C=C Dissociative Imination of Styrenes by a Photogenerated Metallonitrene.

Photolysis of a platinum(II) azide complex in the presence of styrenes enables C=C double bond cleavage upon dissociative olefin imination to aldimido (Pt-N=CHPh) and formimido (Pt-N=CH) complexes as the main products. Spectroscopic and quantum chemical examinations support a mechanism that commences with the decay of the metallonitrene photoproduct (Pt-N) via bimolecular coupling and nitrogen loss as N. The resulting platinum(I) complex initiates a radical chain mechanism via a dinuclear radical-bridged species (Pt-CHCHPhN-Pt) as a direct precursor to C-C scission.

Triplet carbenes with transition-metal substituents.

The extraordinary advances in carbene (R-C-R) chemistry have been fuelled by strategies to stabilize the electronic singlet state via π interactions. In contrast, the lack of similarly efficient approaches to obtain authentic triplet carbenes with appreciable lifetimes beyond cryogenic temperatures hampers their exploitation in synthesis and catalysis. Transition-metal substitution represents a potential strategy, but metallocarbenes (M-C-R) usually represent high-lying excited electronic configurations of the well-established carbyne complexes (M≡C-R).

C-H Bond Activation by Iridium(III) and Iridium(IV) Oxo Complexes.

Oxidation of an iridium(III) oxo precursor enabled the structural, spectroscopic, and quantum-chemical characterization of the first well-defined iridium(IV) oxo complex. Side-by-side examination of the proton-coupled electron transfer thermochemistry revealed similar driving forces for the isostructural oxo complexes in two redox states due to compensating contributions from H and e transfer. However, C-H activation of dihydroanthracene revealed significant hydrogen tunneling for the distinctly more basic iridium(III) oxo complex.

Nitrogen Atom Transfer Catalysis by Metallonitrene C-H Insertion: Photocatalytic Amidation of Aldehydes.

C-H amination and amidation by catalytic nitrene transfer are well-established and typically proceed via electrophilic attack of nitrenoid intermediates. In contrast, the insertion of (formal) terminal nitride ligands into C-H bonds is much less developed and catalytic nitrogen atom transfer remains unknown. We here report the synthesis of a formal terminal nitride complex of palladium.

Coligand role in the NHC nickel catalyzed C-F bond activation: investigations on the insertion of bis(NHC) nickel into the C-F bond of hexafluorobenzene.

The reaction of [Ni(MesIm)] () (MesIm = 1,3-dimesityl-imidazolin-2-ylidene) with polyfluorinated arenes as well as mechanistic investigations concerning the insertion of and [Ni(PrIm)] () (PrIm = 1,3-diisopropyl-imidazolin-2-ylidene) into the C-F bond of CF is reported. The reaction of with different fluoroaromatics leads to formation of the nickel fluoroaryl fluoride complexes -[Ni(MesIm)(F)(Ar)] (Ar = 4-CF-CF , CF , 2,3,5,6-CFN , 2,3,5,6-CFH , 2,3,5-CFH , 3,5-CFH ) in fair to good yields with the exception of the formation of the pentafluorophenyl complex (less than 20%). Radical species and other diamagnetic side products were detected for the reaction of with CF, in line with a radical pathway for the C-F bond activation step using .

A platinum(II) metallonitrene with a triplet ground state.

Metallonitrenes (M-N) are complexes with a subvalent atomic nitrogen ligand that have been proposed as key reactive intermediates in nitrogen atom transfer reactions. However, in contrast to the common classes of nitride complexes (M≡N) and organic nitrenes (R-N), structurally and spectroscopically well defined 'authentic' metallonitrenes with a monovalent atomic nitrogen ligand remain elusive. Here we report that the photolysis of a platinum(II) pincer azide complex enabled the crystallographic, spectroscopic, magnetic and computational characterization of a metallonitrene that is best described as a singly bonded atomic nitrogen diradical ligand bound to platinum(II).