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Hydrogen bonding in the crystal structure of phurcalite, Ca 2 [(UO 2 ) 3 O 2 (PO 4 ) 2 ]·7H 2 O: single‐crystal X‐ray study and TORQUE calculations
Author(s) -
Plášil Jakub,
Kiefer Boris,
Ghazisaeed Seyedat,
Philippo Simon
Publication year - 2020
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
ISSN - 2052-5206
DOI - 10.1107/s2052520620005739
Subject(s) - orthorhombic crystal system , crystal structure , crystallography , uranyl , hydrogen bond , chemistry , space group , x ray crystallography , molecule , physics , ion , diffraction , organic chemistry , optics
The crystal structure of phurcalite, Ca 2 [(UO 2 ) 3 O 2 (PO 4 ) 2 ]·7H 2 O, orthorhombic, a = 17.3785 (9) Å, b = 15.9864 (8) Å, c = 13.5477 (10) Å, V = 3763.8 (4) Å 3 , space group Pbca , Z = 8 has been refined from single‐crystal XRD data to R = 0.042 for 3182 unique [ I > 3σ( I )] reflections and the hydrogen‐bonding scheme has been refined by theoretical calculations based on the TORQUE method. The phurcalite structure is layered, with uranyl phosphate sheets of the phosphuranylite topology which are linked by extensive hydrogen bonds across the interlayer occupied by Ca 2+ cations and H 2 O groups. In contrast to previous studies the approach here reveals five transformer H 2 O groups (compared to three expected by a previous study) and two non‐transformer H 2 O groups. One of the transformer H 2 O groups is, nevertheless, not linked to any metal cation, which is a less frequent type of H 2 O bonding in solid state compounds and minerals. The structural formula of phurcalite has been therefore redefined as {Ca 2 (H 2 [3] O) 5 (H 2 [4] O) 2 }[(UO 2 ) 3 O 2 (PO 4 ) 2 ], Z = 8.