catena-Poly[[dichloridomercury(II)]-N′-nicotinoylnicotinohydrazide]

The title complex, [HgCl₂(C₁₂H₁₀N₄O₂)]_n, is composed of one Hg^II ion, one nnh ligand (nnh = N′-nicotinoylnicotinohydrazide) and two coordinated chloride ions. The Hg^II ion shows a distorted tetra­hedral geometry, being surrounded by two N atoms from two nnh ligands and two chloride ions. Due to the bridging role of nnh, the Hg^II atoms are connected into polymeric chains along the c axis, which are further inter­linked via N—H...O and C—H...Cl hydrogen-bonding inter­actions, forming a three-dimensional network.

trans-Diaqua­bis­[5-(pyridine-3-carboxamido)­tetra­zolido-κ²O,N¹]zinc dihydrate

The title compound, [Zn(C₇H₅N₆O)₂(H₂O)₂]·2H₂O, consists of one Zn^II ion located on the crystallographic inversion centre, two 5-(pyridine-3-carboxamido)­tetra­zolide ligands, two coordinated water mol­ecules and two free water mol­ecules. The Zn^II ion adopts a slightly distorted octa­hedral coordination geometry formed by the N,O-chelating ligands and two O water atoms. The pyridine N atoms are not coordinated. In the crystal, complex mol­ecules are connected by N—H...O, O—H...N and O—H...O hydrogen bonds, forming a three-dimensional network.

Methyl 2-{[(3-methyl-5-oxo-1-phenyl-4,5-dihydro-1H-pyrazol-4-yl­idene)(4-nitro­phen­yl)meth­yl]amino}-3-phenyl­propano­ate

The mol­ecule of the title compound, C₂₇H₂₄N₄O₅, exists in the keto–enamine tautomeric form, stabilized by an intra­molecular N—H...O hydrogen bond. An intra­molecular C—H...·O hydrogen bond also occurs. In the crystal, C—H...O hydrogen bonds link the mol­ecules into chains.