A platinum(ii) metallonitrene with a triplet ground state

Abstract

ational synthetic method development is driven by the ability to relate reactivity to the electronic structures of key transient intermediates. For example, organic nitrenes (R-N) are generally highly reactive monovalent nitrogen species and detailed spectroscopic studies have enabled the assignment of their diverse reaction pathways, such as C-H insertion or N-N coupling, to the accessibility of triplet versus (open shell) singlet spin states 1,2 . In comparison, the well-established class of nitrido complexes (L n MN) commonly features trivalent nitrogen with significant covalent components of M-N σand π-bonding (Fig. 1a) 3 . Increased radical and electrophilic nitrogen character can be formally represented by divalent nitridyl all the way to monovalent metallonitrene contributions 4 . Formal nitrido complexes with predominant subvalent metallonitrene (L n M-N) character, which can be regarded as metal analogues of organic nitrenes, have been proposed as key intermediates in stoichiometric intramolecular [5][6][7][8][9] and intermolecular 10-15 nitrogen atom transfer reactions. However, in contrast to organic nitrenes 16 , authentic metallonitrenes with a monovalent atomic nitrogen ligand remain elusive, which impedes the development of new nitrogen transfer reactions based on electronic structure/reactivity relationships.The emergence of C-H amination and amidation via nitrene transfer as a powerful synthetic tool was fuelled by the development of group 9-11 transition metal catalysts that facilitate selective insertion of coordinated nitrene fragments (Fig. 1b) [17][18][19] . Late transition metals are also instrumental as anode materials in electrocatalytic amine oxidation for synthetic and fuel cell applications [20][21][22] . The dominance of late transition metals in redox transformations of nitrogenous species stimulated fundamental interest in M-N(R) bonding 3 . C-H insertion by L n M-NR species has been associated with electrophilic subvalent nitrene ( 3 NR) 23 or imidyl ( 2 NR − ) [24][25][26] character that arises from low lying d orbitals of late transition met-als. This strongly reduces the imido ( 1 NR 2− ) contribution 27,28 . Similar considerations might apply for metallonitrene (L n M-N) or nitridyl (L n M=N • ) versus nitrido (L n M≡N) species (Fig. 1a). However, intermolecular C-H activation has not been reported for the few known late transition metal nitrido or nitridyl complexes [29][30][31] . The exploitation of nitrogen atom insertion reactivity (Fig. 1b) is still in its infancy; as of yet, catalytic protocols are not known and systematic advances suffer from the lack of well-defined metallonitrene platforms.In this contribution, a formal nitrido complex beyond group 9 is reported. Crystallographic, spectroscopic, magnetic and computational characterization shows a triplet electronic ground state with a predominantly single-bonded metallonitrene (L n Pt ii -N) and nitrogen-centred diradical character. Facile N-atom insertion into C-H, B-H and B-C bonds is demonstrated. In contrast to the...

Terminal Imido Complexes of the Groups 9–11: Electronic Structure and Developments in the Last Decade

“…Yet, even stronger ligand‐centered character of the two anti ‐bonding molecular orbitals of π ‐symmetry (ligand : metal=6 : 4) is found for the latter, thus giving rise to a “genuine” triplet‐nitrene ligand [37] Platina Triplet‐Nitrene: Schneider's platinum nitride complex 9 is a bona fide platina triplet‐nitrene (Figure 7, right) [38] . Both π*‐orbitals are singly occupied and clearly ligand centered (ligand : metal=8 : 2), whereas the σ‐interaction is considerably covalent.…”

Synthesis, structure, and reactivity of uranium(vi) nitrides

“…Metal nitride complexes continue to attract significant attention because of their key roles in the catalytic N 2 hydrogenation for ammonia production and in N-transfer processes. 1 Uranium nitride compounds provide molecular analogues of inorganic uranium nitride materials (UN, UN 2 , U 2 N 3 ) which are effective catalysts in the Haber–Bosch synthesis of ammonia 2 and are considered as potential fuel for nuclear and space-power reactors. 3 Two examples of molecular uranium nitrides, both showing a diamond shaped arrangement of the two nitrides, were obtained from the cleavage of dinitrogen in ambient conditions.…”

“…The previous reports of hydrogenolysis by a terminal U( v ) nitride, 11 e U( iv ) nitride bridged complexes, 9 b ,12 and a U( v ) bis-nitride 10 a are particularly remarkable considering the paucity of examples of direct hydrogenolysis by metal nitride complexes reported in the literature. 1 a ,13 a – f …”

Copper‐Nitrene‐Catalyzed Desymmetric Oxaziridination/1,2‐Alkyl Rearrangement of 1,3‐Diketones toward Bicyclic Lactams

“…Subsequently, Int-D was generated by asymmetric oxaziridination, resulting in the origin of the enantiocontrol in this procedure. Then, the three-membered ring was opened via a N À O bond cleavage accompanied by an alkyl C-N 1,2shift[17] to generate Int-E, which produced the final product lactam 2 a and simultaneously released the catalyst Int-A for the next catalytic cycle (Scheme 3).In conclusion, we have developed a novel copper(I)catalyzed asymmetric intramolecular tandem oxaziridination/ rearrangement reaction. This reaction facilitated the production of various chiral bicyclic lactams with moderate to high enantioselectivities under the mild reaction conditions.…”

“…Subsequently, Int-D was generated by asymmetric oxaziridination, resulting in the origin of the enantiocontrol in this procedure. Then, the three-membered ring was opened via a N À O bond cleavage accompanied by an alkyl C-N 1,2shift [17] to generate Int-E, which produced the final product lactam 2 a and simultaneously released the catalyst Int-A for the next catalytic cycle (Scheme 3).…”