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.