Preparation and properties of a monomeric high-spin Mn(V)-oxo complex.
Oxomanganese(V) species have been implicated in a variety of biological and synthetic processes, including their role as a key reactive center within the oxygen-evolving complex in photosynthesis. Nearly all mononuclear Mn(V)-oxo complexes have tetragonal symmetry, producing low-spin species. A new high-spin Mn(V)-oxo complex that was prepared from a well-characterized oxomanganese(III) complex having trigonal symmetry is now reported. Oxidation experiments with [FeCp(2)](+) were monitored with optical and electron paramagnetic resonance (EPR) spectroscopies and support a high-spin oxomanganese(V) complex formulation. The parallel-mode EPR spectrum has a distinctive S = 1 signal at g = 4.01 with a six-line hyperfine pattern having A(z) = 113 MHz. The presence of an oxo ligand was supported by resonance Raman spectroscopy, which revealed O-isotope-sensitive peaks at 737 and 754 cm(-1) assigned as a Fermi doublet centered at 746 cm(-1)(Δ(18)O = 31 cm(-1)). Mn Kβ X-ray emission spectra showed Kβ' and Kβ(1,3) bands at 6475.92 and 6490.50 eV, respectively, which are characteristic of a high-spin Mn(V) center.
Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, USA.
Taketo
T
Taguchi
Rupal
R
Gupta
Benedikt
B
Lassalle-Kaiser
David W
DW
Boyce
Vittal K
VK
Yachandra
William B
WB
Tolman
Junko
J
Yano
Michael P
MP
Hendrich
A S
AS
Borovik
D004578:Electron Spin Resonance Spectroscopy; D008345:Manganese / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*
D009942:Organometallic Compounds; D008345:Manganese; D010100:Oxygen