Photoinduced linkage isomerism of {RuNO}(6) complexes with bioligands and related chelators.

Five novel complexes containing the {RuNO}(6) fragment and the anions derived from l-histidine (l-his), rac-3-amino-alanine (rac-dap), kojic acid (koj), methyliminodiacetic acid (mida), and thiodiacetic acid (tda) have been synthesised and characterised by single-crystal X-ray diffraction analysis, mass spectrometry, spectroscopic methods (NMR, UV-vis, IR) and elemental analysis. In the irradiated complexes, [Ru(NO)Cl(2)(l-his)] (1), [Ru(NO)Cl(2)(rac-dap)] (2), K[Ru(NO)Cl(3)(koj)] (3), K[Ru(NO)Cl(2)(mida)].(1/2)H(2)O (4), and K[Ru(NO)Cl(2)(tda)].H(2)O (5), the existence of the photoinduced long-lived metastable isonitrosyl state S1 and/or the side-on-bonded S2 state were detected by differential scanning calorimetry (DSC) and/or IR spectroscopy. For all complexes 1-5 full geometry optimisation, frequency analysis and calculation of the isotropic magnetic shielding tensors have been conducted in the framework of DFT theory.