Acetato complexes

The formation of a single complex species rather than the stepwise production of such species will clearly simplify complexometric titrations and facilitate the detection of end points. Schwarzenbach2 realised that the acetate ion is able to form acetato complexes of low stability with nearly all polyvalent cations, and that if this property could be reinforced by the chelate effect, then much stronger complexes would be formed by most metal cations. He found that the aminopolycarboxylic acids are excellent complexing agents the most important of these is 1,2-diaminoethanetetra-aceticacid (ethylenediaminetetra-acetic acid). The formula (I) is preferred to (II), since it has been shown from measurements of the dissociation constants that two hydrogen atoms are probably held in the form of zwitterions. The values of pK are respectively pK, = 2.0, pK2 = 2.7,... 

Cinellu, M.A., Minghetti, G., Pirma, M.V., Stoccoro, S., Zucca, A. and Manassero, M. (2000) Gold(lll) derivatives with anionic oxygen ligands mononuclear hydroxo, alkoxo and acetato complexes. Crystal structure of [Au(bpy)(OMe)2][Pp6]. Journal of the Chemical Society, Dalton Transactions, (8), 1261. 

Scheme 6-1 Preparation of Flydrido(acetato) complexes by metathesis reactions...

The reactions of a neutral 10 as well as a cationic dihydrido(acetato)osmium complex 12 with acetylenic compounds were examined (Scheme 6-17) [11-13]. A vinyU-dene 99, an osmacyclopropene 100, or a carbyne complex 101 were obtained, depending on the starting hydrido(acetato) complexes or the kind of acetylene used. In any case, the reaction proceeded by insertion of a C C triple bond into one of the two Os-H bonds, but the acetato ligands do not take part in the reaction and act as stabilizing ligands. 

Example 1 NIS Studies of an Fe(III)-azide(Cyclam-acetato) Complex... 

The Fe(III)-azide(cyclam-acetato) complex, as seen earlier, serves as a precursor for generation of the superoxidized Fe(V)-nitrido(cyclam-acetato) complex by means of photolysis with 420 nm light [63, 108] (Fig. 5). 

The reactivity of three-coordinate [BpBut]ZnR is summarized in Scheme 12. The Zn-C bonds of [BpBut]ZnR are readily cleaved by H20 and MeC02H to give the hydroxo and acetato complexes [BpBut]Zn(/i-OH) 3 and [BpBut]Zn(7j2-02CMe), respectively. The structure of [BpBut]Zn(/u-OH) 3, determined by x-ray diffraction, is a cyclic trimer, with Zn-OH bond lengths in the range 1.89-1.99 A (Fig. 29). The... 

The electrochemical behaviour of this acetato complex has not been reported, but the analogous benzoato derivative [Mn402(C>2CPh)7 (bipy)2]+ in dichloromethane solution displays a quasireversible one-electron reduction to the corresponding neutral derivative MnnMn3in E°< = + 0.28 V vs. SCE) and a quasireversible one-electron oxidation to the corresponding dication Mn3mMnIV ( 4/ = +1.34 V).66... 

S. Chavan, D.Srinivas, and R. Ratnasamy, Structure and catalytic properties of dimeric copper(II) acetato complexes encapsulated in zeolite-Y, J. Catal. 192, 286-295 (2000). 

Thus, the reactivity of the methyl complexes 14a and 15 is rather similar to [ZnTp (CH3)] and [ZnTp (CH3)] (111,112). Most of the NMR signals of the acetato complex 17 are broad compared to those of [Zn(bd bpza)Cl]. These broad resonances suggest a kVk equilibrium of the carboxylato ligand. Two additional IR signals at 1633 cm and 1602 cm are assigned to Vas(C02) of the and bound acetato... 

The CO2 activation reactions seen for aluminum porphyrins are also observed for In(Por)Me (Por = OEP, TPP), which will insert CO2 in the presence of pyridine and under irradiation by visible light to give the acetato complex In(Por)OC(0)Me. The indium acetato product has been characterized by X-ray crystallography, whereas in the aluminum complex it was observed only by spectroscopy. An alternative synthesis of the acetato complex is by treatment of ln(Por)Cl by alumina and water, followed by acetic acid. For the indium and... 

This first section on Ru(Vl) dioxo complexes complexes concentrates on those with other 0-donor ligands periodate, tellurate and carboxylates. There is a review on ruthenium acetato complexes [552],... 

Ruthenium has a considerable propensity to form polynuclear complexes, particularly with carboxylate ligands which as bridging ligands span the Ru centres, sometimes accompanied by a bridging 0x0 ligand. Preparation and properties of bi- and tri-nuclear acetato complexes of Ru have been reviewed [552]. 

The slow rate of reduction of the acetato complex (0.18 M lsec. x) compared, for example, to the aquo complex (0.5 il/ 1sec. 1) is noteworthy (24), The acetato... 

The way AF decomposes into AI1% and AS+ is as remarkable as the slow rate of reduction of the acetato complex. Other results as well as those for the activation parameters give rise to questions. What is the origin of the very unfavorable entropy of activation W hy are Aand A5J so strongly affected by substitution at a site well removed from the reaction site (compare entries for benzoate and -chlorobenzoate in Table I) when the effect on the rate is so minor W hy don t the values of AS for the first three complexes in Table I change monotonously within the series ... 

Unfortunately, there are only five rate constants for simple acetato complexes reported (2, 8). However, a plot of the log of these rate constants vs. R. W. Taft s ( -parameter (7), which is a measure of electronic effects only, gives an extremely good correlation (Figure D). 

This salt is a white crystalline solid made by treating polonium (IV) hydroxide or chloride with dilute acetic acid. Its solubility in the latter increased from 0.2 mg (of Po210)/liter in 0.1 N acid to 82.5 mg/liter in 2 N acid, indicating complex ion formation. The acetato complex is colorless in solution and appears to be more stable than the hexachloro complex (11). 

Studies of the solubility of polonium(IV) in formic, acetic, oxalic and tartaric acids have provided evidence of complex formation,48 with the acetato complex emerging as more stable than the hexachloro anion. Other studies of the solubility of polonium(IV) hydroxide in carbonate49 and nitrate50 solution, together with investigations51 of the ion exchange behaviour of polonium(IV) at high nitrate ion concentration, have been discussed in terms of the formation of anionic complex species. 

Displacement of the thioaldehyde ligand was similarly observed when acetic acid was added to the dinuclear complex 112 (R = H, see Scheme 26) and the tris(acetato) complex [TifCECC -CsHs ] was formed.69... 

Tethered arene complexes can also be generated in the MeO-Biphep series in reactions that are not acid-promoted. Treatment of the bis(acetato) complex 70a with three equivalents of alkyllithium reagents gives the bis(alkyl) complexes 74a, 74b by cleavage of one of the Ru P bonds 72... 

Pruss, T., Macquarrie, D. J. and Clark, J. H. Cobalt-acetato complexes immobilised on PYPA-organomodihed silica a case study of different ways of immobilisation, J. Mol. Catal., A, 2004, 211, 209-217. 

The bisacetato ruthenium complex 28, on heating in 2-propanol, leads to the bridged hydrido dinuclear complexes 73 and 74. The bistrifluoroacetato complex 28 also leads to complex 73. The Tj2-acetato complex 39 was transformed in hot 2-propanol to another bridged hydrido derivative (75, arene = durene, mesitylene, p-cymene, hexamethylbenzene 60-70%). The introduction of alkyl substituents on the benzene ring is reflected by a shift of the p FI resonance toward high field (14,53). 

The acetato complex is a useful precursor for other species. In some reactions the bridges are partly or wholly displaced by other bridges, or monomeric osmium-(II), -(III) or -(IV) complexes are formed.105... 

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