Preparation, structural characterization, and thermal ammonolysis of two novel dimeric transition silylamide complexes

Cheng, Fei; Hope, Christopher N.; Archibald, Stephen J.; Bradley, John S.; Clark, Stephen; Francesconi, M. Grazia; Kelly, Stephen M.; Young, Nigel A.; Lefebvre, Frédéric

Abstract

The preparation and molecular structures of two novel dimeric transition metal silylamide complexes {Li0.5Zr[NHSi(NMe2)3]1.5[NSi(NMe2)3]0.5[μ -NSi(NMe2)3]}2 and {Li0.5Hf[NHSi(NMe2)3]1.5[NSi(NMe2)3]0.5[μ-NSi(NMe2)3]}2 with a tetrahedral coordination environment are reported. Thermal ammonolysis of  {Li0.5Zr[NHSi(NMe2)3]1.5[NSi(NMe2)3]0.5[μ-NSi(NMe2)3]}2 in an autoclave yields a mesoporous partially lithiated silicon zirconium imide powder Si3Zr(N)(NH)x(NH2)y(NMe2)z with a surface area of 440 m2/g. A microporous partially lithiated silicon hafnium imide powder Si3Hf(N)(NH)x(NH2)y(NMe2)z with a surface area of 232 m2/g was obtained via a similar ammonolysis process of {Li0.5Hf[NHSi(NMe2)3]1.5[NSi(NMe2)3]0.5[μ-NSi(NMe2)3]}2. Both of these silicon zirconium and hafnium imide powders have a disordered octahedral coordination environment. Pyrolysis of these zirconium and hafnium silicon imide powders leads to the formation of mixtures of porous zirconium or hafnium lithium silicon nitride ceramics with a regular octahedral coordination environment. They contain some residual lithium and exhibit a much reduced surface area due to an almost total collapse of the pores during the pyrolysis process.

Citation

Cheng, F., Hope, C. N., Archibald, S. J., Bradley, J. S., Clark, S., Francesconi, M. G., Kelly, S. M., Young, N. A., & Lefebvre, F. (2011). Preparation, structural characterization, and thermal ammonolysis of two novel dimeric transition silylamide complexes. International Journal of Applied Ceramic Technology, 8(2), 467-481. https://doi.org/10.1111/j.1744-7402.2009.02452.x

• Journal Article Type: Article
• Acceptance Date: Dec 31, 2011
• Online Publication Date: Mar 14, 2011
• Publication Date: 2011-03
• Journal: INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY
• Print ISSN: 1546-542X
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 8
• Issue: 2
• Pages: 467-481
• DOI: https://doi.org/10.1111/j.1744-7402.2009.02452.x
• Keywords: Marketing; Materials Chemistry; Condensed Matter Physics; Ceramics and Composites
• Public URL: https://hull-repository.worktribe.com/output/400268