Is pseudohalide CN - a real halide? An easy identification method

Abstract

Abstract Recently, in the light of a great concentration devoted on pseudohalide CN− and cyano radical CN physico-chemical property studies and superhalide behavior exploration in CN− ligated metal compounds, the electronic structure nature of pseudohalide CN− has been directly demonstrated via photoelectron velocity map imaging (PE-VMI) technique as compared to that of Cl−. For the halide Cl−, photoelectrons were observed at 266 nm (4.66 eV) to peak being perpendicular to the laser polarization due to electron emission from the typically parent p orbital. For the analogous pseudohalide CN−, photoelectrons present peak along the laser polarization entirely at 266 nm. Although both of them were often regarded with the same high electron affinity and extremely strong chemical bonding capability to stabilize complexes, the photoelectron angular distributions (PADs) are quietly different, which indicates their different HOMO nature. Thus, using advanced PE-VMI technique, we demonstrate that PADs can provide detailed information about the electronic structure to distinguish electronic structures of pseudohalides and halides.