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Riahi S.,University of Carthage | Mrad M.L.,University of Carthage | Ferretti V.,University of Ferrara | Lefebvre F.,Laboratoire Of Chimie Organometallique Of Surface | Ben Nasr C.,University of Carthage
Acta Crystallographica Section E: Structure Reports Online

In the title hydrated salt, C8H11N2O +·NO3 -·H2O, the N - C bond distances [1.349 (2) and 1.413 (2) Å] along with the sum of the angles (359.88°) around the acetamide N atom clearly indicate that the heteroatom has an sp2 character. The ammonium group is involved in a total of three N - H⋯O hydrogen bonds, two of these are with a water molecule, which forms two O - H⋯O hydrogen bonds. All these hydrogen bonds link the ionic units and the water molecule into infinite planar layers parallel to (100). The remaining two N - H⋯O interactions in which the ammoniun group is involved link these layers into an infinite three-dimensional network. Source

Cheng F.,University of Hull | Hope C.N.,University of Hull | Archibald S.J.,University of Hull | Bradley J.S.,University of Hull | And 5 more authors.
International Journal of Applied Ceramic Technology

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 {Li 0.5Hf[NHSi(NMe2)3]1.5[NSi(NMe 2)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(NMe 2)z with a surface area of 440 m2/g. A microporous partially lithiated silicon hafnium imide powder Si 3Hf(N)(NH)x(NH2)y(NMe 2)z with a surface area of 232 m2/g was obtained via a similar ammonolysis process of {Li0.5Hf[NHSi(NMe 2)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. © 2009 The American Ceramic Society. Source

Sun M.,Saudi Aramco | Zhang J.,King Abdullah University of Science and Technology | Putaj P.,Laboratoire Of Chimie Organometallique Of Surface | Caps V.,King Abdullah University of Science and Technology | And 3 more authors.
Chemical Reviews

Heteropoly compounds (HPC) have revealed their potential to generate catalyst for selectively converting light alkanes to oxygenated products. There are various structures in which they are active the primary structure being that of the heteropolyanion itself, the secondary structure is the three-dimensional arrangements of polyanions, and the tertiary structure representing the manner in which the secondary structure assembles into solid particles. There are also a huge variety of elements inside the HPA. The heteropoly acids can have acidity, which varies dramatically depending on composition. This complexity of situation makes it very difficult to really have a predictive vision of their ability to activate and functionalize alkanes. However, a large amount of data reported suggests that the initial formula of the precatalyst is pivotal to direct the selectivity of the reaction toward different oxygenates. Inclusion of alternative transition metal atoms as addenda is highly influential with iron, vanadium, and antimony being particularly outstanding. Source

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