Synthesis, Molecular Structure, and Electrochemistry of a Paramagnetic Diruthenium(III) Complex. Characterization of Ru₂(hpp)₄Cl₂, Where hpp Is the 1,3,4,6,7,8- Hexahydro-2H-pyrimido[1,2-a]pyrimidinate Ion

The synthesis and characterization of the first paramagnetic diruthenium(III) complex containing two unpaired electrons is described. The investigated compound, represented as Ru2(hpp)4Cl2, where hpp is 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidinate ion, was obtained from the reaction of Ru2(CH3COO)4Cl with excess molten Hhpp under Ar (150 °C, 10 h). It was characterized by X-ray single-crystal diffraction, electrochemistry, ESR, and UV−visible spectroscopy and the data compared to that for other Ru26+ derivatives containing either four unpaired electrons (in the case of a bis-H2O complex) or zero unpaired electrons (in the case of a bis-C⋮CC6H5 derivative).