Decomposition of fluorophosphoryl diazide: a joint experimental and theoretical study

作者：Li, Dingqing; Li, Hongmin; Zhu, Bifeng; Zeng, Xiaoqing^*; Willner, Helge; Beckers, Helmut; Neuhaus, Patrik; Grote, Dirk; Sander, Wolfram

来源：Physical Chemistry Chemical Physics, 2015, 17(9): 6433-6439.

DOI：10.1039/c4cp05694a

• LASER FLASH-PHOTOLYSIS
• AB-INITIO CALCULATIONS
• TIME-RESOLVED IR
• MATRIX-ISOLATION
• DIPHENYLPHOSPHORYL AZIDE
• DECAY PROCESSES
• SPECTROSCOPY
• PHOTOCHEMISTRY
• KINETICS
• NITRENE

The photolytic and thermal decomposition of fluorophosphoryl diazide, FP(O)(N-3)(2), was studied using matrix isolation spectroscopy. Upon ArF laser photolysis (lambda = 193 nm), FPO and a new geminal azido nitrene FP(O)(N-3)N were identified using matrix IR spectroscopy. The nitrene shows a triplet ground state with the zero-field parameters vertical bar D/hc vertical bar = 1.566 cm(-1) and vertical bar E/hc vertical bar = 0.005 cm(-1). Further decomposition of the nitrene into FPO was observed under an irradiation of lambda > 335 nm. In contrast, no nitrene but only FPO was identified after flash vacuum pyrolysis of the diazide. To reveal the decomposition mechanism, quantum chemical calculations on the potential energy surface (PES) of the diazide using DFT methods were performed. On the singlet PES four conformers of the nitrene were predicted. The two conformers (syn and anti) showing intramolecular N-nitrene center dot center dot center dot N-alpha,N-azide interactions are much lower in energy (ca. 40 kJ mol(-1), B3LYP/6-311+G(3df)) than the other two exhibiting N-nitrene center dot center dot center dot O interactions. syn/anti refers to the relative orientation of the P=O bond and the N-3 group. The interconversion of these species and the decomposition into FPO via a novel three-membered ring diazo intermediate cyclo-FP(O)N-2 were computationally explored. The calculated low dissociation barrier of 45 kJ mol(-1) (B3LYP/6-311+G(3df)) of this cyclic intermediate rationalizes why it could not be detected in our experiments.

• 出版日期2015
• 单位苏州大学