Electronic Structure and Reactivity of Dioxygen-Derived Aliphatic Thiolate-Ligated Fe-Peroxo and Fe(IV) Oxo Compounds.

Herein, we examine the electronic and geometric structural properties of O-derived aliphatic thiolate-ligated Fe-peroxo, Fe-hydroxo, and Fe(IV) oxo compounds. The latter cleaves strong C-H bonds (96 kcal mol) on par with the valine C-H bond cleaved by isopencillin N synthase (IPNS). Stopped-flow kinetics studies indicate that the barrier to O binding to [Fe(SN(tren))] () is extremely low ( = 36(2) kJ mol), as theoretically predicted for IPNS.

Influence of Thiolate versus Alkoxide Ligands on the Stability of Crystallographically Characterized Mn(III)-Alkylperoxo Complexes.

The work described herein demonstrates the exquisite control that the inner coordination sphere of metalloenzymes and transition-metal complexes can have on reactivity. We report one of few crystallographically characterized Mn-peroxo complexes and show that the tight correlations between metrical and spectroscopic parameters, established previously by our group for thiolate-ligated RS-Mn(III)-OOR complexes, can be extended to include an alkoxide-ligated RO-Mn(III)-OOR complex. We show that the alkoxide-ligated RO-Mn(III)-OOR complex is an order of magnitude more stable ( = 6730 s, = 1.

Comparison of two MnMn-bis-μ-oxo complexes {[Mn(N(6-Me-DPEN))](μ-O)} and {[Mn(N(6-Me-DPPN))](μ-O)}.

The addition of -butyl hydro-peroxide ( BuOOH) to two structurally related Mn complexes containing -bis-(6-methyl-2-pyridyl-meth-yl)ethane-1,2-di-amine (6-Me-DPEN) and -bis-(6-methyl-2-pyridyl-meth-yl)propane-1,2-di-amine (6-Me-DPPN) results in the formation of high-valent bis-oxo complexes, namely di-μ-oxido-bis-{[,-bis-(6-methyl-2-pyridylmeth-yl)ethane-1,2-di-amine]-manganese(II)}(-) bis-(tetra-phenyl-borate) dihydrate, [Mn(CHN)O](CHB)·2HO or {[Mn(N(6-Me-DPEN))](-O)}(2BPh)(2HO) () and di-μ-oxido-bis-{[,-bis-(6-methyl-2-pyridylmeth-yl)propane-1,3-di-amine]-manganese(II)}(-) bis-(tetra-phenyl-borate) diethyl ether disolvate, [Mn(CHN)O](CHB)·2CHO or {[Mn(N(6-MeDPPN))](-O)}(2BPh)(2EtO) (). Complexes and both contain the 'diamond core' motif found previously in a number of iron, copper, and manganese high-valent bis-oxo compounds. The flexibility in the propyl linker in the ligand scaffold of , as compared to that of the ethyl linker in , results in more elongated Mn-N bonds, as one would expect.