The conversion of AsF5 and SbF5 into novel arsenic- and antimony(V) pseudohalogen species: preparation, characterization and hybrid DFT computation of Lewis base stabilized M(N3)5 species (M=As, Sb)

When reacted with five equivalents of trimethylsilylazide and one equivalent of a Lewis base (LB=pyridine, quinoline, NH3, N2H4 and NH2CN), AsF5 and SbF5 form 1:1 adducts: As(N3)5·LB and Sb(N3)5·LB. The adducts are stable at ambient temperature, but highly explosive towards mechanical impact or increasing temperature. Vibrational and multinuclear NMR spectra and theoretical calculations show that all compounds are nitrogen-coordinated donor–acceptor adducts, and that the strengths of the nitrogen bridges (determined by calculating the bond dissociation enthalpy) increase in the order NH2CN, pyridine, NH3 to N2H4 and from As(N3)5 to Sb(N3)5. 5·LB and Sb(N3)5·LB (LB=pyridine, quinoline, NH3, N2H4 and NH2CN) were obtained by reacting AsF5 and SbF5 with five equivalents of Me3SiN3 in the presence of LB. Vibrational and multinuclear NMR spectra and theoretical calculations (B3LYP) show that all compounds are nitrogen-coordinated donor–acceptor adducts.