CHEMISTRY · Multi-part · AP · Chemistry · Compound Structure and Properties · Compound Structure and Properties
Problem
Phosphoryl dichloride, POCl3, is a phosphorylating agent commonly used in organic synthesis.
(a) Draw two distinct plausible Lewis structures for POCl3—one featuring a P=O double bond and one featuring only P–O single bonding with expanded valence on phosphorus. Show all lone pairs.
(b) Calculate the formal charges on every atom for each Lewis structure from part (a).
(c) Identify which of the two structures makes the larger contribution to the resonance hybrid and justify your choice using formal-charge considerations and octet satisfaction.
(d) On the basis of your preferred resonance hybrid, rank the following bond lengths from shortest to longest: the P–O bond, a P–Cl bond within POCl3, and a typical P–O single bond in an alkyl phosphate (∼160pm). Provide reasoning for your ranking.