Synthesis and X-ray structure of bis(trifluoromethyl)(N,N-diethyldithiocarbamato)-copper; a remarkably stable perfluoroalkylcopper(III) complex

Abstract

The reaction between trifluoromethylcadmium reagent and Br2Cu(edtc) (edtc = N,N-diethyldithiocarbamato) or Cdl+[(CF3)2Cu]-with [Et2NC(S)S]2 in DMF (dimethylformamide) at -30 "C yields the stable Culll perfluoroalkylcopper complex, (CF&CuSC(S)NEt2.Perfluoroalkylcopper reagents exhibit excellent thermal stability compared to their hydrocarbon analogues and have consequently received extensive utilization in preparative organic chemistry ,1,2 but their composition and structure is not clearly defined. Perfluoro-t-butylcopper has been described as a 2 : 3 dioxane adduct, but no structural data was provided.3 Except for the recent proposal of [CF~CUII-by Chambers ,4 these reagents have been formally represented as RFCu or RFCu.CuI.l Our recent report2 that multiple trifluoromethylcopper species, with significantly different physical and chemical properties, can be detected spectroscopically suggested that this formalism for perfluoroalkylcopper reagents is oversimplified. Thus, we have focused on the identification and composition of these different trifluoromethylcopper moieties to better understand the nature of these reagents.Recent developments in the 'CF3Cu' system have demon-strated5 that two of these compounds are CF3Cu.L (1) (L = metal halide) and the cuprate CdI+[(CF3)2Cu]-(2). In contrast to the slow oxidation of (I), the cuprate (2) is readily oxidized by a variety of oxidants. For example, oxidation with thiuramdisulphide converts (2) to (CF3)2CuII*edtc (edtc = N,N-diethyldithiocarbamato) (3), the first stable trifluoromethyl Cu"1 compound (Scheme 1

Organocopper Compounds: From Elusive to Isolable Species, from Early Supramolecular Chemistry with RCuI Building Blocks to Mononuclear R2–nCuII and R3–mCuIII Compounds. A Personal View

“…It appeared that, whereas the reaction was successful, the Cu(III) species formed with R = alkyl rapidly decomposed into the stable copper(I) dithiocarbamate and other products from R. What I missed indeed was the use of a Cd(CF 3 ) 2 reagent and a fluorous alkyl group as shown by Willert-Porada et al in the late 1980s, because that would have resulted in the isolation of the stable diorganocopper(III) compound (CF 3 ) 2 CuS 2 CNEt 2 . 45 The second approach, based on the use of intramolecular coordination for the stabilization of the copper−carbon bond to form stable organocopper species, appeared in contrast to be extremely successful, however. 29a It resulted in the synthesis of stable organocopper(I) materials that, moreover, could be produced with acceptable purity and in larger quantities and hence facilitated our biological testing.…”

“…However, in 1989 (CF 3 ) 2 CuS 2 CNEt 2 was isolated and characterized (vide infra) as the first example of an organocopper(III) species. 45 Later homoleptic tetraorganocuprate(III) anions were reported: i.e., a [Cu(CF 3 ) 4 ]  anion with a bulky PNP cation. 83 In the meantime mechanistic studies of copper-catalyzed and -mediated reactions showed direct evidence that organocopper(III) intermediates were playing a crucial role in the product-forming step of many of these reactions.…”

“…Nevertheless, any attempt to synthesize and isolate such species had proved fruitless except in the case of (CF 3 ) 2 CuS 2 CNEt 2 . 45 Recently, this situation has fundamentally changed with the synthesis of a series of different organocopper(II) and -(III) compounds. These compounds commonly have the [R x CuL n ]X z−x (X = anion) stoichiometry in which z is either 2 or 3 and x can be 1, 2, or 3.…”

Synthesen und Eigenschaften von Pentafluorethylkupfer(I)- und -(III)-Verbindungen: Cu(C2F5) · D, [Cu(C2F5)2]- und (C2F5)2CuSC(S)N(C2H5)2

“…1). Die Cu±C-und Cu±S-Absta È nde sind im Gegensatz zur homologen Trifluormethylkupfer-Verbindung (CF 3 ) 2 Cu(edtc) [7] symmetriebedingt jeweils gleich. Der ku È rzeste intra- [21].…”

Kupferkatalysierte aerobe oxidative C‐H‐Funktionalisierungen: Trends und Erkenntnisse zum Mechanismus

“…[124] Von Ullmann-Kreuzkupplungen von Arylhalogeniden wird gewçhnlich angenommen, dass sie über einen Cu I /Cu III -Katalysezyklus ablaufen (Schema 57), [120,125] [126] und auf der Grundlage von DFT-Rechnungen bestätigt. [127] [129][130][131][132][133] In den letzten Jahren wurden einige Kupfer(II)-und Kupfer(III)-Komplexe synthetisiert und kristallographisch charakterisiert, [134][135][136][137][138][139][140] und die erhaltenen Ergebnisse dienen als wichtige Grundlage bei der Betrachtung derartiger Intermediate in Cu-katalysierten Oxidationen. Mehrere dieser Komplexe wurden über Cu II -vermittelte Aktivierung einer C-H-Bindung eines Makrocyclus hergestellt.…”