title: Silicon-29 NMR Studies of Tetraalkylammonium Silicate Solutions. 1. Equilibria, (29)Si Chemical Shifts, and (29)Si Relaxation.
abstract: The addition of tetraalkylammonium cations to aqueous silicate solutions enhances the abundance of symmetric, cagelike, polysilicate anions including the cubic octamer, Si(8)O(20)(8)(-). The equilibrium ratio of tetramethylammonium (TMA) cations to the octameric silicate anion is 8:1 for solutions with a concentration ratio [OH(-)]:[Si] >/= 1:1. Evidence indicates that organocations directly associate with cagelike polyanions to form a protective shell of hydrophobic hydration that impedes hydrolysis of the central anion.
authors.affiliation: Department of Chemistry, Lakehead University, Thunder Bay, Ontario, P7B 5E1, Canada, and School of Chemical Sciences, University of Illinois at Urbana-Champaign, 505 South Mathews Avenue, Urbana, Illinois 61801.
authors.forename: Stephen D.
authors.initials: SD
authors.lastname: Kinrade
authors.forename: Christopher T. G.
authors.initials: CT
authors.lastname: Knight
authors.forename: David L.
authors.initials: DL
authors.lastname: Pole
authors.forename: Raymond T.
authors.initials: RT
authors.lastname: Syvitski