2,2′:6′,2′′-Terpyridine switches from tridentate to monodentate coordination in a gold(iii) terpy complex upon reaction with sodium azide

Abstract

Reaction of [AuCl(terpy-κ³-N^{1,1′,1′′})]Cl₂ with an excess of sodium azide did not result in the expected exchange of the chlorido by an azido ligand to give [Au(N₃)(terpy-κ³-N^{1,1′,1′′})]²⁺. Instead, X-ray structure analysis showed that the isolated product is [Au(N₃)₃(terpy-κ¹-N¹)], in which the terpyridine ligand is in a very rare monodentate coordination mode. This is also the dominant species in solution, together with a minor amount of [Au(N₃)₂(terpy-κ²-N^1,1′)]⁺. The stability of the tris(azido)gold(III) moiety relative to other possible species was also confirmed by DFT calculations.