Penta- and hexa-coordinated beryllium and phosphorus in high-pressure modifications of CaBe2P2O8

Abstract

Beryllium in inorganic compounds is usually coordinated to four oxygen atoms, but higher coordination numbers have been predicted. Here the authors observe a pressure induced stepwise transition in CaBe2P2O8 where Be coordination changes to trigonal-bipyramidal and octahedral, implying that d orbitals are not mandatory for high coordination.