Tetrafluoroborate anion

[Jovian Cheung 1K]

Today it was mentioned that boron forms the tetrafluoroborate anion (BF₄^-) with fluorine, provided that there is a coordinate bond. Yet when I search up the structure of BF₄^- online, none of the images contain an arrow between boron and fluorine. Would someone mind explaining this to me please? Thank you! :-)

[Venya Vaddi 1L]

I think the arrow from the diagram in Dr. Lavelle's powerpoint was just to visually show how the fluoride ion is added to BF₃ to form BF₄^- with a coordinate covalent bond.

[Madelyn Romberg 1H]

Going off of this question, why does the boron trifluoride atom not form a coordinate covalent bond with the fluorine to get an octet opposed to adding an additional fluorine atom?

[Jovian Cheung 1K]

Going off of this question, why does the boron trifluoride atom not form a coordinate covalent bond with the fluorine to get an octet opposed to adding an additional fluorine atom?

I think this is exactly what it does to form BF₄^-, where one of the F donates a pair of electrons to B. But as F only comes with 7 valence electrons, we would need an extra electron to be able to do that... hence the negative charge for the molecule.
Does that sound right?

Thank you guys! :-)