Preparation, characterization, and structural studies of new ruthenium(II) and ruthenium(III) complexes incorporating pyrazole ligands

Abstract

Multimetallic complexes containing disparate metals have been established to have practical utilities. We previously reported a strategy for preparing such species by using combinations of neutral pyrazole (Hpyz, C3N2H4) and anionic pyrazolyl ligands (pyz, C3N2H3–), and herein are reported several new complexes that should be capable of incorporating a second metal center. Two of the complexes, [Ru(1,5-cod)(Hpyz)3Cl][BPh4] and Ru(1,5-cod)(Hpyz)2(pyz)2 (cod = cyclooctadiene), were prepared from [Ru(cod)Cl2]2, while [Ru(tmeda)(Hpyz)2Cl2][BF4] (tmeda = tetramethylethylenediamine) was prepared from the neutral Ru(II) complex Ru(tmeda)(Hpyz)2Cl2 via one electron oxidation by the ferricinium ion. The first two complexes, one cationic and the other uncharged, involve Ru(II), while the tmeda complex involves Ru(III). All three species have been structurally characterized.