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Published March 2004 | public
Journal Article

An infrared and ^1H MAS NMR investigation of strong hydrogen bonding in ussingite, Na_2AISi_3O_8(OH)

Abstract

The mineral ussingite, Na_2AlSi_3O_8(OH), an "interrupted" tectosilicate, has strong hydrogen bonding between OH and the other nonbridging oxygen atom in the structure. Infrared spectra contain a strongly polarized, very broad OH-stretching band with an ill-defined maximum between 1500 and 1800 cm^(−1), and a possible OH librational bending mode at 1295 cm^(−1). The IR spectra confirm the orientation of the OH vector within the triclinic unit cell as determined from X-ray refinement (Rossi et al. 1974). There are three distinct bands in the ^1H NMR spectrum of ussingite: a predominant band at 13.5 ppm (TMS) representing 90% of the structural hydrogen, a second band at 15.9 ppm corresponding to 8% of the protons, and a third band at 11.0 ppm accounting for the remaining 2% of structural hydrogen. From the correlation between hydrogen bond length and ^1H NMR chemical shift (Sternberg and Brunner 1994), the predominant hydrogen bond length (H...O) was calculated to be 1.49 Å, in comparison to the hydrogen bond length determined from X-ray refinement (1.54 Å). The population of protons at 15.9 ppm is consistent with 5–8% Al–Si disorder. Although the ussingite crystal structure and composition are similar to those of low albite, the bonding environment of OH in low albite and other feldspars, as characterized through IR and ^1H NMR, is fundamentally different from the strong hydrogen bonding found in ussingite.

Additional Information

© 2004 Springer-Verlag. Received: 22 April 2003. Accepted: 16 October 2003. E.A.J. thanks Sonjong Hwang for assistance with the 1H NMR measurements. This research was supported by National Science Foundation grants EAR-0125767 and EAR-9804871. The sample of ussingite was donated by D.S. Barker (UT Austin). The authors thank E. Libowitzky and an anonymous reviewer for improving the manuscript. This is contribution number 8959 of the Division of Geological and Planetary Sciences of the California Institute of Technology.

Additional details

Created:
August 22, 2023
Modified:
October 24, 2023