Conversion of a Fleeting Open-Shell Iron Nitride into an Iron Nitrosyl.

Terminal metal nitrides have been proposed as key intermediates in a series of pivotal chemical transformations. However, exploring the chemical activity of transient tetragonal iron(V) nitrides is largely impeded by their facile dimerization in fluid solutions. Herein, in situ EPR and Mössbauer investigations are presented of unprecedented oxygenation of a paramagnetic iron(V) nitrido intermediate, [Fe N(cyclam-ac)] (2, cyclam-ac =1,4,8,11-tetraazacyclotetradecane-1-acetate anion), yielding an iron nitrosyl complex, [Fe(NO)(cyclam-ac)] (3).

Ambient Stable Cyanomethylcopper(III) Complex: a Strong Cu-C Bond Supported by a PS3-Tripodal Chelator.

An organocuprate(III) complex, [Cu(PS3)(CHCN)] (2), was identified along with a sequential derivative, [Cu(PS3)(CN)] (3), and an intermediate, [Cu(PS3)(HN═PPh)] (4), formed in a relative transformation. Apical ligands among these complexes all strongly associate with a robust trigonal copper(III) platform. The nature of the ligand binding was spectroscopically and computationally investigated through a series of copper(III) complexes.

Electron Paramagnetic Resonance Signature of Tetragonal Low Spin Iron(V)-Nitrido and -Oxo Complexes Derived from the Electronic Structure Analysis of Heme and Non-Heme Archetypes.

Iron(V)-nitrido and -oxo complexes have been proposed as key intermediates in a diverse array of chemical transformations. Herein we present a detailed electronic-structure analysis of [Fe(N)(TPP)] (1, TPP = tetraphenylporphyrinato), and [Fe(N)(cyclam-ac)] (2, cyclam-ac = 1,4,8,11-tetraazacyclotetradecane-1-acetato) using electron paramagnetic resonance (EPR) and Fe Mössbauer spectroscopy coupled with wave function based complete active-space self-consistent field (CASSCF) calculations. The findings were compared with all other well-characterized genuine iron(V)-nitrido and -oxo complexes, [Fe(N)(MePytacn)](PF) (3, MePytacn = methyl- N', N″-bis(2-picolyl)-1,4,7-triazacyclononane), [Fe(N){PhB( t-BuIm)}] (4, PhB(BuIm) = phenyltris(3- tert-butylimidazol-2-ylidene)borate), and [Fe(O)(TAML)] (5, TAML = tetraamido macrocyclic ligand).

Nickel(iii)-mediated oxidative cascades from a thiol-bearing nickel(ii) precursor to the nickel(iv) product.

A nickel(ii) complex, Ni(HPS2) (1) that contains two pendant thiols, is rapidly aerobically oxidized in the presence of an amine to produce a diamagnetic nickel(iv) complex, Ni(PS2) (2). This process was investigated spectroscopically at a temperature of -80 °C. Absorption spectra revealed that the deprotonation of one pendant thiol of 1 triggers an oxidative cascade; EPR findings indicate that single-spin species comprised of nickel(iii) intermediates are produced in the reaction solution.

A Structurally Characterized Nonheme Cobalt-Hydroperoxo Complex Derived from Its Superoxo Intermediate via Hydrogen Atom Abstraction.

Bubbling O into a THF solution of Co(BDPP) (1) at -90 °C generates an O adduct, Co(BDPP)(O) (3). The resonance Raman and EPR investigations reveal that 3 contains a low spin cobalt(III) ion bound to a superoxo ligand. Significantly, at -90 °C, 3 can react with 2,2,6,6-tetramethyl-1-hydroxypiperidine (TEMPOH) to form a structurally characterized cobalt(III)-hydroperoxo complex, Co(BDPP)(OOH) (4) and TEMPO.

Synthesis of Quaternary-Carbon-Containing β -Amino Acids by the Rh -Catalyzed Enantioselective Arylation of α-Substituted β-Nitroacrylates.

An enantioselective Rh -catalyzed conjugate addition reaction of α-substituted β-nitroacrylates with various arylboronic acids by using chiral Rh diene catalysts is described for the first time. The addition reaction proceeds under mild conditions in a range of common organic solvents and additives, and it affords the corresponding quaternary-carbon-containing α,α-disubstituted β-nitropropionate products in up to 63 % yield and 99 % ee. Reaction of either (E)- or (Z)-β-nitroacrylates provided the same enantiomer of the product, and a range of esters and aryl groups were tolerated.

Thioiminium and thiaphospholanium derived from acetonitrile via nickel(II)-(2-mercaptophenyl)phosphine complexation.

[Ni(P(o-C6H4S)(o-C6H4SC(CH3)=NH2)(C6H5))2](ClO4)2 (2) with two thioiminium functionalities is derived from CH3CN solvent under anhydrous conditions. Moreover, thiaphospholanium salts, [(C6H5)P(C6H4SC(CH3)(NHCOCH3))(o-C6H4SH)](ClO4) (3) and [(C6H5)2-P(C6H4SC(CH3)(NH3))](ClO4)2 (5), can be obtained through a similar Pinner-type nitrile activation. These results demonstrate the possible intermediate of enzymatic nitrile transformation and also provide an approach to the preparation of 2-amino-1,3-benzothiaphospholanium derivatives.

Synthesis, structures and electrochemical and photophysical properties of anilido-benzoxazole boron difluoride (ABB) complexes.

A new series of four-ring-fused π-conjugated anilido-benzoxazole boron difluoride (ABB) dyes were synthesized by employing an unsymmetrical bidentate ligand under a mild reaction condition. X-ray structural analysis demonstrated that the four-ring-fused π-conjugated skeleton is nearly coplanar, and almost orthogonal to the side anilido phenyl group with dihedral angles of 74-86°. The synthesized complexes exhibit very bright luminescence in solution (Φf = 0.