Photoinduced linkage isomerism of binuclear bis(pyrazole-3,5-dicarboxylato)-bridged {RuNO}6 centres

The two novel binuclear pyrazole-3,5-dicarboxylato-bridged {RuNO}6 complexes K2[{Ru(NO)Cl}2(μ-pzdc)2] (1) and [{Ru(NO)(H2O)}2(μ-pzdc)2]·4H2O (2) (pzdc = pyrazole-3,5-dicarboxylate) were synthesized and characterized by elemental analysis, mass spectrometry and spectroscopic methods (NMR, UV–vis, IR). 2 was investigated by means of single-crystal X-ray diffraction analysis. On irradiation, in both 1 and 2 the existence of photoinduced long-lived metastable isonitrosyl states SI were detected by low-temperature infrared spectroscopy.