Photochromism of {bis(diphenylphosphino)methane}(1-alkyl-2-(arylazo)imidazole)silver(I) hexaflurophosphate complexes.

Graphical abstract Phosphino bridged Ag(I) complex of 1-alkyl-2-(arylazo)imidazole is structurally characterized and UV light irradiation initiates trans -to- cis isomerisation. Reverse is also carried out by heat treatment. Rate of photoisomerisation of free ligand is faster than coordinated ligand which may be due to higher molar mass of the associated photochrome. Highlights • Diphenylphosphino bridging Ag(I)-dimer complex of arylazoimidazoles. • Single crystal X-ray structure of one of the complexes was established. • Coordinated arylazoimidazole undergoes UV-light irradiated photoisomerisation. • Free ligand shows higher rate of trans -to- cis photoisomerisation that that of complex phase. • Reverse process, cis -to- trans isomerisation is thermally controlled. Abstract The coordinated 1-alkyl-2-(arylazo)imidazole (RaaiR/) in [Ag(μ-dppm)(RaaiR/)] 2 (PF 6) 2 (dppm, bis-(diphenylphosphino)methane) undergoes light induced trans -to- cis isomerization about N N bond. The quantum yields (ϕ t→c) of trans -to- cis isomerization of coordinated RaaiR/ in the complex is lower than the free ligand data. The reverse transformation, cis -to- trans , is carried out at different temperatures (298–313 K) and activation energy (E a) has been calculated. It is found that E a (free ligands) > E a (coordinated ligand in the complexes). The structures of the complexes have been established by spectral (UV–Vis, IR, and 1H NMR) data. One of the complexes, [Ag(μ-dppm)(HaaiEt)] 2 (PF 6) 2 has been structurally confirmed by single crystal X-ray diffraction study. [ABSTRACT FROM AUTHOR]