Sodium Tetraazidoaurate(III)—From NaAuCl 4 ·2H 2 O to NaAu(N 3 ) 4 and Beyond One Step at a Time

The novel sodium tetrachlorido-/azidoaurate(III) dihydrates NaAuCl4- x(N3)x·2H2O (x = 0, 1, 2, 3, 4) provide the first example of a complete series of gradual substitution on square planar complex anions to be described. Transparent yellow to dark orange single crystals of these phases were synthesized by reaction of NaN3 and AuCl3 or HAuCl4 in different molar ratios from aqueous solution. Controlled dehydration of NaAu(N3)4·2H2O led to NaAu(N3)4·H2O and NaAu(N3)4 in form of orange microcrystalline powders, the latter being a highly explosive material. Predominant structural features of all phases are discrete anions AuCl4- x(N3)x- with gold in an ordered square planar coordination of azide/chloride anions. Vibrational spectra show good agreement with other known azidoaurates(III).