Chlorine trifluoride is an interhalogen compound with the formula ClF3. This colorless, poisonous, corrosive, and extremely reactive gas condenses to a pale-greenish yellow liquid, the form in which it is most often sold (pressurized at room temperature). The compound is primarily of interest in plasmaless cleaning and etching operations in the semiconductor industry, in nuclear reactor fuel processing, as a component in rocket fuels, and other industrial operations. Preparation, structure, and properties It was first reported in 1930 by Ruff and Krug who prepared it by fluorination of chlorine; this also produced ClF (chlorine monofluoride) and the mixture was separated by distillation. 3 F2 + Cl2 → 2 ClF3 The molecular geometry of ClF3 is approximately T-shaped, with one short bond (1.598 Å) and two long bonds (1.698 Å). This structure agrees with the prediction of VSEPR theory, which predicts lone pairs of electrons as occupying two equatorial positions of a hypothetic trigonal bipyramid. The elongated Cl-F axial bonds are consistent with hypervalent bonding. Pure ClF3 is stable to in quartz vessels; above this temperature, it decomposes by a free radical mechanism to its constituent elements. Reactions Reactions with many metals give chlorides and fluorides. With phosphorus, it yields phosphorus trichloride (PCl3) and phosphorus pentafluoride (PF5), while sulfur yields sulfur dichloride (SCl2) and sulfur tetrafluoride (SF4). ClF3 also reacts with water to give hydrogen fluoride and hydrogen chloride, along with oxygen and oxygen difluoride (OF2): ClF3 + H2O → HF + HCl + OF2 ClF3 + 2H2O → 3HF + HCl + O2 It will also convert many metal oxides to metal halides and oxygen or oxygen difluoride. It occurs as a ligand in the complex . One of the main uses of ClF3 is to produce uranium hexafluoride, UF6, as part of nuclear fuel processing and reprocessing, by the fluorination of uranium metal: U + 3 ClF3 → UF6 + 3 ClF The compound can also dissociate under the scheme: ClF3 → ClF + F2 Uses Semiconductor industry In the semiconductor industry, chlorine trifluoride is used to clean chemical vapour deposition chambers. It has the advantage that it can be used to remove semiconductor material from the chamber walls without the need to dismantle the chamber. Unlike most of the alternative chemicals used in this role, it does not need to be activated by the use of plasma since the heat of the chamber is sufficient to make it