Single-Crystal Neutron Structure Analysis of (NH4)21[H3Mo57V6(NO)6O183(H2O)18]·53 H2O

✍ Scribed by H.D. Lutz; R. Nagel; S.A. Mason; A. Müller; H. Bögge; E. Krickemeyer

• Book ID: 102605170
• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 446 KB
• Volume: 165
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.2001.9507

✦ Synopsis

The crystal structure of (NH 4 ) 21 [H 3 Mo 57 V 6 (NO) 6 O 183 (H 2 O) 18 ] . 53 H 2 O, a supramolecular heteropoly cluster compound (space group P6 3 /mmc, Z=2, final R1=0.1302 (I42r(I)) for 1745 unique reflections), was redetermined by single-crystal neutron diffraction studies at 20 K. The X-ray diffraction results reported in 1994 by Mu¨ller et al. (Z. Anorg.

Allg. Chem. 620, 599) are confirmed. Additionally, we could localize many hydrogen positions not found so far and establish a phase transition near 240 K. Many of the ammonium ions, the ligand and hydrate H 2 O molecules, and the hydroxy group are orientationally disordered, even at 20 K. The central cavity of the structure is built up by two twelve-membered rings consisting of six O-HÁ Á ÁO hydrogen bonds each. These strong hydrogen bonds are obviously decisive for the stability of the cluster. The hydrate H 2 O molecules are stronger-hydrogen-bond acceptor groups than the oxoligands of the cluster. # 2002 Elsevier Science (USA)