[open quotes]Dimerization[close quotes] of the [Co[sub 2][sup III](OH)[sub 2]] core to the first example of a [Co[sub 4][sup III]O[sub 4]] Cubane. Potential insights into photosynthetic water oxidation

Journal Article · Wed Jul 14 00:00:00 EDT 1993 · Journal of the American Chemical Society; (United States)

DOI:https://doi.org/10.1021/ja00067a077· OSTI ID:5901944

Dimitrou, K; Folting, K; Streib, W E; Christou, G ^[1]

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1. Indiana Univ., Bloomington (United States)

Intense effort is currently directed toward elucidating the structure and mode of action of the Mn[sub 4] aggregate responsible for photosynthetic water oxidation in green plants and cyanobacteria. The arrangement of the metal ions at any of the oxidation levels (S[sub n] states; n =-1 to 4) of this water oxidation center (WOC) is currently unclear. We have extended our WOC modeling studies to encompass Co. The reasoning is that we may obtain Co[sup III] systems that are structurally analogous to, but more stable than, the Mn[sup III]/Mn[sup IV] species present at the highest S[sub n] states or that are intermediates in the O[sub 2] evolution process. For example, Co[sup III] and Mn[sub IV] both favor octahedral geometry and have similar effective ionic radii. Thus, it is a possibility that stable Co[sup III][sub 4] complexes could be structurally analogous to unstable Mn[sup IV][sub 4] complexes at higher S[sub n] states and could thus provide insights into the latter. Similarly, Co[sup III] is known to form stable peroxide complexes, whereas Mn[sub 4]O[sub 2][sup 2] species thought to be formed on oxidation of S[sub 3] are not observed, and only O[sub 2] and regenerated S[sub 0] are found. We herein describe our initial successes in this area, the preparation of Co[sub 2], Co[sub 3], and Co[sub 4] complexes. The Co[sub 3] and Co[sub 4] species possess the first examples of [Co[sub 3]([mu][sub 3]-O)([mu]-OH)[sub 3]][sup 4+] partial cubane and [Co[sub 4]([mu][sub 3]-O)[sub 4]][sup 4+] cubane cores and represent interesting developments in the otherwise well-explored chemistry of Co[sup III]. The Co[sub 4] species is also the first M[sub 4]O[sub 4] cubane complex with biologically-relevant ligands. 16 refs., 2 figs.

• OSTI ID: 5901944
• Journal Information: Journal of the American Chemical Society; (United States), Vol. 115:14; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
COBALT COMPLEXES
MOLECULAR STRUCTURE
SYNTHESIS
WATER
OXIDATION
DIMERIZATION
MANGANESE COMPLEXES
PHOTOSYNTHESIS
CHEMICAL REACTIONS
COMPLEXES
HYDROGEN COMPOUNDS
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
POLYMERIZATION
TRANSITION ELEMENT COMPLEXES
140505* - Solar Energy Conversion- Photochemical
Photobiological
& Thermochemical Conversion- (1980-)
400201 - Chemical & Physicochemical Properties