Synthesis, structural characterization and magnetic properties of polymeric azido Mn(II) complexes based on methyl-pyridine- N -oxide co-ligands

Crystal structures of four dimeric manganese(II) bromide coordination complexes with various derivatives of pyridine N-oxide

Four manganese(II) bromide coordination complexes have been prepared with four pyridine N-oxides, viz. pyridine N-oxide (PNO), 2-methyl-pyridine N-oxide (2MePNO), 3-methyl-pyridine N-oxide (3MePNO), and 4-methyl-pyridine N-oxide (4MePNO). The compounds are bis-(μ-pyridine N-oxide)bis-[aqua-dibromido-(pyridine N-oxide)manganese(II)], [Mn2Br4(C5H5NO)4(H2O)2] (I), bis-(μ-2-methyl-pyridine N-oxide)bis-[di-aqua-dibromido-manganese(II)]-2-methyl-pyridine N-oxide (1/2), [Mn2Br4(C6H7NO)2(H2O)4]·2C6H7NO (II), bis-(μ-3-methyl-pyridine N-oxide)bis-[aqua-dibromido-(3-methyl-pyridine N-oxide)manganese(II)], [Mn2Br4(C6H7NO)4(H2O)2] (III), and bis-(μ-4-methyl-pyridine N-oxide)bis-[di-bromido-methanol(4-methyl-pyridine N-oxide)manganese(II)], [Mn2Br4(C6H7NO)4(CH3OH)2] (IV). All the compounds have one unique MnII atom and form a dimeric complex that contains two MnII atoms related by a crystallographic inversion center. Pseudo-octa-hedral six-coordinate manganese(II) centers are found in all four compounds. All four compounds form dimers of Mn atoms bridged by the oxygen atom of the PNO ligand. Compounds I, II and III exhibit a bound water of solvation, whereas compound IV contains a bound methanol mol-ecule of solvation. Compounds I, III and IV exhibit the same arrangement of mol-ecules around each manganese atom, ligated by two bromide ions, oxygen atoms of two PNO ligands and one solvent mol-ecule, whereas in compound II each manganese atom is ligated by two bromide ions, one O atom of a PNO ligand and two water mol-ecules with a second PNO mol-ecule inter-acting with the complex via hydrogen bonding through the bound water mol-ecules. All of the compounds form extended hydrogen-bonding networks, and compounds I, II, and IV exhibit offset π-stacking between PNO ligands of neighboring dimers.

Structure, DFT Calculations, and Magnetic Characterization of Coordination Polymers of Bridged Dicyanamido-Metal(II) Complexes

Three coordination polymers of metal(II)-dicyanamido (dca) complexes with 4-methoxypyridine-N-oxide (4-MOP-NO); namely, catena-[Co(µ1,5-dca)2(4-MOP-NO)2] (1), catena-[Mn(µ1,5-dca)2(4-MOP-NO)2] (2), catena-[Cd(µ1,5-dca)2(4-MOP-NO)2] (3), and the mononuclear [Cu(κ1dca)2(4-MOP-NO)2] (4), were synthesized in this research. The complexes were analyzed by single crystal X-ray diffraction as well as spectroscopic methods (UV/vis, IR). The polymeric 1-D chains in complexes 1–3 were achieved by the doubly µ1,5-bridging dca ligands and the O-donor atoms of two axial 4-MOP-NO molecules in trans configuration around the distorted M(II) octahedral. On the other hand, the two “trans-axial” pyridine-N-oxide molecules in complexes 2 and 3 display opposite orientation (s-trans). The DFT (density functional theory) computational studies on the complexes 1–3 were consistent with the experimentally observed crystal structures. Compounds 1 and 2 display weak antiferromagnetic coupling between metal ions (J = −10.8 for 1 and −0.35 for 2).

Reversible crystal-to-amorphous structural transformations and magnetic variations in single end-on azide-bridged MII (M = Mn, Ni) coordination polymers

Azide-bridged coordination polymers undergo reversible crystal-to-amorphous phase transformations during the hydration–dehydration process.

Structure, magnetic properties and DFT calculations of azido-copper(ii) complexes with different azido-bonding, nuclearity and dimensionality

Cu(ii) compounds derived from diamine substituted alkyl or phenyl groups with azido acting as the bridging ligand were synthesized and were structurally and magnetically characterized.

Manganese(II) chloride complexes with pyridine N-oxide (PNO) derivatives and their solid-state structures

Three manganese(II) N-oxide complexes have been synthesized from the reaction of manganese(II) chloride with either pyridine N-oxide (PNO), 2-methyl-pyridine N-oxide (2MePNO) or 3-methyl-pyridine N-oxide (3MePNO). The compounds were synthesized from methano-lic solutions of MnCl2·4H2O and the respective N-oxide, and subsequently characterized structurally by single-crystal X-ray diffraction. The compounds are catena-poly[[aqua-chlorido-manganese(II)]-di-μ-chlorido-[aqua-chlorido-manganese(II)]-bis-(μ-pyridine N-oxide)], [MnCl2(C5H5NO)(H2O)] n or [MnCl2(PNO)(H2O)] n (I), catena-poly[[aqua-chlorido-man-gan-ese(II)]-di-μ-chlorido-[aqua-chlorido-manganese(II)]-bis-(μ-2-methyl-pyridine N-oxide)], [MnCl2(C6H7NO)(H2O)] n or [MnCl2(2MePNO)(H2O)] n (II), and bis-(μ-3-methyl-pyridine N-oxide)bis-[di-aqua-dichlorido-manganese(II)], [Mn2Cl4(C6H7NO)2(H2O)4] or [MnCl2(3MePNO)(H2O)2]2 (III). The MnII atoms are found in pseudo-octa-hedral environments for each of the three complexes. Compound I forms a coordination polymer with alternating pairs of bridging N-oxide and chloride ligands. The coordination environment is defined by two PNO bridging O atoms, two chloride bridging atoms, a terminal chloride, and a terminal water. Compound II also forms a coordination polymer with a similar metal cation; however, the coordination polymer is bridged between MnII atoms by both a single chloride and 2MePNO. The distorted octahedrally coordinated metal cation is defined by two bridging 2MePNO trans to each other, two chlorides, also trans to one another in the equatorial (polymeric) plane, and a terminal chloride and terminal water. Finally, complex III forms a dimer with two bridging 3MePNOs, two terminal chlorides and two terminal waters forming the six-coordinate metal environment. All three compounds exhibit hydrogen bonding between the coordinating water(s) and terminal chlorides.