The title compound, Rb2Ga2O(BO3)2, is part of the homologous series A2Ga2O(BO3)2 (A = Na, K, Rb and Cs). The structure contains pairs of gallium-centered tetrahedra connected through a shared oxygen vertex. Orthoborate triangles connect the basal vertices of the tetrahedra, forming a three-dimensional network with voids occupied by rubidium ions.
Smith, Robert W.; Hu, Chunhua; and DeSpain, Christopher D., "Dirubidium Digallium Oxide Bis(orthoborate)" (2008). Chemistry Faculty Publications. 9.