Unprecedented Sequential Deprotonation of Ruthenium–Aqua Framework Affording Ruthenium–Oxo–Dithiolene Complex

A new type of aqua ruthenium–terpyridine complexes with dithiolenes (S2C2Ph2, S2C6H8) were synthesized. The pKa values were 3.8 and 7.0 for S2C2Ph2 complex and 6.5 for S2C6H8 one. The S2C2Ph2 complex gives the corresponding oxo one by the sequential deprotonation, whereas the S2C6H8 complex is just converted to the hydroxo one.