2-Amino-ethanaminium iodide.

The title salt, [NH(3)CH(2)CH(2)NH(2)](+)·I(-), has an array structure based on strong inter-molecular N-H⋯N hydrogen bonding formed between the ammonium and amine groups of adjacent cations. This inter-action gives a helical chain of cations that runs parallel to the b axis. The four remaining NH group H atoms all form hydrogen bonds to the iodide anion, and these iodide anions lie in channels parallel to the cation-cation chains.

catena-Poly[[(nitrito-κO,O')silver(I)]-μ-1,2-bis-[1-(pyridin-4-yl)ethyl-idene]hydrazine-κN:N'].

The asymmetric unit of the title compound, [Ag(NO(2))(C(14)H(14)N(4))](n), contains half of the repeating formula unit (Z' = 1/2). The Ag(I) ion lies on a twofold rotation axis. The primary structure consists of a one-dimensional coordination polymer formed by the Ag(I) ions and the bipyridyl azine ligand in which there is an inversion center at the mid-point of the N-N bond.

5,7,7,12,14,14-Hexamethyl-4,8-diaza-1,11-diazo-niocyclotetra-deca-4,11-diene diiodide dihydrate.

The asymmetric unit of the title compound, C(16)H(34)N(4) (2+)·2I(-)·2H(2)O, contains one half-cation, one iodide anion and one water mol-ecule. The cation has crystallographically imposed centrosymmetric symmetry. Despite some differences in the unit-cell dimensions, packing analysis on a cluster of 15 cations and a comparison of the hydrogen bonding suggests that this compound is isostructural with its bromide analogue.

1-Benz-yloxy-4-(2-nitro-ethen-yl)benzene.

The title compound, C(15)H(13)NO(3), crystallizes with three independent mol-ecules per asymmetric unit (Z' = 3). One of these mol-ecules is found to have a configuration with a greater twist between its two aromatic rings than the other two [compare 70.26 (13) and 72.

4-(Benz-yloxy)benzaldehyde.

The title compound, C(14)H(12)O(2), has an essentially planar conformation with the two aromatic rings forming a dihedral angle of 5.23 (9)° and the aldehyde group lying in the plane of its aromatic group [maximum deviation = 0.204 (3) Å].

The cobalt(II) salt of the azo dye Orange G.

Crystallizing the cobalt(II) salt of the azo dye Orange G from water was found to give the solvent-separated ion-pair species hexa-aqua-cobalt(II) 7-oxo-8-(2-phenyl-hydrazin-1-ylidene)-7,8-dihydro-naphthalene-1,3-disulfonate tetra-hydrate, [Co(H(2)O)(6)](C(16)H(10)N(2)O(7)S(2))·4H(2)O. The asymmetric unit of the cobalt(II) salt contains three independent octa-hedral [Co(OH(2))(6)](2+) cations, three azo anions, all with similar configurations, and 12 uncoordinated water mol-ecules. The structure is closely related to that of one of the known magnesium analogues.

Cephalexin: a channel hydrate.

The antibiotic cephalexin [systematic name: D-7-(2-amino-2-phenylacetamido)-3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid] forms a range of isomorphic solvates, with the maximum hydration state of two water molecules formed only at high relative humidities.