2,2 -Bipyrimidine, ligand structure

Baker, M.H., Dorweiler, J.D., Ley, A.N., etal (2009) Structure and emission spectra of dinuclear landianide(lll) P-diketonate complexes widi abridging 2,2 -bipyrimidine ligand. Polyhedron, 28, 188—194. 

Rate and equilibrium constant data, including substituent and isotope effects, for the reaction of [Pt(bpy)2]2+ with hydroxide, are all consistent with, and interpreted in terms of, reversible addition of the hydroxide to the coordinated 2,2 -bipyridyl (397). Equilibrium constants for addition of hydroxide to a series of platinum(II)-diimine cations [Pt(diimine)2]2+, the diimines being 2,2 -bipyridyl, 2,2 -bipyrazine, 3,3 -bipyridazine, and 2,2 -bipyrimidine, suggest that hydroxide adds at the 6 position of the coordinated ligand (398). Support for this covalent hydration mechanism for hydroxide attack at coordinated diimines comes from crystal structure determinations of binuclear mixed valence copper(I)/copper(II) complexes of 2-hydroxylated 1,10-phenanthroline and 2,2 -bipyridyl (399). 

Fig. 3. The monodentate coordination of the squarate ligand to Cu(II) in the structure of [Cu(2,2 -bipyrimidine)(C404)(H20)3] 2H2O reported by Castro et al. (66).

In a similar vein, self-assembly of the dimethyl derivative of the corresponding tris(bipyridine) ligand in the presence of bipyrimidine and copper(I) spontaneously generates the new ladder structure 49. A similar tetranuclear structure derived from the corresponding bis(bipyridine) ligand has also been reported. 

Two of the classical bis-nitrogen ligands to assemble porphyrins (predominantly zinc metallated) are the bidentate l,4-diazabicyclo[2.2.2]octane (DABCO) and 4,4 -bipyridine (bipy). Other di-topic nitrogen-ligands studied include hydrazine, 4,4 -bipyrimidine, diaza-pyrene, 5,5 -dicyano-2,2 -bipyri-dine, perylene-bisimide, extended bipyridine units and non-covalently linked di-pyridyl ligands via bipy-metal interactions. The formation of various bis-porphyrin and multiporphyrin assemblies using these versatile ligands were studied in detail by Sanders, Anderson, Hunter, Branda and many others. The structures of the supramolecular multi-porphyrin architectures are schematically represented in Fig. 9. 

Decurtins, S., Schmalle, H. W., Schneuwly, R., Zheng, L.-M., Ensling, J., and Hauser, A., Synthesis, crystal structure, and optical and magnetic properties of a novel two-dimensional copper(II) network formed conjointly with /x-bipyrimidine, /x-oxalato, and /x-chloro ligands, Inorg. Chem., 34, 5501-5506 (1995). 

In approach (iii), polyimine ligands such as 2,2 -bipyrimidine, 2,2 -bipyrazine with lower n levels are employed to shift the energies and the redox potentials of the resulting complexes. Figure 2 shows the structure of some of the polyimine ligands that have been widely used in this context. Table 5 presents some representative data on the turning of properties in this... 

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