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[Cu(en)(phen)2]+ is crystallized along with two phenanthroline and eight lattice water molecules either as a chloride or a nitrate salt. The cation has almost identical structural and spectral properties which correspond to a tetragonally elongated octahedral geometry with the en ligand in the equatorial plane. EPR parameters reveal a slight rhombicity in the coordination polyhedron. Even though both compounds have the same composition (except for the anions), the hydrogen bond networks involving the lattice water molecules and anions are quite different in the two compounds. There are also extensive π-stacking interactions involving the phenanthroline molecules, both coordinated and non-coordinated. The non-bonding interactions have a major directing role in the crystallization of the tris-chelate cation. The analogous mixed ligand complex of 2,2-bipyridine could not be crystallized.

Two new mixed ligand complexes of copper(II) with acetylacetonate (acac), 2,2′-bipyridine (bpy) and 1,10-phenanthroline (phen) belonging to the class of cytotoxic and antineoplastic compounds known as CASIOPEINAS® were synthesized and structurally characterized. Crystals of both complexes [Cu(acac)(bpy)(H2O)]NO3 · H2O (1), [Cu(acac)(phen)Br] (2) contain square pyramidal Cu(II) complex species. In frozen solution both compounds give well resolved EPR spectra with very similar parameters.

The title compound, [Fe2O(SO4)2(C10H8N2)4], crystallizes as two different hydrates, viz. 11H2O, (I), and 15H2O, (II). The complex is binuclear, in which the two FeIII atoms are coordinated in an octahedral geometry to four N atoms from the two bipyridine ligands, to one O atom from the sulfate ion and to an oxide ion on a twofold axis, which acts as a bridge between the symmetry-related units. The Fe...Fe separation is 3.556 (4) A and the Fe-O-Fe angle is 161.6 (2) degrees in (I); the corresponding values are 3.544 (1) A and 165.8 (2) degrees in (II). In (II), one of the O atoms of the sulfate ion is disordered over two positions. In both compounds, the solvent water molecules form slightly different one-dimensional hydrogen-bonded networks which pass along the c axis of the unit cell. In (I), three solvent water molecules and, in (II), one solvent water molecule, are situated on the twofold axis. In both (I) and (II), the central O atom of the metal complex lies on a twofold axis.

The reactions of oxalic acid with Mg 2+ , Ca 2+ and Zn 2+ in aqueous medium were investigated. When 0·01 m oxalic acid solutions spiked with various levels of Zn 2+ were titrated against standard KMnO 4 solutions, a linear relationship was obtained between the amount of precipitated oxalate and the metal ion concentrations. A similar observation was made for Ca 2+ , but higher proportions of the oxalate were precipitated at equivalent metal ion concentrations. The relationshps were also confirmed by titrating standard metal ion solutions, spiked with various levels of oxalic acid, against standard EDTA solutions. When Mg 2+ was present in solution with Zn 2+ or Ca 2+ or with the mixture, it inhibited the precipitation of the oxalates. The inhibitory action was most noticeable when the metal ions were present in solution in a 1:1:1 molar ratio. In all cases, the higher the proportion of Mg 2+ , the less the precipitation of the oxalates of the other two metals.

Five green leafy vegetables (Talinum triangulare, Amaranthus hybridus, Celosia argentea, Corchorus olitorius and Vernonia amygdalina) were analysed for their ascorbic acid contents. The intersite variation in the values was rather high when compared with both the intrasite and the between-sample variations. For a particular site, Celosia argentea had the lowest ascorbic acid content (181 mg/100 g dry wt) while Talinum triangulare had the highest (354 mg/100 g dry wt). In direct sunlight, an average of 64·0% of the initial ascorbic acid content was lost in 8 h. An open laboratory did not, however, appreciably reduce the loss. On the other hand, in darkness, only about 16·0% loss occurred within the same period. In a household refrigerator, the decrease in the vitamin was almost arrested, as an average of only 0·5% loss occurred after 8 h. The patterns of ascorbic acid change in both vegetables were similar despite the different initial levels.

Five green leafy vegetables commonly consumed in Nigeria (Talinum triangulare, Corchorus olitorius, Celosia argentea, Amaranthus hybridus and Vernonia amygdalina) were examined for their chlorophyll contents. These varied between 0.038% for Talinum triangulare and 0.137% for Vernonia amygdalina, with chlorophyll-a constituting between 68 and 75% of the total chlorophyll. By bringing the temperature of the leaves to 100°C, at least 56% of the total chlorophyll was lost, the rate of loss decreasing with the initial total chlorophyll content. When the leaves were blanched by immersion in boiling water, they showed a greater rate of chlorophyll loss. This was reduced when the pH was adjusted to 6.

Twelve locally grown green leafy vegetables were analysed for their mineral contents. The following concentration ranges (in mg g−1 dry weight) were obtained for the elements determined: sodium, 0·11–0·76; potassium, 0·36–1·07; calcium, 0·24–0·73; phosphorus, 0·18–0·39; magnesium, 0·66–1·76; manganese, 0·03–0·12; iron, 0·35–0·56; zinc, 0·04–0·12.

The fat content of some common tubers grown in Nigeria was determined and the distribution of fatty acids in them was measured by gas-liquid chromatography (GLC). The fat content was low (

Two new derivatives are proposed for determination of nitrosamines by GLC. One is formed by reaction with di(2-chloroethyl) phosphochloridate and the other by reaction with m-trifluorotoluene sulphonyl chloride.

The hydrocarbon constituents of the leaf waxes of eight species of Khaya were analysed for taxonomic purposes using GLC. The leaf waxes contained neither isoalkanes nor alkanes and the bulk of the n-alkanes were in the range of C25 to C33, odd-carbon number compounds predominating. It was found that the percentage composition of the n-alkane constituents of the leaf waxes varied with the age of leaves, young leaves having n-C29 as the most abundant alkane, whereas older leaves had n- C31.