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The tetradentate ligand N,N'-dibenzyl-N,N'-bis(2-pyridylmethyl)-1,2-cyclohexanediamine (bbpc) was used to prepare cobalt(II) diacetonitrilo and cobalt(III) peroxo complexes, the latter of which was structurally characterized. The cobalt(III) peroxo compound forms from reactions between the cobalt(II) complex, hydrogen peroxide, and a base, and it stoichiometrically reacts with aldehydes to yield mixtures of alkenes and ketones. The cobalt(II) precursor is capable of catalyzing the activation of weak C-H bonds by either iodosobenzene or m-chloroperbenzoic acid. This chemistry differs from most previously characterized cobalt-mediated C-H activation in that (1) it is catalytic, rather than stoichiometric, with respect to the cobalt and (2) it does not need a second Lewis acid metal ion in order to proceed.

The formation of a ferric hydroperoxide species from [Fe(bbpc)(MeCN)2](2+) (bbpc = N,N'-dibenzyl-N,N'-bis(2-pyridylmethyl)-1,2-cyclohexanediamine) and its subsequent decomposition were analyzed kinetically. The rate of decay is not strongly influenced by the presence of either water or substrate, suggesting that the ferric hydroperoxide degrades through O-O bond homolysis and is not the relevant metal-based oxidant in the observed catalysis of C-H activation. The rate law corresponding to the complex's formation from O2 is consistent with the intermediacy of a mononuclear ferric superoxo species.

The ligand N,N'-bis(2-pyridylmethyl)-bis(ethylacetate)-1,2-ethanediamine (debpn) coordinates divalent transition metal ions in either a pentadentate or hexadentate fashion. The coordination number correlates with the ionic radius of the metal ion, with larger cations being heptacoordinate as assessed by solid-state analysis. With Mn(II), the debpn ligand is hexadentate and remains bound to the oxophilic metal ion, even when dissolved in water. The ligand's incomplete coordination of the manganous ion allows water molecules to coordinate to the metal center. These two properties, coupled with the high paramagnetism associated with the S = 5/2 metal center, enable [Mn(debpn)(H(2)O)](ClO(4))(2) to serve as a stable and effective magnetic resonance imaging contrast agent despite the ligand's lack of both a macrocyclic component and an anionic charge.

Copper(I) sulfide (Cu(2)S) nanodisks with controllable size and aspect ratio have been synthesized by using a one-pot colloidal process, in which no pre-prepared organometallic precursors are required. The reaction involves the injection of dodecanethiol into a hot solution containing copper salt, surfactants, and a high boiling-point organic solvent. Copper thiolate forms at the beginning of the reaction which effectively acts as a precursor whose decomposition leads to further nucleation and growth of Cu(2)S nanocrystals. The nanocrystals begin as small nanodots in the early stages of the reaction, gradually turning into nanodisks with aspect ratios (average disk diameter divided by thickness) up to 2.0, while the band gap of the nanocrystals decreases accordingly. As the growth of nanocrystals follows the monomer addition mechanism, the diameter, thickness, aspect ratio, and optical property of the Cu(2)S nanodisks can be tuned systematically by changing the reaction time, the amount of surfactants, and the concentration of the precursors. This synthesis provides a simple and highly reproducible method for the preparation of Cu(2)S nanocrystals that may find potential applications in the fabrication of photovoltaic devices.

The compound N,N'-dineopentyl-N,N'-bis(2-pyridylmethyl)-1,2-ethanediamine (dnbpn) and its ferrous complex [Fe(dnbpn)(OTf)2] were synthesized. The Fe(II) complex was used to catalyze the oxidation of hydrocarbons by H2O2 and O2. Although the catalyzed alkane oxidation by H2O2 displays a higher preference for secondary over tertiary carbons than those associated with most previously reported nonheme iron catalysts, the catalytic activity is markedly inferior. In addition to directing the catalyzed oxidation toward the less sterically congested C-H bonds of the substrates, the neopentyl groups destabilize the metal-based oxidants generated from H2O2 and the Fe(II) complex. The presence of benzylic substrates with weak C-H bonds stabilizes an intermediate which we have tentatively assigned as a high-spin ferric hydroperoxide species. The oxidant generated from O2 reacts with allylic and benzylic C-H bonds in the absence of a sacrificial reductant; less substrate dehydrogenation is observed than with related previously described systems that use O2 as a terminal oxidant.