Bis(μ-ferrocene­carboxyl­ato)bis­[aqua­­bis(ferrocene­carboxyl­ato)methano­l­erbium(III)] methanol disolvate

In the centrosymmetric title coordination compound, [Er₂{Fe(C₅H₅)(C₆H₄O₂)}₆(CH₃OH)₂(H₂O)₂]·2CH₃OH, the two Er^III ions are bridged by two ferrocene­carboxyl­ate anions as asymmetrically bridging ligands, leading to dimeric cores. The Er^III ion has a distorted dodeca­hedral coordination with six coordinating O atoms derived from the ferrocene­carboxyl­ate ligands and two coordinated O atoms from one water mol­ecule and one methanol mol­ecule. The asymmetric unit comprises a half of the complex mol­ecule and a methanol solvent mol­ecule. Intra­molecular O—H...O and C—H...O inter­actions occur. In the crystal, mol­ecules are linked by inter­molecular O—H...O hydrogen bonds and C—H...O as well as C—H...π inter­actions.

2′,6′-Bis(4-carb­oxy­phen­yl)-4,4′-bipyridin-1-ium nitrate 0.25-hydrate

In the title compound, C₂₄H₁₇N₂O₄⁺·NO₃⁻·0.25H₂O, the central pyridine ring of the 2′,6′-bis­(4-carb­oxy­phen­yl)-4,4′-bipyridin-1-ium cation is almost coplanar with one benzene ring [dihedral angle = 1.03 (5)°], while it makes dihedral angles of 9.59 (5)° with the other benzene ring and 13.66 (6)° with the pyridinium ring. In the crystal, N—H...O and O—H...O hydrogen bonds link the cations and nitrate anions into a sheet in the (302) plane. The crystal structure also exhibits π–π inter­actions between the central pyridine ring and the benzene rings of neighboring mol­ecules [centroid–centroid distance = 3.6756 (13) Å].