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Wikipedia's Boron trifluoride; Structure and bonding says:

In the boron trihalides, BX3, the length of the B–X bonds (1.30 Å) is shorter than would be expected for single bonds,7 and this shortness may indicate stronger B–X π-bonding in the fluoride. A facile explanation invokes the symmetry-allowed overlap of a p orbital on the boron atom with the in-phase combination of the three similarly oriented p orbitals on fluorine atoms.7 Others point to the ionic nature of the bonds in BF3.8

7 Chemistry of the Elements N. N. Greenwood, A. Earnshaw, Elsevier (1997)

8Gillespie, Ronald J. (1998). "Covalent and Ionic Molecules: Why Are BeF2 and AlF3 High Melting Point Solids whereas BF3 and SiF4 Are Gases?". Journal of Chemical Education. 75 (7): 923.

Google's English dictionary uses Oxford languages and gives the following definition and synonym for "facile":

adj ignoring the true complexities of an issue; superficial. "facile generalizations"

Similar: simplistic, superficial, oversimple, oversimplified, schematic

I also noticed that the references cited are from 1997 and 1998 and in the subsequent near-quarter-century quantum-mechanical computational techniques have improved substantially. So I'd like to ask:

Question: Is the shortness of boron trifluoride's bonds better understood and explained now than it was "way back" in the 20th century?

uhoh
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    I guess the disappointing answer to your question is: No. Look up charge-shift bond and see for yourself if that makes understanding and explaining easier. || @Tyberius You've linked to the same post twice; I can only guess that this was not intended. – Martin - マーチン Mar 24 '22 at 22:13
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    Semi-related post about BCl3 dimerization that touches on the bond lengths. Also, a much earlier study linked in the comments about simulating the BF3 with ab initio methods. – Tyberius Mar 24 '22 at 23:27

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