Boron trifluoride dipole moment

SAMPLE SOLUTION (a) Boron trifluoride is planar with 120° bond angles. Although each boron-fluorine bond is polar, their combined effects cancel and the molecule has no dipole moment. 

Cyclodehydration of a-(thioaroylthio)- or a-(thiocarbamoylthio)carboxylic acids (96) with acetic anhydride in the presence of catalytic amounts of boron trifluoride etherate, or with a mixture of acetic anhydride and triethylamine (1 1), leads to the 2-aryl- or 2-amino-l,3-dithiolium-4-olates (97) listed in Table VIII.Chemical properties, dipole moments, NMR, IR, and UV spectra, and charge distribution calculations are consistent with a mesoionic structure. " ... 

PRACTICE PROBLEM 2.3 Boron trifluoride (BF3) has no dipole moment (fJL = 0 D). Eixplain how this observation... 

Thus, IBr has a nonzero dipole moment, which points from the Br atom to the I atom, (b) Because fluorine is more electronegative than boron, each B—F bond in BF3 (boron trifluoride) is polar, and the three bond moments are equal. According to the VSEPR model, however, BF3 should be trigonal planar and the symmetry of the trigonal planar shape means that the three bond moments exactly cancel one another ... 

Which of the following species will not have permanent dipole moments (a) Hydrogen cyanide, HCN (b) Carbonyl sulfide, OCS (c) Phosphorus pentachloride, PCI5 (d) Trimethylamine, N(CH3)3 (e) Boron trifluoride, BF3 (f) Diborane, which has the following structure ... 

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