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Mechanistic Elucidation of the Stepwise Formation of a Tetranuclear Manganese Pinned Butterfly Cluster via N-N Bond Cleavage, Hydrogen Atom Transfer, and Cluster Rearrangement.

Authors :
Hamilton, Clifton R.
Gau, Michael R.
Baglia, Regina A.
McWilliams, Sean F.
Zdilla, Michael J.
Source :
Journal of the American Chemical Society. 12/31/2014, Vol. 136 Issue 52, p17974-17986. 13p.
Publication Year :
2014

Abstract

A mechanistic pathway for the formation of the structurally characterized manganese-amide-hydrazide pinned butterfly complex, Mn4(μ3-PhN-NPh-γ³N,N')2(μ-PhN-NPh-γ³-N,N')(μ-NHPh)2L4 (L = THF, py), is proposed and supported by the use of labeling studies, kinetic measurements, kinetic competition experiments, kinetic isotope effects, and hydrogen atom transfer reagent substitution, and via the isolation and characterization of intermediates using X-ray diffraction and electron paramagnetic resonance spectroscopy. The data support a formation mechanism whereby bis[bis-(trimethylsilyl)amido]manganese(II) (Mn(NR2)2, where R = SiMe3) reacts with N,N'-diphenylhydrazine (PhNHNHPh) via initial proton transfer, followed by reductive N--N bond cleavage to form a long-lived Mnlv imido multinuclear complex. Coordinating solvents activate this cluster for abstraction of hydrogen atoms from an additional equivalent of PhNHNHPh resulting in a Mn(II)phenylamido dimer, Mn2(μ-NHPh)2-(NR2)2L2. This dimeric complex further assembles in fast steps with two additional equivalents of PhNHNHPh replacing the terminal silylamido ligands with η¹-hydrazine ligands to give a dimeric Mn20-NHPh)2 (PhN-NHPh)2L4 intermediate, and finally, the addition of two additional equivalents of Mn(NR2)2 and PhNHNHPh gives the pinned butterfly cluster. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
00027863
Volume :
136
Issue :
52
Database :
Academic Search Index
Journal :
Journal of the American Chemical Society
Publication Type :
Academic Journal
Accession number :
100583469
Full Text :
https://doi.org/10.1021/ja508244x