title: Reversible deprotonation and protonation behaviors of a tetra-protonated γ-Keggin silicodecatungstate.
abstract: The potentiometric titration of a γ-Keggin tetra-protonated silicodecatungstate, [γ-SiW(10)O(34)(H(2)O)(2)](4-) (H(4)·I), with TBAOH (TBA = [(n-C(4)H(9))(4)N](+)) showed inflection points at 2 and 3 equiv of TBAOH. The (1)H, (29)Si, and (183)W NMR data suggested that the in situ formation of tri-, doubly-, and monoprotonated silicodecatungstates, [γ-SiW(10)O(34)(OH)(OH(2))](5-) (H(3)·I), [γ-SiW(10)O(34)(OH)(2)](6-) (H(2)·I), and [γ-SiW(10)O(35)(OH)](7-) (H·I), with C(1), C(2v), and C(2) symmetries, respectively. Single crystals of TBA(6)·H(2)·I suitable for the X-ray structure analysis were successfully obtained and the anion part was a monomeric γ-Keggin divacant silicodecatungstate with two protonated bridging oxygen atoms. Compounds H(3)·I, H(2)·I, and H·I were reversibly monoprotonated to form H(4)·I, H(3)·I, and H(2)·I, respectively.
authors: Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors: Kosei
authors: K
authors: Sugahara
authors: Shinjiro
authors: S
authors: Kuzuya
authors: Tomohisa
authors: T
authors: Hirano
authors: Keigo
authors: K
authors: Kamata
authors: Noritaka
authors: N
authors: Mizuno