The reactivity of bromine azide, BrN3, towards elemental bromine, Br-2
, was studied experimentally in the gas phase and in CH2Cl2 solution.
The gas phase IR spectra of a 1:10 mixture of BrN3 and Br-2 are in acc
ord with the formation of small amounts of nitrogen tribromide, NBr3 b
ut it was not possible to isolate the NBr3 from the reaction mixture.
The structure and vibrational data of NBr3 have been computed ab initi
o at RHF and at electron correlated MP2 and MP4(SDQ) levels of theory
using a 6-31G basis set for nitrogen and a quasi-relativistic pseudop
otential for bromine (LANL2DZ). The computed (MP4(SDQ)/LANL2DZ) struct
ural parameters are: d(N-Br) = 2.025 Angstrom, (BrNBr) = 107.7 degrees
. The observed IR data (v(1) 350, v(3) 530 cm(-1)) are in good agreeme
nt with those calculated at MP2/LANL2DZ level of theory (v(1) 395, v(2
) 203, v(3) 526, v(4) 145 cm). N-14 NMR spectroscopy revealed that in
solution at or below room temperature BrN, does not react with Br-2 to
form NBr3. However, above -40 degrees C BrN3 reacts with Br-2 to form
a weak complex of the type{Br(2n+1)N-+(3)-}. (N-14 NMR, CH2Cl2, rel.
to MeNO2. Br--N-a--N-b--N-c: -142 (N-b), -178 (N-c), -328 (N-a) ppm; {
Br(2n+1)N-+(3)-}: -132 (N-a and N-c), -304 (N-b) ppm.) (C) 1997 Elsev
ier Science Ltd.