Potassium pentaborate

Abstract

The title compound, K[B5O7(OH)2], was obtained from a hystructure is composed of one K+ cation and a polyborate ∞1[B5O7(OH)2] - anion, which consists of two six-membered rings linked by a common BO4 tetra-hedron. The [B5O7(OH) 2]- units are linked together through two exocyclic O atoms to neighbouring units, forming a helical chain structure extending parallel to [010]. Adjacent chains are further connected into a three-dimensional structure by K - O bonds and weak O - H⋯O hydrogen-bond interactions. © Qi Wu 2011.