[fran008]

Can someone help explain the bonding in the compound NH3BF3

Is B ionically boded to F? I mean the difference in electronegativity is big enough to consider it ionic, but then again, using Fajan's rules, B3+ is a small cation favouring some covalent character. Could it b possible that NH3 binds to N Covalently by a coordinate bond and bond to F ionically?

Any help greatly appreciated!

[Mitch]

You wouldn't expect ionic bonding between non-metals.

[plu]

The bonding in NH₃BF₃ is primarily covalent in nature.  The bond between the nitrogen and boron in this compound is a special type of covalent bond commonly known as a coordinate covalent bond or dative bond due to the fact that both electrons in the bond are coming from one of the molecules (the nitrogen).  This molecule is, in fact, a prime example of a Lewis acid-base reaction, where the NH₃ is acting as a Lewis base, donating a pair of electrons to the BF₃, which in turn accepts the electrons, acting as a Lewis acid.

[AgG]

what plu said.