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(N-3)5 species (M = As, Sb)

When reacted with five equivalents of trimethylsilylazide and one equivalen t of a Lewis base (LB = pyridine, quinoline, NH3, N2H4 and NH2CN), AsF5 and SbF5 form 1:1 adducts: As(N-3)(5).LB and Sb(N-3)(5).LB. The adducts are st able at ambient temperature, but highly explosive towards mechanical impact or increasing temperature. Vibrational and multinuclear NMR spectra and th eoretical calculations show that all compounds are nitrogen-coordinated don or-acceptor adducts, and that the strengths of the nitrogen bridges (determ ined by calculating the bond dissociation enthalpy) increase in the order N H2CN pyridine, NH3 to N2H4 and from As(N-3)(5), to Sb(N-3)(5). As(N-3)(5).L B and Sb(N-3)(5).LB (LB = pyridine, quinoline, NH3, N2K4 and NH2CN) were ob tained by reacting AsF5 and SbF5 with five equivalents of Me3SiN3 in the pr esence of LB. Vibrational and multinuclear NMR spectra and theoretical calc ulations (B3LYP) show that all compounds are nitrogen-coordinated donor-acc eptor adducts. (C) 2001 Elsevier Science B.V. All nights reserved.