Aryl C–H Amination by Diruthenium Nitrides in the Solid State and in Solution at Room Temperature: Experimental and Computational Study of the Reaction Mechanism

Abstract

Diruthenium azido complexes Ru(2)(DPhF)(4)N(3) (1a, DPhF = N,N'-diphenylformamidinate) and Ru(2)(D(3,5-Cl(2))PhF)(4)N(3) (1b, D(3,5-Cl(2))PhF = N,N'-bis(3,5-dichlorophenyl)formamidinate) have been investigated by thermolytic and photolytic experiments to investigate the chemical reactivity of the corresponding diruthenium nitride species. Thermolysis of 1b at ~100 °C leads to the expulsion of N(2) and isolation of Ru(2)(D(3,5-Cl(2))PhF)(3)NH(C(13)H(6)N(2)Cl(4)) (3b), in which a nitrogen atom has been inserted into one of the proximal aryl C-H bonds of a D(3,5-Cl(2))PhF ligand. A similar C-H insertion product is obtained upon thawing a frozen CH(2)Cl(2) solution of the nitride complex Ru(2)(DPhF)(4)N (2a), formed via photolysis at -196 °C of 1a to yield Ru(2)(DPhF)(3)NH(C(13)H(10)N(2)) (3a). Evidence is provided here that both reactions proceed via direct intramolecular attack of an electrophilic terminal nitrido nitrogen atom on a proximal aryl ring. Thermodynamic and kinetic data for this reaction are obtained from differential scanning calorimetric measurements and thermal gravimetric analysis of the thermolysis of Ru(2)(D(3,5-Cl(2))PhF)(4)N(3), and by Arrhenius/Eyring analysis of the conversion of Ru(2)(DPhF)(4)N to its C-H insertion product, respectively. These data are used to develop a detailed, experimentally validated DFT reaction pathway for N(2) extrusion and C-H functionalization from Ru(2)(D(3,5-Cl(2))PhF)(4)N(3). The diruthenium nitrido complex is an intermediate in the calculated reaction pathway, and the C-H functionalization event shares a close resemblance to a classical electrophilic aromatic substitution mechanism.

Synthesis, characterization and thermal properties of trimetallic N3–CrCr⋯M–N3 azide complexes with M = Cr, Mn, Fe, and Co

“…14 Notably, this thallium metathesis reaction was found to proceed only in the case of M = Cr and M = Co; reactions of the Mn or Fe complexes with TlPF 6 did not produce the desired compounds. The labile acetonitrile solvent ligands of [Cr 3 (dpa) 4 (NCCH 3 ) 2 ](PF 6 ) 2 (8) and [Cr 2 Co(dpa) 4 (NCCH 3 ) 2 ]-(PF 6 ) 2 (9) are easily displaced by azide ligands upon reaction with a methanolic solution of sodium azide to generate the corresponding diazide compounds Cr 3 (dpa) 4 (N 3 ) 2 (10) and Cr 2 Co-(dpa) 4 (N 3 ) 2 (11) in good yields (>60%).…”

“…[4][5][6][7] Recently, our group has investigated the isolation, characterization and chemical reactivity of terminal nitrido compounds containing metal-metal multiple bonds. [8][9][10] Heterometallic nitride complexes are generally rare, 11,12 and we have sought synthetic routes to heterometallic nitrido compounds that contain metal-metal bonds. As a first step to such compounds, we report here the synthesis and characterization of heterometallic azide complexes containing the quadruply bonded dichromium unit, and examine their potential for thermal activation to form nitrido species.…”

C−H Activation by an Iron‐Nitrido Bis‐Pocket Porphyrin Species

“…Their roles as nitrogen synthons in organic reactions have aroused increasing interest in recent years [3f, 28] . While C−H activation has been reported/proposed for several terminal metal‐nitrido species, [29] reactivity study of this elementary step remains relatively sparse and has so far been limited to an isolable Ru‐nitrido complex, [29g,i] a metastable dinuclear Ru‐nitrido complex, [29f, 30] and the LML′CT excited state of an Os‐nitrido complex [29m, 31] . In this work, we have studied the HAT reactivity of a highly reactive and short‐lived Fe porphyrin nitrido species by employing the nanosecond LFP technique.…”

Direct Synthesis of Silylamine from N2 and a Silane: Mediated by a Tridentate Phosphine Molybdenum Fragment

“…Addition of an E À Hb ond to at erminal M N [14] and M = NR [15] has been reported in rare instances.M oreover, none of these complexes were prepared from N 2 ,e xcept as ingle recent example of the addition to Fe=NÀNR 2 . [16] A metal fragment that can achieve N 2 splitting,f ollowed by nitride and imide functionalization by EÀHbonds all the way to the free amine has never been reported.…”