P—N Bond Length Alterations Monitored by Infrared Absorption and Fourier Transform Raman Spectroscopy in Combination with Density Functional Theory Calculations

Abstract

Fourier transform (FT) Raman and infrared spectroscopy in combination with density functional theory calculations have been applied to the vibrational characterization of the dimeric zinc diphenylphosphanyl(trimethylsilyl)amide complex [(Me₃Si)₂NZnPh₂PNSiMe₃]₂ and the ortho-metallated species [Li(o-C₆H₄PPh₂NSiMe₃)]₂·Et₂O in relation to their parent starting materials diphenylphosphanyl (trimethylsilyl)amine Ph₂P–N(H)SiMe₃ and iminophosphorane Ph₃P=NSiMe₃. The spectroscopic changes evidenced in the spectra were correlated with the structural parameters in order to provide insight as to what extent the P–N bond is affected by the coordination to the metal center. The employment of density functional theory (DFT) calculations in addition to these spectroscopic methods offers the possibility of predicting whether the Lewis-basic imido nitrogen atom is involved in coordination not only in the solid state, but also in the gas phase.