Mechanistic Studies of CC Bond Cleavage of Nitriles by Dinuclear Metal Cryptates

Abstract

We previously reported that dinuclear copper(II) cryptate [Cu(2)L](4+) cleaves the C-C bond of acetonitrile at room temperature to produce a cyano-bridged dinuclear cryptate and methanol, whereby the reaction mechanism has not yet become clear. We have now systemically investigated this reaction, and four cryptates, [Cu(2)L](ClO(4))(4) (1), [Zn(2)L](ClO(4))(4) (2), [Cu(2)L(H(2)O)(2)](CF(3)SO(3))(4) (5), and [Cu(2)L(OH)(OH(2))](ClO(4))(3) (6) are reported here. Cryptates 1 and 2 can cleave the C--C bonds of acetonitrile, propionitrile, and benzonitrile at room temperature under open atmospheric conditions to give cyano-bridged cryptates [Cu(2)L(CN)](ClO(4))(3) (3) and [Zn(2)L(CN)](ClO(4))(3) (4), respectively, and the corresponding alcohol. In contrast, 5 and 6 do not show any C-C bond activation of nitriles, as the interior axial positions of Cu(II) in 5 and 6 are occupied by water/OH(-). The C-C bond cleavage of (S)-(+)-2-methylbutyronitrile by 2 produced (R)-(-)-2-butanol only; that is, the cleavage reaction proceeds through an S(N)2 pathway (Walden inversion).

A Dinuclear Cobalt Cryptate as a Homogeneous Photocatalyst for Highly Selective and Efficient Visible‐Light Driven CO2 Reduction to CO in CH3CN/H2O Solution

“…According to this mechanism, dinuclear metal cryptates with suitable M⋅⋅⋅M separations would be superior to mononuclear ones for CO 2 ‐to‐CO conversion, as two metal ions within a catalyst may provide synergistic catalysis, that is, one may serve as a catalytic center to bind and reduce CO 2 and the other may act as an assistant catalytic site to facilitate the removal of the OH group, which will significantly prompt the conversion of CO 2 into CO. Indeed, some dinuclear metal cryptates and analogues with suitable M⋅⋅⋅M separations have shown the recognition of superoxide (O 2 2− ), OH − and CN − ,, and other small molecules and anions, as well as the cooperative bimetallic activation of small molecules such as acetonitrile, and CO 2 ,…”

A Fivefold Interpenetrating dmd Topological Copper(I) Cyanide Complex Formed by C–C Bond Cleavage of Acetonitrile

“…In most cases, these reactions occurred under rigorous experimental conditions in which air‐sensitive or expensive organometallic catalysts were used, for example, Cp(CO) 2 Fe(SiMe 3 ) (Cp = cyclopentadienyl),2 [Ni(dippe)H] 2 [dippe = bis(diisopropylphosphanyl)ethane],3 [Me 2 Si(C 5 Me 4 ) 2 ]MoH 2 ,4 and [(C 5 Me 5 )Rh(PMe 3 )(SiPh 3 )(CH 2 Cl 2 )][BAr′ 4 ] [Ar′ = 3,5‐C 6 H 3 (CF 3 ) 2 ] 5. In other cases, Ag,6 Cu,7 and Zn8 complexes were used to cleave the C–C bond of acetonitrile, mainly under solvothermal conditions, under which there is competition between coordination and reduction reactions. Only a few mechanisms for the C–C bond cleavage of acetonitrile have been put forward; therefore, such systems still deserve study.…”

Copper‐Catalyzed Aromatic CH Bond Cyanation by CCN Bond Cleavage of Inert Acetonitrile

“…Although the detailed mechanism remained unclear at the current stage, a tentative reaction mechanism is proposed on the basis of the mechanistic studies described above and previous findings, [12,20] Finally, the Cu I species is oxidized by oxygen to regenerate the Cu II species, which may be the resting state of the catalyst. [21]…”

“…[7][8] We conceived that it is possibly unfeasible that CuA C H T U N G T R E N N U N G (OAc) 2 undergoes oxidative addition of the C À CN bond. Consequently, based on Lus work on the S N 2-type cleavage of nitriles, [12] we hypothesized that, in the presence of an acid additive, h 2 -coordinated iminoacyl copper(II) complex D might be attacked by a nucleophilic reagent and result in CÀCN bond splitting to form a copper cyanide complex (path c). Keeping this hypothesis in mind, a series of acids were screened.…”