Photochemistry of Azide Complexes of Gold, Silver, Platinum and Palladium. Generation of the Metallic State

Abstract

The photochemistry of the following azide complexes in organic solvents has been investigated: [Au(N3)4]⁻, [Au(N3)2]⁻, [Ag(PPh3)2N3],
[Pt(N3)6]2⁻, [Pt(N3)4]2⁻, [Pd(N3)4]2⁻, and [Pd2(N3)6]2⁻. All complexes underwent a photochemical reduction of the metal and oxidation
of azide upon ligand to metal charge transfer excitation. The photolysis of the complexes with the metals in the lower oxidation states
(Au(I), Ag(I), Pt(II), Pd(II)) led ultimately to the generation of free metals which form colloids. These colloids were characterized by their
absorption spectra which showed the typical plasmon bands in the case of gold and silver. Pt(0) and Pd(0) produced during the photolysis
can be intercepted with allyl chloride to form [Pt(π-allyl)Cl]4 and [Pd(π-allyl)Cl]2. Most photoreactions took place with rather large quantum yields.