Complexes of [Re(CO)3Cl] with different oxidation states of the polyfunctional bmtz/H2bmtz ligand system (bmtz=3,6-bis(2-pyrimidyl)-1,2,4,5-tetrazine)

Combining fac-[Re(CO)3Cl] with components of the ligand redox system bmtz/bmtzradical dot−/H2bmtz/H2bmtzradical dot− (bmtz=3,6-bis(2-pyrimidyl)-1,2,4,5-tetrazine) has led to the isolation of the complexes (H2bmtz)Re(CO)3Cl, (μ-H2bmtz)[Re(CO)3Cl]2 and (μ-bmtz)[Re(CO)3Cl]2. Other species characterized were (bmtz)Re(CO)3Cl (UV/Vis, IR), [(H2bmtz)Re(CO)3Cl]radical dot− (UV/Vis, IR, EPR), {(μ-H2bmtz)[Re(CO)3Cl]2}radical dot− (UV/Vis, IR, EPR) and {(μ-bmtz)[Re(CO)3Cl]2}radical dot− (UV/Vis, IR, X band and high-field EPR). The results confirm bmtz as very strong and H2bmtz as moderate π acceptor ligand versus one or two chelate-bonded low-valent metal centers. Reactivity is observed in terms of oxidative proton and reductive chloride dissociation.