1,10-phenanthroline type ligands

Il)cycles formed with 2,2 -bipyridine or 1,10-phenanthroline type ligands to give a variety of target compounds (Scheme 18). These syntheses are more feasible than previous, where the complexes cis-[RuCl2(bpy)2] or fRuCl .(tpy)] have been used to cyclometalate 2-phenyl-pyridine and its derivatives (230-233). A bunch of diverse compounds have been prepared in good yields. Crystal structures of some of them are shown in Fig. 21 and their useful properties are summarized in Table IX. 

This methodology was later extended to aromatic imines using 1,10-phenanthroline-type ligands, yielding selectively the monoalkylated product (Scheme 19.94) [137]. 

Special features strongly related to the compactness of the phenylene-bridged knots were also observed during the photophysical studies. All die compounds, as usual for copper complexes with phenanthroline-type ligands [116, 117], exhibit MLCT luminescence in CH2C12 at room temperature. Only one emission band, assigned to the lowest MLCT excited state, is observed even for the complexes con-... 

A considerable amount of work has focused on understanding die photophysical behavior of the halo analogue complexes ReX(CO)3(diimine). These complexes, where the diimine is a bipyridine- or a phenanthroline-type ligand, show... 

The versatility of the structural types possible for 1,10-phenanthroline ligands is exemplified in a review article on metal-to-ligand charge-transfer (MLCT) excited states of copper(ll) bis-phenanthroline coordination compounds, where 14 different 1,10-phenanthroline-based ligands were discussed (Figure 2) <2000CCR243>. 

By redesigning the above acyclic podand-type ligand 3 into a cyclic cryptate, the issue of stability can be resolved resulting in kinetically stable complexes (Scheme 4) [102]. The Tb(III) and Eu(III) complexes of cryptate 5 show an increase in lanthanide emission lifetimes of 0.72 ms and 0.41 ms, respectively, upon excitation at 310 nm. Similar results are found with the phenanthroline analogue 6 with Eu(III). A large number of modifications of these cryptates have been reported, all showing enhancements in the lanthanide ion emission [103-106]. 

Rare Earth Complexes with 1,10-Phenanthroline (15) Type Ligands... 

A Cu(II) complex with a bipyridine-type ligand (Cu-4) is effective in the controlled polymerization of styrene and acrylates in the presence of Al(0-i-Pr)3, which most probably serves as a reducing agent of Cu(II) into Cu(I).93-94 A fluoroalkyl-substituted bipyridine ligand (L-7) was also employed in supercritical carbon dioxide for the polymerization of fluorinated acrylates and methacrylates.95 Similar pyridine-based bidentate ligands, 1,10-phenanthroline and its... 

Rate parameters for the reaction of nickel(II) with pyridine, bipyridine, phenanthroline, and terpyridine are available [118] for dimethyl-sulphoxide and acetonitrile solvents along with similar data for terpyridine in methanol and ethylene glycol (Table 12). To test whether or not substitution is normal in type, ligand substitution rate coefficients (fej) are compared with the respective solvent exchange rates (fes) by means of a ratio R defined as... 

Regarding determinations of a single species, iron, copper, and aluminum are the metal ions most frequently determined. The reactivity of iron(II) toward ferroin-type ligands (1,10-phenanthroline, 2,2 -bipyr-idyl, ferrozine, etc.) is the basis for a munber of methods. The special interest of aluminum can be ascribed to its fluorescent chelates, which allow the highly sensitive kinetic determination of this metal ion. 

Besides the application of amine extractants as described above, there are numerous examples of the use of phenanthroline- and oxine-type ligands as extractants, both primary and secondary. Results relating to their application to lanthanide separations have been reviewed by Preiser (1988). Selected examples of their use in lanthanide/ actinide separation are presented below in the discussion of soft-donor ligands (section 8). 

Type of reaction C-N bond formation Reaction conditions DMF/EtsN, room temperature Synthetic strategy Sequential three-component one-pot reaction Catalyst Cu(OAc)2.H20, 1,10-phenanthroline (as ligand)... 

Chiral Phenanthrolines in Asymmetric Catalysis. Synthetic modifications on the Phenanthroline core can provide access to highly valuable chiral phenanthroline derivatives with important applications in asymmetric catalysis (Scheme 1). For example, LI has been utilized in copper-catalyzed allylic oxidations, L2 in palladium-catalyzed allylation reactions, and L3-type ligands in rhodium-catalyzed enantioselective hydrosilylation reactions of acetophenone. ... 

There are more examples of a second type in which the chirality of the metal center is the result of the coordination of polydentate ligands. The easiest case is that of octahedral complexes with at least two achiral bidentate ligands coordinated to the metal ion. The prototype complex with chirality exclusively at the metal site is the octahedral tris-diimine ruthenium complex [Ru(diimine)3 with diimine = bipyridine or phenanthroline. As shown in Fig. 2 such a complex can exist in two enantiomeric forms named A and A [6,7]. The bidentate ligands are achiral and the stereoisomery results from the hehcal chirality of the coordination and the propeller shape of the complex. The absolute configuration is related to the handness of the hehx formed by the hgands when rotated... 

In conforming to an expected linear free energy relationship, the Ce(lV) oxidation of various 1,10-phenanthroline and bipyridyl complexes of Ru(II) in 0.5 M sulphuric acid are consistent with the requirements of the Marcus treatment . The results for the oxidation of the 3- and 5-sulphonic-substituted ferroin complexes by Ce(IV) suggest that the ligand does not function as an electron mediator, and that the mechanism is outer-sphere in type. Second-order rate coefficients for the oxidation of Ru(phen)j, Ru(bipy)3, and Ru(terpy)3 are 5.8x10, 8,8 X 10, and 7.0 x 10 l.mole . sec, respectively, in 0.5 M H2SO4 at 25 °C a rapid-mixing device was employed. 

Molecular Metal Complexes Compounds of this type do not form delocalized electronic bands in the sohd state, and their color is due to intramolecular electronic transitions. Many complexes of transition metals with organic ligands belong to this class. complexes with phenanthroline (red/colorless) and Ru + + with 2,2 -... 

Some other examples of metal-catalyzed substitutions are given in Scheme 11.10. Entries 1 to 3 are copper-catalyzed reactions. Entry 1 is an example of arylation of imidazole. Both dibenzylideneacetone and 1,10-phenanthroline were included as ligands and Cs2C03 was used as the base. Entry 2 is an example of amination by a primary amine. The ligand used in this case was (V,(V-diethyl sal icyl amide. These conditions proved effective for a variety of primary amines and aryl bromides with both ERG and EWG substituents. Entry 3 is an example of more classical conditions. The target structure is a phosphodiesterase inhibitor of a type used in treatment of asthma. Copper powder was used as the catalyst. 

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