DETECTION OF REACTION INTERMEDIATES - PHOTOSUBSTITUTION OF (POLYPYRIDINE)RUTHENIUM(II) COMPLEXES USING ON-LINE ELECTROSPRAY MASS SPECTROMETRY

摘要

Photosubstitution of Ru(bpy)(2)BX(2) (bpy = 2,2'-bipyridine; B = 3,3'-dimethyl-2,2'-bipyridine (dmbpy) or 2-(aminomethyl)pyridine (ampy); and X = ClO4- or PF6-) has been studied in both acetonitrile and pyridine by using on-line electrospray mass spectrometry. For the complexes with B = dmbpy and ampy, intermediates with a monodentate (one-legged) B ligand, Ru(bpy)(2)BS2+ and Ru(bpy)(2)BSX(+) (S = soh ent molecule), were detected for the first time in the electrospray mass spectra, together with the photosubstitution products Ru(bpy)(2)S-2(2+) and Ru(bpy)(2)S(2)X(+). For the complex with B = ampy, minor photoproducts that resulted from dissociation of bpy, Ru(bpy)BS22+ and Ru(bpy)BS(2)X(+), were detected. The solvent-released ions Ru(bpyS2+, Ru(bpy)(2)(2+), and Ru(bpy)(2)SX(+), which were secondary products from collision-induced dissociation of the photosubstitution reaction, were also seen. The effects of solvent and intensity of irradiation on the photoreactions were also studied. It was shown for the first time that the reaction intermediates with B = dmbpy can be detected after photoirradiation of electrosprayed charged droplets at the spray needle of the electrospray mass spectrometer, The electrospray technique, combined with use of a now-through photoreaction cell or with direct photoirradiation of electrosprayed charged droplets, was demonstrated to be a powerful tool for the study of photosubstitution and for the detection of reaction intermediates. [References: 25]