Bipyridine donor ligand

The most frequently reported mixed C/N-donor ligands are the 2-phenylpyridine anion, ppy (170), orthometalated 2,2 -bipyridine, C3N bpy (171), and derivatives, for example (172). 

The presence of zinc with bidentate nitrogen donor ligands in the formation of novel composite materials by hydrothermal reactions has been studied. A zinc-containing one-dimensional material, [Zn(phenanthroline)Mo04] was isolated from molybdate, and from vanadium oxide in the presence of zinc 2,2 -bipyridine [Zn(2,2,-bipyridine)2V40i2] was obtained.212,213... 

A A -coordi nation was found in the zinc complex of 2,2 -dipyridyl diselenide, [ZnLCl2].214 The tridentate ligand 6-(2-aminophenyl)-2,2 -bipyridine contains two pyridyl and one aniline donor ligand to form a complex of the form [ZnL2]2+. The X-ray structure shows a distorted octahedral metal center with each ligand twisting from planar to accommodate the meridional binding.215... 

Triply bridging carbonates between three zinc centers have been identified in nine different X-ray structures deposited in the CSD 458,461,465-467 For example, a binuclear ft-OH zinc complex with a tetradentate /V-donor ligand absorbs atmospheric carbon dioxide to a triply bridged carbonate.468 Examples are also known where the metal atoms are in varying coordination environments. The complex cation [Zn3(bipyridine)6(/U3-C03)(H20)2]4+ contains one penta- and two hexacoordinate zinc centers.469 A tetrapodal compartmental ligand forms a tetrameric complex with zinc that contains the carbonate bridging between three of the four zinc centers.470... 

Tetramethyl- or tetraphenyl- (cyclobutadiene)nickel dihalides undergo reductive ligand substitution with nitrogen donor ligands such as 2,2 -bipyridine or 1,4-diaza-1,3-dienes with the addition of sodium metal237. The 2,2/-bipyridyl ligand is readily displaced and reaction of this complex with a variety of olefins and alkynes leads to cycloaddition reactions with the cyclobutadiene ligand. 

The lowest energy MLCT transition of Ru polypyridyl complexes of the type tris-[Ru(4,4/-dicarboxy-2,2/-bipyridine)3] (1), can be lowered so that it absorbs more in the red region of the visible spectrum by replacing one 4,4/-dicarboxy-2,2/-bipyridine (dcbpy) with two thiocyanate donor ligands [Ru(dcbpy)2(NCS)2] (2). In complex 2, the two 4,4/-dicarboxylic acid 2,2 -bipyridine ligands pull while the two thiocyanate donor ligands push electrons. The oxidation potential of the complex 2 is 0.85 V vs. SCE, which is cathodically shifted significantly (0.65 V vs. SCE) compared to the homoleptic type of complex 1, which shows Ru(III/II) couple at 1.5 V vs. SCE. Thus, the... 

Transition-metal ions are employed as nodes and bifunctional ligands as spacers. Commonly used spacer ligands are pseudohalides such as cyanide, thiocyanate, and azide, and N-donor ligands such as pyrazine, 4,4 -bipyridine, and 2,2/-bipyrimidine. Besides discrete supermolecules, some one-, two-, and three-dimensional architectural motifs generated from this strategy are shown in Fig. 20.3.9. 

The crystal structure and photophysics of arhenium(I) bipyridine 9-ethylguanine complex [Re(bpy)(CO)3(EtG)]+ (2) have been reported by Thorp and co-workers [19]. In CH2C12 solution, the complex emits at ca. 600 nm with a lifetime of 0.17 ps and an emission quantum yield of 0.054. Electrochemical measurements reveal that EtG is similar electronically to electron-rich pyridines, such as py l-NMe, and py-4-NH2, and is a much better n-donor ligand than pyridine, trimethylphosphine, and acetonitrile. 

At the moment we are investigating the influence of different donor ligands on the structural features especially of the rubidium and cesium derivatives. Such adducts are prepared by adding the corresponding ligand to a suspension of hypersilyl rubidium 4 or cesium 5 in npentane until a clear solution is obtained. Although, in some cases side-reactions occur, such as deprotonation (diphenylmethane) or reduction (pyrene, bipyridine). In addition to the toluene solvates 4a and Sa already mentioned above, the only two crystalline derivatives isolated so far are the adducts with THF as a typical cr-donor and with biphenyl as a further Ji-donor (Fig. 6 and Fig. 7). 

Bis-oxo-Ru(VI) complexes containing nonlabile oxidation-resistant nitrogen-donor ligands such as pyridine, bipyridine. 

SUver(n) forms stable complexes with a variety of nitrogen donor ligands such as pyridine, substituted bipyridine, phenanthrohne, or citrazinic acid. They are usually obtained by reaction of a silver(I) salt with peroxodisulfate in the presence of the ligand. ... 

Numerous complexes of niobium(IV) and niobium(V) halides with various nitrogen-donor ligands have been reported in the literature. The products obtained from these reactions are critically dependent upon the reaction conditions. " Tetrakis(isothiocyanato)bis(2,2 -bipyridine)niobium(IV) can be prepared directly from the hexakis(isothiocyanato)niobate(IV) complex or by the reduction of the hexakis(isothiocyanato)niobate(V) ion according to the published method. This method can also be extended to the preparation of other analogous complexes. 

The effect of the salt bridge on electron transfer can be determined directly by a comparative kinetics study of a D—[amidinium-carboxylate]—A complex and its switched interface D—[carboxylate-amidinium]—A congener. We have reported such a study for a supramolecular series of complexes where the donor is a ruthenium(II) polypyridyl with one bipyridine (bpy) ligand modified by either amidinium or carboxylate and the acceptor is the complementarity modified 3,5-dinitrobenzene (DNB) [162, 163]. The same donor-acceptor pair bridged by a symmetrical dicarboxylic acid interface has also been examined. 

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