Oxygen difluoride

Structure and bonding

It is a covalently bonded molecule with a bent molecular geometry and a F-O-F bond angle of 103 degrees. Its powerful oxidizing properties are suggested by the oxidation number of +2 for the oxygen atom instead of its normal −2.

Reactions

Above 200 °C, OF₂ decomposes to oxygen and fluorine by a radical mechanism.

2 OF₂ → O₂ + 2 F₂

OF₂ reacts with many metals to yield oxides and fluorides. Nonmetals also react: phosphorus reacts with OF₂ to form PF₅ and POF₃; sulfur gives SO₂ and SF₄; and unusually for a noble gas, xenon reacts (at elevated temperatures) yielding XeF₄ and xenon oxyfluorides.

Reactions of oxygen difluoride and hydrogen halides or halide salts produce the free halogen. For example:

4 HCl + OF₂ → 2 HF + H₂O + 2 Cl₂

Oxygen difluoride reacts with water to form hydrofluoric acid:

OF₂ + H₂O → 2 HF + O₂

It can oxidize sulfur dioxide to sulfur trioxide and elemental fluorine:

OF₂ + SO₂ → SO₃ + F₂

However, in the presence of UV radiation, the products are sulfuryl fluoride (SO₂F₂) and pyrosulfuryl fluoride (S₂O₅F₂):

OF₂ + 2 SO₂ → S₂O₅F₂

Safety

Oxygen difluoride is considered an unsafe gas due to its oxidizing properties. It reacts explosively with water, hydrogen sulfide, sulfur tetrafluoride, diborane, nitrogen oxides, nitrosyl fluoride, and charcoal. It also reacts with halogens, reducing agents, adsorbent materials, combustibles, platinum, hydrocarbons, metal oxides, red phosphorus, boron powder, steam, and moist air. The gas is heavier than air, and upon escape from containment, the concentration of OF₂ in the air quickly becomes hazardous. Hydrofluoric acid, produced by the hydrolysis of OF₂ with water, is highly corrosive and toxic, capable of causing necrosis, leaching calcium from the bones and causing cardiovascular damage, among a host of other highly toxic effects. Acute poisoning effects from OF₂ include: pulmonary edema, bleeding lungs, headaches, and skin and eye irritation or burns. Short-term exposure can cause lachrymation (secretion of tears, especially in abnormal abundance). and irritation of the respiratory tract. Chronic exposure to oxygen difluoride, like that of other chemicals that release fluoride ions, can lead to fluorosis and other symptoms of chronic fluoride poisoning. Oxygen difluoride may be associated with kidney damage. The maximum workplace exposure limit is 0.05 ppm.

Fresh air, rest, and immediate medical attention are needed upon inhalation of OF₂ as the symptoms of lung edema often are not present until a few hours have passed, and they are aggravated by physical effort.

Popular culture

In Robert L. Forward's science fiction novel Camelot 30K, oxygen difluoride was used as a biochemical solvent by fictional life forms living in the solar system's Kuiper belt. While OF₂ would be a solid at 30 K, the fictional alien lifeforms were described as endothermic, maintaining elevated body temperatures and liquid OF₂ blood by radiothermal heating.