Characterization of dislocations in protein crystals using synchrotron white-beam topography

Synthesis and characterization of an azido-bridged dinuclear ruthenium(II) polypyridylamine complex forming a mixed-valence state

We have synthesized a mononuclear ruthenium(II) azido complex (1) and a dinuclear ruthenium(II) μ-azido complex (2) having N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine (N4Py) as a pentadentate ancillary ligand. In the crystal structure of 2, intramolecular π-π stacking was found between the pyridine rings of the two different N4Py ligands, contributing to stabilize the dinuclear μ-azido structure. π donation from the HOMO π* orbital of the μ-azido ligand to the Ru-N(pyr) bond increases the bond order between the terminal and central N atoms in the μ-azido ligand to strengthen the N-N bonds of the μ-azido ligand. The μ-azido complex 2 was revealed to exhibit a stepwise oxidation behavior in CH3CN to afford a Ru(II)-μ-azido-Ru(III) mixed-valence (MV) state upon one-electron oxidation. The MV state of one-electron-oxidized 2 was categorized in the Robin-Day class II with the electronic coupling constant (H(ab)) of 570 cm(-1).