ja9b10320_si_001.cif (16.21 MB)
Isolation and Study of Ruthenium–Cobalt Oxo Cubanes Bearing a High-Valent, Terminal RuV–Oxo with Significant Oxyl Radical Character
dataset
posted on 2019-12-05, 16:41 authored by Jaruwan Amtawong, David Balcells, Jarett Wilcoxen, Rex C. Handford, Naomi Biggins, Andy I. Nguyen, R. David Britt, T. Don TilleyHigh-valent RuV–oxo intermediates have
long been
proposed in catalytic oxidation chemistry, but investigations into
their electronic and chemical properties have been limited due to
their reactive nature and rarity. The incorporation of Ru into the
[Co3O4] subcluster via the single-step assembly
reaction of CoII(OAc)2(H2O)4 (OAc = acetate), perruthenate (RuO4–), and pyridine (py) yielded an unprecedented Ru(O)Co3(μ3-O)4(OAc)4(py)3 cubane featuring an isolable, yet reactive, RuV–oxo
moiety. EPR, ENDOR, and DFT studies reveal a valence-localized [RuV(S = 1/2)CoIII3(S = 0)O4] configuration
and non-negligible covalency in the cubane core. Significant oxyl
radical character in the RuV–oxo unit is experimentally
demonstrated by radical coupling reactions between the oxo cubane
and both 2,4,6-tri-tert-butylphenoxyl and trityl
radicals. The oxo cubane oxidizes organic substrates and, notably,
reacts with water to form an isolable μ-oxo bis-cubane complex
[(py)3(OAc)4Co3(μ3-O)4Ru]–O–[RuCo3(μ3-O)4(OAc)4(py)3]. Redox activity
of the RuV–oxo fragment is easily tuned by the electron-donating
ability of the distal pyridyl ligand set at the Co sites demonstrating
strong electronic communication throughout the entire cubane cluster.
Natural bond orbital calculations reveal cooperative orbital interactions
of the [Co3O4] unit in supporting the RuV–oxo moiety via a strong π-electron donation.
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Keywords
EPROAcCo IICo 3 O 4Natural bondRu Vchemical propertiescubane clusterreactive natureoxo cubane oxidizesassembly reactionSignificant oxyloxo cubanecubane coreH 2 O3 cubanepyridyl ligandnon-negligible covalencyoxidation chemistryisolable μ- oxo bis-cubaneDFT studieselectron-donating abilityCo sitestrityl radicalsIIIENDORπ- electron donation
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