Ligands phenanthroline-containing

The phenanthroline-containing ligands 66a and b (Chart 5.19) have been incorporated into Cu complexes and electropolymerized [74]. The geometry at the Cu" " center in poly-[Cu(66a)2] and poly-[Cu(66b)2] was probed using X-ray absorption. It was shown that the Cu centers in poly-[Cu(66b)2] contribute to the conductivity of the film. Removal of the copper with cyanide causes the structure of the polymer to irreversibly collapse in poly-[Cu(66a)2], whereas the presence of the hexyl chains in poly-[Cu(66b)2] help to maintain an intact polymer structure after the removal of the metal. 

Pyridine-based N-containing ligands have been tested in order to extend the scope of the copper-catalyzed cyclopropanation reaction of olefins. Chelucci et al. [33] have carefully examined and reviewed [34] the efficiency of a number of chiral pyridine derivatives as bidentate Hgands (mainly 2,2 -bipyridines, 2,2 6, 2 -terpyridines, phenanthrolines and aminopyridine) in the copper-catalyzed cyclopropanation of styrene by ethyl diazoacetate. The corresponding copper complexes proved to be only moderately active and enantios-elective (ee up to 32% for a C2-symmetric bipyridine). The same authors prepared other chiral ligands with nitrogen donors such as 2,2 -bipyridines 21, 5,6-dihydro-1,10-phenanthrolines 22, and 1,10-phenanthrolines 23 (see Scheme 14) [35]. 

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. 

Non-heme iron catalysts containing multidentate nitrogen ligands such as pyri-dines and amines have been studied by various groups [42a, 52-54], Jacobsen and coworkers presented an MMO mimic system for the epoxidation of aliphatic alkenes in which the catalyst self-assembles to form the active species [54] (Scheme 3.5). Interestingly, small amounts of an additive (one equivalent of acetic acid) increased the catalytic performance, presumably due to the intermediate formation of peroxya-cetic acid [55, 56]. The reactions proceeded quickly even with terminal aliphatic alkenes, which are generally considered difficult substrates. Another catalyst system available for the epoxidation of terminal alkenes uses phenanthroline as ligand [57]. 

Both molecules contain the same donor atom configuration. Diacetyldioxime is highly specific for nickel and palladium. If the same donor atom configuration is incorporated into a heterocyclic system, as in the phenanthrolines, the ligands become specific for copper and iron. This specificity can be directed by choice of the substituents R in the molecule if R = H, the ligand is specific for iron with R = CH3 and/or C 6H5. the ligand is copper-specific. 

A 1,10-phenanthroline-containing polyamine macrocycle (78) was designed to complex with Zn2+ ion and, because of the rigidity of the phenanthroline moiety, leave some free binding sites at the metal for ligands such as water, which easily depro-tonate to give stable hydroxo species. The hydrolysis of methyl acetate in the gas phase by such a monohydroxy-Zn(II) complex [Zn(78)(OH)]+ has been investigated by quantum mechanical procedures and some pathways delineated.78... 

Scheme 31 Proposed mechanism for LNA hydrolysis mediated by a zinc complex of a phenanthroline-containing polyamine ligand.

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 ... 

Five-coordinated metal centers have never been used as templates for synthesizing [2]catenanes. In order to make a 5-coordinated catenane, zinc(II) seemed to be an appropriate template. In fact, this cation forms stable pentacoordinated complexes with nitrogen-containing ligands. A terpy (terpy = 2,2 6, 2"-terpyridine) and a phen (phen= 1,10-phenanthroline) form a convenient set of ligands. ... 

Palladium forms fewer carbonyl clusters than nickel and platinum. However, palladium clusters containing ligands possessing strong a donor properties such as phosphines, 2,2 -bipyridine and 1,10-phenanthroline... 

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