The synthesis and structure of the beta-diketiminato Ni(I) lutidine adducts [MexNN]Ni(2,4-lutidine) (x = 2 (2); x = 3 (3)) are described which serve as synthons to the "naked" 13-electron [MexNN]Ni fragments in reactions with N3Ad to give Ni-imido complexes. The singly bridged imide {[Me2NN]Ni}2(mu-NAd) (4) possesses short Ni-Ni (2.506(1) A) and Ni-N(imido) distances (1.732(4)-1.752(4) A). Steric modification of the beta-diketiminate ligand to include an additional methyl group in the N-aryl 4-position affords the Ni(III) terminal imide [Me3NN]Ni=NAd (8) isolated in 52% yield. The X-ray structure of terminal imide 8 reveals a contracted Ni-N(imido) bond distance (1.662(2) A) and an only somewhat bent imido linkage (Ni-N-C = 164.5(2) degrees ) consistent with a significant degree of multiple bond character. Frozen glass EPR studies of 5 indicate a rhombic environment in which one of the signals exhibits strong hyperfine coupling (A = 22 G) to the imido 14N (I = 1) nucleus. The terminal imide 5 undergoes complete imido group transfer to CO and CNBut to give AdNCO and AdNCNBut, respectively, as well as with PMe3 to afford AdN=PMe3. Exemplifying the radical character at the imido N atom, 5 adds to cobaltocene and abstracts a H atom from 1,4-cyclohexadiene to give the Ni(II)-amides [Me3NN]Ni-NAd(eta4-C5H5)CoCp (7) and [Me3NN]Ni-NHAd (8).

The synthesis and structure of a novel beta-diketiminato Co(I) arene adduct [Me2NN]Co(eta6-toluene) (2) are described, that serves as a synthon to the reactive, "naked" 12-electron [Me2NN]Co fragment via loss of toluene in its reactions with dioxygen, organoazides, and a nitrosobenzene. Exposure of 2 to dioxygen in ether leads to {[Me2NN]Co}2(mu-O)2 (3), a rare example of a cobalt-oxo complex thermally stable at room temperature. The X-ray structure of 3 reveals a short Co-Co separation of 2.716(4) A and exhibits positional disorder for the bridging oxo groups; the predominant configuration contains oxygen atoms in square-planar sites with short Co-O distances (1.784(3) and 1.793(4) A). Reaction of 2 with organoazides N3R (R = 3,5-Me2C6H3 (Ar) or 1-adamantyl (Ad)) results in the formation of imido complexes whose structure depends on the nature of the azido substituent. The synthesis and structures of both {Me2NN]Co}2(mu-NAr)2 (4) with arylimido groups in tetrahedral bridging sites or the three-coordinate, 16-electron [Me2NN]CoNAd (5) are described. The X-ray structure of terminal imide 5 reveals a short Co-N bond distance (1.624(4) A) and only somewhat bent imido linkage (Co-N-C = 161.5(3) degrees ) consistent with a significant degree of multiple bond character. Complex 2 cleaves the O=N bond of the nitrosobenzene O=NAr (Ar = 3,5-Me2C6H3) to form the binuclear oxo-imido complex {[Me2NN]Co}2(mu-O)(mu-NAr) (6) that possesses a structure intermediate between square-planar 3 and tetrahedral 4 in which the [Me2NN]Co fragments are mutually orthogonal.

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Covalent metal–ligand interactions can lead to Cu K pre-edge transitions that result from metal-to-ligand charge transfer, instead of 1s → 3d, character.

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Among the transition metals, copper-based catalyst systems enable the widest range of N-containing reagents in C−H amination to allow for the direct incorporation of versatile N-based functionalities via ubiquitous C−H bonds. In addition to nitrene-based approaches involving sulfonyliminoiodinanes (PhINSO 2 R), diverse non-nitrene protocols have been developed that allow for the direct use of organic amides, nitrosoarenes, and hydroxylamines, strained heterocycles such as oxaziridines, acetonitrile, secondary sulfonylamines, and even alkylamines and arylamines. Synthetic, mechanistic, and theoretical studies reveal discrete copper nitrenes [Cu]NR and copper amides [Cu]−NHR to be key reactive intermediates in C−H amination. Copper-catalyzed sp 3 C−H amination is reviewed, connecting catalytic reactivity patterns with likely copper intermediates wherever possible, with the goal to stimulate the further development of C−H functionalization reactions with copper which possess significant sustainability advantages over other contemporary approaches involving noble metals.

The synthesis and structure of two thermally stable neutral beta-diketiminato copper(I) olefin complexes are presented along with the structure of a Cu(II)2(mu-OH)2 dimer that results from the reaction of the Cu(I) ethylene complex with O2 via the proposed intermediacy of a Cu(III)2(mu-O)2 species.

En route to catalysis: Two equivalents of the three‐coordinate copper(II) amide [(Cl2NN)Cu]‐NHAd participate in stoichiometric CH amination by a H‐atom abstraction/radical capture sequence. This active species may be generated through a copper(II) tert‐butoxide intermediate to allow for the unprecedented catalytic amination of sp3‐CH bonds with unactivated alkylamines. This method greatly expands the range of amines for catalytic CH amination since most protocols require N‐based electron‐withdrawing groups.