{4,6-Bis[(E)-1-methyl-2-(pyridin-2-yl-methyl-idene-κN)hydrazinyl-κN]pyrimidine-κN}dichloridocopper(II) methanol disolvate monohydrate.

The title compound, [CuCl(2)(C(18)H(18)N(8))]·2CH(3)OH·H(2)O, contains a penta-coordinated Cu(II) atom bonded to the tridentate 4,6-bis-[(E)-1-methyl-2-(pyridin-2-yl-methyl-idene)hydrazin-yl]pyrimidine ligand and two Cl atoms. The geometry around the Cu(II) atom is distorted square-pyramidal. The mol-ecules pack in the crystal structure via O-H⋯Cl, O-H⋯N, C-H⋯Cl and C-H⋯O hydrogen bonds, C-H⋯π and π-π inter-actions [centroid-centroid distances of the pyrimidine-pyridine and pyridine-pyridine inter-actions are 3.750 (3) and 3.850 (3) Å, respectively], forming sheet-like assemblies.

Di-mu-halogeno-bis[halogeno(triphenylphosphine)mercury(II)], [Ph3PHgX(mu-X)2XHgPPh3], reinvestigated at 120 K for X = Cl and Br, and a second polymorph for X = I, also at 120 K.

Di-mu-chloro-bis[chloro(triphenylphosphine)mercury(II)], [Hg2Cl4(C18H15P)2], (I), and di-mu-bromo-bis[bromo(triphenylphosphine)mercury(II)], [Hg2Br4(C18H15P)2], (II), have been reinvestigated at 120 K. The molecules of (I) lie across inversion centres in space group P2(1)/n, and in both (I) and (II) the complexes are linked into three-dimensional frameworks by a combination of C-H...X (X = Cl and Br) and C-H...pi(arene) hydrogen bonds. At 120 K, di-mu-iodo-bis[iodo(triphenylphosphine)mercury(II)], [Hg2I4(C18H15P)2], (III), crystallizes as a new polymorphic form having Z' = 1/2, where the complexes lie across inversion centres in space group P2(1)/n; the complexes are linked into sheets by a combination of C-H...I and C-H...pi(arene) hydrogen bonds. In the Z' = 1 polymorph of this compound, a single C-H...I hydrogen bond generates simple chains.

The 2:1 adducts of (benzoylmethylene)triphenylphosphorane with fumaric and terephthalic acids.

Co-crystals of the ylide (benzoylmethylene)triphenylphosphorane (BPPY) with either fumaric acid, viz. (benzoylmethylene)triphenylphosphorane-fumaric acid (2/1), C(26)H(21)OP.0.5C(4)H(4)O(4), or terephthalic acid, viz. (benzoylmethylene)triphenylphosphorane-terephthalic acid (2/1), C(26)H(21)OP.0.5C(8)H(6)O(4), have a stoichiometric ratio of 2:1 between the ylide and the corresponding dicarboxylic acid. In both adducts, the acid component lies across a centre of inversion. In neither case is the ylide protonated by the organic acid; instead the H atoms of the non-ionized dicarboxylic acid molecules participate in the formation of strong O-H...O hydrogen bonds with the benzoyl O atom of the ylide species. These structures are the first reported examples of co-crystals containing non-protonated BPPY.

Orthorhombic and monoclinic polymorphs of 1,3,5-triphenylperhydro-1,3,5-triazine-2,4,6-trione at 120 K: chains and sheets formed by C-H...pi(arene) hydrogen bonds.

The title compound, C21H15N3O3, crystallizes in two polymorphic forms. In the orthorhombic polymorph, (I), in space group Fdd2 with Z' = 1, the molecules lie in general positions, while in the monoclinic polymorph, (II), in space group C2/c with Z' = 1/2, the molecules lie across twofold rotation axes. In each polymorph, the molecules are linked by a single C-H.pi(arene) hydrogen bond, forming chains in polymorph (I) and sheets in (II).