Synthesis of a copper-supported triplet nitrene complex pertinent to copper-catalyzed amination

Abstract

Terminal copper-nitrenoid complexes have inspired interest in their fundamental bonding structures as well as their putative intermediacy in catalytic nitrene-transfer reactions. Here, we report that aryl azides react with a copper(I) dinitrogen complex bearing a sterically encumbered dipyrrin ligand to produce terminal copper nitrene complexes with near-linear, short copper–nitrenoid bonds [1.745(2) to 1.759(2) angstroms]. X-ray absorption spectroscopy and quantum chemistry calculations reveal a predominantly triplet nitrene adduct bound to copper(I), as opposed to copper(II) or copper(III) assignments, indicating the absence of a copper−nitrogen multiple-bond character. Employing electron-deficient aryl azides renders the copper nitrene species competent for alkane amination and alkene aziridination, lending further credence to the intermediacy of this species in proposed nitrene-transfer mechanisms.

Synthesis, characterization and C–H amination reactivity of nickel iminyl complexes

“…40,47 Two low-lying pre-edge absorptions are present for both 3 and 4 at 395.4 eV, accompanied by a smaller side-band at 396.3 eV. These peak energies are consistent with those encountered for the redoxactive N-donor ligands in Fe-iminyl (394.5 and 394.8 eV), 40 Niaminyl (397.0 eV), 47 and Cu-nitrene 48 (doublet with peaks at 395.3 and 395.9 eV) complexes. This tentative assignment of these transitions as N 1s into partially occupied, N-localized orbitals present in 3 and 4, respectively is further supported by time-dependent density functional theory (TDDFT) calculations (vide infra).…”

C−H Bond Activation by an Imido Cobalt(III) and the Resulting Amido Cobalt(II) Complex

“…[4] This is reminiscent of observations in metal-oxido chemistry, where terminal late transition metal oxido complexes are inherently labile for the same reasons. Therefore, isolable imido complexes of copper, [5] nickel, [6] and cobalt [3,[7][8][9][10][11][12][13][14][15][16][17][18][19] are scarce and knowledge on the structure, electronic situation and their reactivity is limited.…”

Pyrrole Functionalization by Copper‐Catalyzed Nitrene Transfer Reactions

“…In spite of the continuous development in this area, we noticed that literature reports of the use of pyrroles as substrates for the incorporation of nitrenes in a catalytic manner are scarce. [4] This is despite the existence of several potential reaction sites in this molecule capable of interacting with the electrophilic metalÀ nitrene intermediate [5] responsible for the transfer step (Scheme 2). Thus, pyrrole displays two olefinic sites, which may add the nitrene leading to aziridine rings, as well as C sp2 À H and NÀ H bonds also susceptible of being modified.…”