Dinucleating ligands

Di- and Oligonuclear Ni11 Complexes with Compartmental Dinucleating Ligands 424... 

Di- and oligonuclear complexes with open-chain alkoxo- or phenolato-based dinucleating ligands 427... 

In most cases the Ni11 ions are low spin and in square planar coordination environment. Dinickel(II) complexes [Ni2L(pyrazolate)] of dinucleating ligands like (725) and dinickel complexes such as (726) feature two nearly reversible electrode processes at very negative potential,... 

Di- and oligomtclear complexes with dinucleating ligands incorporating diazine, diazole, and triazenido bridging units... 

Bis(2-pyridyl)-l,2,4,5-tetrazine (bptz, (846)) can act as a dinucleating ligand towards Nin. 2056 From the reaction of [Ni(MeCN)6]2+ with bptz, tetranuclear squares [Ni4(bptz)4(MeCN)8]8+ or metallapentagons [Ni5(bptz)5(MeCN)10]10+ have been isolated, depending on the choice of the templating counteranion (C1C)4 or BF4- vs. SbF6-).2057,2058... 

As a part of their efforts to model dinuclear copper active sites, Reed and co-workers reported, using alkoxo-based dinucleating ligands, a few very interesting systems from the viewpoint of magnetostructural correlations (379) (TBP Cu-Cu 3.325A 2.1 278cm ), (380) (TBP ... 

The ligands H2L19, H2L23-H2L31 are effective dinucleating ligands towards various divalent metal ions. Complexes of composition [Mn2(LR)(p-L )]+ (M — Mn, Fe, Co, Ni, Zn, Cd)... 

Schneider and coworkers have reported on the hydrolysis of BNPP by Pr(III) in the presence of the potentially dinucleating ligand 45 [66]. An aqueous solution of a 2 1 Pr(III)/45 complex which was prepared in organic solvent is 70 times more reactive toward BNPP than the metal salt alone at pH 7.0 and 323 K. The rate enhancement over spontaneous hydrolysis is 5 x 106-fold. The authors suggest cooperation of two metal ions, but there is no direct evidence for the presence of a dinuclear-Pr complex in aqueous solution. Catalytic turnover was not demonstrated. 

The application of dinuclear metal catalysts to the Kharasch-Sosnovsky reaction is mechanistically intriguing due to their illustrated role in mediating biological oxidations (119). Fahmi (120) examined a variety of dinucleating ligands with Cu(MeCN)4PF6 as catalysts in the allylic oxidation of cyclohexene, Eq. 102. In these studies, early results have been inferior to those obtained from bis(oxa-zoline)-copper catalysts. 

Square planar dinuclear complexes of type (363) formed by dinucleating ligands which have no unsaturated bonds have also been reported.2599... 

More examples of dinuclear homo- and hetero-metallic complexes which have been prepared with some dinucleating ligands are reported in Table 102 together with some physicochemical properties and preparative routes. 

Table 102 Nickel(II) Complexes with some Dinucleating Ligands...

A typical example of the more complex reactions that may occur when aromatic compounds react with dioxygen in the presence of copper salts is seen in Fig. 9-30. When solutions of the hexadentate ligand 9.14 react with copper salts and dioxygen, a complex of a new ligand is obtained. The new phenolic compound that is formed acts as a dinucleating ligand and its dinuclear copper(n) complexes turn out to be effective oxygenation catalysts for other substrates. 

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