2015年7月22日 · Note that this mechanism does in fact include hydride transfers (it has to). Though you were right in thinking that $\ce{BH3}$ wouldn't immediately donate a hydride, coordinating to a lone pair weakens the $\ce{B-H}$ bonds and makes hydride transfers possible. $\ce{BH3}$ and $\ce{NaBH4}$ really aren't as different as you might first think.

2017年3月19日 · In BH3, Boron is less electronegative than H (i.e. hydrogen) , hence in the syn addition I have shown, hydrogen ends up being attached to a more substituted carbon atom. For every bonding orbital we have an anti-bonding orbital which lies exactly opposite to the bonding orbital and each bonding-antibonding orbital pair can contain a maximum of ...

2012年5月4日 · $\ce{B}$ has an $2s^22p^1$ valence shell, so three covalent bonds gives it an incomplete octet. $\ce{BH3}$ has an empty $2p$ orbital. This orbital overlaps the existing $\ce{B-H}$ $\sigma$ bond cloud (in a nearby $\ce{BH3}$), and forms a 3c2e bond. It seems that there are a lot more compounds with 3c2e geometry. I'd completely forgotten that ...

2016年7月20日 · The double bond is the thing that matters. Perhaps I should have made it clear that there is and initial syn addition of BH3 across the double bond. This is called hydroboration. The reaction in my answer starts with 1-methyl-cyclopent-1-ene. $\endgroup$ –

2015年3月28日 · What is the mechanism of the reduction of organic acids with borane? Borane reductions don't work well with electron deficient carbonyl groups. Why is that so, and how isn't the carboxyl group an

2022年1月30日 · This reaction is taken from: Pintér, Á.; Sud, A.; Sureshkumar, D.; Klussmann, M. Autoxidative Carbon-Carbon Bond Formation from Carbon-Hydrogen Bonds.

2014年11月29日 · $\ce{BH3}$ Borane dimerizes because the boron atom is electron deficient - it has an empty p orbital. This species is so electron deficient that it will form bonding interactions with nearly any electron pairs, including those already in sigma bonds. (More properly the B-H-B bonds are three-center-two-electron bonds).

2018年2月11日 · The σ$_v$ planes in a molecule are a direct result of the C$_n$ main axis i.e. they are interchangeable if you perform the C$_n$ operation on them.

So I was a bit confused. Hydrogen and Boron seem to be the only outliers to the octet rule. Hydrogen makes sense because it has only one shell and 2 electrons complete its shell.

2020年1月11日 · $(i)$ I know that $\ce{(i)BH3/THF (ii) H+}$ can reduce carboxylic acid, but I am unaware if it can reduce ester. $(ii)$ I only knew that, the reduction of ester in presence of carbonyl group could be done by first protecting the carbonyl group (converting it to cyclic ketal by reacting with ethylene glycol) and then using $\ce{LiAlH4}$ .