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The possibility of formation of a solid solution in the system Ca 1 − x La x Sn 1 − x Co x O 3 has been explored up to x = 0.20. Formation of a solid solution was studied using X-ray diffraction. It has been thus found that a solid solution forms in this system up to x = 0.10. A.c. and d.c. conductivities were measured to elucidate the electrical conduction behaviour in this system.

Bull. Chem. Soc. Ethiop., 4(1), 61-65 (1990).

New simple and mixed complexes of 1-(2-pyridylazo)-2-naphthol (PAN) and 1,10-phenanthroline (phen) or 2,2′-bipyridyl (bipy) with nickel(II) and zinc(II) were synthesized and characterized by elemental analyses, conductivity, infrared, electronic spectra, room temperature magnetic measurements, and X-ray diffraction studies. The I. R. data suggest the coordination of PAN through oxygen and (pyridine) nitrogen, whereas phen and bipy coordinate through the pyridine nitrogens. The UV-Vis. spectra along with magnetic measurements favor a tetrahedral geometry for the complexes. The podwer X-ray diffraction studies indicate tetragonal symmetry for all these complexes except for Ni(II)-PAN-phen, which has orthorhombic symmetry. aPresent address: School of Materials Science and Technology, I. T, B.H.U., Varanasi - 221 005, India Referee I: C. E. Barnes Referee II: T. C. Strekas

Electrical properties of lanthanum- and cobalt-doped strontium stannate, SrSnO3, have been studied as a function of temperature. All the compositions investigated have cubic structure. Measurement of Seebeck coefficient in one of the cobalt-doped SrSnO3 sample shows that it exhibitsp-type conductivity. Results of AC conductivity measurements show that conduction occurs by hopping of charge carriers in lanthanum-doped samples and forx=0·01 in cobalt-doped sample. Inx=0·05 sample in cobalt-doped system, conduction seems to occur in extended states.

Oxovanadium(IV) and dioxouranium(VI) complexes of 1-(2-pyridylazo)-2-naphthol (PAN) and 4-(2-pyridylazo) resorcinol (PAR) have been prepared and characterised by elemental analyses, various physico-chemical methods and magnetic measurements. The I. R. observations suggest that PAN is coordinated through oxygen and (pyridine) nitrogen, whereas PAR is coordinated through (pyridine) nitrogen and the ortho-hydroxyl group. The spectral-studies suggest that oxovanadium(IV) complexes have the coordination number five and dioxouranium(Vl) complexes have the coordination number six for the cations.

Depanment of Chemistry, Banaras Hmdu University, Varanasi-221 005 Manuscript received 5 November 1992, revtsed 22 Match1994, accepted 6 April 1994 The anion-exchange behaviour of a number of metal-4-(2-pyridylazo)resorcinal (PAR) complexes on Dowex-1-XB (Cl--form) in ethanolic medium has been studied. The distribution coefficients were determined by batch technique for predicting the conditions for the possible separations on column. The effect of pH and different organic solvents on the distribution coefficients has also been studied. The column chromatographic separations achieved were quantitative. The distribution coefficients, column elution behaviour of metal complexes and the results of separation of synthetic mixtures along with elution curves are presented.

Les deux composes cristallisent dans le systeme orthorhombique. Leurs parametres cristallins valent respectivement: a=10,98 A b=8,43 A c=6,64 A et a=12,12 A b=8,96 A c=8,04 A

Bivalent and trivalent cobalt complexes with 1-(2-pyridylazo)-2-naphthol (PAN), PAN+1, 10-phenanthroline and PAN+2, 2′-bipyridyl were prepared and characterized by physico-chemical and magnetic measurements. The spectral studies suggest that PAN behaves as a bidentate ligand and is coordinated to metal ions through oxygen and (pyridine) nitrogen, whereas 1, 10-phenanthroline and 2, 2′-bipyridyl are coordinated through (pyridine) nitrogen. The tentative ν(M−O) and ν(M−N) band assignments in the lower i.r. region, and magnetic moment data favour four coordination for the complexes studied.