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Oxygen Atom Transfer in Models for Molybdenum Enzymes: Isolation and Structural, Spectroscopic, and Computational Studies of Intermediates in Oxygen Atom Transfer from Molybdenum( VI ) to Phosphorus( III )
Author(s) -
Millar Andrew J.,
Doonan Christian J.,
Smith Paul D.,
Nemykin Victor N.,
Basu Partha,
Young Charles G.
Publication year - 2005
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200401101
Subject(s) - chemistry , molybdenum , steric effects , denticity , reactivity (psychology) , crystallography , oxygen , ligand (biochemistry) , nuclear magnetic resonance spectroscopy , stereochemistry , crystal structure , inorganic chemistry , organic chemistry , medicine , biochemistry , alternative medicine , receptor , pathology
Intermediates in the oxygen atom transfer from Mo VI to P III , [Tp i Pr MoOX(OPR 3 )] (Tp i Pr =hydrotris(3‐isopropylpyrazol‐1‐yl)borate; X=Cl − , phenolates, thiolates), have been isolated from the reactions of [Tp i Pr MoO 2 X] with phosphines (PEt 3 , PMePh 2 , PPh 3 ). The green, diamagnetic oxomolybdenum( IV ) complexes possess local C 1 symmetry (by NMR spectroscopy) and exhibit IR bands assigned to ν(MoO) (approximately 950 cm −1 ) and ν(PO) (1140–1083 cm −1 ) vibrations. The X‐ray crystal structures of [Tp i Pr MoOX(OPEt 3 )] (X=OC 6 H 4 ‐2‐ s Bu, S n Bu), [Tp i Pr MoO(OPh)(OPMePh 2 )], and [Tp i Pr MoOCl(OPPh 3 )] have been determined. The monomeric complexes exhibit distorted octahedral geometries, with coordination spheres composed of tridentate fac‐ Tp i Pr and mutually cis monodentate terminal oxo, phosphoryl (phosphine oxide), and monoanionic X ligands. The electronic structures and stabilities of the complexes have been probed by computational methods, with the three‐dimensional energy surfaces confirming the existence of a low‐energy steric pocket that restricts the conformational freedom of the phosphoryl ligand and inhibits complete oxygen atom transfer. The reactivity of the complexes is also briefly described.