Molecular Gallosilicates and Their Group 4 Multimetallic Derivatives

Abstract

Reaction between the silanediol (HO)(2)Si(OtBu)(2) and gallium amides, LGaCl(NHtBu) and LGa(NHEt)(2) (L = [HC{C(Me)N(Ar)}(2)](-), Ar = 2,6-iPr(2)C(6)H(3)), respectively, resulted in the facile isolation of molecular gallosilicates LGaCl(μ-O)Si(OH)(OtBu)(2) (1) and LGa(NHEt)(μ-O)Si(OH)(OtBu)(2) (2). Compound 2 easily reacts with 1 equiv of water to form the unique gallosilicate-hydroxide LGa(OH·THF)(μ-O)Si(OH)(OtBu)(2) (3). Compounds 1-3 contain the simple Ga-O-SiO(3) framework and are the first structurally authenticated molecular gallosilicates. These compounds may be used not only as models for gallosilicate-based materials but also as further reagents because of the presence of reactive functional groups attached to both gallium and silicon atoms. Accordingly, seven molecular heterometallic compounds were obtained from the reactions between compound 3 and group 4 amides M(NMe(2))(4) (M = Ti, Zr) or M(NEt(2))(4) (M = Ti, Zr, Hf). Hence, by tuning the reactions conditions and stoichiometries, it was possible to isolate and structurally characterize the complete 1:1 and 2:1 series (4-10). Completely inorganic cores of types M-O-Ga-O-Si-O and spiro M[O-Ga-O-Si-O](2) were obtained and characterized by common spectroscopic techniques.

Ga[OSi(OtBu)3]3·THF, a thermolytic molecular precursor for high surface area gallium-containing silica materials of controlled dispersion and stoichiometry

“…While all ammonia desorption traces exhibit similar features below 375°C, notable differences in desorption peaks are observed at higher temperatures. In UCB1-GaSi 3 a major peak is observed between 450-500°C that remains only as a trace signal upon dilution of the gallium content in UCB1-GaSi 10 . A new major signal is observed at higher temperatures (578°C) that also appears in even more gallium-poor UCB1-GaSi 20 and UCB1-GaSi 50 (642 and 622°C).…”

Perfluorinated Dialkoxysilanediols Resisting Self‐Condensation

“…Like the parent acid and in spite of the steric protection, I and II are thermally unstable with respect to self‐condensation, which somewhat hampers their use for synthetic applications. Nonetheless, a number of discrete siloxanes [3,4] and metallasiloxanes [5–8] derived from I have been reported. This includes, for instance, Mo 2 [O 2 Si(O t ‐Bu 2 ) 2 ] 3 , which has been used as single‐source precursor for the preparation of the atomically well mixed binary element oxide Mo 2 Si 3 O 10 that is not accessible by the conventional sol‐gel process [5] …”

Boron, aluminium, gallium, indium and thallium

“…M(NMe 2 ) 4 ; M = Ti, Zr or Hf). 295 Very high electron affinity neutral molecules, such as (F 2 )GaF 2 , have reportedly been observed in solid argon and neon matrices from the reaction of F 2 with MF 2 species (M = B, Al, Ga, In and Tl), identification being made by matrix IR spectroscopy combined with DFT calculations. 296…”