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

• Published in: Nature communications Vol. 10; no. 1; pp. 1 - 6
• Main Authors: Pakhomova, Anna, Aprilis, Georgios, Bykov, Maxim, Gorelova, Liudmila, Krivovichev, Sergey S., Belov, Maxim P., Abrikosov, Igor A., Dubrovinsky, Leonid
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 26-06-2019; Nature Publishing Group; Nature Portfolio
• Subjects: 119/118; 639/638/263/910; 639/638/263/915; Anions; Beryllium; Beryllium compounds; Beryllium oxide; Chemical properties; Crystals; Humanities and Social Sciences; Inorganic compounds; Low pressure; Molecular orbitals; multidisciplinary; Organic chemistry; Oxides; Oxygen atoms; Phosphorus; Pressure; Science; Science (multidisciplinary); Single crystals; Theoretical analysis; X-ray diffraction
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-10589-z

Beryllium oxides have been extensively studied due to their unique chemical properties and important technological applications. Typically, in inorganic compounds beryllium is tetrahedrally coordinated by oxygen atoms. Herein based on results of in situ single crystal X-ray diffraction studies and ab initio calculations we report on the high-pressure behavior of CaBe
2
P
2
O
8
, to the best of our knowledge the first compound showing a step-wise transition of Be coordination from tetrahedral (4) to octahedral (6) through trigonal bipyramidal (5). It is remarkable that the same transformation route is observed for phosphorus. Our theoretical analysis suggests that the sequence of structural transitions of CaBe
2
P
2
O
8
is associated with the electronic transformation from predominantly molecular orbitals at low pressure to the state with overlapping electronic clouds of anions orbitals.
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 CaBe
2
P
2
O
8
where Be coordination changes to trigonal-bipyramidal and octahedral, implying that d orbitals are not mandatory for high coordination.