What I know is, elements with octet are stable, But In BF3, Boran doesn't get octet, So, How come BF3 molecule exist? If it exists, How do we know whether it is BF3 or not? Is there any proof that shows BF3 exists?
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$\begingroup$ mathesongas.com/pdfs/products/Boron-Trifluoride-Pure-Gas.pdf $\endgroup$– A.K.Aug 24, 2018 at 17:14
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3$\begingroup$ Do you mean, for example, how do we know that BF3 exists in a monomeric form and not as a hypothetical B2F6 dimer which would be octet-complete (analogous to Al2Cl6)? $\endgroup$– orthocresol ♦Aug 24, 2018 at 17:38
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1$\begingroup$ If the dimer were a thing, at low temperatures where there's no scrambling, you should see 1 peak by fluorine NMR instead of 2. $\endgroup$– ZheAug 24, 2018 at 19:16
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$\begingroup$ Possible duplicate of chemistry.stackexchange.com/questions/57784/… $\endgroup$– MithoronAug 24, 2018 at 19:46
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$\begingroup$ chemistry.stackexchange.com/questions/32240/… chemistry.stackexchange.com/questions/51626/… $\endgroup$– MithoronAug 24, 2018 at 19:46
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2 Answers
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Boron trifluoride, as described in Wikipedia is proved to exist the way everything in chemistry is ultimately proved, by experiment. The octet rule is really only a model that describes the electronic structure of some but not all molecules. Boron trifluoride is one of those (many, actually) molecules for which the octet rule is not really correct. The actual electronic structure is not just a single Lewis structure but a combination of multiple contributing structures, some of which do satisfy the octet rule and some of which don't.
answered Aug 24, 2018 at 19:11
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$\begingroup$ The octet rule is not really a model either; it's a rationalisation of an observation. It's been shown for many compounds to work, and on that basis it was suggested it works for many more. Also the octet rule is an upper limit. $\endgroup$– Martin - マーチン ♦Aug 25, 2018 at 12:35
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Yes $\ce{BF_3}$ does exist. In fact its a Lewis acid . Since it doesn't have its octet complete it is called as hypovalent. Also there is Back bonding happening in $\ce{BF_3}$ as Fluorine has electrons to donate and Boron has empty orbital available and the back bonding is of the type $\ce{2Pπ-2Pπ}$ due to which there is partial double bond character and hence it helps in making boron less electrophilic thereby increasing its stability. Here are some properties of boron trifluoride -https://en.m.wikipedia.org/wiki/Boron_trifluoride
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$\begingroup$ What you said is theroetically possible, But where can I get real existence proof?, I mean, Can you show me the existence of BF3 not in theoretical way.??(like with photos, Composition of a Bf3 compound or anything but theory?) $\endgroup$ Aug 24, 2018 at 17:31
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1$\begingroup$ To make your answer better I'd add some of the known physical properties and synthetic routes. Maybe even references to commercial sources. Heck, you can buy it from chemical suppliers. $\endgroup$ Aug 25, 2018 at 13:05
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$\begingroup$ @Matt_black the OP exactly wants some proof of existance of Borontrifluoride so if you can then please add some proif in the answer $\endgroup$– PanAug 26, 2018 at 4:56