Mono complexes copper

Evans suggests that the catalyst resting state in this reaction is a 55c Cu alkene complex 58, Scheme 4 (35). Variable temperature NMR studies indicate that the catalyst complexes one equivalent of styrene which, in the presence of excess alkene, undergoes ready alkene exchange at ambient temperature but forms only a mono alkene-copper complex at -53°C. Addition of diazoester fails to provide an observable complex. These workers invoke the metallacyclobutane intermediate 60 via a formal [2 + 2] cycloaddition from copper carbenoid alkene complex 59. Formation of 60 is the stereochemistry-determining event in this reaction. The square-planar S Cu(III) intermediate 60 then undergoes a reductive elimination forming the cyclopropane product and Complex 55c-Cu, which binds another alkene molecule. 

DR. MARGERUM Yes, it does turn up in a number of instances. The example you are talking about was an EDTA reaction with a copper triglycine in which the released triglycine catalyzed the substitution of the EDTA. This resulted from the fact that the bis-triglycine complex is faster to undergo substitution than is the mono complex. The released triglycine formed a bis complex and the EDTA then attacked that. 

Patra AK, Dhar S, Nethaji M, Chakravarty AR. Visible light-induced nuclease activity of a ternary mono-phenanthroline copper(II) complex containing L-methionine as a photosensitizer. Chem Commun 2003 1562-3. 

The reaction between acetylacetone and copper(II) to form the mono complex is considerably slower than other substitution reactions of Cu(II). Pearson and Anderson [98] have discussed the system in terms of the following equilibria... 

Diaz, G., S. Diez, L. Lopez, R. Munoz, M.M. Campos-Vallette, V. Manriquez, and O. Wittke (1993). Spectra and structure of polyamine-copper(II) complexes. Infrared spectrum and normal coordinate calculations of mono(diethylenetriamine) copper(II) nitrate. Vib. Spectrosc. 6, 37, and references cited therein. 

Mistaken identity mono-coordinate copper(I) and silver(I) complexes... 

The Vilsmeier formylation of copper deuteroporphyrin dimethyl ester (6) in which unsubstituted /3-positions are present yields a complex mixture of mono- and disubstituted formylation products which can be partially separated by chromatography on neutral alumina.106... 

Chemical analysis revealed that commercial food grade copper chlorophyllin is not a single, pure compound, but is a complex mixture of structurally distinct porphyrins, chlorin, and non-chlorin compounds with variable numbers of mono-, di-, and tri- carboxylic acid that may be present as either sodium or potassium salts. Although the composition of different chlorophyllin mixtures may vary, two compounds are commonly found in commercial chlorophyllin mixtures trisodium Cu (II) chlorin Cg and disodium Cu (II) chlorin which differ in the number of... 

The oxidation of phenol, ortho/meta cresols and tyrosine with Oj over copper acetate-based catalysts at 298 K is shown in Table 3 [7]. In all the cases, the main product was the ortho hydroxylated diphenol product (and the corresponding orthoquinones). Again, the catalytic efficiency (turnover numbers) of the copper atoms are higher in the encapsulated state compared to that in the "neat" copper acetate. From a linear correlation observed [7] between the concentration of the copper acetate dimers in the molecular sieves (from ESR spectroscopic data) and the conversion of various phenols (Fig. 5), we had postulated [8] that dimeric copper atoms are the active sites in the activation of dioxygen in zeolite catalysts containing encapsulated copper acetate complexes. The high substratespecificity (for mono-... 

The complexes [Cu(NHC)(MeCN)][BF ], NHC = IPr, SIPr, IMes, catalyse the diboration of styrene with (Bcat) in high conversions (5 mol%, THF, rt or reflux). The (BcaO /styrene ratio has also an important effect on chemoselectivity (mono-versus di-substituted borylated species). Use of equimolecular ratios or excess of BCcat) results in the diborylated product, while higher alkene B(cat)j ratios lead selectively to mono-borylated species. Alkynes (phenylacetylene, diphenylacety-lene) are converted selectively (90-95%) to the c/x-di-borylated products under the same conditions. The mechanism of the reaction possibly involves a-bond metathetical reactions, but no oxidative addition at the copper. This mechanistic model was supported by DFT calculations [68]. 

More recently, a study with di- and mono-carbene Pd(II) complexes has demonstrated that the Sonogashira coupling of activated and non-activated aryl iodides can be carried out in an aqueous, aerobic medium and in the absence of amines. These results suggest that the moisture-sensitive copper-acetylide may not be present in this particular transformation, and that a Pd-acetyhde could be formed by deprotonation of the coordinated alkyne instead of transmetallation [130]. 

In their pursuit of determining solution structures of dinuclear copper complexes as carried out for complex (29) (Section 6.6.3.1.1). Comba reported complex (431) (r = 0.02 Cu-Cu 6.9 A, comparable with the values of 7.2 A predicted by molecular mechanics calculations and 6.7 A obtained from the simulated EPR spectrum).54 They reported369 complexes (432) (square planar) and (433) (Cu-Cu 3.35 A) as well. As part of studying magnetic properties of mono-, di-, and... 

Scheme 4 Formation of mono-, di-, tri-, and tetranuclear olefin-copper complexes.

In the very recent past, metal complex catalysis has been used with advantage for the stereo- and enantio selective syntheses based on the Henry and Michael reactions with SENAs (454-458). The characteristic features of these transformations can be exemplified by catalysis of the reactions of SENAs (327) with functionalized imides (328) by ligated trivalent scandium complexes or mono-and divalent copper complexes (454) (Scheme 3.192). Apparently, the catalyst initially forms a complex with imide (328), which reacts with nitronate (327) to give the key intermediate A. Evidently, diastereo- and enantioselectivity of the process are associated with preferable transformations of this intermediate. 

Similarly, we have also seen already how the copper(II) tetrakis (amine) complex forms in a step manner with four separate stages, rather than in a single step, forming the mono-ammine complex, then the to-ammine, the fra-amminc and finally the /e/ra/d.v-ammine complex. So we start to appreciate that the actual reaction occurring during the burning of octane is more complicated than it first appears to be the ratios in the stoichiometric equation are not useful in determining the reaction mechanism. 

The regioselectivity is maintained with mono- and even disubstituted propargylic chlorides (Table 9.33) [56], The copper complex affords allenylcarbinols (A) and the nickel complex favors homopropargylic alcohols (B). In the latter case, the syn adducts are predominant, suggestive of an acylic transition state. 

Formation of 772-complexes is known for both mono- and bis-phospho-nio-benzophospholides and has been observed (Scheme 18) in the reactions of the cation 23 with Jonas reagent to give the cobalt complex 49 [49], addition of the zwitterion 25 to a Mo-Mo triple bond to afford the dinuclear complex 50 [47], and finally, upon treatment of 26 with copper iodide to yield the complex 51 [46] which is peculiar because of the presence of the same ligand in two different coordination modes. Whereas it is clear that the metal atoms in all complexes supply inappropriate templates for the formation of 77 -complexes, the preference of rf-(,n)- over a possible a-coordina-tion is less well understood [49]. 

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