Malabika Nayak

Syntheses, Structures, and Magnetic Properties of Diphenoxo-Bridged CuIILnIII and NiII(Low-Spin)LnIII 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.

Syntheses and crystal structures of CuIIBiIII, CuIIBaIICuII, [CuIIPbII]2 and cocrystallized (UVIO2)2.4CuII complexes: structural diversity of the coordination compounds derived from N,N′-ethylenebis(3-ethoxysalicylaldiimine)

Syntheses, characterization and structures of heterodinuclear compound [CuIIL1BiIII(NO3)3] (1), sandwich type heterotrinuclear compound [(CuIIL1)2BaII(NO3)2]·0.2H2O (2), heterotetranuclear compound [{CuIIL1PbII(µ-NO3)(NO3)}2] (3) and heterohexanuclear [2 × 1 + 1 × 4] cocrystal [(UVIO2)2(µ-H2O)2(NO3)4]·4[CuIIL1⊂(H2O)] (4) are described in this investigation (H2L1 = N,N′-ethylenebis(3-ethoxysalicylaldiimine)). Compounds 1 and 4 crystallize in orthorhombic P212121 and triclinic Pī systems, respectively, while the space group of compounds 2 and 3 is monoclinic P21/c. The structure of 1 consists of a diphenoxo-bridged CuIIBiIII dinuclear core containing three chelating nitrates and a 10-coordinate bismuth(III) centre. The dinuclear cores are self-assembled to two dimensions through intermolecular nitrate oxygen⋯copper(II) semicoordination and weak C–H⋯O hydrogen bonds. Compound 2 is a double-decker CuIIBaIICuII system in which a barium(II) ion is sandwiched between two mononuclear [CuIIL1] moieties. The barium(II) centre is 11-coordinate, four phenoxo and four ethoxy oxygen atoms and one chelating and one monodentate nitrate ions. Compound 3 is a tetranuclear system (dimer of two dinuclear moieties) in which one nitrate is chelating, while the second nitrate behaves as both a chelating and bridging ligand. The lead(II) centre is 9-coordinate in this compound. Compound 4 is a [2 × 1 + 1 × 4] cocrystal of one diaqua-bridged diuranyl(VI) moiety, containing two chelating nitrates and 8-coordinated hexagonal bipyramidal uranium(VI) centres and four inclusion species [CuIIL1⊂(H2O)]. The governing factor for the self-assembled cocrystallization in 4 are the C–H⋯·π and C–H⋯O hydrogen bonds. The compounds reported in this investigation and other heteronuclear systems derived from N,N′-ethylenebis(3-ethoxysalicylaldiimine) indicate that this ligand system is an important example which gives rise to structurally diverse heteronuclear compounds. In addition to the structural diversity, the structural resemblance of bismuth(III) with lanthanides(III) and utilization of noncovalent interactions to form self-assembly and cocrystals are the major outcomes of the present investigations.

A unique example of a three component cocrystal of metal complexes

The synthesis, characterization and structure of a [3 × 1 + 2 × 1 + 1 × 2] cocrystal [(NiIIL1)2NaI(NO3)]·[{NiIIL1NaI(H2O)2}{NiIIL1}2(NO3)] derived from the hexadentate Schiff base compartmental ligand N,N′-ethylenebis(3-ethoxysalicylaldimine) (H2L1) are described. The compound crystallizes in the monoclinic system (space group C2/c). The structure consists of one trinuclear double-decker [(NiIIL1)2NaI]+ cation, one dinuclear [NiIIL1NaI(H2O)2]+ cation and two mononuclear [NiIIL1] moieties. Each of the two coordinated water molecules of the dinuclear unit is encapsulated in the O4 cavities of the two mononuclear [NiIIL1] moieties resulting in the formation of a tetranuclear self-assembly, which is further interlinked with the trinuclear sandwich species due to Ni⋯Ni interaction to result in an overall one-dimensional topology in the title compound. A unique example of a three component cocrystal of metal complexes, existence of NaI in two entirely different environments in spite of being surrounded by the same blocking ligand and structural resemblance of sodium(I) with 3d metal ions are the major outcomes of the present investigation.

Syntheses and crystal structures of dinuclear, trinuclear [2 × 1 + 1 × 1] and tetranuclear [2 × 1 + 1 × 2] copper(II)–d10 complexes (d10 ⇒ ZnII, CdII, HgII and AgI) derived from N,N′-ethylenebis(3-ethoxysalicylaldimine)

Syntheses, characterization and crystal structures of heterotetranuclear [2 × 1 + 1 × 2] co-crystals [{CuIILZnII(H2O)2}{CuIIL}2](ClO4)2 (1) and [{CuIILCdII(H2O)2(CH3CN)}{CuIIL}2](ClO4)2 (2), dinuclear compound [CuIILHgII(CH2COCH3)](ClO4) (3) and heterotrinuclear [2 × 1 + 1 × 1] co-crystal [{CuIILAgI(H2O)}{CuIIL}](ClO4) (4) derived from N,N′-ethylenebis(3-ethoxysalicylaldimine) (H2L) are reported herein. Compounds 3 and 4 crystallize in the orthorhombic Pbca and monoclinic P21/c systems, respectively, while the space group of compounds 1 and 2 is monoclinic C2/c. The structure of 3 consists of a monophenoxo-bridged CuIIHgII dinuclear core in which the mercury(II) centre is dicoordinated by the bridging phenoxo oxygen atom and the CH2 carbon atom of the mono-deprotonated acetone anion. The coordination environment of HgII in this compound is almost linear. In the CuII2AgI compound 4, one diphenoxo-bridged [CuIILAgI(H2O)]+ cation is co-crystallized with one mononuclear [CuIIL] moieties. On the other hand, the structures of the CuII3MII compounds 1 (M = Zn) and 2 (M = Cd) consist of one diphenoxo-bridged dinuclear CuIIMII unit and two mononuclear [CuIIL] moiety; the composition of the dinuclear unit being [CuIILZnII(H2O)2]2+ and [CuIILCdII(H2O)2(CH3CN)]2+ for 1 and 2, respectively. The AgI (in 4), ZnII (in 1) and CdII (in 2) ions in the diphenoxo-bridged dinuclear cores are tri-, tetra- and heptacoordinated, respectively. The metal ions are coordinated to two bridging phenoxo oxygen atoms, with the silver(I) and zinc(II) centres being additionally coordinated to one and two water molecules, respectively. While in the case of cadmium(II), the additional five coordination positions are occupied by two ethoxy oxygen atoms, two water oxygen atoms and one acetonitrile nitrogen atom. The coordination environment of silver(I) in 4 is pyramidal with a scalene O3 triangle as the base, whereas those of zinc(II) and cadmium(II) in 1 and 2 are distorted tetrahedral and distorted pentagonal bipyramidal, respectively. The coordinated water molecule in 4 and each of the two coordinated water molecules in 1 and 2 are encapsulated into the O4 compartment of a [CuIIL] moiety resulting in the [2 × 1 + 1 × 1] (for 4) or [2 × 1 + 1 × 2] (for 1 and 2) cocrystallization and self-assemblies. Clearly, the encapsulation of the coordinated water molecule(s) is the governing force for the formation of dinuclear-mononuclear co-crystals in 1, 2 and 4. In addition all four compounds 1–4 have π–π stacking interactions which form dimers between pairs of adjacent molecules in the structure of 3 consisting of CuIIHgII dimers, while one-dimensional stacks are formed in the CuII3ZnII (1), CuII3CdII (2) and CuII2AgI (4) complexes. The compositions of the title compounds are compared with the related systems derived from the same ligand. The [2 × 1 + 1 × 1] co-crystal, 4, is a new type of system in terms of the number of components. Again, in spite of the tri-, tetra- and hepta-coordinated nature of the second metal ion in the dinuclear cores, co-crystallization in 1, 2 and 4, respectively, are new observations. The accommodation/coordination of varieties of metal ions by the O4 compartment of H2L has also been highlighted in the present investigation.

Strongly hydrogen bonded interlocked infinite double helices in a crown ether based gadolinium(III) hexacyanoferrate(III) supramolecule

The strong O–H⋯N and O–H⋯O hydrogen bonds involving two types of crystallographically different hexacyanoferrate(III) anions and water molecules in [GdIII(18-crown-6)(H2O)3][FeIII(CN)6]·2H2O result in 3-D assembly consisting of the novel example of interlocked infinite double helices.

Synthesis and crystal structure of a triple-decker CuII3TlI2 complex: first example of a thallium(I) system in the imino-phenolate Schiff base ligand family

This report deals with the synthesis, characterization, and crystal structure of a heteropentanuclear CuII3TlI2 compound [(CuIIL)3TlI2](NO3)2 (1), where H2L=N,N′-ethylenebis(3-ethoxysalicylaldimine). This compound crystallizes in the monoclinic crystal system within space group C2/c. Each of the two symmetry related thallium(I) centers is located between a terminal and a common, central [CuIIL] by forming bonds with four phenoxo and three ethoxy oxygens. The three [CuIIL] moieties are parallel and hence 1 is a triple-decker system. Neighboring triple-decker moieties are interlinked by π⋯π stacking interaction and weak hydrogen bonds to generate 3-D self-assembly in 1. Salient features in the composition and structure of the title compound are discussed; the title compound is the first example of a thallium(I) system in imino-phenolate Schiff base family. Synthesis and crystal structure of [(CuIIL)3TlI2](NO3)2 is described, where H2L = N,N′-ethylenebis(3-ethoxysalicylaldimine). This is a sandwich, triple-decker system and the sole TlI complex derived from an iminophenolate ligand.

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, characterization, spectroscopy, and quantum chemical calculation of two 2-(N-2′-aminopyridylo)pyridinium salts: observation of an acyclic water pentamer

Syntheses, characterization, and studies of two 2-(N-2′-aminopyridylo)pyridinium salts, [DPA1HA [Fe(CN)6]3− · 5H2O (1) and [DPA1HA]+Cl− · 2H2O (2; DPA1HA = monoprotonated 2,2′-dipyridylamine (DPA) having one pyridine nitrogen protonated) are described. X-ray single crystal structure of 1 has been determined. This complex crystallizes in monoclinic P21/n space group with a = 18.691(8) Å, b = 11.685(6) Å, c = 20.392(9) Å, β = 117.03(3)°, and Z = 4. Quantum chemical calculations on neutral, monoprotonated, and diprotonated 2,2′-dipyridylamine have been performed to understand the site of protonation in 1. The water molecules in 1 are interlinked to result in the generation of the rare example of an acyclic water pentamer. The water pentamer is hydrogen bonded with the ferricyanide anion to generate a two-dimensional water-ferricyanide sheet. The overall supramolecular structure of 1 is three-dimensional due to hydrogen bonding interactions of the organic cations with both the ferricyanide anion and water cluster. Compound 2 has been characterized by elemental analyses and IR spectrum. Quantum chemical calculations in the gaseous state and the isolation of 1 and 2 in the solid state indicate that monoprotonation of DPA at one pyridine nitrogen is more favorable. However, spectrophotometric titration of DPA with acid indicates that di-(or tri-) protonation takes place in solution.

Bis(nitrate)diaquauranyl(VI) synthon to generate [1 x 2+1 x 1] and [1 x 1+1 x 1] co-crystalized 3d center dot center dot center dot 5f self-assemblies

The syntheses, characterization and crystal structures of four copper(II)/nickel(II)⋯uranyl(VI) self-assemblies of composition [{NiIIL1}2·{(UVIO2)(NO3)2(H2O)2}] (1), [{CuIIL2}2·{(UVIO2)(NO3)2(H2O)2}]·0.68H2O (2), [{NiIIL2}2·{(UVIO2)(NO3)2(H2O)2}] (3) and [{CuIIL3}·{(UVIO2)(NO3)2(H2O)2}]n (4) are described in this investigation (H2L1, H2L2 and H2L3 are the Schiff base ligands obtained on condensing 3-ethoxysalicylaldehyde with ethylenediamine, o-phenylenediamine and trans-1,2-diaminocyclohexane, respectively). Compounds 1 and 4 crystallized in the monoclinic P21/n and C2/c space groups, respectively, while compounds 2 and 3 crystallized in the triclinic space group P. Two water molecules of the [(UVIO2)(NO3)2(H2O)2] moiety in 1–4, have a linear H2O–U–OH2 arrangement. Each of these two water molecules in 1–3 interacts with the O(phenoxo)2O(ethoxy)2 compartment of a mononuclear copper(II) or nickel(II) moiety due to the formation of bifurcated hydrogen bonds between each of the two water hydrogen atoms and a pair of one phenoxo and one ethoxy oxygen atoms resulting in the interlinking of the two mononuclear 3d units by the [(UVIO2)(NO3)2(H2O)2] synthon and therefore these three compounds may be considered as supramolecular dimers. Compounds 1–3 are also two component [1 × 2 + 1 × 1] co-crystals consisting of two mononuclear copper(II) or nickel(II) units and one [(UVIO2)(NO3)2(H2O)2] moiety. On the other hand, in 4, two water molecules, from two different [(UVIO2)(NO3)2(H2O)2] moieties, interact with one O(phenoxo)2O(ethoxy)2 compartment resulting in the formation of a self-assembled one-dimensional topology. Again, since one mononuclear copper(II) unit and one [(UVIO2)(NO3)2(H2O)2] moiety exist in a single crystal in 4, this compound is a two component [1 × 1 + 1 × 1] co-crystal. The outcomes of the present study utilize [(UVIO2)(NO3)2(H2O)2] synthon to derive 3d⋯5f co-crystals, provide the first observation of the interaction of two water molecules with one O(phenoxo)2O(ethoxy)2 compartment, demonstrate the formation of supramolecular dimers and show the first example of a one-dimensional self-assembly resulting from water⋯O4 compartment hydrogen bonds, and the first example of [1 × 2 + 1 × 1] co-crystals in 3-ethoxysalicylaldehyde-diamine ligand system.