Anions as ligands

As shown in Scheme 4-6, the reaction proceeds via a Ti(IV) mixed-ligand complex A bearing allyl alkoxide and TBHP anions as ligands. The alkyl peroxide is electrophilically activated by bidentate coordination to the Ti(IV) center. Oxygen transfer to the olefinic bond occurs to provide the complex B, in which Ti(IV) is coordinated by epoxy alkoxide and r-butoxide. In complex B,... 

Substituted dithioformate anions as ligands R C(S)S are usually called dithiocarbamates (R = R2N), alkyl and aryl dithiocarbonates or xanthates (R = RO), alkyl and aryl trithiocar-bonates or thioxanthates (R = RS). Dithioacid anions (R = alkyl, aryl) have been rarely used as ligands of nickel(II) because of their instability. Structural properties of selected nickel(II) complexes with substituted dithioformate, dithiolene and related ligands are shown in Table 90. 

In this way the symmetric and asymmetric bonding of the 0X0 anions as ligands to the copper(II) ion may be considered responsible for a significant range of the six- to nine-coordinate geometries of the copper(II) ion. 

Since 1961 [20], determination of the composition of complex species present in an anion-exchanger phase has been sought through the analysis of equilibrium distribution measurements between resins and solutions. The distribution ratio of a metal ion, M , defined as the rado of total concentrations of the metal in the two phases of a system containing a monovalent anion as ligand, L, can be represented by... 

Cerium(IV) forms double salts readily, the best-known one being cerium(IV) ammonium nitrate, CetNOj NH Oj. Although many complex cationic and anionic cerium(IV) species are present in solution, few have been isolated, and these are mostly with anions as ligands. Since the 4f transition elements often form complexes with oxygen compounds, it is possible to prepare Ce(lV) complexes with phosphine oxides or 2,2 -bipyridine 1,1 -dioxide.1-3... 

There are now at least a dozen synthetic routes to metallocarboranes including (i) coordination using nido-carborane anions as ligands, (ii) polyhedral expansion reactions, (iii) polyhedral contraction reactions, (iv) polyhedral subrogation and (v) thermal metal transfer reactions. These first five routes were all devised by... 

The use of phosphacyclohexadienyl anions as ligands in homogeneous catalysis was also explored. As previously seen, either n- or c-complexes can be formed upon reaction with transition metal precursors depending on the substitution scheme of the phosphinine nucleus. Only one report deals with the catalytic activity of -complexes. In 2005, it was shown that the rf-Rh(I) complex 120 displays a very good catalytic activity in the hydroformylation of terminal and internal olefins. Very high conversion yields and TON were obtained in the hydroformylation of... 

The methods based on complex formation may be classified into two groups on the basis of the nature of the complex species formed (i) Metal complexes with the analyte anion as ligand (ii) Ion-pair compounds with the analyte anion as counter ion. 

Group As cation As anion As ligand organic compounds... 

It was found while studying the mechanism of electron transfer (ET) across the interface between two immiscible liquids that specific anion adsorption occurs at the octane-water interface in the presence of metalloporphyrins. This adsorption increases in the order of Cl , Br , I , and is caused by coordinative bonding of the anions as ligands of the porphyrin metal atoms. 

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