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Mononuclear and tetranuclear manganese complexes as models for the manganese aggregate of the photosystem II oxygen-evolving complex

Thesis/Dissertation ·
OSTI ID:5601857

A series of mononuclear and tetranuclear manganese complexes was prepared and characterized in order to gain insight into the possible structure and mechanism of the manganese aggregate of the photosystem II oxygen evolving complex (MnOEC). One study consists of three isostructural manganese complexes with the formulation, [Mn(HB(Me[sub 2]pz)[sub 3])[sub 2]][sup n+] (n =0,1,2). A comparison of their magnetic, spectroscopic and structural properties is presented. The second set of compounds consists of four structurally distinct tetranuclear manganese complexes prepared in attempts to synthesize a dimer of di-[mu]-oxo dimers molecule. The first tetranuclear complex consists of two oxo-diacetate dimers linked by spanning hexadentate tppn (N,N,N[prime],N[prime]-tetra(2-methylpyridyl)-propanediamine) ligands, with the formulation [(Mn[sub 2](O)(OAc)[sub 2])[sub 2] (tppn)[sub 2]][sup 4+]. The authors decided to determine whether one could accomplish this goal using the modified ligand Htphph, N,N,N[prime],N[prime]-tetra(2-methylpyridyl)-2-hydroxypropanediamine. Three complexes were obtained using Htphp including the desired dimer of di-[mu]-oxo dimers complex. The least oxidized compound, [(Mn[sub 2](tphpn)(OAc)(H[sub 2]O))[sub 2]O][sup 4+], consists of two alkoxide bridge MN[sup II]Mn[sup III] dimers connected via a relatively rare example of a Mn[sup III]-O-M[sup III] linear oxo bridge. Rearrangement of this aggregate with concomitant oxidation by one electron yields, [(Mn[sub 2](tphpn)(H[sub 2]O)(X))[sub 2]O[sub 2]][sup 3+] X = ClO[sub 4][sup [minus]] or CF[sub 3]SO[sub 3][sup [minus]], a species containing a Mn[sup III]Mn[sup IV] di-[mu]-oxo dimer linked to two mononuclear Mn[sup II] sites.

Research Organization:
California Univ., Berkeley, CA (United States)
OSTI ID:
5601857
Country of Publication:
United States
Language:
English

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Related Subjects

14 SOLAR ENERGY
140505 -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ABSORPTION SPECTROSCOPY
BIOMIMETIC PROCESSES
CATIONS
CHARGED PARTICLES
CHEMICAL PREPARATION
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COMPLEXES
DIMERS
ELECTRON SPIN RESONANCE
ELEMENTS
IONS
KINETICS
LIGANDS
MAGNETIC RESONANCE
MANGANESE COMPLEXES
MOLECULAR STRUCTURE
NONMETALS
NUCLEAR MAGNETIC RESONANCE
OXIDATION
OXYGEN
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
REACTION KINETICS
RESONANCE
SPECTROSCOPY
SYNTHESIS
TRANSITION ELEMENT COMPLEXES
X-RAY SPECTROSCOPY