Preparation and Characterization of the Binary Group 13 Azides M(N3)3 and M(N3)3'CH3CN (M = Ga, In, TI), [Ga(N3)5](2-), and [M(N3)6](3-) (M = In, TI) (Preprint)

There has been much interest in polyazido compounds during the last two decades. In particular, the potential of group 13 azides as precursors for the synthesis of the corresponding nitrides has been studied in great detail due to their usefulness for semiconductor and optoelectronic applications. Although most of these efforts were devoted to gallium azides, aluminium and indium azides were also explored. For thallium, the monoazide is well known and is an impact and highly friction sensitive compound, similar in properties to silver azide and lead diazide. However, little is known about the triazide. To our knowledge, the only previous report deals with the formation of a highly explosive yellow solid, formed by the reaction of TlOH3 with HN3. Based on its elemental analysis, it had the composition TlN32 and was proposed to be the mixed TlITlIII salt, TlTlN34, but this interpretation was subsequently questioned. The syntheses and characterisation of molecules with a high number of azido groups is very challenging due to the high energy content of the azido group which is responsible for their frequently encountered explosive and shock-sensitive nature. In this paper, we wish to communicate the syntheses of GaN33, InN33, and TlN33 in SO2 and CH3CN solutions, their 11 adducts with CH3CN, and the first examples of multiply charged group 13 polyazido anions, GaN352-, InN363- and TlN363-. We also report the crystal structures of the tetraphenylphosphonium salts of the GaN352-, InN363- and TlN363 anions, and the vibrational spectra and electronic structure calculations for all the compounds.