Dinitrogen extrusion from diazidophenylborane: Computational analysis of PhBNx (x = 6, 4, 2) isomers

The energies and structures of possible intermediates in the dinitrogen extrusion from diazidophenylborane 4a to give phenylborylene 11a were determined using density functional (B3LYP), multiconfigurational (CASSCF and MRMP2), and coupled cluster (CCSD(T)) computations in conjunction with basis sets of up to cc-pVTZ quality. Formation of 11a and nitrogen from 4a is an exothermic process (−21 kcal mol⁻¹). The triplet electronic ground state of azidophenylborylnitrene 5a (PhBN₄) is only 26 kcal mol⁻¹ higher in energy than 4a and the phenyl shift in 5a to yield N-azidophenyliminoborane 7a is highly exothermic.