AbstractWir berichten über die Synthesen, Kristallstrukturen und physikalischen Eigenschaften von [HFe19O14(OEt)30] und [{Fe11(OEt)24}∞]. Das oktaederförmige Molekül [HFe19O14(OEt)30] kann als dreidimensionaler Ausschnitt aus dem Natriumchloridgitter aufgefasst werden, wobei das zentrale Eisenion von sechs μ6‐Oxo‐Gruppen koordiniert ist. [{Fe11(OEt)24}∞] ist ein gemischtvalentes Koordinationspolymer, in dem die FeIII‐Ionen ein dreidimensionales (10,3)‐b‐Netz bilden. Die Anordnung der FeIII‐Ionen ist mit der von Siliciumionen in α‐ThSi2 vergleichbar. Die beschriebenen Strukturen zeigen eine Schnittstelle zwischen Molekül‐ und Festkörperchemie auf.

EuIII and TbIII complexes with a benzoate and a tripod N7 ligand, [LnIII(H3L)benzoate](ClO4)2·H2O·2MeOH (LnIII=EuIII and TbIII; H3L=tris[2-(((imidazol-4-yl)methylidene)amino)ethyl]amine), were synthesized and crystallized into an isomorphous structure. Each LnIII ion is coordinated by one tripod ligand and one benzoate, resulting in a nona-coordinated capped square antiprism geometry. The solid-state emission spectra displayed sharp bands of the f–f transitions. TbIII complex exhibits a magnetic anisotropy and the ac susceptibility measurements exhibited an out-of-phase signal under 1000G bias field, indicative slow relaxation of magnetization.

The syntheses, crystal structures, and physical properties of [HFe19 O14 (OEt)30 ] and {Fe11 (OEt)24 }∞ are reported. [HFe19 O14 (OEt)30 ] has an octahedral shape. Its core with a central Fe metal ion surrounded by six μ6 -oxo ligands is arranged in the rock salt structure. {Fe11 (OEt)24 }∞ is a mixed-valence coordination polymer in which Fe(III) metal ions form three 3D interpenetrating (10,3)-b nets. The arrangement of the Fe(III) ions can also be compared to that of Si ions in α-ThSi2 . Thus, the described structures are at the interface between molecular and solid-state chemistry.

Two new Phen-Co(II) complexes bridged by a hydroxyl isophthalate ligand, {[Co(dimphen)(HIA)]·H2O}n (1) and {[Co(phen)(HIA)]·H2O}n (2) (dimphen = 2,9-dimethyl-1,10-phenanthroline, phen = 1,10-phenanthroline, HIA = 5-hydroxyisophthalic acid), have been synthesized by carefully tuning the basicity of the reaction medium. In addition to single-crystal X-ray crystallography, the complexes were also characterized by IR spectroscopy, thermogravimetric and elemental analyses. Structurally, both complexes are 1D zigzag polymers with different metal nuclearities. Variable-temperature magnetic susceptibility measurements revealed ferromagnetic coupling within the chain while antiferromagnetic ordering is propagated in parallel running interchain via π–π interactions at low temperature.

Single crystal to single crystal (SC-SC) transformation involving cooperative movement of atoms represents one of the most fascinating phenomena in coordination polymers. Here, we describe a novel two-dimensional coordination polymer {[Gd-2(L)(3)(DMF)(2)(H2O)(2)]center dot (DMF)(2)center dot(H2O)(5.5)}(n) (1) synthesized from carboxylate-based flexible ligand 5-[(anthracen-9-ylmethyl)-amino]-isophthalic acid and Gd(III) ion by the solvothermal technique. The complex undergoes solvent-induced rearrangement reactions with the cleavage and formation of coordination bonds and substantial movement of the anthracene side groups without losing crystallinity to form the daughter products as {[Gd-2(L)(3)(H2O)(4)]center dot (DMF)(4)center dot(H2O)(1.5)}(n) (1a), [Gd-2(L)(3)(DMF)(2)(H2O)]center dot(DMF)(2)center dot(DCM)(2)center dot (H2O)(5)}(n) (1b), and [Gd(L)(2)(DEF)](n) (1c). These transformations exhibit a crystallographic snapshot of "carboxylate-shift" process which is further supported by IR spectroscopy, elemental analysis, and powder X-ray diffraction patterns. To the best of our knowledge, it is the first example of carboxylate shift in a Gd(III) coordination polymer. The mother crystal 1 and the daughters 1a and 1c exhibit 4-connected sql topology, while 1b shows a 3-connected hcb topology. Magnetic susceptibility measurements at variable temperature indicate the existence of antiferromagnetic interactions in all the complexes. The photoluminescent properties of the complexes in the solid state are also investigated at room temperature.

Three novel μ2-aqua bridged dinuclear Ni(II) complexes, [Ni2(HL1)4(H2O)] (1), [Ni2(HL2)4(H2O)] (2) and [Ni2(HL3)4(H2O)] (3) have been synthesized using Schiff base ligands derived from 5-amino-1-pentanol and salicylaldehyde (H2L1), 5-bromo salicylaldehyde (H2L2) and 3-methoxy salicylaldehyde (H2L3), respectively. They are characterized by a variety of physical techniques including elemental analysis, infrared and UV–Vis spectroscopy, NMR, cyclic voltammetry, variable temperature magnetic measurements and single crystal X-ray diffraction. X-ray crystallographic analysis reveals that all the three complexes possess distorted octahedral environment with a bridging aqua ligand. Complexes 1 and 3 exhibit 3D supramolecular architecture whereas 2 demonstrates a 2D netlike arrangement along ab plane. Catecholase activity of the dinuclear Ni(II) systems are investigated using 3,5-di-tert-butylcatechol as the substrate. The complexes are efficient catalysts with turnover numbers 1.87 × 104, 1.79 × 104 and 1.38 × 104 h−1 for 1, 2 and 3, respectively. The probable structures of the intermediates formed during the process are proposed on the basis of kinetic and spectral analyses. The magnetic data disclose that weak ferromagnetic couplings are transmitted between the metal centers and the magnetic properties are correlated with the structural features around the Ni(II) centers.

Through varying the auxiliary N-donor ligands nine new compounds have been synthesized and characterised structurally and spectroscopically. The magnetic properties of the complexes have been investigated and discussed in the context of their structures.

Terbium(III) and dysprosium(III) complexes with a tripodal N7 ligand containing three imidazoles (H3L) and a bidentate acetate ion (OAc(-)), [Ln(III)(H3L)(OAc)](ClO4)2·MeOH·H2O (Ln = Tb, 1; Ln = Dy, 2), were synthesized and studied, where H3L = tris[2-(((imidazol-4-yl)methylidene)amino)ethyl]amine. The Tb(III) and Dy(III) complexes have an isomorphous structure, and each Tb(III) or Dy(III) ion is coordinated by the tripodal N7 and the bidentate acetate ligands, resulting in a nonacoordinated capped-square-antiprismatic geometry. The magnetic data, including temperature dependence of the magnetic susceptibilities and field dependence of the magnetization, were analyzed by a spin Hamiltonian, including the crystal field effect on the Tb(III) ion (4f(8), J = 6, S = 3, L = 3, g(J) = 3/2, (7)F6) and the Dy(III) ion (4f(9), J = 15/2, S = 5/2, L = 5, g(J) = 4/3, (6)H(15/2)). The Stark splittings of the ground states (7)F6 of the Tb(III) ion and (6)H(15/2) of the Dy(III) ion were evaluated from the magnetic analyses, and the energy diagram patterns indicated an easy axis (Ising type) anisotropy for both complexes, which is more pronounced for 2. The solid-state emission spectra of both complexes displayed sharp bands corresponding to the f-f transitions, and the fine structures assignable to the (5)D4 → (7)F6 transition for 1 and the (6)F(9/2) → (6)H(15/2) transition for 2 were related to the energy diagram patterns from the magnetic analyses. 1 and 2 showed an out-of-phase signal with frequency dependence in alternating current (ac) susceptibility under a dc bias field of 1000 Oe, indicative of a field-induced SIM.

Metal-based cancer chemotherapeutic agent of the type Co(II) complex [Co(mpca)₂]·H₂O (1), where, Hmpca = 9-methyl-[1,10]phenanthroline-2-carboxylic acid was synthesized and characterized by various spectroscopic and analytical techniques and further authenticated by single crystal X-ray diffraction methods. In vitro DNA binding studies of complex 1 with CT DNA was carried out by several biophysical techniques in accordance with molecular docking technique which revealed that 1 binds to DNA via intercalation mode having GC-rich sequences. Complex 1 cleaves pBR322 DNA via hydrolytic pathway (validated by T4 DNA ligase assay). Furthermore, complex 1 exhibits significant inhibitory effects on the catalytic activity of Topo-I at 25 μM concentration and further validated by molecular docking studies.

The new iron(II) complex [Fe(NCS)(2)(CH3OH)(2)(bpta)(2)] (bpta = 3,5-bis(3-pyridyl)-1,2,4-thiadiazole) has been prepared by refluxing Fe(NCS)(3) or Fe(NCS)(2) with thionicotinamide in methanol solution. It is supposed that the bpta ligand is generated in situ by the oxidative dimerization of thionicotinamide. The complex was characterized by X-ray structural analysis at 150 and 293 K, elemental analysis, spectral and magnetic measurements. The compound crystallizes in the monoclinic P2(1) space group, with unit cell parameters at 293 K: a = 7.869(2), b = 17.056(3), c = 12.637(3) angstrom, beta = 102.88(1)degrees. The crystal structure analysis showed that the iron atom has a distorted octahedral environment with FeN4O2 chromophore. Iron atom is coordinated by two nitrogen atoms from NCS ions, by two oxygen atoms from methanol molecules in the equatorial plane and by two nitrogen atoms of pyridine rings from dpta ligands in axial positions. The crystal lattice forms 2D supramolecular network which is stabilized by a system of hydrogen bonds and pi-pi stacking interactions. Variable-temperature magnetic susceptibility data in the temperature range 1.8-300 K show that the octahedral iron(II) is high-spin S = 2(T-5(2g)) and as a result effects due to zero-field splitting are anticipated at low temperatures. Structural parameters and infrared spectra of similar complexes are compared and discussed. (C) 2014 Elsevier B. V. All rights reserved.

The synthesis, spectral and magnetic properties, crystal and electronic structures of five dimeric copper(II) carboxylates, [Cu2(2-tpc)4(H2O)2] (1), [Cu2(2-tpc)4(DMSO)2] (2) (where 2-tpc is 2-thiophenecarboxylate and DMSO is dimethylsulfoxide), [Cu2(5-Me-2-tpc)4(DMSO)2]·2caffeine (3), [Cu2(5-Me-2-tpc)4(H2O)2]·0.488[(5-Me-2-tpcH·H2O)2]·0.012[Cu(5-Me-2-tpc)2(H2O)2] (4) (where 5-Me-2-tpcH and 5-Me-2-tpc are 5-methyl-2-tiophenecarboxylic acid and its deprotonated anion, respectively) and [Cu2(2-fuc)4(H2O)2]·2.5H2O (5) (where 2-fuc is 2-furancarboxylate), are reported. All five complexes adopt dimeric paddle-wheel cage structures as revealed by X-ray analyses. Moreover, the crystal structure of 4 contains, apart from dimeric paddle-wheel molecules, also other molecules that exist as a result of substitutional disorders. EPR spectra and magnetic measurements for 1, 4 and 5 confirmed an antiferromagnetic intramolecular interaction between the Cu(II) ions with −2J coupling constants of 319, 334 and 327cm−1, respectively. Density functional calculations (B3LYP hybrid functional) have been carried out on the experimental geometries in order to study the magnetic properties of the respective complexes. The computed values of 2J are overestimated by ca 110–180cm−1. Our calculations show that the coexistence of various conformers can be the source of different exchange coupling constants, despite their similar electronic structure parameters.

A novel compound [Cu2(μ1,1–N3)2(C2O4)(bpzm)2]n incorporating simultaneously azide and oxalate bridges has been synthesized and characterized in the context of its structural and magnetic properties. The crystal structure has been determined by single-crystal X-ray analysis. Additionally, the compound was characterized using IR, UV–vis and thermal analyses. The investigated complex [Cu2(μ1,1–N3)2(C2O4)(bpzm)2]n represents an interesting magnetic system of Cu(II) centers with alternating ferro- and antiferromagnetic coupling.

Seven novel compounds [Cu(pz)(2)(ScN)(2)](n) (1), [Cu(ind)(2)(SCN)(2)](n)center dot H2O (2), [Cu(4-apy)(SCN)(2)](n) (3), [Cu(4-cpy)(SCN)2](n) (4), [Cu-2(mu-SCN)(2)(SCN)(2)(2-aepy)(2)](n) (5), [Cu(2-ambzim)(SCN)(2)](n) (6) and [Cu-2(mu-SCN)(2) (SCN)(2)(pybzim)(2)] (7) have been synthesized and characterised structurally (by single X-Ray analysis) and spectroscopically. Variable-temperature magnetic susceptibility measurements were performed for the compounds 1, 3, 5, 6 and 7 and their magneto-structural properties were discussed. In structure 1, the weak Cu-S coordination bonds expand molecules [Cu(pz)(2)(SCN)(2)] to the layer extending along crystallographic (100) plane. In 2, 3 and 4, neutral trans-[Cu(ind)(2)(SCN)(2)], trans-[Cu(4-apy)(2)(SCN)(2)] and cis-[Cu(ambzim)(SCN)(2)] molecules are linked by end-to-end thiocyanate groups to an infinite one-dimensional chains. The structures 5 and 7 include neutral dinuclear entities. Copper(II) centers of 5 are doubly bridged by linear thiocyanate anions in end-on fashion, whereas the central ions of 7 are linked by SCNions in end-to-end coordination mode. The dinuclear [Cu-2(mu(1.1)-SCN)(2)(SCN)(2)(2-aePY)(2)] units are further linked by mu(1.3)-double end-to-end thiocyanate groups. Simultaneous existence of both EE and EO bridging modes makes the complex 5 a rare example of thiocyanate-bridged copper(II) structures. (C) 2012 Elsevier Ltd. All rights reserved.

A systematic studies on complex formation between Mn(II) ions, 2,3,5,6-tetra(2-pyridyl)pyrazine and halide or pseudohalide (N3−, NCS− and N(CN)2−) ligands have been carried out and the following complexes [Mn2(μ-Cl)2Cl2(tppz)2] (1), [Mn2Cl2(μ-N3-κN1)2(tppz)2] (2), [MnCl(SCN)(tppz)(H2O)]·H2O (3), [MnCl(dca)(tppz)(H2O)0.57(MeOH)0.47] (4), [Mn(NO3)2(tppz)(H2O)] (5), [Mn(N3)(NO3)(tppz)(H2O)] (6), [Mn(SCN)2(tppz)] (7) and [Mn(NO3)(dca)(tppz)]n (8) have been obtained. The compounds were characterized by elemental analysis, IR, EPR, magnetic measurements and X-ray analysis. Two of them (5 and 6) have been tested as catalysts in oxidation of alcohol to aldehydes/ketones using oxone (2KHSO5·KHSO4·K2SO4) as an oxidant under biphasic reaction conditions (CH2Cl2/H2O) and tetra-n-butylammonium bromide as phase transfer agent under air at room temperature and as catalysts in oxidation of sulfides to sulfoxides with UHP (urea hydrogen peroxide) as oxidant.

A series of 3d-4f binuclear complexes, [M(3-MeOsaltn)(MeOH)(x)(ac)Ln(hfac)(2)] (x = 0 for M = Cu-II, Zn-II; x = 1 for M = Co-II, Ni-II; Ln Gd-III, Dy-III, La-III), have been synthesized and characterized, where 3-MeOsaltn, ac, and hfac denote N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propane-diaminato, acetato, and hexafluoroacetylacetonato, respectively. The X-ray analyses demonstrated that all the complexes have an acetato- and diphenolato-bridged M-II-Ln(III) binuclear structure. The Cu-II-Ln(III) and Zn-II-Ln(III) complexes are crystallized in an isomorphous triclinic space group PT, where the Cu-II or Zn-II ion has square pyramidal coordination geometry with N2O2 donor atoms of 3-MeOsaltn at the equatorial coordination sites and one oxygen atom of the bridging acetato ion at the axial site. The Co-II-Ln(III) and Ni-II-Ln(III) complexes are crystallized in an isomorphous monoclinic space group P2(1)/c, where the Co-II or Ni-II ion at the high-spin state has an octahedral coordination environment with N2O2 donor atoms of 3-MeOsaltn at the equatorial sites, and one oxygen atom of the bridged acetato and a methanol oxygen atom at the two axial sites. Each Ln(III) ion for all the complexes is coordinated by four oxygen atoms of two phenolato and two methoxy oxygen atoms of "ligand-complex" M(3-MeOsaltn), four oxygen atoms of two hfac(-), and one oxygen atom of the bridging acetato ion; thus, the coordination number is nine. The temperature dependent magnetic susceptibilities from 1.9 to 300 K and the field-dependent magnetization up to 5 T at 1.9 K were measured. Due to the important orbital contributions of the Li-III (Tb-III, Dy-III) and to a lesser extent the M-II (N-III, Co-II) components, the magnetic interaction between M-II and Ln(III) ions were investigated by an empirical approach based on a comparison of the magnetic properties of the M-II-Ln(III), Zn-II-Ln(III), and complexes. The differences of chi T-M and M(H) values for the M-II-Ln(III), Zn-II-Ln(III) and those for the M-II-La-III complexes, that is, Delta(T) = (chi T-M)(MLn) - (chi T-M)(znLn)-(chi T-M)(MLa) = J(MLn)(T) and Delta(H) = M-MLn(H) - M-ZnLn(H) - M-MLa(H) = J(MLn)(H), give the information of 3d-4f magnetic interaction. The magnetic interactions are ferromagnetic if M-II = (Cu-II, Ni-II, and Co-II) and Ln = (Gd-III, Tb-III, and Dy-III) The magnitudes of the ferromagnetic interaction, J(MLn)(T) and J(Mln)(H), are in the order Cu-II-Gd-III > Cu-II-Dy-III > Cu-II-Tb-III, while those are in the order of M-II-Gd-III approximate to M-II-Tb-III > M-II-Dy-III for M-II = Ni-II and Co".Alternating current (ac) susceptibility measurements demonstrated that the Ni-II-Dy-III and Co-II-Tb-III complexes showed out-of-phase signal with frequency-dependence and the Ni-II-Dy-III and Co-II-Dy-II complexes showed small frequency-dependence. The energy barrier for the spin flipping was estimated from the Arrhenius plot to be 14.9(6) and 17.0(4) K for the (NiII-TbIII) and Co-II-Tb-III complexes, respectively, under a dc bias field of 1000 Oe.

A novel Mn(II) phosphate coordination polymer, {Mn-2.5(HPO4PO4)H2O)(2)}(n), has been synthesized under solvothermal conditions. This is the first phosphate-based Mn(II) complex, which is obtained in excellent yield without using any external organic amine as a structure directing agent. The complex has a 3D non-interpenetrated unprecedented 5-nodal (5,5,6,6,7)-connected pkb1 topological network. It has been characterized by single-crystal X-ray diffraction, IR spectroscopy, elemental analysis (CHN analyzer and energy-dispersive X-ray spectroscopy), and thermogravimetry. Variable temperature magnetic susceptibility measurements indicate that the complex exhibits spin-canted antiferromagnetic behaviour at low temperature. The electron paramagnetic resonance measurements, at ambient and at low temperature, of the complex are also consistent with magnetic behaviour.

Three novel heterobimetallic coordination polymers [Mn(Me-Im)2Hg(SCN)4]n (1, Me-Im=N-methyl-imidazole), [Mn(tp)(MeOH)Hg(SCN)4]n (2, tp=1,2,4-triazolo-[1,5-a]pyrimidine) and [Mn(bopy)2Hg(SCN)4]n (3, bopy=2-benzoylpyridine) have been synthesized and characterized by spectroscopic methods, single crystal X-ray diffraction analysis and magnetic measurements. X-ray analysis reveals that the compounds create three-dimensional coordination polymers. Variable-temperature magnetic susceptibility measurements show very weak antiferromagnetic interactions between the paramagnetic Mn(II) centers of structures 1, 2 and 3.

New higly unsaturated macrocyclic building blocks [CuLSCN]·ClO4 (1) (L=N-dl-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene) and [NiL(SCN)2] (2) (L=N-dl-5,12-dimethyl-7,14-diisopropyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene) were synthesized and the crystal structures of both compounds were determined. Both complexes crystallizes in monoclinic, space group P21/n (1) and P21/c (2). Their magnetic properties were studied over the temperature range 1.8–300K using a Quantum Design SQUID magnetometer (MPMSXL-5-type). The results indicate that both compounds behave as weakly interacting paramagnetic centers in the crystal lattice. The effects of hydrogen bond mediating the magnetic exchange interactions on the spin density have been evidenced by DFT calculations. The NIR–Vis–UV diffuse-reflectance electronic spectra confirm the square pyramidal and octahedral geometry around Cu2+ and Ni2+ metal ions.

The synthesis and spectral characterization of four new complexes [Cu2(5-Me-2-tpc)4(N-Menia)2] (1), [Cu(5-Me-2-tpc)2(N-Menia)2(H2O)2] (2), [Cu(3-Me-2-tpc)2(N-Menia)2]·H2O (3), and [Cu2(2-tpc)4(N-Menia)]n (4) (where 2-tpc is 2-thiophenecarboxylate, 3-Me-2-tpc is 3-methyl-2-thiophenecarboxylate, 5-Me-2-tpc is 5-methyl-2-thiophenecarboxylate and N-Menia is N-methylnicotinamide) with various structural types is reported and their X-ray structures were determined. The complex molecules of 1–3 are connected through hydrogen bonds into 2D networks. On the other hand, the compound 4 forms 1D zigzag coordination polymer. Electronic, IR, EPR spectra and magnetic susceptibility over the temperature range 1.8–300K are discussed in terms of known crystal and molecular structure. The carboxyl group of the thiophenecarboxylate anions coordinates to the Cu(II) atom as a unidentate (complex 2) or as a bidentate bridging (complexes 1 and 4) as well as bidentate chelating (complex 3) ligand. Based on the IR spectra it can be concluded that hydrogen bonds strongly influence the position and the shape of the stretch vibrations bands assigned to NH and amide carboxyl group CO. EPR spectra and magnetic properties of the complexes 2 and 3 exhibit the magnetism which is typical for isolated monomeric Cu(II) ions and in case of the complexes 1 and 4 as dimeric exchange-coupled copper(II) pairs.

Four new Co(II) containing coordination polymers have been synthesized using an ether bridged tricarboxylic acid ligand, o-cpiaH(3) (5-(2-carboxy-phenoxy)-isophthalic acid). This ligand readily reacts with CoCl2 center dot 6H(2)O in the presence of different nitrogen donor ligands such as 1,10-phenanthroline (phen), 4,4'-bipyridyl (bpy), 4,4'-azopyridine (apy), and 1,4-bis(4-pyridinylmethyl)piperazine (bpmp) under hydrothermal conditions to afford three 3D and one 2D coordination polymers, {Co-3(o-cpia)(2)(phen)(H2O)center dot 5H(2)O}(n) (1), {Co-1.5(o-cpia)(bpy)}(n) (2), {Co-2(o-cpia)(OH)(apy)(0.5)}(n) (3), and {Co(o-cpiaH)(bpmp)(0.5)}(n) (4). Single crystal X-ray studies show that these coordination polymers contain homometallic clusters varying from dimeric to tetrameric depending upon the co-ligand used. In complexes 1 and 2, Co(II) ions form an angular and linear trimeric unit that extends along all directions to generate an overall 3D structure. In contrast, 3 forms a 3D coordination polymer containing a tetranuclear Co(II) unit. When the distance between the two donor N atoms of the co-ligand is further increased as in 4, a (4,4) net connected 2D coordination polymer results where the Co(II) ions form a dimeric paddle wheel unit. In addition to single-crystal X-ray crystallography, the complexes are also characterized by IR spectroscopy, thermogravimetry, and elemental analysis. Variable temperature magnetic susceptibility measurements on the complexes were carried out over the temperature range 1.72-300 K. Complex 1 exhibits ferromagnetic interactions due to uncompensated magnetic moments of the system leading to spin-canted antiferromagnetic behavior, while 2 and 3 show predominantly antiferromagnetic interactions. Complex 4 exhibits weak ferromagnetic behavior below 9 K.