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Preparation, Structural Characterization, and Thermal Ammonolysis of Two Novel Dimeric Transition Silylamide Complexes
Author(s) -
Cheng Fei,
Hope Christopher N.,
Archibald Stephen J.,
Bradley John S.,
Clark Stephen,
Francesconi M. Grazia,
Kelly Stephen M.,
Young Nigel A.,
Lefebvre Frédéric
Publication year - 2011
Publication title -
international journal of applied ceramic technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.4
H-Index - 57
eISSN - 1744-7402
pISSN - 1546-542X
DOI - 10.1111/j.1744-7402.2009.02452.x
Subject(s) - hafnium , zirconium , imide , microporous material , octahedron , silicon , inorganic chemistry , chemistry , crystallography , transition metal , materials science , crystal structure , polymer chemistry , organic chemistry , catalysis
The preparation and molecular structures of two novel dimeric transition metal silylamide complexes {Li 0.5 Zr[NHSi(NMe 2 ) 3 ] 1.5 [NSi(NMe 2 ) 3 ] 0.5 [μ‐NSi(NMe 2 ) 3 ]} 2 and {Li 0.5 Hf[NHSi(NMe 2 ) 3 ] 1.5 [NSi(NMe 2 ) 3 ] 0.5 [μ‐NSi(NMe 2 ) 3 ]} 2 with a tetrahedral coordination environment are reported. Thermal ammonolysis of {Li 0.5 Zr[NHSi(NMe 2 ) 3 ] 1.5 [NSi(NMe 2 ) 3 ] 0.5 [μ‐NSi(NMe 2 ) 3 ]} 2 in an autoclave yields a mesoporous partially lithiated silicon zirconium imide powder Si 3 Zr(N)(NH) x (NH 2 ) y (NMe 2 ) z with a surface area of 440 m 2 /g. A microporous partially lithiated silicon hafnium imide powder Si 3 Hf(N)(NH) x (NH 2 ) y (NMe 2 ) z with a surface area of 232 m 2 /g was obtained via a similar ammonolysis process of {Li 0.5 Hf[NHSi(NMe 2 ) 3 ] 1.5 [NSi(NMe 2 ) 3 ] 0.5 [μ‐NSi(NMe 2 ) 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.