Preparation and Properties of a Monomeric High-Spin MnV鈥揙xo Complex

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• 作者：Taketo Taguchi ; Rupal Gupta ; Benedikt Lassalle-Kaiser ; David W. Boyce ; Vittal K. Yachandra ; William B. Tolman ; Junko Yano ; Michael P. Hendrich ; A. S. Borovik
• 刊名：The Journal of the American Chemical Society
• 出版年：2012
• 出版时间：February 1, 2012
• 年：2012
• 卷：134
• 期：4
• 页码：1996-1999
• 全文大小：273K
• 年卷期：v.134,no.4(February 1, 2012)
• ISSN：1520-5126

文摘

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鈥搊xo complexes have tetragonal symmetry, producing low-spin species. A new high-spin Mn^V鈥搊xo complex that was prepared from a well-characterized oxomanganese(III) complex having trigonal symmetry is now reported. Oxidation experiments with [FeCp₂]⁺ 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^鈥? assigned as a Fermi doublet centered at 746 cm^鈥?(螖¹⁸O = 31 cm^鈥?). Mn K尾 X-ray emission spectra showed K尾鈥?and K尾_1,3 bands at 6475.92 and 6490.50 eV, respectively, which are characteristic of a high-spin Mn^V center.