2,2 -Bipyridyl or 1,10-phenanthroline

The dimethylplatinum(II) complexes having chelate nitrogen ligands, [PtMe2(N-N)] (N-N = 2,2 -bipyridyl or 1,10-phenanthroline) (46) reacted with alcohols (ROH, R = Me, Et, Pr) to give hygroscopic and basic platinum(IV) complexes. 

Other important ligands include those based upon the diazafluorene structure <2000JST91>. It has been shown that the coordination behavior of complexes containing the diazafluorene ring system is quite different to that of the parent 2,2 -bipyridyl or 1,10-phenanthroline systems, and evidence for unsymmetrical chelation has been observed <1998POL2463, 1996IC2253>. 

Mixed dinuclear complexes of tartrates and 2,2 -bipyridyl or 1,10-phenanthroline and chromium(III) have been prepared 934,935 the typical structure is illustrated below (213). Stereochemical correlations have been carried out by oxidatively cleaving the tartrate bridge (214,215).936 The crystal structure of sodium hydrogen bis(//-meso-tartrato)bis(2,2 -bipyridyl)dichromate(III) heptahydrate has been reported.937... 

Complex cations containing 2,2 -bipyridyl or 1,10-phenanthroline as ligands, particularly those of ruthenium, have been encountered in Section 57.3.2.2(iii). However, the bis-chelate complex was generally anchored to a polymer chain by coordination to pendant pyridyl groups although the possibility of electrochemical polymerization of a 4-vinyl-4-methyl-2,2 -bipyridyl was considered.59 In this section, some miscellaneous examples of the role of bipyridyl and phenanthroline complexes are considered. 

Numerous perfluoroalkyl-substituted arenes have been prepared by the coupling of aryl iodides or bromides with perfluoroalkyl iodides in the presence of copper bronze in a dipolar aprotic solvent at elevated temperatures. Perfluoroalkyl bromides and chlorides can be utilized in similar reactions provided a bidentate ligand such as 2,2 -bipyridyl or 1,10-phenanthroline is added 199, 278). Perfluoroalkylcopper reagents are believed to be intermediates in the couplings 200, 201). 

Hence, the first clearcut evidence for the involvement of enol radical cations in ketone oxidation reactions was provided by Henry [109] and Littler [110,112]. From kinetic results and product studies it was concluded that in the oxidation of cyclohexanone using the outer-sphere one-electron oxidants, tris-substituted 2,2 -bipyridyl or 1,10-phenanthroline complexes of iron(III) and ruthenium(III) or sodium hexachloroiridate(IV) (IrCI), the cyclohexenol radical cation (65" ) is formed, which rapidly deprotonates to the a-carbonyl radical 66. An upper limit for the deuterium isotope effect in the oxidation step (k /kjy < 2) suggests that electron transfer from the enol to the metal complex occurs prior to the loss of the proton [109]. In the reaction with the ruthenium(III) salt, four main products were formed 2-hydroxycyclohexanone (67), cyclohexenone, cyclopen tanecarboxylic acid and 1,2-cyclohexanedione, whereas oxidation with IrCl afforded 2-chlorocyclohexanone in almost quantitative yield. Similarly, enol radical cations can be invoked in the oxidation reactions of aliphatic ketones with the substitution inert dodecatungstocobaltate(III), CoW,20 o complex [169]. Unfortunately, these results have never been linked to the general concept of inversion of stability order of enol/ketone systems (Sect. 2) and thus have never received wide attention. 

Standard titration techniques, using indicators [4,5,13] with 2-butanol as the titrant, have greater error (3 standard deviations = 1-5% of value), but usually this is still acceptable. The real advantage of these indicator methods is that virtually no capital investment is required for the equipment. The equipment for the more accurate potentiometric titration method can cost upward of 15,000 dollars. This is why titrations using 2,2 -bipyridyl or 1,10-phenanthroline are more prevalent in the literature. 

Another interesting application is the study of the kinetics of thermodynamically unfavourable oxidations of a series of iron, ruthenium and osmium complexes with 2,2 -bipyridyl or 1,10-phenanthroline (ML32 ") (equation 28). If E ° for is more positive than E° for the... 

The In1 halides react with refluxing acetylacetone (= Hacac) to give a mixture of In(acac)3 and InX2(acac).561 The latter could not be isolated in pure form, but some crystalline derivatives could be produced by reaction with N-donors, e.g. [InX2(acac)(L—L)],EtOH (L—L = 2,2 -bipyridyl or 1,10-phenanthroline) or [InX2(acac)L2],EtOH (L = py or [2Hs]py). These are all apparently six-co-ordinate, with In02X2N2 units, but no decision could be arrived at concerning the symmetry of these. 

The kinetics of oxidation of six iron(ii) complexes containing 2,2 -bipyridyl or 1,10-phenanthroline as ligands have been studied, the mechanism postulated being ... 

Base hydrolysis (and in a very few cases attack by cyanide or other nucleophiles) on a number of coordination compounds with the ligand C=N. Often, the ligand is part of an aromatic ring. For instance, for all the base hydrolyses such as Eq. (66) (substitution of an N-heterocyclic ligand LL, usually 2,2 -bipyridyl or 1,10-phenanthroline, by hydroxide), although there can obviously be no conjugate base formed by protonic dissociation (there are no acidic protons) the rate equations are nevertheless as in Eq. (67) ... 

Some papers describe the grafting on polymers containing bond metal complexes on the surface of organic polymers polyethylene-graft-poly(methylvinylketone)/Schiff base with 2-aminophenol 27 [6,37,155] or salicylaldehyde hydrazide [156], polyethylene-graft-poly (vinyl-1,3-diketone) [157], polytetrafluorethylene-graft-poly(acrylate)-complexes with 2,2 -bipyridyl or 1,10-phenanthroline [157]. 

The first example of pseudobase formation with coordinated pyridine, as opposed to 2,2 -bipyridyl or 1,10-phenanthroline and their derivatives, has been suggested for the reaction " in equation (6). This claim has been... 

Upon reaction with powerful bidentate nitrogen bases, e.g. 2,2 -bipyridyl or 1,10-phenanthroline, the halogen atoms are removed (as anions) from halogen mono- and diorganosilane, leaving these as hexacoordinated silicon cations, e.g. in the preparation of bis(2,2 -bipyridylyl)halo-organosilanonium iodide [522] (Eq. 3.278) ... 

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