Cobalt complexes acetylacetone

CHROMIUM TRIOXIDE-PYRIDINE COMPLEX, preparation in situ, 55, 84 Chrysene, 58,15, 16 fzans-Cinnamaldehyde, 57, 85 Cinnamaldehyde dimethylacetal, 57, 84 Cinnamyl alcohol, 56,105 58, 9 2-Cinnamylthio-2-thiazoline, 56, 82 Citric acid, 58,43 Citronellal, 58, 107, 112 Cleavage of methyl ethers with iodotri-methylsilane, 59, 35 Cobalt(II) acetylacetonate, 57, 13 Conjugate addition of aryl aldehydes, 59, 53 Copper (I) bromide, 58, 52, 54, 56 59,123 COPPER CATALYZED ARYLATION OF /3-DlCARBONYL COMPOUNDS, 58, 52 Copper (I) chloride, 57, 34 Copper (II) chloride, 56, 10 Copper(I) iodide, 55, 105, 123, 124 Copper(I) oxide, 59, 206 Copper(ll) oxide, 56, 10 Copper salts of carboxylic acids, 59, 127 Copper(l) thiophenoxide, 55, 123 59, 210 Copper(l) trifluoromethanesulfonate, 59, 202... 

Photoreduction of cobalt(III) complexes in nonaqueous solvent systems has been little studied because of the limited solubility of cobalt(III) complexes and their tendency to photooxidize the solvent. Irradiation with 365-mjj. light of cis- or trans-Co(en)2C 2 + and Co(en)2Cl(DMSO)2+ in dimethylsulfoxide (DMSO) leads rapidly to production of a green tetrahedral cobalt(II) product apparently with concurrent solvent oxidation.53,71 Irradiation with 365-mjx light of the molecular Co(acac)3 in benzene rapidly gives a red precipitate which may be the cobalt(II) acetylacetonate.53... 

Under the same conditions, cobalt acetylacetonate afforded a mixture of four products the mono-, di-, and triacetylated chelates (XVII, XVIII, and XIX), along with the starting material. In contrast to the chromium chelates, the mixture of cobalt complexes was cleanly separated by chromatography. The identity of each of these products was established by an NMR spectrum. The presence of uncoordinated carbonyl groups was revealed by infrared absorption at 1675 cm.-1... 

CL2099). Dihydrofurans (67) were synthesized by a photochemical reaction of enamines with metallic complexes of diketones (83CL1499). As an example, the reaction with cobalt(III) acetylacetonate is presented. 

Hexaammineplatinum(IV) salts also undergo imine-forming reactions with acetylacetone (equation 49).172 A cobalt(III) acetylacetone complex can be formed as a result of intramolecular addition of cobalt-bound hydroxide ion to acetylacetone. The cobalt-bound oxygen atoms are retained in the new chelate ring (equation 50).173... 

Effect of initiator level. The effect of increasing amounts of cobalt(III) acetylacetonate upon the rate of polymerisation is complex. Whilst the rate always appears to increase as the initiator level increases (in contrast to the behaviour observed when the surfactant level is increased), the order of reaction with respect to initiator depends upon the concentration of surfactant in the aqueous phase. The results summarised in Figure 9 show that the order is approximately the Smlth-Ewart value of 0.4 at high surfactant concentrations, whereas it falls markedly as the surfactant level in the reaction system is lowered. Figure 10 illustrates the rather surprising observation that the order of reaction with respect to initiator appears to vary linearly with the logarithm of the surfactant concentration. 

The precise manner in which the first-order rate constant for the decomposition of cobalt(III) acetylacetonate in aqueous media at 50°C varies with the pH and the surfactant concentration is complex. Empirically, it has been found that the joint variation can be well represented by the equation... 

The results given In Figure 15 are for two aqueous phases, one of which had a pH of 8.5 and the other a pH of 11.1, and both of which contained the same concentration of sodium dodecyl sulphate. Two points are Immediately apparent from these results (a) the normal partition law is obeyed, at least over the range of concentrations investigated, and (b) the partition coefficient Is Independent of the pH of the aqueous phase. The first of these observations implies that cobalt (III) acetylacetonate has the same molecular complexity In both the aqueous and the butadiene phases. These results also show that the initiator partitions in such a way that its concentration in the butadiene phase is considerably greater than that in the aqueous phase in fact, the partition coefficient for this particular aqueous phase at 50°C Is approximately 6.54. 

The asymmetric conjugate addition of diethylzinc with chalcone was also catalyzed by nickel and cobalt complex (Eq. (12.31)) [71]. A catalytic process was achieved by using a combination of 17 mol% of an aminoalcohol 34 and nickel acetylacetonate in the reaction of diethylzinc and chalcone to provide the product in 90% ee [72, 73]. Proline-derived chiral diamine 35 was also effective, giving 82% ee [74]. Camphor-derived tridentate aminoalcohol 36 also catalyzes the conjugate addition reaction of diethylzinc in the presence of nickel acetylacetonate to afford the product in 83% ee [75]. Similarly, the ligand 37-cobalt acetylacetonate complex catalyzes the reaction to afford the product in 83% ee [76]. 

E8.24 The ratio of cobalt to acetylacetone in the complex is 3 1. Converting the given mass percents of Co and C to moles of Co and C, we find that for every one mole of Co in the product we have 15 moles of C moles of Co = 0.28 mol moles of C = 4.2 mol. Considering that every acac" ligand has five carbon atoms, it is obvious that for each mole of Co we have three moles of acac, This ratio is consistent with the formula Co(acac)j. (Consult Section 7.1 for more detail on the acetylacetonate ligand and cobalt coordination complexes.)... 

Certain organometallic compounds can be used to mediate controlled/ living radical polymerization due to their liable and reversibly-cleavable metal-carbon bond. For example, organocobalt complex, such as tetramesitylporphyrinato Co(II) complex [Co(TMP)], has been used to mediate the CRP of aciylates. The first successful cobalt-mediated CRP of VAc was reported by Debuigne and Jerome et. al. using cobalt(ll) acetylacetonate complex Co(acac)2 (Scheme 2) ... 

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