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Copper-mediated aromatic and aliphatic C-H hydroxylations using benign oxidants (O 2 and H 2 O 2 ) have been studied intensively in recent years to meet the growing demand for efficient and green C-H functionalizations. Herein, we report an enantioselective variant of the so-called clip-and-cleave concept for intramolecular ligand hydroxylations by the application of chiral diamines as directing groups. We tested the hydroxylation of cyclohexanone and 1-acetyladamantane under different oxidative conditions (Cu I /O 2 ; Cu I /H 2 O 2 ; Cu II /H 2 O 2 ) in various solvents. As an outstanding example, we obtained ( R )-1-acetyl-2-adamantol with a yield of 37% and >99:1 enantiomeric excess from hydroxylation in acetone using Cu I and O 2 . Low-temperature stopped-flow UV-vis measurements in combination with density functional theory (DFT) computations revealed that the hydroxylation proceeds via a bis(μ-oxido) dicopper intermediate. The reaction product represents a rare example of an enantiopure 1,2-difunctionalized adamantane derivative, which paves the way for potential pharmacological studies. Furthermore, we found that 1-acetyladamantane can be hydroxylated in a one-pot reaction under air with isolated yields up to 36% and enantiomeric ratios of 96:4 using Cu II /H 2 O 2 in MeOH.

A comprehensive mechanistic study of N 2 activation and splitting into terminal nitride ligands upon reduction of the rhenium dichloride complex [ReCl 2 (PNP)] is presented (PNP - = N(CH 2 CH 2 P tBu 2 ) 2 - ). Low-temperature studies using chemical reductants enabled full characterization of the N 2 -bridged intermediate [{(PNP)ClRe} 2 (N 2 )] and kinetic analysis of the N-N bond scission process. Controlled potential electrolysis at room temperature also resulted in formation of the nitride product [Re(N)Cl(PNP)]. This first example of molecular electrochemical N 2 splitting into nitride complexes enabled the use of cyclic voltammetry (CV) methods to establish the mechanism of reductive N 2 activation to form the N 2 -bridged intermediate. CV data was acquired under Ar and N 2 pressure. A series of kinetic models was vetted against the CV data using digital simulations, leading to the assignment of an ECCEC mechanism (where "E" is an electrochemical step and "C" is a chemical step) for N 2 pressure. A series of kinetic models was vetted against the CV data using digital simulations, leading to the assignment of an ECCEC mechanism (where "E" is an electrochemical step and "C" is a chemical step) for N 2 activation that proceeds via initial reduction to Re II , N 2 binding, chloride dissociation, and further reduction to Re I before formation of the N 2 -bridged, dinuclear intermediate by comproportionation with the Re III precursor. Experimental kinetic data for all individual steps could be obtained. The mechanism is supported by density functional theory computations, which provide further insight into the electronic structure requirements for N 2 splitting in the tetragonal frameworks enforced by rigid pincer ligands.

Formic acid (FA) is an attractive compound for H2 storage. Currently, the most active catalysts for FA dehydrogenation use precious metals. Here, we report a homogeneous iron catalyst that, when used with a Lewis acid (LA) co-catalyst, gives approximately 1,000,000 turnovers for FA dehydrogenation. To date, this is the highest turnover number reported for a first-row transition metal catalyst. Preliminary studies suggest that the LA assists in the decarboxylation of a key iron formate intermediate and can also be used to enhance the reverse process of CO2 hydrogenation.

[ReCl3(PPh3)2(NCMe)] reacts with pincer ligand HN(CH2CH2PtBu2)2 (HPNP) to five coordinate rhenium(III) complex [ReCl2(PNP)]. This compound cleaves N2 upon reduction to give rhenium(V) nitride [Re(N)Cl(PNP)], as the first example in the coordination sphere of Re. Functionalization of the nitride ligand derived from N2 is demonstrated by selective C-N bond formation with MeOTf.

Dinuclear copper peroxo complexes obtained from mononuclear copper(I) complexes showed extremely high stabilities under ambient conditions in the solid state and could be heated above 100 degrees C without decomposition. The increased stability could be explained with regard to their molecular structures. Furthermore, the four complexes investigated showed a high potential for aliphatic C-H bond oxidations: for example, technical-grade toluene was oxidized to benzaldehyde in yields of up to 20%.