Syntheses, structures, and magnetic properties of diphenoxo-bridged Cu(II)Ln(III) and Ni(II)(low-spin)Ln(III) compounds derived from a compartmental ligand (Ln = Ce-Yb).

Syntheses, characterization, and magnetic properties of a series of diphenoxo-bridged discrete dinuclear M(II)Ln(III) complexes (M = Cu or Ni, Ln = Ce-Yb) derived from the compartmental Schiff base ligand, H(2)L, obtained on condensation of 3-ethoxysalicylaldehyde with trans-1,2-diaminocyclohexane, are described. Single crystal X-ray structures of eight Cu(II)Ln(III) compounds (Ln = Ce (1), Pr (2), Nd (3), Sm (4), Tb (7), Ho (9), Er (10), and Yb (12)) and three Ni(II)Ln(III) (Ln = Ce (13), Sm (16), and Gd (18)) compounds have been determined. Considering the previously reported structure of the Cu(II)Gd(III) (6) compound (Eur. J. Inorg. Chem. 2005, 1500), a total of twelve structures are discussed/compared in this study. Four types of composition are observed in the Cu(II)Ln(III) complexes: [Cu(II)LLn(III) (NO(3))(3)(H(2)O)] (1-3: Ln = Ce-Nd), [Cu(II)LSm(III)(NO(3))(3)]·CH(3)COCH(3) (4), [Cu(II)(H(2)O)LLn(III)(NO(3))(3)] (5: Ln = Eu; 6: Ln = Gd), and [Cu(II)LLn(III)(NO(3))(3)] (4A: Ln = Sm; 7-12: Ln = Tb-Yb). On the other hand, the Ni(II)Ln(III) complexes are characterized to have two types of composition: [Ni(II)LLn(III)(H(2)O)(NO(3))(3)] (13-15: Ln = Ce-Nd) and [Ni(II)LLn(III)(NO(3))(3)]·0.5CH(3)COCH(3) (16-24: Ln = Sm-Yb). Among twelve X-ray structures, seven belong to three different isomorphous sets (Cu(II)Ce(III) (1), Cu(II)Pr(III) (2), Cu(II)Nd(III) (3), and Ni(II)Ce(III) (13); Cu(II)Tb(III) (7), Cu(II)Ho(III) (9), Cu(II)Er(III) (10), and Cu(II)Yb(III) (12); Ni(II)Sm(III) (16) and Ni(II)Gd(III) (18)), whereas space group/unit cell parameters of two others (Cu(II)Sm(III) (4) and Cu(II)Gd(III) (6)) are of different types. The lanthanide(III) centers in Cu(II)Ce(III) (1), Cu(II)Pr(III) (2), Cu(II)Nd(III) (3), and Ni(II)Ce(III) (13) complexes are eleven-coordinated, while the lanthanide(III) centers in other compounds are ten-coordinated. As evidenced from the dihedral angle (δ) between the CuO(phenoxo)(2) and LnO(phenoxo)(2) planes, variation in the extent of planarity of the bridging moiety in the Cu(II)Ln(III) compounds takes place; the ranges of δ values are 0.8-6.2° in the 4f(1-7) analogues and 17.6-19.1° in the 4f(8-13) analogues. The Cu(II)Gd(III) (6) compound exhibits ferromagnetic interaction (Eur. J. Inorg. Chem. 2005, 1500). The nature of the magnetic exchange interaction in the Cu(II)Ln(III) complexes has been understood by utilizing the empirical approach; the Ni(II)Ln(III) complexes have been used as references. The metal centers in the Eu(III) complex are uncorrelated, while other 4f(1-6) analogues (Ce(III), Pr(III), Nd(III), and Sm(III)) exhibit antiferromagnetic interaction. Among the higher analogues (4f(7-13)), only Yb(III) exhibits antiferromagnetic interaction, while interaction in other analogues (Gd(III), Tb(III), Dy(III), Ho(III), Er(III), and Tm(III)) is ferromagnetic. An important aspect of the present study is the measurement of the magnetic susceptibility of the unblocked samples as well as on blocking the samples with grease to avoid powder reorientation, if any. Comparison of the two sets of data reveals significant difference in some cases.

The coordination polymers poly[mu-4,4'-bipyridyl-di-mu-formato-copper(II)] and catena-poly[[[diaqua(1-benzofuran-2,3-dicarboxylato)copper(II)]-mu-1,2-di-4-pyridylethane] dihydrate].

The title compounds, [Cu(CHO(2))(2)(C(10)H(8)N(2))](n), (I), and {[Cu(C(10)H(4)O(5))(C(12)H(12)N(2))(H(2)O)(2)].2H(2)O}(n), (II), are composed of one-dimensional linear coordination polymers involving copper(II) ions and bidentate bipyridyl species. In (I), the polymeric chains are located on twofold rotation axes at (x, x, 0) and are arranged in layered zones centered at z = 0, 1/4, 1/2 and 3/4 parallel to the ab plane of the tetragonal crystal. Weak coordination of the formate anions of one layer to the copper centers of neighboring layers imparts a three-dimensional connectivity to this structure. In (II), the polymeric chains propagate parallel to the a axis of the crystal. Noncoordinated water molecules link the chains through O-H...O hydrogen bonding in directions perpendicular to c, imparting to the entire structure three-dimensional connectivity. The metal ions adopt distorted octahedral and square-based pyramidal environments in (I) and (II), respectively. This study indicates that, under the given conditions, extended coordination involves Cu(II) centers associating with the bipyridyl ligands rather than with the competing benzofurandicarboxylate entities.

A unique two-dimensional coordination network of 1-benzofuran-2,3-dicarboxylate with lanthanum(III) obtained by solvothermal synthesis.

The title compound, poly[bis[diaqualanthanum(III)]-tris(mu-1-benzofuran-2,3-dicarboxylato)], [La(2)(C(10)H(4)O(5))(3)(H(2)O)(4)](n), was obtained under solvothermal conditions by reacting lanthanum trinitrate hexahydrate with 1-benzofuran-2,3-dicarboxylic acid in a strongly basic environment. It forms an extended two-dimensional coordination network, wherein every lanthanum ion links to four deprotonated diacid ligands, while two of the latter bridge between adjacent metal cations. The component species are additionally linked to one another by hydrogen bonds. The polymeric arrays are tightly stacked one on top of the other, without incorporating any solvent in the interface zones between them, which are lined with the lipophilic benzofuran residues. This study provides the first example of coordination networking with the aid of the 1-benzofuran-2,3-dicarboxylate ligand.

Two- and three-dimensional hydrated coordination polymers of diaqualanthanum(3+) ions with 2-hydroxypropanedioate, oxalate and acetate anions as bridging ligands.

The title compounds, poly[[tetraaquadi-mu-2-hydroxypropanedioato-mu-oxalato-dilanthanum(III)] tetrahydrate], {[La(2)(C(2)O(4))(C(3)H(2)O(5))(2)(H(2)O)(4)].4H(2)O}(n), (I), and poly[[tetra-mu-acetato-tetraaqua-mu-oxalato-dilanthanum(III)] dihydrate], {[La(2)(C(2)O(4))(C(2)H(3)O(2))(4)(H(2)O)(4)].2H(2)O}(n), (II), represent crystalline hydrates of coordination polymers of diaqualanthanum(3+) ions with different combinations of bridging carboxylate ligands, viz. 2-hydroxypropanedioate and oxalate in a 2:2:1 ratio in (I), and acetate and oxalate in a 2:4:1 ratio in (II). While the acetate component was one of the reactants used, the other ligands were obtained in situ by aerial oxidation of the dihydroxyfumaric acid present in the reactions. The crystal structure of (I) consists of two-dimensional polymeric arrays with water molecules intercalated between and hydrogen bonded to the arrays. The oxalate components are located on inversion centres. The crystal structure of (II) reveals an open three-dimensional polymeric connectivity between the interacting components, with the solvent water molecules incorporated within the intralattice voids and hydrogen bonded to the polymeric framework. The La(III) ion and the noncoordinated water molecules are located on axes of twofold symmetry. The oxalate group is centred at the 222 symmetry site, the intersection of the three rotation axes. The coordination number of the La(III) ion in the two structures is 10. The significance of this study lies mainly in the characterization of two new coordination polymers, as well as in the confirmation that dihydroxyfumaric acid tends to rearrange to form smaller components in standard laboratory procedures, and should be considered a poor reagent for formulating hybrid coordination polymers with metal ions.

Square-grid coordination networks of (5,10,15,20-tetra-4-pyridylporphyrinato)zinc(II) in its clathrate with two guest molecules of 1,2-dichlorobenzene: supramolecular isomerism of the porphyrin self-assembly.

The title compound, (5,10,15,20-tetra-4-pyridylporphyrinato)zinc(II) 1,2-dichlorobenzene disolvate, [Zn(C(40)H(24)N(8))].2C(6)H(4)Cl(2), contains a clathrate-type structure. It is composed of two-dimensional square-grid coordination networks of the self-assembled porphyrin moiety, which are stacked one on top of the other in a parallel manner. The interporphyrin cavities of the overlapping networks combine into channel voids accommodated by the dichlorobenzene solvent. Molecules of the porphyrin complex are located on crystallographic inversion centres. The observed two-dimensional assembly mode of the porphyrin units represents a supramolecular isomer of the unique three-dimensional coordination frameworks of the same porphyrin building block observed earlier. The significance of this study lies in the discovery of an additional supramolecular isomer of the rarely observed structures of metalloporphyrins self-assembled directly into extended coordination polymers without the use of external ligand or metal ion auxiliaries.

Square-grid coordination networks of diaquabis(4,4'-bipyridyl)copper(II) crosslinked by hydrogen bonds through two monoanions of 1-benzofuran-2,3-dicarboxylic acid and five molecules of water.

The title compound, poly[[[diaquacopper(II)]-di-mu-4,4'-bipyridyl] bis(3-carboxy-1-benzofuran-2-carboxylate) pentahydrate], {[Cu(C(10)H(8)N(2))(2)(H(2)O)(2)](C(10)H(5)O(5))(2).5H(2)O}(n), crystallizes in a single-framework architecture. It is composed of two-dimensional square-grid coordination networks of 1:2:2 copper-4,4'-bipyridine-water units, wherein each copper ion coordinates equatorially to four bipyridyl units and axially to two water ligands. The polymeric nets are intercalated by layers of the benzofurandicarboxylic acid monoanions and additional water species. An extensive array of hydrogen bonds interlinks the various components of the structure. The Cu atom and the bipyridyl entities are located on axes of twofold rotation. This study confirms the preferred monoanionic nature of the benzofurandicarboxylic acid molecule. It reveals a rarely observed extended coordination polymer composed only of copper ions and bipyridyl linkers, and an interesting hydrogen-bonding connectivity between the polymeric layers aided by the benzofurandicarboxylic acid and water components intercalated in the structure.

Probing the supramolecular interaction synthons of 1-benzofuran-2,3-dicarboxylic acid in its monoanionic form.

1-Benzofuran-2,3-dicarboxylic acid (C(10)H(6)O(5)) is a dicarboxylic acid ligand which can readily engage in organometallic complexes with various metal ions. This ligand is characterized by an intramolecular hydrogen bond between the two carboxyl residues, and, as a monoanionic species, readily forms supramolecular adducts with different organic and inorganic cations. These are a 1:1 adduct with the dimethylammonium cation, namely dimethylammonium 3-carboxy-1-benzofuran-2-carboxylate, C(2)H(8)N(+).C(10)H(5)O(5)(-), (I), a 2:1 complex with Cu(2+) ions in which four neutral imidazole molecules also coordinate the metal atom, namely bis(3-carboxy-1-benzofuran-2-carboxylato-kappaO(3))tetrakis(1H-imidazole-kappaN(3))copper(II), [Cu(C(10)H(5)O(5))(2)(C(3)H(4)N(2))(4)], (II), and a 4:1 adduct with [La(H(2)O)(7)](3+) ions, namely heptaaquabis(3-carboxy-1-benzofuran-2-carboxylato-kappaO(3))lanthanum 3-carboxy-1-benzofuran-2-carboxylate 1-benzofuran-2,3-dicarboxylic acid solvate tetrahydrate, [La(C(10)H(5)O(5))(2)(H(2)O)(7)](C(10)H(5)O(5)).C(10)H(6)O(5).4H(2)O, (III). In the crystal structure, complex (II) resides on inversion centres, while complex (III) resides on axes of twofold rotation. The crystal packing in all three structures reveals pi-pi stacking interactions between the planar aromatic benzofuran residues, as well as hydrogen bonding between the components. The significance of this study lies in the first crystallographic characterization of the title framework, which consistently exhibits the presence of an intramolecular hydrogen bond and a consequent monoanionic-only nature. It shows further that the anion can coordinate readily to metal cations as a ligand, as well as acting as a monovalent counter-ion. Finally, the aromaticity of the flat benzofuran residue provides an additional supramolecular synthon that directs and facilitates the crystal packing of compounds (I)-(III).

The first coordination polymer of lanthanum(III) with a naphthalene-1,4,5,8-tetracarboxylic 1,8-anhydride derivative.

The title compound, catena-poly[[[heptaaqualanthanum(III)]-mu-1,3-dioxo-2-oxa-1H,3H-phenalene-6,7-dicarboxylato-kappa(2)O(6):O(7)] hemi(4,8-dicarboxynaphthalene-1,5-dicarboxylate) dihydrate], {[La(C(14)H(4)O(7))(H(2)O)(7)](C(14)H(6)O(8))(0.5).2H(2)O}(n), is a dihydrate of a coordination polymer between the dianion of naphthalene-1,4,5,8-tetracarboxylic 1,8-anhydride and the heptahydrated lanthanum(III) ion, charge balanced by an additional 4,8-dicarboxynaphthalene-1,5-dicarboxylate dianion that is located on an inversion centre and is not coordinated to the metal ion. The linear polymeric arrays adopt a comb-like structure, and these pack in pairs with one chain interpenetrating another, like two parts of a zip, to optimize stacking interactions between their ligand fragments. All the components of this compound are further interlinked by an extensive pattern of O-H...O hydrogen bonds throughout the crystal structure. The main scientific significance of the results reported here is that they demonstrate for the first time the feasibility of coordination polymerization of the above organic ligand with lanthanide ions. The resulting polymer has a unique architecture. Finally, the reported structure is a rare example where the tetraacid and the diacid anhydride ligand species co-exist in the same crystal.

Hydrated hexacyanometallate(III) salts of triaqua(18-crown-6)lanthanoid(III) and tetraaqua(18-crown-6)lanthanoid(III) cations containing nine- and ten-coordinate lanthanoids.

Tetraaqua(18-crown-6)cerium(III) hexacyanoferrate(III) dihydrate, [Ce(C(12)H(24)O(6))(H(2)O)(4)][Fe(CN)(6)].2H(2)O, and tetraaqua(18-crown-6)neodymium(III) hexacyanoferrate(III) dihydrate, [Nd(C(12)H(24)O(6))(H(2)O)(4)][Fe(CN)(6)].2H(2)O, are isomorphous and isostructural in the C2/c space group, where the cations, which contain ten-coordinate lanthanoid centres, lie across twofold rotation axes and the anions lie across inversion centres. In these compounds, an extensive series of O-H...O and O-H...N hydrogen bonds links the components into a continuous three-dimensional framework. Triaqua(18-crown-6)lanthanoid(III) hexacyanoferrate(III) dihydrate, [Ln(C(12)H(24)O(6))(H(2)O)(3)][Fe(CN)(6)].2H(2)O, where Ln = Sm, Eu, Gd or Tb, are all isomorphous and isostructural in the P\overline{1} space group, as are triaqua(18-crown-6)gadolinium(III) hexacyanochromate(III) dihydrate, [Gd(C(12)H(24)O(6))(H(2)O)(3)][Cr(CN)(6)].2H(2)O, and triaqua(18-crown-6)gadolinium(III) hexacyanocobaltate(III) dihydrate, [Gd(C(12)H(24)O(6))(H(2)O)(3)][Co(CN)(6)].2H(2)O. In these compounds, there are two independent anions, both lying across inversion centres, and the lanthanoid centres exhibit nine-coordination; in the crystal structures, an extensive series of hydrogen bonds links the components into a three-dimensional framework.

Syntheses, structures, and magnetic properties of mononuclear CuII and tetranuclear CuII3MII (M = Cu, Co, or Mn) compounds derived from N,N'-ethylenebis(3-ethoxysalicylaldimine): cocrystallization due to potential encapsulation of water.

Syntheses, structures, and magnetic properties of one mononuclear inclusion compound [CuIIL1 within (H2O)] (1) and three tetrametal systems of the composition [{CuIIL1}2{CuIIL1MII(H2O)3}]ClO4)2 (M = Cu (2), M = Co (3), M = Mn (4)) derived from the hexadentate Schiff base compartmental ligand N,N'-ethylenebis(3-ethoxysalicylaldimine) (H2L1) have been described. Compounds 1 and 2 crystallize in orthorhombic Pbcn and monoclinic P21/c systems, respectively, and the space group of the isomorphous compounds 3 and 4 is monoclinic C2/c. The water molecule in 1 is encapsulated in the vacant O4 compartment because of the hydrogen bonding interactions with the ether and phenolate oxygens, resulting in the formation of an inclusion product. The structures of 2-4 consist of the [CuIIL1MII(H2O)3]2+ cation and two mononuclear [CuIIL1] moieties. In the dinuclear [CuIIL1MII(H2O)3]2+ cation, the metal centers are doubly bridged by the two phenolate oxygens. The second metal center, MII (Cu in 2, Co in 3, and Mn in 4), in the [CuIIL1MII(H2O)3]2+ cation is pentacoordinated by the two phenoxo oxygens and three water molecules. Two of these three coordinated water molecules interact, similar to that in 1, with two mononuclear [CuIIL1] moieties, resulting in the formation of the tetrametal [{CuIIL1}2{CuIIL1MII(H2O)3}]2+ system that consists of the cocrystallized dinuclear (one) and mononuclear (two) moieties. Evidently, the cocrystallization observed in 2-4 is related to the tendency of a water molecule to be encapsulated in the vacant O4 compartment of the mononuclear [CuIIL1] species. In the case of 2, there are two independent [CuIIL1CuII(H2O)3]2+ units. The tau ((beta-alpha)/60, where beta and alpha are the largest and second largest bond angles, respectively) values in the pentacoordinated environment of the two copper(II) centers in 2 are 0.04 and 0.37, indicating almost ideal and appreciably distorted square pyramidal geometry, respectively. In contrast, the tau values (0.54 for 3 and 0.49 for 4) indicate that the coordination geometry around the cobalt(II) and manganese(II) centers in 3 and 4 is intermediate between square pyramidal and trigonal bipyramidal. The variable-temperature (2-300 K) magnetic susceptibilities of compounds 2-4 have been measured. The magnetic data have been analyzed in the model of one exchange-coupled dinuclear CuIIMII moiety and two noninteracting CuII centers. In all three cases, the metal ions in the dinuclear core are coupled by a weak antiferromagnetic interaction (J = -17.4 cm-1, -8 cm-1, and -14 cm-1 for 2, 3, and 4, respectively). The observation of a weak interaction has been explained in terms of the structural parameters and symmetry of the magnetic orbitals.

Syntheses, structures, and magnetic properties of diphenoxo-bridged M(II)Ln(III) complexes derived from N,N'-ethylenebis(3-ethoxysalicylaldiimine) (M = Cu or Ni; Ln = Ce-Yb): observation of surprisingly strong exchange interactions.

A series of heterodinuclear Cu(II)Ln(III) and Ni(II)Ln(III) complexes, [M(II)L(1)Ln(III)(NO(3))(3)] (M = Cu or Ni; Ln = Ce-Yb), with the hexadentate Schiff base compartmental ligand N,N'-ethylenebis(3-ethoxysalicylaldiimine) (H(2)L(1)) have been synthesized and characterized. The X-ray crystal structure determinations of 13 of these compounds reveal that they are all isostructural. All of these complexes crystallize with the same orthorhombic P2(1)2(1)2(1) space group with closely similar unit cell parameters. Typically, the structure consists of a diphenoxo-bridged 3d-4f dinuclear core, self-assembled to two dimensions due to the intermolecular nitrate...copper(II) or nitrate...nickel(II) semicoordination and weak C-H...O hydrogen bonds. Despite that, the metal centers of the neighboring units are well separated (the ranges of the shortest intermolecular contacts (A) are (M...M) 7.46-7.60, (Ln...Ln) 8.56-8.69, and (M...Ln) 6.12-6.20). Variable-temperature (5-300 K) magnetic susceptibility measurements of all the complexes have been made. The nature of exchange interactions in the Cu(II)Ln(III) systems has been inferred from the Deltachi(M)T versus T plots, where Deltachi(M)T is the difference between the values of chi(M)T for a Cu(II)Ln(III) system and its corresponding Ni(II)Ln(III) analogue. Ferromagnetic interactions seem to be exhibited by the Cu(II)Gd(III), Cu(II)Tb(III), Cu(II)Dy(III), Cu(II)Ho(III), Cu(II)Tm(III), and Cu(II)Yb(III) complexes, while, for the Cu(II)Er(III) complex, no definite conclusion could be reached. On the other hand, among the lower members of the series, the complexes of Ce(III), Nd(III), and Sm(III) exhibit antiferromagnetic interactions, while the Cu(II)Pr(III) and Cu(II)Eu(III) analogues behave as spin-uncorrelated systems. The observations made here vindicate the proposition of Kahn (Inorg. Chem. 1997, 36, 930). The Deltachi(M)T versus T plots also suggest that, for most of the Cu(II)Ln(III) complexes, the exchange interactions are fairly strong, which probably could be related to the small dihedral angle (ca. 4 degrees) between the CuO(2) and LnO(2) planes.

Ferromagnetic exchange in two dicopper(II) complexes using a mu-alkoxo-mu-7-azaindolate bridge.

Syntheses, structures, and magnetic properties of two heterobridged mu-alkoxo-mu-7-azaindolate dicopper(II) complexes, [Cu(II)2(L-F)(mu-C7H5N2)] (1) and [Cu(II)2(L-H)(mu-C7H5N2)].CH3OH (2) (H3L-F = 1,3-bis(3-fluorosalicylideneamino)-2-propanol; H3L-H = 1,3-bis(salicylideneamino)-2-propanol) have been reported. Aside from being a new type of heterobridged complex, 1 and 2 exhibit ferromagnetic interaction (2J = 52 cm(-1) for 1 and 33.4 cm(-1) for 2) despite orbital complementarity (7-azaindolate HOMO is antisymmetric).