanthroline. Complex 1 · 3MeCN displays an unusual structural asymmetry (observed for the second time) in its [Fe₄O₂]⁸⁺ core that can be considered as a hybrid of the bent (butterfly) and planar dispositions of four metal ions seen previously in such compounds with transition metals. Complex 1 has been characterized by variable-temperature magnetic susceptibility studies, and by IR and variable-temperature ⁵⁷Fe Mössbauer spectroscopies. Magnetochemical data reveal a diamagnetic ground state (S=0) with antiferromagnetic body-body and body-wingtip interactions between the iron(III) ions of the butterfly core (J_bb=−11 cm⁻¹, J_wb=−70 cm⁻¹). Magnetochemical and Mössbauer studies on 1 show that its structural asymmetry has practically no influence on these properties compared with the more symmetric types.     

Tris(4-oxy-pyridinium)nitrato lanthanide complexes [M(4-O-C6H4NH)3(NO3)2(H2O)2][NO3] {M = La, Ce, Pr, Nd, Eu, Gd} - Synthesis, properties and structural characterization

Preferential formation and X-ray structures of tris(4-hydroxypyridinium) nitrato complexes [M(4-O-C₆H₄NH)₃(NO₃)₂(H₂O)₂][NO₃] {M = La, Ce, Pr, Nd, Eu, Gd} in the simple reaction of 4-hydroxypyridine with the respective nitrates is described. All these compounds are isostructural and crystallize in the space group P2₁2₁2₁. There are, however, minor differences in the hydrogen bonding features. The central metal ion in all these complexes has a coordination number of nine and the geometry may be described as tricapped trigonal prism. The neodinium complex has a chirality opposite to that of the rest of the structures. TGA data are also consistent with the solid state structures of these compounds.     

Synthesis and characterization of lanthanide orthothiophosphates: LaPS4

The single crystal structure of LaPS₄, (1), is reported. The space group is tetragonal, I4(1)/acd. Unit cell dimensions are a = 10.9641(3) Å and c = 19.4828(9) Å. The far infrared absorption and Raman spectra (100-600 cm⁻¹) are consistent with the groups being in a distorted tetrahedral geometry. The room temperature emission spectrum of LaPS₄ doped with Er³⁺ is also presented. Emission peaks at 529, 534, 549, and 554 nm were observed when the sample was excited at 492 nm. The compound reported here is isomorphous and isostructural to several other lanthanide orthothiophosphates.     

Organopalladium(IV) and platinum(IV) complexes containing the bis(pyrazol-1-yl)borate ligand. Structures of PtMe3{(pz)2BH2}(py) (py=pyridine) and Pt(mq)Me2{(pz)2BH2} (mq=8-methylquinolinyl) and detection of a neutral organopalladium(IV) phosphine complex

Neutral palladium(IV) complexes containing the bis(pyrazol-1-yl)borate ligand, PdMe₃{(pz)₂BH₂}(L) [L=py-d₅ (4), PMe₂Ph (6)], are generated in solution by oxidative addition of iodomethane to [PdMe₂{(pz)₂BH₂}]⁻ at −70 °C followed by addition of L; the Pd(IV) complexes reductively eliminate ethane above 0 °C. Stable Pt(IV) analogues of 4 and 6 have been isolated, and comparison of NMR spectra for Pd(IV) and Pt(IV) species support structural assignments for the unstable Pd(IV) complexes. The complex PtMe₃{(pz)₂BH₂}(py) (1a) has been characterised by X-ray diffraction, together with Pt(mq)Me₂{(pz)₂BH₂} (2) (mq=8-methylquinolinyl); both complexes show a fac-PtC₃ configuration for Pt(IV), and for 2 the PtN distances are ∼0.03 Å shorter than in the isostructural Pd(IV) complex.     

Syntheses and characterization of the W(II) and W(III) N2 complexes, [WCl2(PMe3)3]2N2 and [WCl3(PMe3)2]2N2

Refluxing WCl₄(PMe₃)₃ under a nitrogen atmosphere in the presence of two equivalents of sodium amalgam leads to a reduction to the W(II) complex [cis,mer-WCl₂(PMe₃)₃]₂N₂ (1), which can be converted to [mer,trans-WCl₃(PMe₃)₂]₂N₂ (2) via appropriate oxidation/chlorination. Structural data have been obtained for both complexes, and demonstrate significantly increased steric crowding in 1 due to PMe₃/PMe₃ interactions. The N-N bond distances in the two compounds are similar, at 1.279(4) and 1.243(18) Å, respectively.