Phenanthroline complexes of zinc and calcium carbamates.

Bis(N,N-di-n-butyldithiocarbamato-kappa2S,S')(1,10-phenanthroline-kappa2N,N')zinc(II) ethanol hemisolvate, [Zn(C9H18NS2)2(C12H8N2)].0.5C2H6O, (I), and bis(N,N-di-n-hexyldithiocarbamato-kappa2S,S')bis(1,10-phenanthroline-kappa2N,N')calcium(II), [Ca(C13H26NS2)2(C12H8N2)2], (II), are mixed-ligand complexes.

Two polymorphic forms of 2,5-bis(4-methoxycarbonylphenyl)-1,3,4-oxadiazole.

The title compound [systematic name: dimethyl 4,4'-(1,3,4-oxadiazole-2,5-diyl)diphenylenedicarboxylate], C(18)H(14)N(2)O(5), crystallizes under similar conditions in two different orthorhombic crystalline forms. In both forms, the molecule consists of two equivalent parts. In form 1, these parts are related by a twofold axis of space group Pbcn, and in form 2, by a mirror plane of space group Cmc2(1).