3
$\begingroup$

Usually Lewis bases as my textbook says:

2.3 Ligands
The ligands are the ions or molecules bound to the central atom/ion in the coordination entity. This is better visualized as the combination of a Lewis acid (the central atom/ion) with a number of Lewis bases (ligands). The atom of Lewis base that forms the bond to the Lewis acid (central atom/ion) is called donor atom ...

According to me its not compulsory for a ligand to be a Lewis base, as $\ce{BF3}$ is a Lewis acid and can act as a ligand by accepting electrons from a metal in vacant orbital of boron. Is it true?

$\endgroup$
  • 1
    $\begingroup$ In that situation, the thing that the boron is binding to is the ligand. $\endgroup$ – Zhe Oct 17 '18 at 15:04
  • $\begingroup$ I can't understand. Please clarify $\endgroup$ – Harsh jain Oct 17 '18 at 15:22
  • 2
    $\begingroup$ @Zhe Actually OP is right. Ligands can have both acceptor and donor properties like CO, or indeed be only acceptors like BF3. $\endgroup$ – Mithoron Oct 17 '18 at 15:52
  • $\begingroup$ Can H+ also act as ligand for electron rich metals. If it can its a pure acid . AlCl3 might also be such a ligand due to vacant d orbital of Al $\endgroup$ – Harsh jain Oct 17 '18 at 16:29
  • 2
    $\begingroup$ @Harshjain You're going to far there. While H+ and AlCl3 are Lewis acids (and don't even mention this "d-orbital" nonsense) it's a matter of formalism when something can be called Z-Ligand. $\endgroup$ – Mithoron Oct 17 '18 at 17:17
1
$\begingroup$

Yes it can happen. This paper offers an example, in which $\ce{BF3}$ or $\ce{B(C6F5)3}$ adds to a low oxidation state iridium complex. There is really not a lot of mystery behind it. The iridium in its low oxidation state has electrons to offer and the boron with its vacant orbital can take them up.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.