Bifunctional Materials Based on the Photochromic Cation [RuNO(NH₃)₅]³⁺ with Paramagnetic Metal Complex Anions

The synthesis of a series of compounds containing the photochromic mononitrosyl cation, [RuNO(NH 3 ) 5 ] 3+ and metal complex paramagnetic anions [M(CN) 6 ] 3– [M = Cr ( 1 ), Fe( 2 )], [M(ox) 3 ] 3– [M = Cr( 3 ), Fe( 4 )] and [CrNO(CN) 5 ] 3– ( 5 ) is reported. The crystal structures of the salts 1 and 3 are discussed. In contrast to 1 and 3 which exhibit reversible photochromic properties, illumination of 2 and 4 results in an irreversible photochemical reaction and compound 5 is not photochromic at all. The magnetic properties of 1 and 3 have been investigated and complex 1 shows a weak reversible increase in the value of χ M T under light irradiation at low temperature. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)