When reacted with five equivalents of trimethylsilylazide and one equivalent of a Lewis base (LB=pyridine, quinoline, NH 3, N 2H 4 and NH 2CN), AsF 5 and SbF 5 form 1:1 adducts: As(N 3) 5·LB and Sb(N 3) 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 NH 2CN, pyridine, NH 3 to N 2H 4 and from As(N 3) 5 to Sb(N 3) 5. As(N 3) 5·LB and Sb(N 3) 5·LB (LB=pyridine, quinoline, NH 3, N 2H 4 and NH 2CN) were obtained by reacting AsF 5 and SbF 5 with five equivalents of Me 3SiN 3 in the presence of LB. Vibrational and multinuclear NMR spectra and theoretical calculations (B3LYP) show that all compounds are nitrogen-coordinated donor–acceptor adducts.
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