Ru-Zn Heteropolynuclear Complexes Containing a Dinucleating Bridging Ligand: Synthesis, Structure, and Isomerism

Abstract

<p> Mononuclear complexes in- and out-[Ru(Cl)(trpy)(Hbpp)]+ (in-0, out-0; Hbpp is 2,2&prime;-(1H-pyrazole-3,5-diyl)dipyridine and trpy is 2,2&prime;:6&prime;,2&Prime;-terpyridine) are used as starting materials for preparation of Ru&ndash;Zn heterodinuclear out-{[Ru(Cl)(trpy)][ZnCl2](&mu;-bpp)} (out-2) and heterotrinuclear in,in- and out,out-{[Ru(Cl)(trpy)]2(&mu;-[Zn(bpp)2])}2+ (in-3, out-3) constitutional isomers. Further substitution of the Cl ligand from the former complexes leads to Ru&ndash;aquaout,out-{[Ru(trpy)(H2O)]2(&mu;-[Zn(bpp)2])}4+ (out-4) and the oxo-bridged Ru&ndash;O&ndash;Ru complexin,in-{[RuIII(trpy)]2(&mu;-[Zn(bpp)2(H2O)]&mu;-(O)}4+ (in-5). All complexes are thoroughly characterized by the usual analytical techniques as well as by spectroscopy by means of UV&ndash;vis, MS, and when diamagnetic NMR. CV and DPV are used to extract electrochemical information and monocrystal X-ray diffraction to characterize complexes out-2, in-3, out-3, and in-5 in the solid state. Complex out-3 photochemically isomerizes toward in-3, as can be observed by NMR spectroscopy and rationalized by density functional theory based calculations.</p>