Back-bonding between an electron-poor, high-oxidation-state metal and poor π-acceptor ligand in a uranium(v)–dinitrogen complex

Abstract

Back-bonding between an electron-poor, high-oxidationstate metal and poor -acceptor ligand in a uranium(V)-dinitrogen complex . Back-bonding between an electron-poor, high-oxidation-state metal and poor -acceptor ligand in a uranium(V)-dinitrogen complex. Nature Chemistry,11,[806][807][808][809][810][811] Back-bonding between an electron-poor, high-oxidation-state metal and poor π-acceptor ligand in a uranium(V)-dinitrogen complex Abstract A fundamental bonding model in coordination and organometallic chemistry is the synergic, donor-acceptor interaction between a metal and a neutral π-acceptor ligand where the ligand σdonates to the metal, which π-back-bonds to the ligand. This interaction typically involves a metal with an electron-rich, mid-, low-, or even negative, oxidation state and a ligand with a π* orbital.Here, we report that treatment of a uranium-carbene complex with an organo-azide produces a uranium(V)-bis(imido)-dinitrogen complex, stabilised by a lithium counter-ion. This complex, which has been isolated in crystalline form, involves an electron-poor, high-oxidation-state uranium(V) 5f 1 ion that is π-back-bonded to the poor π-acceptor ligand dinitrogen. We propose that this is made possible by a combination of cooperative heterobimetallic uranium-lithium effects and the presence of suitable ancillary ligands rendering the uranium ion unusually electron-rich. This electron-poor back-bonding could have implications for the field of dinitrogen activation.

Stepwise Reduction of Dinitrogen by a Uranium–Potassium Complex Yielding a U(VI)/U(IV) Tetranitride Cluster

“…Although uranium-based inorganic materials were shown to be active catalysts of the Haber–Bosch process for the N 2 conversion to ammonia, an iron-based catalyst was adopted for industrial production of ammonia. As a result, the dinitrogen chemistry of molecular uranium compounds is significantly less developed than d-block metals and mostly involves labile N 2 binding or two-electron N 2 reduction, with only three examples of four-electron N 2 reduction reported recently (complexes A – C in Figure ). …”

A mechanistic investigation of the Pd-catalyzed cross-coupling betweenN-tosylhydrazones and aryl halides

“…Nitrogen, like ethylene, also has a molecular weight of 28 Da, and is present in abundance during the ESI-MS experiment thanks to its use as a desolvation gas, and was a possible explanation for this ion. While many dinitrogen complexes have been reported for metal centers in Groups 3-9, some simple, [267][268][269][270][271] some with carefully constructed coordination environments, [272][273][274][275][276][277][278][279][280] and others evolved for nitrogen fixation, [281][282][283][284][285] such complexes are less common in Groups 10 and 11. Isolated dinitrogen complexes involving platinum are unknown.…”

Facile Dinitrogen and Dioxygen Cleavage by a Uranium(III) Complex: Cooperativity Between the Non‐Innocent Ligand and the Uranium Center

“…[31][32][33][34][35] In addition, molecular uranium systems also exhibit attractive ability for N 2 binding,r eduction, and activation. [36][37][38][39][40][41][42][43][44][45][46] Fori nstance,M azzanti and coworkers reported that the multimetallic diuranium(III) complex [K n {[U(OSi(O t Bu) 3 ) 3 ] 2 (m-E) (E = N, O) is capable of activating N 2 to N 2 4À via af our-electron reduction process. [43,44] Arnold and co-workers found that the four-electron reduction of N 2 was also achieved by the thorium or uranium dinuclear metallacycles,M 2 (mTP) 2 (mTP = [{2-(OC 6 H 2 -t Bu-2,Me-4) 2 CH}-C 6 H 4 -1,3] 4À ;M = U, Th)i nt he presence of as trong reductant (KC 8 ).…”