Copper complexes acetonitrile

Ferrocenyltriphenylphosphonium perchlorate (84) has been synthesized from iodoferrocene, tetrakis(acetonitrile)copper(i), and triphenylphosphine in nitromethane. The authors suggest that iodoferrocene first forms the complex (85) which then breaks down via a four-centred transition state to (84). 

Table 1. Copper complexes used as catalysts for epoxidation of cyclohexene by iodosylbenzene in acetonitrile.

Enantioselective Aziridination of Alkenes. Copper complexes with neutral methylenebis(oxazoline) ligands (1) and (2) have also been employed as enantioselective catalysts for the reaction of alkenes with (Al-tosylimino)phenyliodinane, leading to A-tosylaziridines. The best results have been reported for cinna-mate esters as substrates, using 5 mol % of catalyst prepared from CuOTf and the phenyl-substituted ligand (2) (eq 6). The highest enantiomeric excesses are obtained in benzene, whereas in more polar and Lewis basic solvents, such as acetonitrile, the selectiv-ities are markedly lower. The chemical yield can be substantially improved by addition of 4X molecular sieves. Both Cu - and Cu"-bisoxazoline complexes, prepared from Cu or Cu triflate, respectively, are active catalysts, giving similar results. In contrast to the Cu-catalyzed cyclopropanation reactions discussed above, in which only Cu complexes are catalytically active, here Cu complexes are postulated as the actual catalysts. ... 

Recently, we found that a copper catalyst - as well as ruthenium - is effective for the oxidation of alkanes with molecular oxygen in the presence of acetaldehyde [157]. The catalytic system CUCI2 and 18-crown-6 has proved to be efficient [157cj. Furthermore, we found that specific copper complexes derived from copper salts and acetonitrile are convenient and highly useful catalysts for the aerobic oxidation of unactivated hydrocarbons [158], For example, oxidation of cyclohexane with molecular oxygen (1 atm of O2 diluted with 8 atm of N2) in the presence of acetaldehyde and Cu(OAc)2 catalyst (0.0025 mol%) in CH3CN/CH2CI2 (3 2) at 70°C in an... 

Based on this scheme, the kinetics of decomposition of diazodiphenylmethane and diazofluorene in acetonitrile by ZnCl, ZnBr or Znij has been explained Copper complexes of type 416 or 417 have been invoked to account for kinetics and products of the decomposition of diazodiphenylmethane by CuBr in acetonitrile Copper carbenoids of unspecified structure were assumed in analogous investigations with CuBr and CuClO [but not with CufClOJ which initiates a radical cation pathway, vide infra]. Carbenoids 416 (X = Hal) have been isolated from reactions... 

Figure 3.8 Simulated structure of the cone-4-t-butylcalix[4]arenetetra(/V,/V-diethylacetamide) copper complex with included acetonitrile...

The [3-diketiminato copper complex is a pale yellow solid that is freely soluble in benzene, toluene, chlorobenzene, THF, and acetonitrile while partially soluble in diethyl ether and pentane. In solution, the toluene ligand dissociates. When dissolved in benzene, for example, the NMR spectrum exhibits signals for both LMe Me3cu(benZene) (major species) and [LMe,Me3Cu]2(benzene) (minor species). The copper complex reacts slowly with chloroform and dichloromethane, resulting in a gradual darkening of the solution to purple. 

The reaction is first order in copper complex, but the dependence on [O2] is more complicated and is affected by the presence of MeCN, which moderately decreases the observed rate constant, kobs. In neat acetonitrile or acetonitrile-containing solvent mixtures, the kobs depended linearly on the concentration of 02, and the straight line... 

The corresponding copper complex [Cu4I4(L38)4] was prepared by reaction of L38 and Cul in acetonitrile (117). The structure consists of stepped Cu4I4 clusters bridged by L38 groups, and the resultant polymeric chains are further assembled by short interchain S -S contacts (3.257 A) to form a three-dimensional network (Fig. 20). 

A review of the photochemical properties of copper complexes includes a survey of the photocatalysed reactions of copper-olefin complexes. The addition of acetonitrile to norbornene may be induced by irradiation in the presence of silver ions. The reaction appears to involve excitation of a LMCT excited state of the norbomene-silver complexes and the formation of norbornene radical cations. 

The protein-bound copper can be removed by dialysis against cyanide, sulfide, and other copper complexing agents. Subsequent reintroduction of the copper restores the oxygenating ability of hemocyanin. However, the resynthesis of hemocyanin from apohemocyanin can be achieved only with cuprous, not cupric salts (6, 13). Practically quantitative reconstitution is obtained by the use of the acetonitrile complex of copper (21). The apoprotein appears specific for copper since the binding of other metal ions denatures the protein (6). 

Similarly, the nitrene transfer reaction from 128 is facilitated by a variety of catalysts, including MTO (136) <01JCS(CC)235>, the lri(pyrazolyl)borate-coppcr(l) complex 137 <01OL1423>, and tetrakis(acetonitrile)copper(I) hexafluorophosphate (138) <01JA7707>. In the latter case, the reaction can be carried out using a sulfonamide and the primary oxidant, iodosylbenzene, whereby the actual nitrene transfer reagent 128 is presumed to be formed in situ. In all cases, acetonitrile appears to be the solvent of choice. 

By the same manner, the electropolymerization of the copper complex of 80 (half-unit = 2,6-diacetylpyridine-mono(ethylene(liamine)) was performed, which led to an electroactive polymeric Him whose electrocatalytic properties towards biodegradable agrochemicals were evaluatedOne can cite the example of the electrooxidative polymerization of 81, a 3-[l-(2-amino-phenylimino)-ethyl]-6-methylpyran-2,4-dione Schiff base. The corresponding films are insoluble in most solvents, electroactive in water but electro-inactive in acetonitrile and they display electrocatalytic properties towards the oxidation of hydroquinone . ... 

Copper-based complexes have been found to be excellent catalysts for the aziiidination of alkenes employing PhI=NTs as the nitrene precursor (eq 12). Both Cu and Cu efficiently catalyze the reaction, and the hest results are usually obtained with the cationic complexes tetrakis(acetonitrile)copper(I) perchlorate and copper(n) trifluoromethanesulfonate Good yields are obtained with a variety of substrates, including aliphatic alkenes and enolsUanes (eq 13), the latter delivering a-amino ketones upon hydrolysis of the intervening sUyloxyaziridine. 

Remelli et al. (168) described a selector based on histidine. With this chiral selector L-hr-n-decylhistidine (Fig. 5(c)) the simultaneous enantiomeric separation of D,L-tiyptophan and D,L-phe-nylalanine was successfully performed on hydrophobic layers with MeOH-acetonitrile-THF-water (7.3 5.9 33.9 52.9, v/v/v/v) as eluent. Sinibaldi et al. (165) resolved D,L-dansyl amino acids on reversed phase TLC plates pretreated with a copper -complex of poly-L-phenylalanine amide (Fig. 5 (d)). The polymeric ligand was synthesized by the reaction of optically active amide with ethylene glycol diglycyl ether. The method makes use of a sophisticated liquid chroinatogr q)h for obtaining the desired polymer fraction which is subsequently used for the LEC, and this might limit the application of the separation procedure. However, a simple method is performed by Bhushan et al. (169). Here L-proline was used as a chiral selector on normal phase silica gel (169) and amino acids were resolved with the eluent systems n-butanol-acetonitrile-water (6 2 3, vWv), chloroform-meth-anol-propionic acid (15 6 4, v/v/v) and acetonitrile-methanol-water (2 2 1, v/v/v). 

Copper has been demonstrated to mediate cyanation of aryl bromides and iodides through the activation of C-CN bonds (Scheme 20). Phenylacetonitrile [64], malononitrUe [65], and even acetonitrile as a reaction solvent [66] have been reported to serve as cyanating agents. 2-Phenylpyridines [67] and indoles [68] are directly cyanated by copper-mediated cyanation reaction using phenylacetonitrile, which is supposedly oxidized first at its benzylic position to give benzoyl cyanide, which further reacts with copper complexes to generate a cyanocopper species responsible for the cyanation event. Nevertheless, detailed mechanisms of these cyanation reactions remain elusive. 

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