SYNTHESIS AND CRYSTAL-STRUCTURE OF THORIUM HYDROXY PICRATE HEXADECAHYDRATE (BASIC THORIUM PICRATE)

The title compound, crystallized from the solution produced by dissolution of thorium carbonate in hot, aqueous picric acid (Hpic, 2,4,6-trinitrophenol) as pale yellow needles, has been the subject of a room-temperature single-crystal X-ray study and found to be [(pic)(H2O)(6)Th(mu-OH)(2)Th(OH2)(6)(pic)](pic)(4).2OH(2)O. The compound is triclinic, P $$($) over bar 1, a 14.651(4), b 12.877(6), c 11.838(2) Angstrom, alpha 69.71(3), beta 75.93(2), gamma 80.10(3); Z = 1 (dimeric) f.u.; conventional R on /F/ at convergence was 0.032 for 8281 'observed' (I > 3 sigma(I)) reflections. The thorium is nine-coordinate Th(O-pic)(mu-O)(2)(OH2)(6), the dimer being centrosymmetric and the coordination geometry about thorium being approximately that of a singly capped square antiprism, the capping atom (over a square face) being the slightly more remote of the bridging hydroxy groups. Th-mu-OH are 2.366(3), 2.381(3), Th-OH2 2.479(5)-2.534(4) and Th-O(pic) 2.366(3) Angstrom.