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The silicon effect also manifests in certain compound properties. Trimethylsilylmethylamine (Me 3 SiCH 2 NH 2) is a stronger base (conjugate pK a 10.96) than neopentylamine (conjugate pK a 10.21); trimethylsilylacetic acid (pKa 5.22) is a poorer acid than trimethylacetic acid (pKa 5.00). [1]
Negative hyperconjugation is seldom observed, though it can be most commonly observed when the σ *-orbital is located on certain C–F or C–O bonds. [ 3 ] [ 4 ] In negative hyperconjugation, the electron density flows in the opposite direction (from a π- or p-orbital to an empty σ * -orbital) than it does in the more common ...
Hyperconjugation can be used to rationalize a variety of chemical phenomena, including the anomeric effect, the gauche effect, the rotational barrier of ethane, the beta-silicon effect, the vibrational frequency of exocyclic carbonyl groups, and the relative stability of substituted carbocations and substituted carbon centred radicals, and the thermodynamic Zaitsev's rule for alkene stability.
The carbon-silicon bond is highly electron-releasing and can stabilize a positive charge in the β position through hyperconjugation. Electrophilic additions to allyl- and vinylsilanes take advantage of this, and site selectivity generally reflects this property—electrophiles become bound to the carbon γ to the silyl group.
Carrier mobility in semiconductors is doping dependent. In silicon (Si) the electron mobility is of the order of 1,000, in germanium around 4,000, and in gallium arsenide up to 10,000 cm 2 /(V⋅s). Hole mobilities are generally lower and range from around 100 cm 2 /(V⋅s) in gallium arsenide, to 450 in silicon, and 2,000 in germanium. [1]
Key takeaways. Flashy investments can be a bad deal for individual investors, but there are often warning signs accompanying a bad investment. Investors should research and learn about each ...
Charge conjugation occurs as a symmetry in three different but closely related settings: a symmetry of the (classical, non-quantized) solutions of several notable differential equations, including the Klein–Gordon equation and the Dirac equation, a symmetry of the corresponding quantum fields, and in a general setting, a symmetry in (pseudo-)Riemannian geometry.
Amid controversy surrounding the carnivore diet, researcher Nick Norwitz recently released a video in which he debunks eight myths surrounding the meat-heavy eating plan.