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

Abstract

Combining fac-[Re(CO) 3Cl] with components of the ligand redox system bmtz/bmtz − /H 2bmtz/H 2bmtz − (bmtz=3,6-bis(2-pyrimidyl)-1,2,4,5-tetrazine) has led to the isolation of the complexes (H 2bmtz)Re(CO) 3Cl, (μ-H 2bmtz)[Re(CO) 3Cl] 2 and (μ-bmtz)[Re(CO) 3Cl] 2. Other species characterized were (bmtz)Re(CO) 3Cl (UV/Vis, IR), [(H 2bmtz)Re(CO) 3Cl] − (UV/Vis, IR, EPR), {(μ-H 2bmtz)[Re(CO) 3Cl] 2} − (UV/Vis, IR, EPR) and {(μ-bmtz)[Re(CO) 3Cl] 2} − (UV/Vis, IR, X band and high-field EPR). The results confirm bmtz as very strong and H 2bmtz 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.