Bis(trimethylsilyl)diazene revisited. Density functional theory (DFT) calculations of nitrogen NMR parameters of some azo‐compounds

Calculations of nitrogen NMR parameters [chemical shifts δN and indirect nuclear spin–spin coupling constants J(N,N), J(N,¹³C), J(²⁹Si,N)] of noncyclic azo‐compounds R¹ NN R² (R¹, R² = H, Me, Ph, SiH₃, SiMe₃) and cyclic azo‐compounds [NNCH₂, NN(CH₂)₃ NN(CH₂)₂SiH₂, and NN(SiH₂CH₂SiH₂)] by density functional theory (DFT) methods [B3LYP/6‐311+G(d,p) level of theory] provide data in reasonable agreement with experimental values. The influence of cis‐ and trans‐geometry is reflected by the calculations, and amino‐nitrenes are also included for comparison. The spin–spin coupling constants are analyzed with respect to contact (Fermi contact term, FC) and non‐ contact contributions (paramagnetic and diamagnetic spin‐orbital terms, PSO and DSO, and spin‐dipole term, SD). Bis(trimethylsilyl)diazene 6a can be generated by an alternative method, using the reaction of bis(trimethylsilyl)sulfur diimide with bis‐ (trimethylsilyl)amino‐trimethylsilylimino‐phosphane. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:84–91, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20075