Chemical and photochemical water oxidation catalyzed by mononuclear ruthenium complexes with a negatively charged tridentate ligand.
Two mononuclear ruthenium complexes [RuL(pic)3] (1) and [RuL(bpy)(pic)] (2) (H2L = 2,6-pyridinedicarboxylic acid, pic = 4-picoline, bpy =2,2'-bipyridine) have been synthesized and fully characterized. Both complexes could promote water oxidation chemically and photochemically. Compared with other known ruthenium-based water oxidation catalysts using [Ce(NH4)2(NO3)6] (Ce(IV)) as the oxidant in solution at pH 1.0, complex 1 is one of the most active catalysts yet reported with an initial rate of 0.23 turnover s(-1). Under acidic conditions, the equatorial 4-picoline in complex 1 dissociates first. In addition, ligand exchange in 1 occurs when the Ru(III) state is reached. Based on the above observations and MS measurements of the intermediates during water oxidation by 1 using Ce(IV) as oxidant, [RuL(pic)2(H2O)](+) is proposed as the real water oxidation catalyst.
Duan
Lele
L
Department of Chemistry, Royal Institute of Technology (KTH), Teknikringen 30, 10044 Stockholm (Sweden).
Xu
Yunhua
Y
Gorlov
Mikhail
M
Tong
Lianpeng
L
Andersson
Samir
S
Sun
Licheng
L
D015082:2,2'-Dipyridyl / Q000737:chemistry; D002384:Catalysis; D004563:Electrochemistry; D008024:Ligands; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D010084:Oxidation-Reduction; D010848:Picolinic Acids; D011725:Pyridines / Q000737:chemistry; D012428:Ruthenium / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
D008024:Ligands; D009942:Organometallic Compounds; D010848:Picolinic Acids; D011725:Pyridines; D014867:Water; D015082:2,2'-Dipyridyl; D012428:Ruthenium; C004860:dipicolinic acid
electrochemistry; homogeneous catalysis; oxidation; ruthenium; water splitting