Search

[Display omitted] A complex of mixed carboxylate pentafluorobenzoate (pfb) and phenylacetate (PhAc), viz. [Tb 2 (phen) 2 (pfb) 2 (PhAc) 4 ] (phen is 1,10-phenanthroline), where each rare earth element (REE) ion is simultaneously coordinated to pentafluorobenzoic and phenylacetic acid anions, was for the first time synthesized and structurally characterized. To evaluate the influence of the second type of anion on the structure and photoluminescent properties, compounds with phenylacetic acid anions [Tb 2 (phen) 2 (PhAc) 6 ] and pentafluorobenzoic acid anions [Tb 2 (EtOH) 2 (phen) 2 (pfb) 6 ] were obtained. A change in the composition of the compounds from the phenylacetic acid anion to pentafluorobenzoate led to a change in the geometry of the metal scaffold and the REE polyhedron, a rearrangement of the system of non-covalent interactions according to the Hirshfeld surface analysis, and enhanced luminescence. [ABSTRACT FROM AUTHOR]

Interaction of the pre-organized complex of iron(II) trimethylacetate and 1,10-phenanthroline (phen) [Fe2(piv)4(phen)2] (1) (piv = (Me)3CCO2−)) with 1,6-diaminohexane (dahx) in anhydrous acetonitrile yielded a 1D coordination polymer [Fe3O(piv)6(dahx)1.5]n (2) and an organic salt of pivalic acid (H2dahx)(piv)2 (3). The structure of the obtained compounds was determined by single-crystal X-ray diffraction analysis. The phase purity of the complexes was determined by powder X-ray diffraction analysis. According to the single-crystal X-ray analysis, coordination polymer 2 is formed due to the binding of a triangular carboxylate core {Fe3(μ3-O)(μ-piv)6} with an aliphatic diamine ligand. Thermal behavior was investigated for compounds 1 and 2 in an argon atmosphere. [ABSTRACT FROM AUTHOR]

The reactions of chromium(III) nitrate with M2(cpdc) (cpdc2− – dianion of cyclopropane-1,1-dicarboxylic acid, M = K, Na) and rare-earth metal nitrates taken in a molar ratio of 1 : 3 : 1 yielded heterometallic coordination polymers {[Ln2Cr2(cpdc)6(H2O)9]·8.5H2O}n (1Ln, Ln = Eu, Gd, Tb), crystallizing in tetragonal space group P43212 (P41212). A single crystal X-ray diffraction (XRD) study showed that the crystal structures of these compounds are formed by tris-chelate fragments {Cr(cpdc)3} linked into {Ln–Cr} layers and further into a 3D framework structure due to the bridging coordination of carboxylate groups to Ln atoms. When passing to Ln = Dy, Ho, Y, Er, Yb, the crystals of compounds 2Ln form, where the structure of {Ln–Cr} layers is retained, but the disorder of the interlayer Ln atoms, a decrease in the size of a crystal cell, and a change in the space group to I4 are observed. The use of K2(cpdc) in the syntheses of 1Ln and 2Ln is found to lead to the isolation of a side product, namely, mononuclear complex [Cr(cpdc)(Hcpdc)(H2O)2]·2H2O (3), with the reactions with Na2(cpdc) enabling obtaining only the crystals of heterometallic LnIII–CrIII compounds. Alternating current magnetic susceptibility measurements for the series 1Ln and 2Ln revealed the presence of slow relaxation of magnetization only for 1Eu and 2Y, which is due to the magnetic anisotropy of chromium ions in the presence of magnetic field and their magnetic isolation in a crystal lattice. For 1Eu, 1Gd, 1Tb, 2Dy, and 2Ho, thermal decomposition in an Ar atmosphere was studied. The end product of solid-state thermolysis of 2Dy in air at 1000 °C is shown to be submicron DyCrO3 particles (300–400 nm). [ABSTRACT FROM AUTHOR]

A series of Ba–MII complexes with allylmalonic acid anions (Amal) [BaMII(Amal)2(H2O)3]n (MII = Mn (1), Co (2), Cu (3), and Zn (4)) were synthesized by the reaction of the corresponding transition metal sulfates and barium allylmalonate. The complexes were characterized by IR and EPR spectroscopy, elemental analysis, magnetochemical and solid phase thermal decomposition studies as well as powder and single-crystal X-ray crystallography. The main structural block {MII(Amal)2(H2O)x} (x = 1 for M = Cu, x = 2 for M = Mn, Co, and Zn) in 1–4 is formed by two chelate allylmalonate anions and water molecule(s), which are surrounded by Ba2+ ions. The magnetic measurements of paramagnetic compounds revealed weak ferromagnetic interactions between copper(II) ions in 3, and slow magnetic relaxation in non-zero field (HDC = 1500 Oe) for 2. According to the TGA data of 1–4, they are decomposed via different pathways in the case of MnII, CoII, CuII, and ZnII since the metal ions catalyze different types of processes. However, all the complexes undergo polymerization of the allyl fragment. [ABSTRACT FROM AUTHOR]

Compounds containing bis‐chelate dianionic blocks {M(3d)(cbdc)2}2– (M(3d)=VIVO, CuII) with cations VO2+ and Cu2+ chelated by two anions of dicarboxylic acid have been prepared as crystals when aqueous solutions of vanadyl sulfate VOSO4⋅3H2O or copper sulfate CuSO4⋅5H2O have been allowed to react with sulfates of d‐metals (MnII, CoII, NiII, ZnII, and CdII) and barium salt of cyclobutane‐1,1‐dicarboxylic acid (H2cbdc=C4H6(CO2H)2) in the 1:1:2 ratio. The nature of the M(3d) metal center has been found to influence on the structure of the heterometallic compounds formed. 1D polymers [M(VO)(cbdc)2(EtOH)2(H2O)3]n (M=Mn (1), Co (2), Ni (3)), molecular dinuclear complex [Zn(VO)(cbdc)2(H2O)5]⋅H2O (4), and 1D polymer {[Cd(VO)(cbdc)2(H2O)5]⋅H2O}n (5) are formed when M(3d)=VIVO, whereas in the case of the bis‐chelate block with the CuII atom, ionic compounds [M(H2O)6][Cu(cbdc)2(H2O)] (M=Mn (6), Co (7), Ni (8), Zn (9)) and 2D polymer {[CdCu(cbdc)2(H2O)2]⋅2H2O}n have been synthesized. The isolation of paramagnetic centers in compounds 1–10 is confirmed by magnetic measurements and EPR spectroscopy. The structure of M(3d)‐M heterometallic compounds (M(3d)=VO2+, Cu2+; M=Mn2+, Co2+, Ni2+, Zn2+, Cd2+) with cyclobutane‐1,1‐dicarboxylic acid anions is influenced not only by the nature of the heterometal M at the same M(3d) but also the nature of this M(3d) center, which forms a bis‐chelate block with two anions of substituted malonic acid. [ABSTRACT FROM AUTHOR]

Mononuclear {Cu(Me2mal)2}2- dianion has been used as a building block for the synthesis of six new coordination polymers: {Li2(H2O)2(µ-H2O)[Cu(µ4-Me2mal)(µ-Me2mal)]} n ( 1), {Na2(µ-EtOH)2[Cu(µ5-Me2mal)2]} n ( 2), {K8(µ-H2O)6[Cu(µ-H2O)(µ3-Me2mal)(µ6-Me2mal)]2[Cu2(µ5-Me2mal)4]} n ( 3), {K2M(H2O)5(µ-H2O)3[Cu(µ-Me2mal)(µ3-Me2mal)][Cu(µ-H2O)(µ-Me2mal)(µ3-Me2mal)]} n (M = MgII ( 4) or NiII ( 5); isostructural compounds), and {K4Co3(H2O)8(µ-H2O)4(µ3-OH)2[Cu(H2O)(µ-Me2mal)(µ3-Me2mal)]2[Cu(µ-H2O)(µ3-Me2mal)2]2} n ( 6). It was shown that the structures of the compounds depend on the nature and ionic radius of the heterometal. In particular, the dimensionality of the complexes increases from 1D to 2D and 3D with increasing radius of the s-metal in compounds 1, 2, and 3, respectively. Partial replacement of K+ in 3 by Mg2+, Ni2+, or Co2+ leads to the formation of heterometallic coordination polymers 4 and 5, with 2D structure, and 3D complex 6. The compounds were characterized by single-crystal X-ray diffraction and EPR spectroscopy, and the magnetic properties of compounds 1, 2, and 4- 6 were also studied. Further, the topological analysis of the structures and another 794 known mal-derivatives complexes from Cambridge Structural Database (CSD, version 5.36) was performed. The main regularities determining the coordination modes of ligands and metal cations in relation to structure topology have been established and are discussed. [ABSTRACT FROM AUTHOR]

ABSTRACT Heterometallic d‐4f coordination complexes are of paramount interest in modern coordination chemistry because of their potential applications in organic light‐emitting devices and spintronic materials. Here we report the synthesis and thorough investigation of Ln and MLn (M = Zn, Cd; Ln = Sm, Eu, Gd, Tb) molecular complexes based on 2‐furancarboxylic acid anion (Hfur): [Ln2(NO3)2(fur)4(DME)2] (Ln = Eu, Gd, Tb; DME is dimethoxyethane) and [M2Ln2(NO3)2(fur)8(bpy)2] (M = Zn, Cd; Ln = Eu, Gd, Tb, Sm; bpy is 2,2′‐bipyridyl). The structure and isostructural nature of compounds were determined based on the single‐crystal and powder X‐ray diffraction data. The photophysical properties of the obtained compounds were studied in detail: The energies of the triplet levels of the furoate anion and d‐blocks {M(fur)2(bpy)} (M = Zn, Cd), the relaxation times of the excited states, and the quantum yields were determined. Critical step from Ln complexes to ZnLn and CdLn (Ln = Eu, Tb) is accompanied by an increase in quantum yields, which correlates with a change in the energy of the triplet level of the aromatic part of the complexes and with the results of quantum chemical calculations indicating different schemes for the origination of triplet levels in MLn compounds. [ABSTRACT FROM AUTHOR]

A series of heterometallic carboxylate 1D polymers of the general formula [LnIIICd2(piv)7(H2O)2]n·nMeCN (LnIII = Sm (1), Eu (2), Tb (3), Dy (4), Ho (5), Er (6), Yb (7); piv = anion of trimethylacetic acid) was synthesized and structurally characterized. The use of CdII instead of ZnII under similar synthetic conditions resulted in the formation of 1D polymers, in contrast to molecular trinuclear complexes with LnIIIZn2 cores. All complexes 1–7 are isostructural. The luminescent emission and excitation spectra for 2–4 have been studied, the luminescence decay kinetics for 2 and 3 was measured. Magnetic properties of the complexes 3–5 and 7 have been studied; 4 and 7 exhibited the properties of field-induced single-molecule magnets in an applied external magnetic field. Magnetic properties of 4 and 7 were modelled using results of SA-CASSCF/SO-RASSI calculations and SINGLE_ANISO procedure. Based on the analysis of the magnetization relaxation and the results of ab initio calculations, it was found that relaxation in 4 predominantly occurred by the sum of the Raman and QTM mechanisms, and by the sum of the direct and Raman mechanisms in the case of 7. [ABSTRACT FROM AUTHOR]

Varying the temperature of the reaction of [{Cd(pfb)(H2O)4}+n·n(pfb)−], [Ln2(pfb)6(H2O)8]·H2O (Hpfb = pentafluorobenzoic acid), and 1,10-phenanthroline (phen) in MeCN followed by crystallization resulted in the isolation of two type of products: 1D-polymers [LnCd(pfb)5(phen)]n·1.5nMeCN (Ln = Eu (I), Gd (II), Tb (III), Dy (IV)) which were isolated at 25 °C, and molecular compounds [Tb2Cd2(pfb)10(phen)2] (V) formed at 75 °C. The transition from a molecular to a polymer structure becomes possible because of intra- and intermolecular interactions between the aromatic cycles of phen and pfb from neighboring tetranuclear Ln2Cd2 fragments. Replacement of cadmium with zinc in the reaction resulted in molecular compounds Ln2Zn2 [Ln2Zn2(pfb)10(phen)2]·4MeCN (Ln = Eu (VI), Tb (VIII), Dy (IX)) and [Gd2Zn2(pfb)10(H2O)2(phen)2]·4MeCN (VII). A new molecular EuCd complex [Eu2Cd2(pfb)10(phen)4]·4MeCN (X)] was isolated from a mixture of cadmium, zinc, and europium pentafluorobenzoates (Cd:Zn:Ln = 1:1:2). Complexes II-IV, VII and IX exhibit magnetic relaxation at liquid helium temperatures in nonzero magnetic fields. Luminescent studies revealed a bright luminescence of complexes with europium(III) and terbium(III) ions. [ABSTRACT FROM AUTHOR]

The reactions of VOSO 4 ·3H 2 O with Na 2 (cbdc) (cbdc 2- - dianion of cyclobutane-1,1-dicarboxylic acid) and lanthanide(III) nitrates taken in a molar ratio of 1 : 2 : 1 were found to yield a series of isostructural heterometallic compounds [NaLn(VO) 2 (cbdc) 4 (H 2 O) 10 ] n (1Ln, Ln = Tb, Dy, Ho, Er, Tm, Yb). These compounds are constructed from trinuclear anionic units [Ln(VO) 2 (cbdc) 4 (H 2 O) 8 ] - ({LnV 2 } - ) linked by Na + ions into 1D polymeric chains. The crystal structures of 1Dy and 1Er were determined by single-crystal X-ray diffraction (XRD), and their isostructurality with 1Tb, 1Ho, 1Tm, and 1Yb was proved by powder X-ray diffraction (PXRD). According to alternating current (ac) magnetic susceptibility measurements, 1Dy, 1Er, and 1Yb exhibited field-induced slow relaxation of magnetization. Compound 1Er is the first representative of Er III -V IV single-molecule magnets. Measuring the temperature dependences of the phase memory time ( T m ) for 1Dy and 1Yb using pulsed EPR spectroscopy allowed us to observe the phenomenon of phase relaxation enhancement (PRE) at temperatures below 30 K. In future, this phenomenon may contribute to the evaluation of relaxation times of the lanthanide ions.