Cobalt II Co

Although the cofacial diporphyrins represent a vibrant and innovative direction in dioxygen activation, simple porphyrins and their derivatives also remain an important research area. The dichlorophenyl-substituted porphyrin tdcpp [5,10,15,20-tetrakis(2,6-dichlorophenyl)-porphyrin] forms a complex with cobalt(II), [Co(tdcpp)], and catalyzes the oxidation of conjugated olefins to (after experimental workup) ketones in the presence of dioxygen and triethylsilane (80) a hydroperoxide intermediate has been isolated from these reactions (81). 

Incorporation of (meso-tetraphenylporphyrinato)cobalt(II), [Co(tpp)], into plasma polymer thin films for the possible use as dioxygen-selective permeable membranes has also been reported (91). Comparisons to... 

Cobalt(III) cage complexes can also perform as electron transfer agents in the photoreduction of water.180181 Because of the kinetic inertness of the encapsulated cobalt(II) ion, the cobalt(II)/co-balt(III) redox couple can be repeatedly cycled without decomposition. Thus these complexes are potentially, useful electron transfer agents, e.g, in the photochemical reduction of water, in energy transfer and as relays in photosensitized electron transfer reactions.180,181 The problem of the short excited-state lifetimes of these complexes can be circumvented by the formation of Co(sep)3+ ion pairs, so that the complexes can be used as photosensitizers for cyclic redox processes.182 183... 

Recently, three TPO models have been reported bis (salicylidene)ethylenediaminato cobalt(II) [Co(salen)] in MeOH (14), cobalt(II)tetraphenylporphyrin (CoTPP) (25) in DMF, and manganese phthalocyanine (Mn-Pc) in DMF (16). These models have been reported as having the TPO-mimic function of oxygenating skatole, a tryptophan analogue, to form 2-formamidoacetophenone (FA). However, one of the most critical problems for these models is the lack of structural similarity between the TPO active site (heme) and these models. The structure of these models is not similar to the heme in TPO with respect to the central metal and/or the ligand. Furthermore, Fe(salen) does not possess the TPO-mimic function (14). 

A series of neutral addition compounds of bis(2,4-pentanedio-nato) cobalt (II), Co(acac)2, can be obtained by adding the desired base to a benzene solution of this compound. The adducts are all less soluble than the starting compound the yields are high, and most are quite pure without recrystallization. An ionic compound, sodium tris(2,4-pentanedionato)cobaltate-(II), is also easily made it is somewhat less satisfactory as a starting material for the adducts. 

The corresponding macrobicyclic cobalt(II) [Co(sep)](ZnCl4) H20 complex was prepared by reduction of the [Co(sep)]Cl3 complex with zinc dust in aqueous HCl [95], A similar procedure was used for the synthesis of the dithionate [Co(sep)](S206) salt in the presence of Li2S206 [99], The optically active R- and S-isomers of cobalt sepulchrate were obtained from the optically active parent A-[Co(en)3]Cl3 and A-[Co(en)3]Cl3 complexes [94-95],... 

The reduction of [Co(MEazasar)]Cl3 complex with a large excess of zinc dust in aqueous solution followed by treatment with hydrochloric acid and a Li2ZnCli solution yielded the cobalt(II) [Co(MEazasar)](ZnCLi) H2O sarcophaginate [96]. 

One more product of the condensation of [Co(tame)2] with nitromethane and formaldehyde with a yield of ca 10% was identified in Ref 148 as macrotetracyclic [Co(NOtetrasartame)]Cl3 3H20 sarcophaginate 4. Its reduction with zinc dust in aqueous hydrochloric acid resulted in the corresponding cobalt(II) [Co(AMtetrasartame)] aminosarcophaginate, which can either oxidize to a cobalt(III) complex or demetallate with hydrochloric acid to cleave four-membered chelate fragments. Both macrotetracyclic cobalt(III) complexes are remarkably stable to hydrolysis in acidic (6 molar hydrochloric acid at 60°C) and mildly basic (pH < 9 at 25°C) conditions, although they decompose at pH >9. 

The expanded cobalt(II) [Co(Me8tricosanesar)]2+ and cobalt(III) [Co(Me8tricosatrienesar)] + sarcophaginates have demonstrated usual sterically induced structural and spectral characteristics [151]. The Co-N distances in [Co(Me8tricosatrienesar)]s+ cation are remarkably... 

First, SOMC was applied to Co promotion of M0/AI2O3 sulfide. As shown in Fig. 1, the choice of complex was important for uniform distribution of Co over catalyst pellets. Probably due to its too high reactivity, bis(2,4-pentanedionato)cobalt(II) (Co(CsH702)2) resulted in over-concentration of Co in oirter region of the pellets (Fig. la), while bis(cyclopentadienyl)cobalt (Co(CioHio)2) led to a uniform distribution over the entire catalyst pellets at the same concentration of Co (Fig. lb). Selective reaction between Co-containing complexes and Mo sulfide edge sites should give more efficient Co-promotion. More local analyses like EDS and IR(CO) should be done to verify if, by use of Co(CioHio)2, closer association was really achieved between sulfide slabs and incorporated Co. 

Hollow fiber = HF flat membrane = flat, Cobaltodihistidine = Co (tpHb [N,N -bis salicylideneimino)di-n-propylamine] cobalt (II) = Co SalPr) [N,N -bis(3-methoxy/salycylidene) ethylenediamine] cobalt (II) = Co MeOsalen) [N,N -bis(3-methoxysalycylidene)-tetramethyle-thylenediamine] cobalt (II) = Co(3-Me Osaltmen) a,a,a,a-meso-tetrakis(o-pivalamidophenyl) porphynato cobalt(II) 1-methylimidazole or lauryimidazole = (CoPIm) N,N -ethylene-bis 5-nitro-salicyliden-iminato)cobalt II) = Co(5-NO2-Saltmen). 

N.m.r. line-broadening and shift effects have been investigated for CoL [L = (12)] in H2O, MeOH, and DMT. " Crystalline and molecular susceptibilities and their orientations of cobalt(ii) phthalocyanine [Co(pc)], bis(pentane-2,4-dithionate)cobalt(ii) [Co(pdt)2], and the analogous copper(ii) complexes have been reported. E.s.r. has been used to show that addition of DMF or DMSO to aqueous solutions of cobalt(ii)tetraphenylporphyrintetrasulphonate [Co(tpps)] results in a... 

In a similar way, Norman et al. [331] synthesized PMMA oligomers by ATRP. The methacrylic double bond of the resulting macromonomer was directly obtained by elimination of the terminal halogen by catalytic CTAs, such as 5,10,15,20-lclraphcnyl-21 Lf,23f/-porphine cobalt(II) [Co(tpp)]... 

Cobalt catalysts, mainly used in early studies of asymmetric hydroformylation, show only low effectiveness. Examples are bis[(S)-iV-a-methylbenzylsalicylaldimidato]cobalt(II) [Co(R )-(Sal)2] or CoL2 [L = (S -N-a-methylbcnzylsalicylaldiminc], prepared in situ from (Sl-V-a-mcthylbcn-zylsalicylaldimine and octacarbonyldicobalt21,131. In situ formation of chiral cobalt catalyst with Co2(CO)8 or HCo(CO)4 is also achieved with the chiral diphosphane Diop129. 

Ilinitch et al. [13, 14] have studied the catalytic oxidation of sulfides. For this reaction, macroporous polymeric membranes, impregnated with a sodium salt of tetra(sulfophthalocyanine)cobalt(II) (Co-TSPC), were used. The MR utilized included macroporous membranes and operated in a flow-through configuration. 

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