A Transient Iron Carbide Generated by Cyaphide Cleavage.

Despite their potential relevance as molecular models for industrial and biological catalysis, well-defined mononuclear iron carbide complexes are unknown, in part due to the limited number of appropriate C synthons. Here, we show the ability of the cyaphide anion (C≡P) to serve as a C source. The high spin ( = 2) cyaphide complex PhB(BuIm)Fe-C≡P (PhB(BuIm) = phenyl(tris(3--butylimidazol-2-ylidene)borate) is readily accessed using the new cyaphide transfer reagent [Mg(NacNac)(CP)] (NacNac = CH{C(CH)N(Dipp)} and Dipp = 2,6-di(iso-propyl)phenyl).

Hydrogen atom abstraction by a high spin [Fe=S] complex.

Iron sulfur clusters are critical to a plethora of biological processes; however, little is known about the elementary unit of these clusters, namely the [Fe=S] fragment. Here, we report the synthesis and characterization of a terminal iron sulfido complex. Despite its high spin ( = 5/2) ground state, structural, spectroscopic, and computational characterization provide evidence for iron sulfur multiple bond character.

Simple magnesium alkoxides: synthesis, molecular structure, and catalytic behaviour in the ring-opening polymerization of lactide and macrolactones and in the copolymerization of maleic anhydride and propylene oxide.

The synthesis of two chiral bulky alkoxide pro-ligands, 1-adamantyl--butylphenylmethanol HOCAdBuPh and 1-adamantylmethylphenylmethanol HOCAdMePh, is reported and their coordination chemistry with magnesium(II) is described and compared with the coordination chemistry of the previously reported achiral bulky alkoxide pro-ligand HOCBuPh. Treatment of -butyl--butylmagnesium with two equivalents of the racemic mixture of HOCAdBuPh led selectively to the formation of the mononuclear bis(alkoxide) complex Mg(OCAdBuPh)(THF). H NMR spectroscopy and X-ray crystallography suggested the selective formation of the -symmetric homochiral diastereomer Mg(OCAdBuPh)(THF)/Mg(OCAdBuPh)(THF).

Synthesis, electronic structures, and reactivity of mononuclear and dinuclear low-valent molybdenum complexes in iminopyridine and bis(imino)pyridine ligand environments.

Molybdenum in redox non-innocent ligand environments features prominently in biological inorganic systems. While Holm and coworkers, along with many other researchers, have thoroughly investigated formally high-oxidation-state molybdenum (Mo(IV)-Mo(VI)) ligated by dithiolenes, less is known about molybdenum in other formal oxidation states and/or different redox-active ligand environments. This work focuses on the investigation of low-valent molybdenum in four different redox non-innocent nitrogen ligand type environments (mononucleating and dinucleating iminopyridine, mononucleating and dinucleating bis(imino)pyridine).

Synthesis, characterization, and alkoxide transfer reactivity of dimeric Tl(OR) complexes.

Reaction of LiOCBuPh with TlPF forms the dimeric Tl(OCBuPh) complex, a rare example of a homoleptic thallium alkoxide complex demonstrating formally two-coordinate metal centers. Characterization of Tl(OCBuPh) by H and C NMR spectroscopy and X-ray crystallography reveals the presence of two isomers differing by the mutual conformation of the alkoxide ligands, and by the planarity of the central Tl-O-Tl-O plane. Tl(OCBuPh) serves as a convenient precursor to the formation of old and new [M(OCBuPh)] complexes (M = Cr, Fe, Cu, Zn), including a rare example of T-shaped Zn(OCBuPh)(THF) complex, which could not be previously synthesized using more conventional LiOR/HOR precursors.

Synthesis of a mononuclear magnesium bis(alkoxide) complex and its reactivity in the ring-opening copolymerization of cyclic anhydrides with epoxides.

Synthesis of a new mononuclear magnesium complex with a bulky bis(alkoxide) ligand environment and its reactivity in ring-opening polymerization (ROP) and ring-opening copolymerization (ROCOP) are reported. Reaction of n-butyl-sec-butylmagnesium with two equivalents of HOR (HOR = di-tert-butylphenylmethanol, HOCtBu2Ph) formed Mg(OR)2(THF)2. The reaction proceeded via the Mg(OR)(sec-Bu)(THF)2 intermediate that was independently synthesized by treating n-butyl-sec-butylmagnesium with one equivalent of HOR.

Tying the alkoxides together: an iron complex of a new chelating bulky bis(alkoxide) demonstrates selectivity for coupling of non-bulky aryl nitrenes.

New chelating bis(alkoxide) ligand H[OO] and its iron(ii) complex Fe[OO](THF) are described. The coordination of the ligand to the metal center is reminiscent of the coordination of two monodentate alkoxides in previously reported Fe(OR)(THF) species. Fe[OO](THF) catalyzes selective and efficient dimerization of non-bulky aryl nitrenes to yield the corresponding azoarenes.

Catalytic Nitrene Homocoupling by an Iron(II) Bis(alkoxide) Complex: Bulking Up the Alkoxide Enables a Wider Range of Substrates and Provides Insight into the Reaction Mechanism.

The reaction of HOR' (OR' = di-t-butyl-(3,5-diphenylphenyl)methoxide) with an iron(II) amide precursor forms the iron(II) bis(alkoxide) complex Fe(OR')(THF) (2). 2 (5-10 mol %) serves as a catalyst for the conversion of aryl azides into the corresponding azoarenes. The highest yields are observed for aryl azides featuring two ortho substituents; other substitution patterns in the aryl azide precursor lead to moderate or low yields.