Crystal engineering of coordination polymers using 4,4′-bipyridine as a bond between transition metal atoms

This critical review describes how halocarbons can function as effective binding sites of anions via halogen bonding, the noncovalent interaction whereby halogen atoms accept electron density. The focus is on the binding and coordination of oxyanions, by far the most numerous class of anions in organic chemistry. It is shown how a large variety of inorganic and organic oxyanions can form discrete adducts and 1D, 2D, or 3D supramolecular networks with chloro-, bromo-, and iodocarbons. Specific examples are discussed in order to identify new supramolecular synthons based on halogen bonding and to outline some general principles for the design of effective and selective receptors based on this interaction. The interaction allows for several other anions to self-assemble with halocarbons and mention is also given to the halogen bonding-based coordination of halides, polycyano- and polyoxometallates (72 references).

Halogen bonding: a general route in anion recognition and coordination

Synthesis, structures and fluorescence of nickel, zinc and cadmium complexes with the N,N,O-tridentate Schiff base N-2-pyridylmethylidene-2-hydroxy-phenylamine

Tridentate Schiff-base carboxylate-containing ligands, derived from the condensation of 2-imidazolecarboxaldehyde with the amino acids β-alanine (H2L1) and 2-aminobenzoic acid (H2L5) and the condensation of 2-pyridinecarboxaldehyde with β-alanine (HL2), d,l-3-aminobutyric acid (HL3), and 4-aminobutyric acid (HL4), react with copper(II) perchlorate to give rise to the helical-chain complexes {[Cu(μ-HL1)(H2O)](ClO4)}n (1), {[Cu(μ-L2)(H2O)](ClO4)·2H2O}n (2), and {[Cu(μ-L3)(H2O)](ClO4)·2H2O}n (3), the tetranuclear complex {[Cu(μ-L4)(H2O)](ClO4)}4 (4), and the mononuclear complex [Cu(HL5)(H2O)](ClO4)·1/2H2O (5). The reaction of copper(II) chloride with H2L1 leads not to a syn−anti carboxylate-bridged compound but to the chloride-bridged dinuclear complex [Cu(HL1)(μ-Cl)]2 (6). The structures of these complexes have been solved by X-ray crystallography. In complexes 1−4, roughly square-pyramidal copper(II) ions are sequentially bridged by syn−anti carboxylate groups. Copper(II) ions exhibit CuN2O3 coordination e...

Helical-chain copper(II) complexes and a cyclic tetranuclear copper(II) complex with single syn-anti carboxylate bridges and ferromagnetic exchange interactions.

Two new metal-organic based polymeric complexes, [Cu(4)(O(2)CCH(2)CO(2))(4)(L)].7H(2)O (1) and [Co(2)(O(2)CCH(2)CO(2))(2)(L)].2H(2)O (2) [L = hexamethylenetetramine (urotropine)], have been synthesized and characterized by X-ray crystal structure determination and magnetic studies. Complex 1 is a 1D coordination polymer comprising a carboxylato bridged Cu(4) moiety linked by a tetradentate bridging urotropine. Complex 2 is a 3D coordination polymer made of pseudo-two-dimensional layers of Co(II) ions linked by malonate anions in syn-anti conformation which are bridged by bidentate urotropine in trans fashion. Complex 1 crystallizes in the orthorhombic system, space group Pmmn, with a = 14.80(2) A, b = 14.54(2) A, c = 7.325(10) A, beta = 90 degrees, and Z = 4. Complex 2 crystallizes in the orthorhombic system, space group Imm2, a = 7.584(11) A, b = 15.80(2) A, c = 6.939(13) A, beta = 90.10 degrees (1), and Z = 4. Variable temperature (300-2 K) magnetic behavior reveals the existence of ferro- and antiferromagnetic interactions in 1 and only antiferromagnetic interactions in 2. The best fitted parameters for complex 1 are J = 13.5 cm(-)(1), J' = -18.1 cm(-)(1), and g = 2.14 considering only intra-Cu(4) interactions through carboxylate and urotropine pathways. In case of complex 2, the fit of the magnetic data considering intralayer interaction through carboxylate pathway as well as interlayer interaction via urotropine pathway gave no satisfactory result at this moment using any model known due to considerable orbital contribution of Co(II) ions to the magnetic moment and its complicated structure. Assuming isolated Co(II) ions (without any coupling, J = 0) the shape of the chi(M)T curve fits well with experimental data except at very low temperatures.

Syntheses of Two New 1D and 3D Networks of Cu(II) and Co(II) Using Malonate and Urotropine as Bridging Ligands: Crystal Structures and Magnetic Studies

Synthesis, characterization and structural studies of mono- and polynuclear complexes of zinc(II) with 1,10-phenanthroline, 2,2′-bipyridine and 4,4′-bipyridine

The compound [Cu(phen)(O2CCF3)2]n (phen = 1,10-phenanthroline) has been synthesized and its crystal structure determined. It crystallizes in monoclinic space group C2/c, with a = 19.229(7), b = 11.281(5), c = 7.621(2) A, β = 104.305(12)°, and Z = 4. The crystal structure is polymeric, being built from infinite zigzag chains of trifluoroacetate bridged copper(II), with the phenanthroline ligands being stacked between the chains. The variable-temperature (13–300 K) magnetic susceptibility and ESR data are reported and a weak ferromagnetic exchange interaction is observed with the exchange parameter estimated as J = 2.9 cm−1.

Structural and magnetic properties of a syn-anti carboxylate bridged one-dimensional copper(II) complex with ferromagnetic exchange interaction

Synthesis and structure of a heptacoordinated cadmium(II) complex

Synthesis, characterisation, reactivity and X-ray crystal structure of a mixed-ligand η1-salicylaldehyde complex of Mn (III)

The single pyrazine-bridged polymeric complex {[Ni(pyz)(H 2 O) 4 ](NO 3 ) 2 .2H 2 O} n has been synthesised and characterised by elemental analyses, IR and UV-vis spectra, and a single-crystal X-ray diffraction study. The coordination around the Ni centre is perfectly octahedral. The Ni(H 2 O) 4 coordination planes are bridged by pyrazine ligands forming an infinite chain structure. Two nitrate anions and two water molecules exist in the lattice and are linked by intermolecular hydrogen bonds to the coordinated water molecules.

Sutapa Sen

Papers

Synthesis, characterization and structural studies of mono- and polynuclear complexes of zinc(II) with 1,10-phenanthroline, 2,2′-bipyridine and 4,4′-bipyridine

Structural and magnetic properties of a syn-anti carboxylate bridged one-dimensional copper(II) complex with ferromagnetic exchange interaction

Synthesis and structure of a heptacoordinated cadmium(II) complex

Synthesis, characterisation, reactivity and X-ray crystal structure of a mixed-ligand η1-salicylaldehyde complex of Mn (III)

A Pyrazine-Bridged Ni(II) Coordination Polymer