This problem is an exercice in calculating a molecular formula, and "hunting" the missing atom. Compound 1 exhibits "heteronuclear" coupling to either F or P atoms, both common in a wide range of organic and inorganic compounds.
Strong supporting evidence for the stucture could be obtained by looking at the infrared spectra. Those compounds containing a C=O group would show a strong peak at 1650-1750 cm-1.