Leucophosphite K[Fe2(PO4)2(OH)(H2O)]·H2O: Hydrogen Bonding and Structural Relationships

✍ Scribed by Stefan Dick; Thomas Zeiske

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 337 KB
• Volume: 133
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1997.7519

✦ Synopsis

Hydrogen atom positions in leucophosphite K[Fe 2 (PO 4 ) 2 (OH)(H 2 O)] • H 2 O were elucidated by Rietveld refinement of a powder neutron scattering diffractogram. Crystal data: a ‫؍‬ 975.6(3), b ‫؍‬ 966.4(3), c ‫؍‬ 976.9(4) pm, ‫؍‬ 102.43(2)°°, R wp ‫؍‬ 0.084. This experiment proved that the Fe-atoms in the tetrameric Fe 4 O 2 building units of leucophosphite are bridged by hydroxo groups and that the phosphate tetrahedra are not protonated. While the water molecule O (10) bound to Fe acts only as a H-bond donor, the second water molecule O (11) between the tetrameric units donates and accepts H-bonds. Together with oxygen atoms from phosphate groups a six-membered ring of oxygen atoms, connected by hydrogen bonds, is formed. Water O ( 11) is held in the structure by comparably weak H-bonds so that it is already lost at 396(3) K. Fe 4 O 2 tetramers topological analogous to those in leucophosphite are found in the minerals spheniscidite, melonjosephite, and amarantite, and in a number of synthetic iron complexes. The structural relationships of leucophosphite with compounds containing M 4 O 2 clusters (M ‫؍‬ Al, Ga, Mo) are discussed.