Is [PF5Cl]- polar?

MaYbee

To determine if [PF5Cl]- is polar, we need to consider its molecular geometry and the polarity of its individual bonds.

1. Determine the molecular geometry:
The formula [PF5Cl]- suggests that it contains six atoms (one phosphorus, five fluorine, and one chlorine). To find the shape, we can use the Valence Shell Electron Pair Repulsion (VSEPR) theory. In this case, the central phosphorus (P) atom will have five fluorine (F) atoms and one chlorine (Cl) atom bonded to it. This arrangement gives us a trigonal bipyramidal shape, with the phosphorus at the center and the five fluorine atoms forming a plane around it, and the chlorine atom situated at one of the axial positions.

2. Determine the polarity of individual bonds:
Next, we examine the individual bonds in [PF5Cl]-. The bond between phosphorus and fluorine (P-F) is generally considered polar because fluorine is more electronegative than phosphorus. Similarly, the bond between phosphorus and chlorine (P-Cl) will likely be polar for the same reason.

3. Consider the overall molecular polarity:
In a trigonal bipyramidal molecule, the overall molecular polarity depends on both the arrangement of the polar bonds and the relative magnitude of their dipole moments. In this case, the five P-F bonds are symmetrically arranged around the central phosphorus atom, canceling out any overall dipole moment. As a result, the P-F bonds contribute equally to the overall molecular polarity. On the other hand, the P-Cl bond is in an axial position, which won't cancel out with the P-F bonds. Therefore, the P-Cl bond will contribute to the overall polarity.

Based on this analysis, [PF5Cl]- can be considered polar. The presence of the polar P-Cl bond in combination with the overall molecular geometry leads to an unequal distribution of charge and a net dipole moment for the molecule.