Question

How many single bonds are formed by boron?

Answer 1

Up to 4.

Explanation:

Tetrahydrocarbyl borates, `R_4B^-`, can be formed fairly easily. The boron centre has a formal negative charge.

These are typically formed by the action of an alkyl lithium on a borane in an inert solvent:

`R_3B + R'^(-)Li^(+) rarr R_3R'B^(-)Li^(+)`