Imidazole ligand, monodentate

Heptanuclear Trigonal Prismatic Clusters Stabilized by Monodentate Imidazole Ligand... 

In 2013, the rhodium-based protocol was extended to a ruthenium catalyst modified with a monodentate 2-phosphino-substitued imidazole ligand in the hydroaminomethylation of2-octene (Scheme 5.32) [150]. 

Diamine chelate complexes are more stable than the monodentate amine heterocycles and, therefore, can be studied under physiological conditions. The imidazole complexes are unstable in aqueous solution and decompose rapidly to technetium oxide hydrate. Six-membered ring chelates are significantly less stable than five-membered ones. Lesser flexibility of the ligand, such as 1.2-diamino-cyclohexane, parallels somewhat lower stability of the complex [53] ... 

The substitution of [Tc02(py)4]" in DMF or DMF/MeOH mixtures with monodentate ligands such as cyanide, imidazole, or multidentate chelators such as cyclam and en has been studied. For all the ligands, complete replacement of the pyridines occurs. A dependence on the added alcohol is observed, whereas there is little or no dependence on the nature of the incoming ligand. The... 

Imidazoles act as monodentate donors for palladium, forming complexes [PdC LJ and [PdLJCfe.216"221 Both cis and trans isomers of the former complexes have been isolated and their antitumour properties investigated.216 A polymeric compound [Pd(imidazolato)2] has also been isolated which contains bidentate bridging imidazolato ligands. 

Chelation sometimes does not take place automatically, as illustrated by the coordination of histamine, 4-(2-aminoethyl)imidazole (19 R = H). It appears to tautomerize and coordinates with the non-chelating nitrogen, whereas the NH2 group is protonated, so that a monodentate ligand (in fact a 4-substituted imidazole) coordinates to the metal, in this case Ni with NCS- anions in the compound [Ni(NCS)4(hamH)2] (hamH = histaminium cation).70... 

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