Tetrafluoroborate anion

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Jovian Cheung 1K
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Joined: Fri Sep 28, 2018 12:16 am

Tetrafluoroborate anion

Postby Jovian Cheung 1K » Wed Oct 31, 2018 8:23 pm

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
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Re: Tetrafluoroborate anion

Postby Venya Vaddi 1L » Wed Oct 31, 2018 8:56 pm

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 3L
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Joined: Tue Oct 02, 2018 12:16 am

Re: Tetrafluoroborate anion

Postby Madelyn Romberg 3L » Thu Nov 01, 2018 9:46 pm

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
Posts: 48
Joined: Fri Sep 28, 2018 12:16 am

Re: Tetrafluoroborate anion

Postby Jovian Cheung 1K » Fri Nov 02, 2018 10:11 pm

Madelyn Romberg 3L wrote: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! :-)


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