Copper II Complexes

The solid readily dissolves chemically in concentrated hydrochloric acid, forming a complex, and in ammonia as the colourless, linear, complex cation [H3N -> Cu <- NHj] (cf AgCl) if air is absent (in the presence of air, this is oxidis to a blue ammino-copper(II) complex). This solution of ammoniacal copper(I) chloride is a good solvent or carbon monoxide, forming an addition compound CuCl. CO. H2O, and as such is used in gas analysis. On passing ethyne through the ammoniacal solution, a red-brown precipitate of hydrated copper(I) dicarbide (explosive when dry) is obtained ... 

Sigel and co-workers" investigated the interaction between the aromatic rings of phenyl carboxylates (Ph-(CFl2)n-C02) and 1,10-phenanthroline in ternary copper(II) complexes. Variation of the number of methylene units between the aromatic ring and the carboxylate group (n=0-5) revealed that the arene - arene interaction is most pronounced for n=l. This interaction is more efficient in a 60% 1,4-... 

This interpretation is supported by literature studies on copper(II) complexes containing two -amino-acid ligands. For N-unsubstituted -amino-acid ligands, deductions as to position of the cis -trans geometrical equilibrium in solution are difficult as illustrated by the fact that for some -amino acids solid complexes have been isolated of both the ds and trans geometry. In contrast it seems as if copper(II) complexes containing two N-alkylated -amino-acid ligands crystallise exclusively in the trans form ". ... 

In contradistinction to this, weak ferromagnetism has been observed in a number of chloro and bromo complexes of the type M2[CrX4] (M = a variety of protonated amines and alkali metal cations, X = Cl, Br), which are analogous to previously known copper(II) complexes (p. 1192). They have magnetic moments at room temperature in the region of 6BM (compared... 

Evans et al. reported that the bis(imine)-copper (II) complex 25, prepared from chiral bis(imine) ligand and Cu(OTf)2, is also an effective chiral Lewis acid catalyst [34] (Scheme 1.44, Table 1.18). By tuning the aryl imine moiety, the bis(2,6-dichlor-ophenylimine) derivative was found to be suitable. Although the endojexo selectivity for 3-alkenoyloxazolidinones is low, significant improvement is achieved with the thiazolidine-2-thione analogs, for which both dienophile reactivity and endojexo selectivity are enhanced. 

Chiral C2-symmetric bisoxazoline-copper(II) complexes [30, 31] were introduced as catalysts for cycloaddition and ene reactions of glyoxylates with dienes [9] leading to intense activity in the use of these catalyst for different cycloaddition reactions. 

The enantioselective cycloaddition reaction catalyzed by chiral BOX-copper(II) complexes has been used for conjugated cyclic dienes, e.g. 1,3-cyclohexadiene 5c, as shown in Scheme 4.21 [9, 32]. This cycloaddition reaction is dependent on sol-... 

Chiral BOX-zinc(II) complexes can also catalyze the cycloaddition reaction of glyoxylates with, e.g., 2,3-dimethyl-l,3-butadiene and 1,3-cyclohexadiene [36]. The reaction gave for the former diene a higher cycloaddition product/ene product ratio compared with the corresponding chiral copper(II) complexes the ee, however, was slightly reduced. For the reaction of 1,3-cyclohexadiene slightly lower yield and ee were also found. 

The chiral BOX-copper(II) complexes are effective catalysts for enantioselective cycloaddition reactions of a,/ -unsaturated acyl phosphonates [48] and a,/ -unsaturated keto esters [38b, 49]. 

We therefore prepared a new chiral ligand, (l ,J )-isopropylidene-2,2 -bis[4-(o-hy-droxybenzyl)oxazoline)], hereafter designated J ,J -BOX/o-HOBn. To our delight, the copper(II) complex catalyst prepared from J ,J -BOX/o-HOBn ligand and Cu(OTf)2 was quite effective (Scheme 7.45). Especially, the reaction of O-benzylhydroxylamine with l-crotonoyl-3-isopropyl-2-imidazolidinone in dichloromethane (0.15 m) at -40°C in the presence of J ,J -BOX/o-HOBn-Cu(OTf)2 (10 mol%) provided the maximum enantioselectivity of 94% ee. 

Cyanato-copper(II) complexes with nitrogen organic ligands preparation, properties and structure. J. Kohout, M. Hvastijova and J. Gazo, Coord. Chem. Rev., 1978, 27,141-172 (116). 

The stereochemistry and electronic properties of fluxional six-coordinate copper(II) complexes. B. Hathaway, M. Duggan, A. Murphy, J. Mullane, C. Power, A. Walsh and B. Walsh, Coord. Chem. Rev., 1981,36, 267-324 (132). 

Azoresorcinol, pyridyl-metal complexes dyes, 6, 74 Azurins, 6, 651, 652 copper(II) complexes, 2, 772 5, 721 electron transfer reactions, 6, 653 NMR, 6, 652 Raman spectra, 6, 652 spectra, 6, 652 thioether complexes, 2, 557 Azurite... 

Formazan, l-(2-hydroxophenyl)-3,5-diphenyl-copper(II) complexes dyes, 6, 81... 

Naphthoic acid, 3-hydroxy-copper(II) complexes, 2, 483 metal complexes IR spectra, 2, 469... 

Pinacolone, o-(diphenylphosphino)benzoyl-coordination chemistry, 2, 401 Ping-pong reactions copper(II) complexes, 5, 717 Piperidine, /V-hydroxy-metal complexes, 2, 797 P a values azole ligands, 2, 77 Plant roots amino acids, 2, 962 carboxylic adds, 2,962 Plants... 

Propane-1,2-diol, 3-mercapto-metal complexes, 2,804 Propan-l-ol, 2-amino-2-methyl-copper(II) complexes, 2,795 Propan-l-ol, 2,3-dimercapto-chelating agent heavy metal poisoning, 6,767 Propan-l-ol, 3-(methylamino)-copper(II) complexes, 2,795 Propan-2-ol... 

Johnson J. S., Evans D. A. Chiral Bis(Oxazoline) Copper(II) Complexes Versatile Catalysts for Enantioselective Cycloaddition, Aldol, Michael, and Carbonyl Ene Reactions Acc. Chem. Res. 2000 33 325-335... 

Evans D. A., Rovis T., Johnson J. S. Chiral Copper(II) Complexes As Lewis Acids for Catalyzed Cycloaddition, Carbonyl Addition, and Conjngate Addition Reactions. Pure Appl. Chem 1999 71 1407-1415... 

The discussion above might have pertained for example, to the energies and electronic spectra of titanium(iii) compounds. The same ideas can be applied with just one modification to the i/-electron properties of copper(ii) complexes and other... 

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