Photolysis of PCl₃/POCl₃ with Oxygen Dopant Using 193 nm ArF Excimer at Low Temperatures: Oxygen Insertion through ‘Phosphadioxirane’ Pathway

Abstract

Photolysis was performed on PCl 3 and POCl 3 in the presence of oxygen dopant in Ar matrix at low temperatures using 193 nm ArF excimer laser. The photo irradiation initially facilitated the formation of ozone in situ in the low temperature matrix. For PCl 3 + O 2 photolysis with 193 nm ArF excimer, initially POCl 3 was produced and subsequent oxygen atom insertion on POCl 3 generated PO 2 Cl 3 . Furthermore, secondary reaction channel opens up in PCl 3 + O 2 photolysis to form a variety of photoproducts such as POCl, P III O 2 Cl, P V O 2 Cl and PO 3 Cl. The insertion of oxygen atom on POCl through phosphadioxirane intermediate generated P III O 2 Cl and the direct oxygen atom addition resulted in P V O 2 Cl. A successive oxygen insertion on P V O 2 Cl triggered the PO 3 Cl generation. The identification of all the photoproducts was confirmed through 18 O 2 isotopic experiments and quantum chemical computations performed using density functional theory (DFT). Computations carried out at B3LYP level of theory with 6-311 + + G(d,p) basis set were used to correlate the structure of photo products obtained experimentally. Interestingly, photo irradiation of POCl 3 with oxygen dopant in Ar matrix @193 nm ArF excimer resulted in the generation of PO 2 Cl 3 , PO 3 Cl 3 and PO 4 Cl 3 photo products by a sequential insertion of oxygen atoms through phosphadioxirane intermediate. A compelling evidence for the passage of the reaction through phosphadioxirane intermediate is established through 18 O 2 isotopic substitution experiments.