Chromium(II) and chromium(II) tri-tert-butoxysiloxy complexes
- Univ. of California, La Jolla, CA (United States)
The authors have been exploring the structure, bonding, and chemistry of transition-metal and main-group complexes that possess oxygen-rich alkoxysiloxy ligands such as [minus]OSi(O[sup t]Bu)[sub 3]. A primary focus of these studies is the development of molecular, single-source precursors to homogeneous, ultrapure metal silicates. The authors have found that titanium, zirconium, hafnium, and aluminum derivatives of [minus]OSi(O[sup t]Bu)[sub 3] thermally decompose at low temperatures (100-200[degrees]C) with elimination of isobutylene and water to give metal-containing silicates. Previous observations suggested the possible use of this methodology in new syntheses of supported catalysts, particularly since chemical reactivities and selectivities are known to be very sensitive to the size and shape of the supported metal catalyst particles. Silica- and aluminosilica-supported chromium catalysts are used widely for the catalytic polymerization of ethylene. To examine alkoxysiloxy derivatives of chromium as precursors to chromium-supported catalysts, the authors have begun to explore synthetic routes to Cr-OSi(O[sup t]Bu)[sub 3] complexes. On the basis of previously reported routes to siloxide and alkoxide complexes of chromium, approaches based on either the silanol HOSi(O[sup t]Bu)[sub 3] or alkali metal derivatives MOSi(O[sup t]Bu)[sub 3] (M = Li, Na, K) as starting materials seem possible. The authors report two siloxide complexes which result from the reaction of Cr(NEt[sub 2])[sub 4] with HOSi(O[sup t]Bu)[sub 3]. While this reaction does not provide a high yield of a single product that can be used in a convenient route to chromium silicate materials, it does offer the opportunity to closely compare analogous chromium(II) and chromium(III) siloxide complexes Cr[OSi(O[sup t]Bu)[sub 3]][sub 2](NHEt[sub 2])[sub 2] (1) and Cr[OSi(O[sup t]Bu)[sub 3]][sub 3](NHEt[sub 2])[sub 2] (2).
- OSTI ID:
- 5109709
- Journal Information:
- Inorganic Chemistry; (United States), Vol. 32:23; ISSN 0020-1669
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CHROMIUM COMPOUNDS
CHEMICAL PREPARATION
CHEMICAL REACTION YIELD
CRYSTAL STRUCTURE
MOLECULAR STRUCTURE
SILOXANES
VALENCE
X-RAY DIFFRACTION
COHERENT SCATTERING
DIFFRACTION
ORGANIC COMPOUNDS
ORGANIC SILICON COMPOUNDS
SCATTERING
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS
YIELDS
400201* - Chemical & Physicochemical Properties