JEE MainChemistryChemical Bonding and Molecular Structure
Consider the mixed-halogen molecule PCl ₃ F ₂ . According to VSEPR theory and Bent's rule, what is the correct spatial arrangement of the fluorine atoms and the resulting net dipole moment ( ) of the molecule?
Options
- ABoth F atoms occupy equatorial positions and 0 .
- BBoth F atoms occupy axial positions and 0 .
- CBoth F atoms occupy axial positions and = 0 .
- DOne F atom occupies an axial position, the other occupies an equatorial position, and 0 .
Correct answer
C. Both F atoms occupy axial positions and = 0 .
Step-by-step solution
The central phosphorus atom in PCl ₃ F ₂ undergoes sp ^3 d hybridization, resulting in a trigonal bipyramidal geometry. According to Bent's rule, more electronegative substituents prefer hybrid orbitals with less s-character. In a trigonal bipyramidal geometry, the axial positions are formed by pd hybrid orbitals (which have zero s-character), while the equatorial positions are formed by sp ^2 hybrid orbitals (which have 33.3% s-character). Therefore, the more electronegative fluorine atoms will occupy the two axia