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).
Intermediates in the oxygen atom transfer from Mo(VI) to P(III), [Tp(iPr)MoOX(OPR3)] (Tp(iPr) = hydrotris(3-isopropylpyrazol-1-yl)borate; X = Cl-, phenolates, thiolates), have been isolated from the reactions of [Tp(iPr)MoO2X] with phosphines (PEt3, PMePh2, PPh3). The green, diamagnetic oxomolybdenum(IV) complexes possess local C(1) symmetry (by NMR spectroscopy) and exhibit IR bands assigned to nu(Mo==O) (approximately 950 cm(-1)) and nu(P==O) (1140-1083 cm(-1)) vibrations. The X-ray crystal structures of [Tp(iPr)MoOX(OPEt3)] (X = OC6H4-2-sBu, SnBu), [Tp(iPr)MoO(OPh)(OPMePh2)], and [Tp(iPr)MoOCl(OPPh3)] have been determined. The monomeric complexes exhibit distorted octahedral geometries, with coordination spheres composed of tridentate fac-Tp(iPr) 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.
Millar
Andrew J
AJ
School of Chemistry, University of Melbourne, Victoria, 3010, Australia.
Doonan
Christian J
CJ
Smith
Paul D
PD
Nemykin
Victor N
VN
Basu
Partha
P
Young
Charles G
CG
D001881:Borates / Q000138:chemical synthesis / Q000737:chemistry; D018360:Crystallography, X-Ray; D004798:Enzymes / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008958:Models, Molecular; D008982:Molybdenum / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010720:Phosphines / Q000138:chemical synthesis / Q000737:chemistry*; D011720:Pyrazoles / Q000138:chemical synthesis / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
D001881:Borates; D004798:Enzymes; D009942:Organometallic Compounds; D010720:Phosphines; D011720:Pyrazoles; D008982:Molybdenum