A rare `mesh of trees' (mot) net: poly[aquahemi[µ4-1,6-bis(1,2,4-triazol-1-yl)hexane](µ2-5-nitroisophthalato)cadmium(II)].

In the title coordination compound, [Cd(C(8)H(3)NO(6))(C(5)H(8)N(3))(0.5)(H(2)O)](n), each Cd(II) atom is six-coordinated in a distorted octahedral environment surrounded by three carboxylate O atoms from two different 5-nitroisophthalate (5-NIP(2-)) ligands, two N atoms from two distinct 1,6-bis(1,2,4-triazol-1-yl)hexane (bth) ligands and one water molecule. The Cd(II) centres are bridged by the bth ligands, which lie across centres of inversion, to give a honeycomb-like two-dimensional layer structure; the layers are further connected by the bridging 5-NIP(2-) ligands with a κ(2);κ(1)-µ(2) coordination mode to generate the final three-dimensional structure. Topologically, taking the the Cd(II) atoms and the bth ligands as different four-connected nodes and the 5-NIP(2-) ligands as linkers, the three-dimensional structure can be simplified to a rare `mesh of trees' (mot) net with the Schäfli symbol (6(6))(6(4).8(2))(2).

Chlorido(5-formyl-2-hydroxy-phenyl-κC)mercury(II).

In the planar (r.m.s. deviation = 0.027 Å) title compound, [Hg(C(7)H(5)O(2))Cl], the Hg(II) atom shows a typical linear coordination by a C atom of the benzene ring and a Cl atom. Inter-molecular O-H⋯O hydrogen bonds are present in the crystal structure, resulting in chains propagating along the b axis. The crystal studied was a non-merohedral twin, with a twin ratio of 0.802 (2):0.198 (2).

(E)-N'-(4-Pyridylmethyl-ene)-2-(quinolin-8-yl-oxy)acetohydrazide sesquihydrate.

In the title compound, C(17)H(14)N(4)O(2)·1.5H(2)O, the mean planes of the pyridine ring and quinoline group make a dihedral angle of 21.0 (2)°. One water molecule lies on a twofold rotation axis. The organic mol-ecules and the three water mol-ecules are linked into infinite chains by N-H⋯O, O-H⋯O and O-H⋯N hydrogen bonds.