Preparation and crystal structure of bis(protonated 2,6-diacetylpyridine bis(phenylhydrazone)) uranyl tetrachloride,CH3CN

The reaction of 2,6-diacetylpyridine-bis(phenylhydrazone),L, with commercial uranyl chloride under a variety of different conditions gave only complexes of the type [2LH]²⁺[UO₂Cl₄]^2?,xCH₃CN (x = 1 or 2). The structure of the title compound was determined by X-ray analysis. The crystals are triclinic, space groupP¯1,a=12.77(1),b= 23.12(2),c= 8.11(1) Å, α = 94.33(3) °, β = 89.43(3) °, γ = 98.22(3) ° andZ= 2. The structure was solved by Fourier methods, and refined by least-squares toR= 0.074 for 5210 reflections which were measured on an automatic diffractometer. The [UO₂Cl₄]^2? anions have approximately^4mm _m (D _4h ) symmetry, with the uranyl group perpendicular to a plane in which the four chlorine atoms occupy the corners of a square. The organic cations are approximately planar. Shortening in the C-N (chain) bond distances suggests the presence of a mesomeric effect extended over the entire organic system.