Synthesis, crystal structures, and magnetic properties of two three-dimensional octacyanotungstate(IV)-based bimetallic frameworks with 4,4′-bipyridine dioxide (4,4′-dpdo)

Abstract

W(CN) 8 ]}·CH 3 OH·H 2 O (2). Compound 1 crystallizes in the orthorhombic system, space group P2 1 2 1 2 with cell constants a=10.397(2) Å, b= 11.321(2) Å, c=12.295(3) Å and Z=2, whereas 2 crystallizes in the monoclinic system, space group P2 1 /c with cell constants a=13.038(3) Å, b=13.784(3) Å, c=13.225(3) Å, β=93.44(3)º and Z=4. In complex 1, each [W IV (CN) 8 ] 4− unit with a square antiprismatic geometry is connected to four Mn 2 dimers through four bridging CN − ions forming wavelike alternating -W-Mn 2 -W-Mn2-layers, which are further linked through 4,4′-dpdo ligands coordinated to the Mn ions into a three-dimensional open framework. In complex 2, each [W IV (CN) 8 ] 4− ion still adopts a square antiprismatic geometry, whereas it bonds to seven copper ions through seven CN − ions leading to cage-like undulate layers further bridged by 4,4′-dpdo ligands into a three-dimensional network. Due to the bridging role of the long rigid 4,4′-dpdo ligand, there exist plenty of large cavities in the open frameworks of complexes 1 and 2 occupied by solvent clusters containing H 2 O or CH 3 OH molecules. To our knowledge, it is noted that 4,4′-dpdo displays a μ-4,4,4′,4′ mode, which was first experimentally observed, although predicted before. Magnetic studies show that complex 1 displays an antiferromagnetic coupling between Mn Ⅱ ions, while complex 2 exhibits a weak ferromagnetic interaction between Cu Ⅱ ions.

Magnetic interactions controlled by light in the family of Fe(ii)–M(iv) (M = Mo, W, Nb) hybrid organic–inorganic frameworks

“…The best fit parameters J FeFe (superexchange coupling constant) and D (zfs parameter) summarized in Table 1 are similar for both compounds. The reported J FeFe values are in line with previous studies of systems bridged by the 4,4′-bpdo linker, 42,43 as well as D parameters falling in the expected range for iron( ii ) systems. 44–47 Nonetheless, the obtained J and D should be treated rather as approximate values, as our model does not account for superexchange interactions transferred by long [–NC–M IV (CN) 6 –CN–] linkers and dipole–dipole interactions between neighbouring iron( ii ) ions.…”

Manganese(II)-Octacyanometallate(V) Bimetallic Ferrimagnets with Tc from 41 to 53 K Obtained in Acidic Media

“…All cyanide groups bridge from W V to Mn II ions giving rise to two coordination environments around Mn II ions. The bond lengths of C−N are 1.121(8), 1.140(11), and 1.114(16) Å, while those of W−C are 2.169(7), 2.176(8), and 2.170(11) Å, respectively, comparable with the reported values. ,− Mn1 has an occupancy rate of 0.75 and accepts 0.75 × 4 cyanide groups by equatorial plane and 0.5 × 2 formate ions and 0.25 × 2 water molecules by the axis directions completing the six-coordinated sphere corresponding to a Mn II ion. In fact, the formate ion is also a bridge between Mn1 and its asymmetrical atoms.…”

“…Up to date, there have been several 3D manganese−octacyanometallate bimetallic complexes reported. For the description, as further below, their structures can be roughly classified as four types by the construction: (i) A typical structure is −[W(CN) 8 ]−Mn 4 −[W(CN) 8 ]−Mn 4 − columnar linkages that share the nodes of Mn II ions and interlock to form the 3D networks, as reported previously; ,, (ii) The well-known [Mn 9 M 6 ] clusters are connected by a bidentate organic ligand to the 3D cluster array; , (iii) The square Mn 2 W 2 units share the nodes of W ions leading to the 3D networks with small pores; ,, and (iv) [W(CN) 8 ] bridges between Mn II ions with N-heterocyclic chelated ligands forming the 3D metal−organic framework. , The structure of complex 1 is different from all the reported complexes, although it crystallizes in tetragonal system similar to those with typical structures. ,, The asymmetrical unit of complex 1 contains an octacyanotungstate(V), 1.75 molecules of manganese(II) with 1.5 molecules of coordinating water and 0.5 molecules of formate ion and one lattice water molecule, in which most atoms are disordered in position leading to a very complicated structure. As shown in Figure a, octacyanotungstate takes a bicapped trigonal prismatic configuration with three disordered cyanide groups occupying four positions of C2N2 and its symmetrical sites.…”

Highlights of recent advances in functional coordination polymers made in China

“…In this regard, Gao et al [3] II species, which are essentially based on the interactions between the metal ions and bridging carboxylate groups. Feng and co-workers [7] prepared a 2D Mn II coordination polymer hydrothermally using 1,4-benzenebis(thioacetic acid) as bridging tectons and 1,10-phenanthroline as a chelating co-ligand.…”