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The crystal structure of the complex (α R ,6 R )-Na[Gd(H 2 O)-AAZTA-C 2 H 4 COOBn]·3H 2 O·EtOH was determined by single crystal X-ray diffraction; the complex represents a bifunctional derivative of Gd-AAZTA, previously reported as original scaffold for the development of efficient contrast agents for MRI. The Gd(III) ion is nine coordinated with three nitrogens, five carboxylate oxygens and one water oxygen in a monocapped distorted square antiprism coordination polyhedron. Three of the five carboxylic groups are monodentate while a fourth is bidentate bridging an adjacent Gd ion with the formation of a polymeric structure. The influence on the overall structure of the propionate side arm introduced for conjugation purposes was discussed, and a computational approach to predict the structure of its (α R ,6 S ) isomer is presented and compared with the X-ray structure of the (α R ,6 R ) epimer.

The crystal structure of catena-di(μ2-2-thiobarbiturato-O,S)aqualead(II) C8H8N4O5S2Pb (C4H4N2O2S is 2-thiobarbituric acid, H2TBA) is determined. Crystallographic data for catena-[Pb(H2O)(μ2-HTBA-O,S)2] are as follows: a = 6.5972(1) A, b = 9.8917(2) A, c = 10.0893(2) A, α = 106.702(1)°, β = 93.395(2)°, γ = 107.48(1)°, V = 593.82(2) A3, space group \(P\bar 1\), Z = 2. The Pb2+ ion is linked with six monodentate HTBA− ligands through two O atoms and four S atoms and also connected with a water molecule. Additionally, there is a shortened Pb-S contact (3.622 A), given which the complex polyhedron represents a distorted square antiprism. Hydrogen bonds N-H…O and O-H…O form a branched three-dimensional network. The structure is also stabilized by the π-π interaction of heterocyclic HTBA− ions.

Complex behaviours of americium(III) and europium(III) with nitrate anions have been studied using density functional theory and small-core quasi-relativistic effective core potential. The structural parameters of a series of hydrated and nitrate complexes of Am(III) and Em(III) are probed and compared to available EXAFS studies. The thermodynamic stability of these species is calculated by simulating related complexation reactions both in the gas phase and aqueous solution. For taking into account the solvent effect, both the solvation model density (SMD) implicit solvent model and the conductor-like screening model (COSMO) are adopted for comparison. From our calculations, the octa–aqua and non-aqua species of Am(III) and Eu(III), [M(H2O)8,9]3+ (M = Am, Eu), form square antiprism and trigonal prism structures, respectively. In the presence of rich-enough nitrate ions, at most three nitrate anions can chelate to Am(III)/Eu(III) ions in a bidentate fashion in the first coordination shell, owing to the str...

Five new lanthanide tetrahydrofuran-2-carboxylate (THFC) complexes [Ln(THFC)2(H2O)2]·L·H2O (Ln = Eu; L = Cl−, Br−, NO3− and Ln = Tb; L = Cl−, NO3−) have been synthesized. The crystal structures of four compounds were solved by the X-ray diffraction method. The Ln3+ ions are coordinated to eight oxygen atoms: six oxygen atoms are provided by two tridentate bridging-cyclic THFC ligands, and the other two by water molecules. The Ln3+ coordination polyhedron can be described as a distorted square antiprism. The structures consist of planar layers linked by hydrogen bonds through outer-sphere L anions and H2O molecules. The influence of the L anion on the Eu3+ luminescence center is analyzed with the help of luminescence and IR vibrational spectroscopy. The distortions of the square antiprism increase with the size of the L outer-sphere anions. Consequently, the lowering of the symmetry of the crystal field around the Eu3+ ion appears as an extra splitting of the 7FJ levels under the influence of the crystal field components of the second and fourth ranks.

Motivated by photoinduced magnetism in the mixed-valent bimetallic compounds with the general formula Cu2II [MoIV(CN)8]·xH2O, we investigate their ground-state properties, in comparison with those of nickel-molybdenum analogs, by employing a group-theoretical technique. These bimetallic assemblies consist of octacyanomolybdenum complexes with a square antiprism configuration and crystallize in the I4/m tetragonal symmetry. We set up a relevant three-band extended Hubbard Hamiltonian and systematically calculate its broken-symmetry solutions. An itinerant ferromagnetism extending over both the Cu and the Mo sublattices closely competes with the localized paramagnetism in Cu2[Mo(CN)8] whereas spins are rather localized in the Ni sublattice and an antiferromagnetism is likely to predominate in the ground-state phase diagram in Ni2[Mo(CN)8].

A new ternary potassium cobalt stannide, K13CoSn17–x (x = 0.1), was obtained by reacting the mixture of the corresponding pure elements at high temperature, and structurally characterized by single-crystal X-ray diffraction study. K13CoSn17–x (x = 0.1) crystallizes in the orthorhombic space group Pbca (No. 61) with a = 26.2799(7) A, b = 24.1541(6) A, c = 29.8839(6) A, V = 18969.3(8) A3, and Z = 16. Its structure contains isolated [CoSn9] monocapped square antiprism and [Sn4] tetrahedron in the ratio 1:2, forming a hierarchical variant of Laves phase MgZn2. The structural relation between the title compound with MgZn2 as well as other binary stannides is also discussed.

An investigation of the coordination behavior of sulfur-containing mixed-donor tribenzo-macrocycles L-L (L: 20-membered O3S2, L : 20-membered O2S3, and L : 23-membered O4S2) with d -metal (Ag, Hg, and Pb) salts is reported. The X-ray structures of five complexes (1-5) with different structural types and stoichiometries, including monoto dinuclear species have been determined. Reactions of L and L with the silver(I) salts (PF6 − and SCN−) afforded two dinuclear 2:2 (metal-to-ligand) complexes with different arrangements: a sandwich-type cyclic dinuclear complex [Ag2(L 2)2](PF6)2·3CH2Cl2 (1) and a linear dinuclear complex [Ag2(L 3)2(SCN)2] (2), in which two monosilver(I) complex units are linked by an Ag-Ag contact. Reactions of L and L with mercury(II) salts (SCN− and Cl−) gave a mononuclear 1:1 complexes [Hg(L1)(SCN)2] (3) and [Hg(L2)Cl2] (4) with anion coordination in both cases. L 2 reacts with lead(II) perchlorate to yield a mononuclear sandwich-type complex [Pb(L2)2(ClO4)2] (5), giving an overall metal coordination geometry of eight with a square antiprism arrangement. From these results, the effects of the donor variation and the anioncoordination ability on the resulting topologies of the soft metal complexes are discussed.

The mixed-ligand lanthanide(III) complexes derived from the tetraiminodiphenolate (L1H2) or octaiminotetraphenolate (L2H4) macrocyclic ligands and acetate (OAc−) or benzoate (OBz−) anions have been synthesized and structurally characterized. With the ligand combination L1H2 and OBz−, either the dimeric complexes [{Ln(L1H2)}2(μ2-η1:η1-OBz)4](ClO4)2 (Ln = La (1), Nd (2) and Eu (3)) or the monomeric complexes [Ln(L1H2)(η2-OBz)2](ClO4)·n solvent (Ln = Tb (4), Lu (5) and Y (6)) have been obtained. The X-ray crystal structures of 1, 4 and 6 have been determined, of which 4 and 6 have the same structure. L1H2 and OAc− combination affords the dimeric complexes [{Ln(L1H2)(η2-OAc)(μ-OAc)}2](ClO4)2 (Ln = La (7), Nd (8) and Y (9)) and the structure of 9 has been determined. In complexes 1–9, L1H2 uses two imino nitrogens and the two phenolate oxygens for metal coordination, while the other two uncoordinated imine nitrogens are protonated and intramolecularly hydrogen-bonded to the phenolate oxygens. The metal centre in all the cases is 8-coordinate and has distorted square antiprism geometry. With the octaiminotetraphenolate macrocyclic ligand (L2H4) dinuclear complexes of composition [Ln2(L2H4)(OAc)2(NO3)4]·nH2O (Ln = La (10), Pr (11), Nd (12) and Y (13)) have obtained. The structures determined for 11 and 12 have shown that they are isostructural and there are two independent molecules (A and B) in the unit cell. The molecule A has the bond types [Ln2(L2H4)(η2-OAc)2(η2-NO3)2(η1-NO3)2] and its 9-coordinate metal centre obtains a tricapped trigonal prismatic geometry, while the molecule B is [Ln2(L2H4)(η2-OAc)2(η2-NO3)4] whose 10-coordinate metal centre has a sphenocorona geometry. In these compounds, four uncoordinated imine nitrogens are protonated and hydrogen-bonded to the phenolate oxygens. The luminescence spectra of [{Eu(L1H2)}2(μ-OBz)4]2+ (32+) in acetonitrile (at 298 K) and in acetonitrile-toluene glassy matrix (at 77 K) have been studied.

In this paper, we report the syntheses, crystal structures, and magnetic properties of two manganese(II)–octacyanoniobate(IV)-based magnets: MnII2[NbIV(CN)8](3-pyridinemethanol)8·2H2O (1) and MnII2[NbIV(CN)8](3-aminopyridine)8·2H2O (2). 1 and 2 possess 3D network structures where a [Nb(CN)8]4− ion is connected to four Mn ions, and a Mn ion is connected to two [Nb(CN)8]4− ions via bridged cyanides. The coordination geometry of [Nb(CN)8] in 1 is square antiprism, while that in 2 is dodecahedron. Magnetic measurements show that 1 and 2 are ferrimagnets with Curie temperatures (TC) of 24 and 43 K, respectively, although the coordination numbers of the bridged CN groups around Nb and Mn ions are the same. The difference in TC can be understood by considering the difference in the coordination geometries of [Nb(CN)8]. Molecular orbital calculations of [NbIV(CN)8] using the discrete variational (DV)-Xα method indicate that the population of the 2p orbital on the bridged N with a dodecahedron geometry is larger than that with a square antiprism geometry. The calculation results suggest that the charge population of the 2p orbital on the cyano-nitrogen affects the superexchange interaction for the magnetic orbital of Nb C N Mn, which determines the TC value.

In this study, the composition and stability constants of a mixed ligand complex of Sc(III), Y(III) and La(III) ion by using NTA (H3B) (Nitrilotriacetic acid) and HEDTA (H3B) (N-(2-hydroxyethyl)ethylenedinitrilotriacetic acid) as a primary ligand and 2,3-DHBA (H(3)A) (2,3-dihydroxybenzoic acid) as secondary ligand have been determined by using a potentiometric method and the BEST computer programme at 25 degrees C, in a 0.1 M NaCl ionic medium. The complex stability was found to follow the trend Sc(III) > Y(III) > La(III) based on the ionic radius of the metal ions.

Two sets of isostructural mononuclear compounds, [Ln(LOMe)2(H2O)2](PF6) [1, Ln = Er; 3, Ln = Gd; LOMe = CpCo{P(O)(O(CH3))2}3] and Ln(LOMe)2(NO3) (2, Ln = Er and 4, Ln = Gd), are synthesized by self-assembly of the respective lanthanide ions and tripodal chelate ligands. The Ln ions are encircled by two LOMe ligands, and two water molecules or one nitrate anion. Each octacoordinated Ln center adopts a distorted square antiprism geometry. The Er complex (2) chelated by a nitrate anion shows slow dynamics in magnetic relaxation, diagnostic of a single-ion magnet. Quantum tunneling in 2 is effectively blocked by application of an external field. Weak intermolecular magnetic interactions occur in 2, and are supported by the magnetic behavior of 4. Chemical dilution of Er with the diamagnetic Y ion can nullify magnetic interactions and suppress quantum tunneling. Generation of slow relaxation dynamics in the Er system is related to the anisotropic charge distribution supplied by the coordination of ligands with different charge densities, as observed in the Dy analogue. This suggests that magnetic anisotropy arises in a coordination system when an anisotropic lanthanide ion (Dy and Er) is surrounded by a ligand environment with anisotropic charge density, resulting in slow magnetic relaxation.

The structures and energetics of the tetracarbaboranes C4Bn−4Hn (n = 6 to 13) have been investigated by density functional theory and coupled cluster calculations. In general, the lowest energy structures of the tetracarbaboranes C4Bn−4Hn minimize the number of C–C polyhedral edges as well as the degrees of the carbon vertices. For the C4B2H6 and C4B3H7 systems the lowest energy structures are pyramidal structures having all four carbon atoms located on the base of the pyramid. The lowest energy structure for the 9-vertex C4B5H9 system is a capped square antiprism. The frameworks of the lowest energy C4B4H8 and C4B6H10 structures resemble those of the isoelectronic experimentally known B8H12 and B10H14 structures. However, an experimentally known S4 adamantane-like 10-vertex structure found in Me4C4B6Et6 based on a tetracapped octahedron lies only ∼7 kcal mol−1 in energy above the lowest energy structure. The lowest energy structures for the 11- to 13-vertex C4Bn−4Hn (n = 11, 12, 13) systems can be derived from an (n + 1)-vertex closo deltahedron by removing a high-degree vertex. At least three of the four carbon atoms are located on edges of the resulting pentagonal or hexagonal open face in the low-energy structures. However, the structures of the experimentally known R4C4B8H8 (R = Me, Et) obtained from the dimerization of R2C2B4H42− differ from these low-energy structures. The Me4C4B8H8 polyhedron has a C4 chain and two tetragonal faces whereas the Et4C4B8H8 polyhedron has a hexagonal face with two C2 units. These structures lie within 2 kcal mol−1 of each other thereby accounting for the fluxional properties of these systems observed by NMR spectroscopy.

The angular distribution function (ADF) associated with the oxygen–metal ion-oxygen angle (OMO) of several trivalent lanthanoid and actinoid aquaions has been used to identify the most probable coordination geometry of these aquaions in aqueous solutions. The ADFs extracted from the molecular dynamics trajectories have been compared with continuous distribution functions corresponding to the geometry of a reference polyhedron pattern. The procedure incorporates specific quantum-mechanical information on the aquaion under study. The new method is applied to the analysis of four M(H2O)n3+ aquaions in water, M = Lu and Cf for n = 8, and M = La and Ac for n = 9. For those that are 8-coordinated, the square antiprism (SA) coordination geometry is preferred. For the 9-fold coordination, the simulation ADFs are more similar to the continuous ADF derived from a Gyro-elongated-SA rather than to the usually proposed trigonal tricapped prism. Advantages of these continuous distributions with respect to the usually e...

The hydration of K+(H2O) n has been widely studied and believe to be important for understanding solvent properties in biological and chemical systems. However, understanding the structure and the spectrum information K+(H2O) n with changing n is limited. Here, we investigated the clusters K+(H2O) n=1–16 and further studied the IR spectrums of the most stable clusters with density functional theory. The configuration, bond length, vibration frequency were given out. It shows that K+(H2O)8(H2O) n , a distorted square antiprism in inner layer, is the main configuration with hydration distance r K - OI 0.296 nm when the hydration number n is bigger than 8. The saturated hydration number is 8 in the first hydration layer and the water molecules of the second hydration sphere have little effect on the inner ones when n> 8. A detailed classification about the hydrated water molecules was made according to the role of acceptor or donor hydrogen bonding in clusters. The vibration frequency of the different kinds of water molecules were also detailly identified. The results are valuable for further determination of the K+(H2O) n clusters in aqueous solutions.

The structure and stability features of Na+Xe n (n ≤ 54) clusters are theoretically investigated via model potential energy surfaces (PES) and unconstrained global optimization. The potential energy is described in terms of pair-additive potentials including polarization parametrized from accurate ab initio data on Na+Xe, complemented by three-body contributions describing the interaction between the dipoles induced by the sodium ion on the rare gas atoms. We show that the three-body contributions stabilize the linear or planar structures versus more compact shapes for n< 4. At larger sizes, the growth around the square antisprism (SA) or capped square antisprism (CSA) core is favored while icosahedral pattern based isomers exist but not as the lowest ones. A transition in the metal ion coordination from 8 (square antiprism) to 12 (icosahedron) is seen to occur near n = 50. The results are discussed and analyzed in view of existing accurate ab initio calculations on Na+Xe2 and comparisons with similar metal-ion clusters.

Reaction of the binary Zintl anion (Sn2Sb2)2− with the β-diketiminato complex [LCu(NCMe)] (L=nacnac=[(N(C6H3iPr2-2,6)C(Me))2CH]−) in ethylenediamine or DMF affords the ternary cluster dimer {[CuSn5Sb3]2−}2 (1) as its [K(crypt-222)]+ salt. The chemical formulation of 1 is supported by energy-dispersive X-ray spectroscopy (EDX) and quantum chemical calculations. Each monomeric part of the dimer represents a trimetallic “[CuSn5Sb3]2−” cluster, with an architecture in between a tricapped trigonal prism and a capped square antiprism. As shown by quantum chemical investigations, the presence of Sb atoms and, in particular, of Cu atoms in the cluster skeleton makes the monomeric unit behave like an inhomogeneous superatom, which clearly prefers to dimerize, thereby producing a relatively short, yet virtually non-bonding Cu⋅⋅⋅Cu distance.

An isophthalate-bearing DOTA monoamide derivative has been synthesised and used to prepare a family of lanthanide complexes. Luminescence and NMR studies in solution show that the predominant form of the complexes in solution is a mono-capped square antiprism about the lanthanide centre, in which a solvent molecule occupies the ninth coordination site. The crystal structure of the terbium complex is presented and is in close agreement with the solution state data.

Dual-photosensitized stable EuΙΙΙ and TbΙΙΙ complexes, namely [Eu(dpq)(tfnb)3] (1) and [Tb(dpq)(tfnb)3] (2), in which dpq=dipyrido[3,2-d:2′,3′-f]quinoxaline and Htfnb=4,4,4-trifluoro-1-(2-napthyl)-1,3-butanedione, were designed as bioimaging and light-responsive therapeutic agents. Their X-ray structures, photophysical properties, biological interactions, photoinduced DNA damage, photocytotoxicity, and cellular uptake properties were studied. Discrete mononuclear complexes adopt an eight-coordinated {LnN2O6} distorted square antiprism geometry with bidentate N,N-donor dpq and O,O-donor tfnb ligands. The designed probes have the advantage of dual-sensitizing antennae (dpq, Htfnb) to modulate their desirable optical properties for cellular imaging and light-responsive intracellular damage. The remarkable photostability, absence of inner-sphere water (q

The hydration structure and dynamics of Sc(3+) in aqueous solution have been investigated using a combined approach based on quantum mechanical (QM) calculations, molecular dynamics (MD) simulations, and extended X-ray absorption fine structure (EXAFS) spectroscopy. An effective Sc-water two-body potential has been generated from QM calculations and then used in the MD simulation of Sc(3+) in water, and the reliability of the entire procedure has been assessed by comparing the theoretical structural results with the EXAFS experimental data. The outstanding outcome of this work is that the Sc(3+) ion forms a well-defined capped square antiprism (SAP) complex in aqueous solution, where the eight water molecules closest to the ion are located at the vertexes of a SAP polyhedron, while the ninth water molecule occupying the capping position is unusually found at a very long distance from the ion. This far-coordinated water molecule possesses a degree of structure comparable with the other first shell molecules surrounding the ion at much shorter distances, and its presence gave us the unique opportunity to easily identify the geometry of the Sc(3+) coordination polyhedron. Despite very strong ion-water interactions, the Sc(3+) hydration shell is very labile, as the far-coordinated ligand allows first shell water molecules to easily exchange their positions both inside the solvation shell and with the rest of the solvent molecules.

A series of novel isocloso-diiridaboranes [(Cp*Ir)2B6H6], 1, 2; [1,7-(Cp*Ir)2B8H8], 4; [1,4-(Cp*Ir)2B8H8], 5; [(Cp*Ir)2B9H9], 8; isonido-[(Cp*Ir)2B7H7], 3; and 10-vertex cluster [5,7-(Cp*Ir)2B8H12], 6 (Cp* = η(5)-C5Me5) have been isolated and structurally characterized from the pyrolysis of [Cp*IrCl2]2 and BH3·thf. On the other hand, the corresponding rhodium system afforded 10- and 11-vertices clusters [5-(Cp*Rh)B9H13)], 7, and [(Cp*Rh)2B9H9], 9, respectively. Clusters 1 and 2 are topological isomers. The geometry of 1 is dodecahedral, similar to that of its parent borane [B8H8](2-), in which two of the [BH] vertices are replaced by two [Cp*Ir] fragments. The geometry of 2 can be derived from a nine-vertex tricapped trigonal prism by removing one of the capped vertices. Compounds 4 and 5 are 10-vertex isocloso clusters based on a 10-vertex bicapped square antiprism structure. The only difference between them is the presence of a metal-metal bond in 5. The solid-state structures of 8 and 9 attain an 11-vertex geometry in which a unique six-membered B6H6 moiety is bonded to the metal center. In addition, quantum-chemical calculations have been used to provide further insight into the electronic structure and stability of the clusters. All the compounds have been characterized by IR and (1)H, (11)B, and (13)C NMR spectroscopy in solution, and the solid-state structures were established by X-ray crystallographic analysis.

The title compound, which has a ten-atom deltahedral cluster core of Ge9 Pd, was synthesized through insertion of Pd(PPh3 ) into the tetrasubstituted nona-germanium cluster [(Me3 Si)Si]3 EtGe9 through a reaction of the latter with Pd(PPh3 )4 . This first reaction of neutral tetrasubstituted nine-atom clusters shows that they retain reactivity despite their neutral charge. The Ge9 Pd core is the first that incorporates a 5-connected transition metal other than from Group VI, a noble metal in this case. Single-crystal X-ray diffraction shows that the ten-atom core is a closo-cluster with the expected shape of a bicapped square antiprism. (1) H and (13) C NMR spectroscopy show that, in contrast to the parent tetra-substituted [(Me3 Si)Si]3 EtGe9 , the new compound does not exhibit dynamics. Relativistic DFT calculations are used to explain the differences.

International audience; New ferrocenoylacetonate complexes of several rare earth elements, [Ln(fca)3(bpy)]·MeC6H5 (Ln = Pr (1), Eu (2), Gd (3), Tb (4), Dy (5), Ho (6), Y (7); bpy – 2,2’-bipyridine; Hfca – FcCOCH2COMe) as well as scandium ferrocenoylacetonate [Sc(fca)3]·0.5MeC6H5 (8), were synthesized and characterized by single crystal X-ray diffraction analysis. In the crystal lattice of the isostructural complexes 1–7, two [Ln(fca)3(bpy)] molecules form a pair due to stacking interactions between the bpy ligands. The Ln3+ ions are coordinated in a square antiprism geometry with a coordination number of 8. The Sc3+ ions in complex 8 are coordinated in an octahedral geometry. Thermolysis of complexes 1–7 was studied under air and argon atmospheres; in the first case, it affords perovskites LnFeO3 as one of the products. Complexes 4–6 display single-molecule magnet properties, and the effective relaxation barrier for the Dy complex 5, was found to be Δeff/kB = 241 K, which is one of the highest values obtained for a mononuclear β-diketonate lanthanide complex.

We use molecular simulation to study the structural and dynamic properties of glassy nanoclusters formed both through the direct condensation of the vapor below the glass transition temperature, without the presence of a substrate, and \textit{via} the slow supercooling of unsupported liquid nanodroplets. An analysis of local structure using Voronoi polyhedra shows that the energetic stability of the clusters is characterized by a large, increasing fraction of bicapped square antiprism motifs. We also show that nanoclusters with similar inherent structure energies are structurally similar, independent of their history, which suggests the supercooled clusters access the same low energy regions of the potential energy landscape as the vapor condensed clusters despite their different methods of formation. By measuring the intermediate scattering function at different radii from the cluster center, we find that the relaxation dynamics of the clusters are inhomogeneous, with the core becoming glassy above the glass transition temperature while the surface remains mobile at low temperatures. This helps the clusters sample the highly stable, low energy structures on the potential energy surface. Our work suggests the nanocluster systems are structurally more stable than the ultra-stable glassy thin films, formed through vapor deposition onto a cold substrate, but the nanoclusters do not exhibit the superheating effects characteristic of the ultra-stable glass states., 4 Figures

A new ligand grafted polymeric resin (BenzoDODA SDVB) was synthesized by covalently attaching plutonium selective ligand (BenzoDODA) on to styrene divinyl benzene (SDVB) polymer matrix. BenzoDODA SDVB resin was evaluated for separation and recovery of plutonium(IV) from nitric acid medium. Sorption of Pu(IV) was found to decrease with the increase in nitric acid concentration, with very small sorption above 7.0 M HNO 3 . Sorption kinetics was fast enough to achieve the equilibrium within 60 min of contact where the kinetic data fitted well to pseudo-second-order model. Sorption isotherm data fitted well to Langmuir model suggesting chemical interaction between the BenzoDODA moiety and plutonium(IV) ions. Sorption studies with some of representative radionuclides of high level waste showed that BenzoDODA SDVB is selective and therefore could be a promising solid sorbent for separation and recovery of plutonium. Further, the theoretical calculations done on BenzoDODA SDVB resin suggested Pu(NO 3 ) 4 ·BenzoDODA (1:1) sorbed complex conformed to generally observed square antiprism geometry of the plutonium complexes, with contributions from oxygen atoms of four nitrate ions as well as from four oxygen atoms present in BenzoDODA (two phenolic ether oxygen atoms and two carbonyl oxygen atoms of amidic moiety).

The preparation of discrete tetranuclear lanthanide/alkali metal (Ae) assemblies bearing a tribenzoylmethane ligand (LH) is discussed. These assemblies have the general formula [Ln(Ae·HOEt)(L)4]2, where Ln3+ = Gd3+, Tb3+, Dy3+, Ho3+ and Ae+ = Na+, K+, Rb+. The coordination geometries of the lanthanide species were analyzed and compared, revealing a trend between an eight-coordinate square antiprism and triangular dodecahedron dependent on the nature of lanthanide, alkali metal, and lattice solvent. The potassium-containing analogs were also analyzed for their magnetic susceptibility.

Two thallium (I) thorium (IV) fluorides, TlTh3F13 and TlThF5 were obtained by solid state synthesis and their crystal structures determined from single crystal X-ray diffraction data recorded at room temperature with an APEX-II CCD diffractometer. TlTh3F13 is orthorhombic, space group Pmc21, with a=8.1801(2) A, b=7.4479(2) A, c=8.6375(2) A, V=526.24(2) A3, Z=2 and TlThF5 is monoclinic, space group P21/n, with a=8.1128(5) A, b=7.2250(4) A, c=8.8493(6) A, β=116.683(3)°, V=463.46(5) A3, Z=4. The structure of TlTh3F13 comprises layers of corner and edge-sharing ThF9 polyhedra further linked by chains of trans connected tricapped trigonal prisms ThF9 through corners and edges. The three dimensional thorium frameworks delimits channels parallel to [0 0 1] where the 11-coordinated Tl+ ions are arranged into double columns located in mirror planes of the structure. TlTh3F13 is isotypic with RbTh3F13, RbU3F13 and with one of the two polymorphs of CsTh3F13. The structure of TlThF5 may be regarded as a layer structure built up from the regular succession of ∞2[M′F5]− corrugated layers further held by the Tl+ ions along the [1 0 1] direction. The layers are built up from edge and corner-sharing thorium polyhedra where each (ThF9)5− monocapped square antiprism is connected to five others by sharing three edges and two corners. TlThF5 is isostructural with β-NH4UF5 and with one of the polymorphs of CsThF5. A comparison of the different structural types of MM′F5 pentafluorides is presented and a diagram of repartition of their structures is given. From the comparison of the Tl structures with their Rb or Cs homologs, where very similar monovalent cation environments are observed it should be concluded to a stereochemically inactivity of the 6s2 lone pair of Tl(I) in both TlTh3F13 and TlThF5, contrary to what is observed in richer Tl(I) content Tl3ThF7 fluorothorate.

We construct a microscopic theory on the photomagnetism in the cyano-bridged bimetallic assemblies Cu2[Mo(CN)8]·𝓍H2O. Going through a grouptheoretical analysis on the ground-state properties, we simulate photoirradiation and the resultant magnetization dynamics with a time-dependent Hartree-Fock method. It is not c-axis-polarized photons but those polarized in the ab plane that induce a macroscopic magnetization. Absorption of the photon energy is double-stepped and the occurrence of a significant magnetization is simultaneous with the second stage (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Here we develop a general approach to calculating the energy spectrum and the wave functions of the low-lying magnetic levels of a lanthanoid ion submitted to the crystal field created by the surrounding ligands. This model allows us to propose general criteria for the rational design of new mononuclear lanthanoid complexes behaving as single-molecule magnets (SMMs) or acting as robust spin qubits. Three typical environments exhibited by these metal complexes are considered, namely, (a) square antiprism, (b) triangular dodecahedron, and (c) trigonal prism. The developed model is used to explain the properties of some representative examples showing these geometries. Key questions in this area, such as the chemical tailoring of the superparamagnetic energy barrier, tunneling gap, or spin relaxation time, are discussed. Finally, in order to take into account delocalization and/or covalent effects of the ligands, this point-charge model is complemented with ab initio calculations, which provide accurate information on the charge distribution around the metal, allowing for an explanation of the SMM behavior displayed by some sandwich-type organometallic compounds.

A new amide-based multidentate ligand, N,N′-1,2-ethanediyl-bis{2-[(N,N-diethylcarbamoyl)methoxy]benzamide} (L) reacts with M(Pic)3 · 6H2O to give rare-earth picrate complexes [M2L2(Pic)4(H2O)2](Pic)2 (M = La (1), Nd (2), Eu (3), Gd (4), Tb (5), Dy (6), Yb (7), Y (8)). X-ray single-crystal diffraction analyses indicate that dinuclear complexes 3 · 2C4H8O2, 6 · 2C4H8O2, and 8 · 2CH3CN are isomorphous. Each metal is nine-coordinate by four oxygen atoms of two ligands, four oxygen atoms of two bidentate picrates, and one water molecule with a distorted monocapped square antiprism. With hydrogen bonds between the free picrate anions and the coordination cations the complexes exhibit 2-D layers. The luminescent properties of 3 [Eu2L2(Pic)4(H2O)2](Pic)2 are described and factors that influence luminescent intensities are also discussed.

Schäferite, NaCa2Mg2(V5+O4)3; palenzonaite, NaCa2Mn22+(V5+O4)3; berzeliite, NaCa2Mg2(As5+O4)3; and manganberzeliite, NaCa2Mn2+2(As5+O4)3, are cubic minerals with garnet structures (space group Iad) in which tetrahedrally coordinated V5+ and/or As5+ at the Z site are charge balanced by disordered Na+ and Ca2+ at the X site, and divalent Mg2+ and Mn2+ cations at the octahedrally coordinated Y site. The crystal chemistry of palenzonaite (from the Molinello and Gambatesa mines, Italy, and the Fianel mine, Switzerland), berzeliite (from Långban, Sweden, and Montaldo, Italy), and manganberzeliite (from Varenche, Italy, and the Gozaisho mine, Japan) were studied by electron microprobe analysis and single-crystal X-ray diffraction methods. Structure refinements converged to R1 values of 1.36–2.42%. The tetrahedral site in these garnet structures is mainly occupied by pentavalent As5+ or V5+ (only up to about 20% randomly distributed Si4+ is present). Charge balance is maintained by variations in the Ca/Na ratio at the X site. Heterovalent substitution (Na+ ↔ Ca2+) at the distorted square antiprism X site in vanadate- and arsenate-bearing garnets allows full occupancy of the octahedral Y site by divalent cations (primarily Mg2+ and Mn2+). There is a positive correlation between the and bond lengths and the mean ionic radii of the substituent elements, but there is no correlation between the bond length and the variable Na/Ca site occupancy. The ionic radii of octahedrally coordinated Mg2+ and Mn2+ are such that the shared octahedral–dodecahedral edges are similar in length to the unshared octahedral edges, which is a measure of lattice distortion in garnet structures.

The preparation of tetrakis((+)-hfbc) lanthanide(III) complexes with an encapsulated alkali metal and ammonium ions M[Ln((+)-hfbc)4] (hereafter abbreviated as M-Ln : (+)-hfbc, (+)-heptafluorobutyrylcamphorate; M, ammonium or benzyl ammonium ions as well as alkali metal ions) was reported and discussed. The electronic circular dichroism (CD) spectra in the intraligand π−π* transition of M–Ln were examined in view of the solvent effect. Here, the concentration, alkali metal, and ammonium ion dependences are compared with the solid CD, 5D0 7F0(Eu(III)) excitation spectra, circularly polarized luminescence, and vibrational circular dichroism. It has been revealed that the dodecahedral eight coordinate DD-8-M-Ln complexes in crystals are equilibrated between the diastereoselectively formed square antiprism eight coordinate SAPR-8-M-Ln and [Ln((+)-hfbc)3] in EtOH and CH3CN solutions or between the SAPR-8-M-Ln and DD-D2d(mmmm)-8-M-Ln complexes in CHCl3 solution. The observed CD couplets are found to reflect the exciton CD couplets which are useful to determine the four-bladed SAPR-(llll) absolute configuration around the lanthanide(III) ion. Chirality 24:1055–1062, 2012. © 2012 Wiley Periodicals, Inc.

Novel compounds of Gd(III), Tb(III), Er(III), and Tm(III) with 4,4′-bipyridine (4-bpy) and trichloroacetates are prepared. The title compounds are isomorphic and isostructural in the solid state. All atoms in the studied compound lie in general positions of the Cc space group. The coordination polyhedra around central atoms can be described as bicapped trigonal prisms slightly disordered towards a square antiprism. All 4-bpy molecules are located in the outer coordination sphere together with four trichloroacetate anions and four water molecules. One of the nitrogen atoms of one 4-bpy is protonated due to stoichiometry.

A highly volatile air and moisture stable eight-coordinate samarium complex, [Sm(hfaa)3(pz)2] (hfaa = anion of hexafluoroacetylacetone and pz = pyrazole), has been synthesized and structurally characterized by single crystal X-ray diffraction. The complex crystallizes in the monoclinic space group P21/c and the coordination polyhedron around the samarium ion is best describable as a distorted square antiprism. The NMR spectrum reveals that both the pz units remain coordinated to the samarium in solution. The quantum yield of the complex is determined to be 0.012 in solution. The lifetime of the complex is found to be 0.039 ms (χ2 = 1.071). The experimental intensity parameter (ηSm) is calculated for the complex.

Two new one-dimensional europium coordination polymers, namely {[Eu(2,4-dcp) 3 (H 2 O) 2 ]·(4,4′-bpy)(H 2 O)} n ( 1 ) and {[Eu(2,4-dcp) 3 (H 2 O) 2 ]·(4,4′-bpy) 1.5 (H 2 O) 2 } n ( 2 ) were hydrothermally synthesized by controlling the pH of the reaction solution, and were characterized by elemental analysis, IR, TGA, powder X-ray diffraction and single crystal X-ray diffraction. Single-crystal X-ray diffraction studies indicate that the two europium coordination polymers adopt analogous linear chain structures with a {Eu 2 (2,4-dcp) 5 (H 2 O) 4 }, and a {Eu 2 (2,4-dcp) 6 (H 2 O) 4 } dimeric repeat units for 1 and 2 , respectively. The europium centers of 1 and 2 are also bound to two water molecules resulting in nine-coordinate, distorted tricapped trigonal-prism and monocapped square antiprism geometries, respectively. The pyridine nitrogen atoms of the 4,4′-bpy ligands do not coordinate to the metal centers in complexes 1 – 2 ; instead, they direct the formation of 2D sheet networks via hydrogen bonding interactions. Both 1 and 2 emit the intense red characteristic luminescence of Eu 3+ ion at room temperature, with long lifetimes of up to 0.8879 and 0.7571 ms, respectively.

The hydration of the Bi(III) ion was determined via an ab initio quantum mechanical charge field molecular dynamics (QMCF-MD) simulation. Ten picosecond sampling was carried out to determine structural and dynamical properties of the Bi(III) ion in aqueous solution. In the first hydration shell, the ion is 9-fold coordinated with a maximum probability of the Bi-O distance at 2.51 Å. In total, 11 exchanges were observed in the first-shell showing associative, dissociative, and interexchange character. As with the dominant existence of 9-fold coordination, the geometry of the Bi(III) ion is in between the tricapped trigonal prism and the capped square antiprism.

Three barbital-based alkaline earth metal complexes, [Ca(Barb)2] · 3H2O (1), [Ba2H(Barb)5] (2) and [Mg(Barb)2] · 2H2O (3) (Barb = 5,5-diethyl barbiturate sodium salt), were synthesized and characterized with elemental analysis, thermal analysis, and infrared, Raman, ultraviolet, and NMR (1H and 13C) spectroscopies. Single-crystal X-ray diffraction studies reveal that 2 is a dimer. Each barium(II) is surrounded by an O7N2 donor set in an approximate monocapped square antiprism with Ba–O distances ranging from 2.6512(14) to 2.9168(15) A and Ba–N distances of 2.7601(15) and 3.2558(17) A. The complex forms polymeric networks in the solid state with different coordinating abilities of O and N donors and N–H···O hydrogen bonds. The antimicrobial activities of 1–3 were observed against different gram-positive and gram-negative bacteria, yeast, and molds. Variable antimicrobial activity against the different bacteria strains was observed and compared with that of standard antibiotics; minimum inhibitory concentra...

New complexes of yttrium and lanthanum bromides and erbium chloride with carbamide (Ur), [Y(Ur)4(H2O)4]Br3 (I) and [La(Ur)4(H2O)4]Br3 (II), [La(Ur)6(H2O)2]Br3 (III), and [Er(Ur)6Cl]Cl2 (IV), are synthesized and studied by X-ray diffraction analysis. In structures I–III, the coordination of the ligands (water and carbamide) by the metal occurs through the oxygen atoms. The coordination polyhedron of the rare-earth metal atoms is a distorted square antiprism (coordination number 8), and the bromide ions are not included into the internal coordination sphere of the complexes. In compound IV, the internal coordination sphere of the complex includes six carbamide molecules and one chloride ion, and the coordination polyhedron of Er is a distorted pentagonal bipyramid (coordination number 7). Specific features of the structures of the crystalline carbamide derivatives of chlorides, bromides, and iodides of the considered rare-earth metals are compared. A distortion of the planar structure of some carbamide ligands, depending on their number in the complex cation and on the nature of the complex, is observed.

Solvent-dependent luminescence of Eu(III) complexes composed of oxo-linked bidentate phosphine oxide ligands, 4,5-bis(diphenylphosphoryl)-9,9-dimethylxanthene (xantpo), 4,5-bis(di-tert-butylphosphoryl)-9,9-dimethylxanthene (tBu-xantpo) and low-vibrational frequency hexafluoroacetylacetonato (hfa) ligands is reported. The Eu(III) complexes, Eu(hfa)2(xantpo)2 and Eu(hfa)3(tBu-xantpo), exhibit eight-coordinated square antiprism and trigonal dodecahedron structure, respectively. Their emission quantum yield, emission lifetime, and radiative and non-radiative rate constant are characterized using acetone, acetone-d6, toluene, chloroform, and DMF. The relationship between photophysical properties and coordination structures of eight-coordinated Eu(III) complexes is discussed for the first time.

New complexes of composition [Bi(DMSO)8][Fe(NCS)6] (1) and [Al(DMSO)6][Al(NCS)6] (2) have been prepared, and an octahedral hexarodanoaluminate anion has been structurally characterized for the first time. Crystals of compound 1 are triclinic, space group \(P\bar 1\), a = 11.2368(4) A, b = 11.4063(4) A, c = 21.0711(9) A, α = 92.9520(10)°, β = 99.9430(10)°, γ = 111.9290(10)°, V = 2447.69(16) A3, Z = 2, ρcalc = 1.680 g/cm3, R1 = 0.0564; crystals of compound 2 are cubic, space group \(Pa\bar 3\), a = 15.8201(4) A, V = 3959.39(17) A3, Z = 4, ρcalc = 1.462 g/cm3, R1 = 0.0475. The bismuth coordination polyhedron BiO8 in compound 1 is a distorted square antiprism with broken square faces (Bi-O, 2.368-2.582 A). In the structure of 2, the cation disordered in a complex manner has an octahedral configuration (Al-O, 1.888(11)-1.912(11) A).

Slow evaporation of the filtrate derived from the reaction in water between 2-thiobarbituric acid (H2TBA) and equimolar amount of potassium hydroxide results in the formation of crystals of two coordination polymers: unhydrated [K(μ 3-S,O-HTBA)] n (1) and hydrated [K(μ 2-S,O-HTBA)(μ 2-S,O-H2TBA)(μ-H2O)] n (2), which depend on the absence (1) or presence (2) of methanol solutions of organotin chloride. The hydrate 2 was isolated from the filtrates when di-n-butyltin dichloride, dimethyltin(IV) dichloride, diphenyltin(IV) dichloride, tri-n-butyltin chloride, or triphenyltin(IV) chloride were used during the reaction. The crystal structures show that coordination of potassium occurs through the S and O donors. The potassiums have distorted tetragonal bipyramidal and distorted cubic coordination environments in 1 and distorted square antiprism coordination in 2. Both structures exhibit intermolecular N–H ··· O hydrogen-bond interactions, which form TBA chains while the water in 2 produces a richer hydrogen-bo...

The explorative lanthanide coordination chemistry of 4′,5′-bis-(propylthio)tetrathiafulvenyl[ i ]dipyrido[3,2- a :2′,3′- c ]phenazine (TTF-dppz) is described. Thereby, four new Ln(III) complexes, [Ln(NO 3 ) 3 (TTF-dppz) 2 ] with Ln(III) = Nd ( 1 ), Eu ( 2 ), Gd ( 3 ), Tb ( 4 ), have been prepared and characterized. An X-ray crystallographic study of [Gd(NO 3 ) 3 (TTF-dppz) 2 ] ( 3 ) shows that the Gd(III) ion is coordinated to six oxygen atoms from three bidentate nitrate ligands and four nitrogen atoms from two bidentate TTF-dppz molecules forming a distorted bicapped square antiprism coordination geometry. The UV-vis spectra of the four Ln(III) complexes show very strong absorption bands in the UV region consistent with ligand centred electronic π-π* transitions and an intense broad absorption band in the visible region corresponding to a spin-allowed electronic π-π* 1 ILCT transition from the TTF-dppz ligand. Upon coordination, the 1 ILCT band of the free TTF-dppz ligand is bathochromically shifted. The electrochemical studies reveal that all complexes undergo two reversible oxidation and one (quasi)reversible reduction processes, ascribed to the successive oxidations of the TTF moiety and the reduction of the dppz unit, respectively. Moreover, the magnetic properties of complexes 3 and 4 are discussed.

A series of [Ln(CH3CONH2)4(H2O)4]I3 (Ln = rare-earth metal) complexes was completed with seven new compounds (Ln = Ce, Pr, Sm, Tb, Tm, Yb, Lu); two (Ln = Ce, Tm) were studied by X-ray diffraction. The coordination polyhedron of eight oxygen atoms is a distorted square antiprism. No tetrad effect was found for Ln–O bond lengths. The structure is stabilized by a system of intermolecular hydrogen bonds. The most striking feature of the structures is the recently predicted ionic acetamide coordination. The acetamide molecules are non-planar (the Ln–O–C–N torsion angles are 159–170°) and Ln–O–C bond angles vary in the 146.0–156.8° range.

Phosphinoylated calixarenes feature high coordination ability toward f elements and a great potentiality toward actinide/rare earth separation. Here, we report three characteristic properties of a tetra-phosphinoylated p-tert-butylcalix[4]arene, B(4)bL(4) functionalized with phosphinoyl pendant arms: (i) its coordination ability toward Th(IV) complexation in organic medium, (ii) its ability to separate thorium from yttrium, lanthanum, and europium in three different organic media, and (iii) the X-ray crystal structure of the La complex. Thorium(IV) forms 1:1 and 1:2 (M:L) complexes with B(4)bL(4): Th(NO3)(4)(B(4)bL(4))(n)center dot xH(2)O (n = 1, x = 1, 1; n = 2, x = 4, 2). Spectroscopic data point to the inner coordination sphere of 1 and 2 containing nitrate ions and water molecules. Molecular modeling of 1 yielded an 8-coordinate species and its coordination polyhedron can be described as a distorted square antiprism while that for 2, a 9-coordinate species, as a distorted tricapped trigonal prism. The extraction study of tetravalent thorium and trivalent rare-earth (Y, La, Eu) ions from acidic nitrate media by B(4)bL(4) in chloroform shows thorium being much more extracted than the rare earths, with selectivity close to 100%. The extraction behavior can be easily modulated by changing the initial conditions (pH, nitrate concentration). The X-ray structure of [LaB(4)bL(4)(H2O)(5)] CH3CN center dot(ClO4)(3) points to the La-III ion lying on a C-4 axis and being 9-coordinated by the four O(P) atoms and five O atoms from water molecules. It is located in the middle of the void formed by the four O-CH2-PO(Me)(2) pendant arms. (C) 2011 Elsevier B.V. All rights reserved.

Characteristic triboluminescence from a lanthanide coordination polymer with a non-centrosymmetric structure is reported. The lanthanide coordination polymer is composed of luminescent EuIII ions and bidentate phosphane oxides, poly[3,3′-bis(diphenylphosphoryl)-2,2′-bipyridine][tris(hexafluoroacetylacetonate)]europium (poly-Eu-BIPYPO) crystals. The coordination geometry of poly-Eu-BIPYPO is categorized as an asymmetric eight-coordinate square antiprism (8-SAP). The space group of the crystal is also classified as the non-centrosymmetric Cc, which is suitable for piezoelectricity and triboluminescence. The photoluminescence quantum yield of poly-Eu-BIPYPO crystals excited at 380 nm is found to be 61 %. Triboluminescence of the lanthanide coordination polymer is observed upon breaking, even at ambient temperature and in daylight. The remarkable triboluminescence phenomenon and geometrical structure of lanthanide coordination polymer are demonstrated.

The compounds, Cd(BF 4 )(TaF 6 ) and Cd(BF 4 )(BiF 6 ), have been synthesized and characterized by single-crystal X-ray diffraction and Raman spectroscopy. Both isostructural compounds crystallize in the monoclinic P2 1 /c space group with a = 8.2700(6) A, b = 9.3691(6) A, c = 8.8896(7) A, β = 94.196(3)°, V = 686.94(9) A 3 for Cd(BF 4 )(TaF 6 ) and a = 8.3412(8) A, b = 9.4062(8) A, c = 8.9570(7) A, β = 93.320(5)°, V = 701.58(11) A 3 for Cd(BF 4 )(BiF 6 ). Eight fluorine atoms (4 BF 4 − + 4 AF 6 − ) form a surrounding around the cadmium atom in the shape of distorted square antiprism. These compounds are not isostructural with mixed-anion analogues of Ca, Sr, Ba and Pb studied earlier.

An amide-type acyclic polyether, N,N′-bis(p-methoxyphenyl)-3-oxapentanediamide (L), and its three lanthanide coordination compounds, [Ln(NO3)(L)2(H2O)2] · (NO3)2 [Ln = Pr (1), Nd (2), and Dy (3)], have been synthesized and characterized by elemental analysis, IR spectroscopy, thermal analysis, and X-ray diffraction. Single crystal X-ray structure analyses reveal that 1 and 2 have the same structure and crystallize in the monoclinic crystal system with C2/c space group. The coordination geometry around the central atom is a distorted bicapped square antiprism. Extensive intermolecular hydrogen bonds in 1 and 2 result in 3-D supramolecular networks. Complex 3 exhibits luminescence in the visible region upon excitation with UV-rays.

The first examples of ternary sulfates containing refractory metals and trivalent ions of the rare-earth group and bismuth were prepared by solvothermal synthesis from H2SO4/SO3 mixtures. The tungsten compounds RE2[W2O3(SO4)6] (RE = Sm–Gd, Ho) were obtained by the reaction of WOCl4 and RE2O3 in oleum (25 % SO3). They crystallize in the monoclinic space group C2/c and contain the unique [W2O3(SO4)6]6– anion. Thermal decomposition leads to the oxides RE2O(WO4)2. Tetragonal rare-earth–niobium sulfates of the type RE2Nb2O2(SO4)3[H(SO4)2]2 (RE = Y, Ce–Nd, Sm–Er) (space group P21m) were synthesised from NbCl5 and RE2O3 in 100 % H2SO4. They contain [O3SO···H···OSO3]3– ions featuring a strong hydrogen bond and form a polymeric structure with niobium in an octahedral coordination and the rare-earth ion is surrounded by eight [SO4] tetrahedra in the form of a square antiprism. The decomposition temperature of RE2Nb2O2(SO4)3[H(SO4)2]2 depends on the size of the respective rare-earth ion with a maximum in thermal stability found for RE = Sm–Gd (≈550 °C). The reaction of NbCl5 and Sm(NO3)3·6H2O in oleum (25 % SO3) yielded Sm2Nb2O2(SO4)5(S2O7), which is a possible intermediate of the thermal decomposition of Sm2Nb2O2(SO4)3[H(SO4)2]2. It crystallizes in the monoclinic space group I2/a and contains 2∞[NbO(SO4)2/2(SO4)3/3] layers connected by 2∞[Sm(SO4)2/4(S2O7)2/4] units to a polymeric structure. Reaction of NbCl5 with (BiO)2CO3 or Eu2O3 in 95 % H2SO4 yielded M2Nb4O5(SO4)8 (M = Bi, Eu, monoclinic, space group C2/c). These compounds contain the unprecedented [M2Nb4O5]16+ cluster cation and decompose into MNbO4 and Nb2O5 on heating.

Synthesis was carried out, and structure solved for the new dinuclear erbium(III) complex having a composition of Na4[Er2(EDTA)2(C2O4)] · 8H2O (where EDTA stands for ethylenediamine-N,N′-tetraacetate). The compound was characterized by IR and UV spectroscopy, mass spectrometry, and X-ray crystallography. In the structure of the compound, erbium(III) has C.N. 8 and a coordination polyhedron shaped as a square antiprism. The EDTA and oxalate ions manifest their characteristic coordination modes: N,O-chelate hexadentate and bridge-cyclic tetradentate, respectively.

The crystal structure of the [Eu(Tol)3]2 · 2DPH complex (Tol = toluic acid anion, DPG = diphenylguanidine) was determined by X-ray crystallography. The coordination polyhedron of a Eu atom [EuO6] (CN = 8) is a distorted square antiprism with nonplanar quadrilateral faces. Diphenylguanidine molecules have been shown to be randomly distributed over the symmetry centers of a unit cell with site occupancies of 0.5. The π stacking interaction C-H…Cg exists in the structure to stabilize it. Luminescent characteristics of the compound have been determined.

A dysprosium complex [Dy(2-pyrazinecarboxylic acid)3(H2O)2] n · 6nH2O (1) was prepared by hydrothermal reactions and structurally characterized by single-crystal X-ray diffraction. Complex 1 is an infinite 1-D structure with Dy3+ binding with six oxygens and three nitrogens to yield a distorted monocapped square antiprism. The [Dy(2-pyrazinecarboxylic acid)3(H2O)2] n and lattice water interconnect via π–π and hydrogen-bonding interactions to form a 3-D supramolecular network. Photoluminescent investigations at room temperature reveal that 1 exhibits two intensive emissions that can be ascribed to 4 F 9/2 → 6 HJ transitions (J = 15/2 and 13/2) of Dy3+ ions.