Terpyridyl complexes

In the 2,2, 2"-terpyridyl complex [AuCl(terpy)]Cl2-H20, one chloride and the water molecule coordinate very weakly to the square planar [AuCl(terpy)]2+ ion.108... 

The infrared spectra of the mono-terpyridyl complexes have been analyzed. Sinha [307, 330—332] has found the breathing vibration of... 

Sinha [380] whilst examining the terpyridyl complexes of the rare earths found only a very slight increase of the e value for the 5Ln band (c 3) compared to that in the aquo ion (e = 2.36). The bLi transition in the Eu(Terp)Cl3 complex occurs at 25390 cm-1 as a small sharp peak whilst that for the Eu(Terp)2Gl3 complex is split into two components occuring at 25410 and 25340 cm-1 respectively. The broad electron transfer bands are superposed on the 5In transition and occur at 24460 and 24350 cm-1 for Eu(Terp)Cl3 and Eu(Terp)2Cl3 complexes respectively. 

Aspley CJ, Williams JAG (2001) Palladium-catalysed cross-coupling reactions of ruthenium bis-terpyridyl complexes strategies for the incorporation and exploitation of boronic acid functionality. New J Chem 25 1136... 

Baitalik S, Wang X, Schmehl RH. A Trimetallic mixed Ru(II)/Fe(II) terpyridyl complex with a long-lived excited state in solution at room temperature. J Am Chem Soc 2004 126 16304-5. 

Zhang D, Wu L-Z, Zhou L, et al. Photocatalytic hydrogen production from Hantzsch 1,4-dihydropyridines by platinum(II) terpyridyl complexes in homogeneous solution. / Am Chem Soc 2004 126 3440-1. 

Related to our work on the bipyridyl acetylides, we have also demonstrated that proper selection of the acetylide ligand makes possible the design of Ptn terpyridyl complexes that exhibit acetylide 3IL excited states [20]. The perylene complexes 3.7 and 3.8 do not display photoluminescence, however, indirect evidence that the triplet excited state is indeed populated was indicated through the sensitization of singlet oxygen. Transient absorption measurements (Fig. 7) confirmed that regardless of the polyimine ligand used, the lowest excited state in these molecules is 3IL localized in the perylenylacetylide moiety. It is clear in Fig. 7a and b that the identical features are observed in the absorption difference spectra of 3.7 and 3.8, whereas the difference spectrum of the phenylacetylide complex is clearly distinct, illustrative of the marked differences between 3IL and 3CT excited absorptions. 

Work on Ptn terpyridyl complexes has not been limited to just mononuclear systems. Yam and coworkers have also investigated complexes wherein two platinum centers are attached through alkynyl bridges more specifically they studied chromophores of the type f Hu. tpy )Ptf( =C)nI>tf Hu. tpy)]2+ (3.10) [65], These structures exhibit photoluminescence in both the solid state and in room temperature solutions, the latter assigned as 3CT in nature mixed with 3IL and 3LLCT character. 

Nitrogen is, after oxygen, the most frequently encountered donor atom in the coordination chemistry of osmium. There is a large and growing body of work on the ammine, pyridine, ethylenediamine and porphyrin complexes, but the most popular and rapidly growing field of study at the present time is that of the polypyridyls , the 2,2 -bipyridyl, 1,10-phenanthroline and 2,2,2,6 - terpyridyl complexes of the metal. 

It has now become fashionable to call the bipyridyl, phenanthroline and terpyridyl ligands, and substituted forms of these, the polypyridyls (see Table 9). In section 46.4.4.6.i. we consider the first two together, while terpyridyl complexes are dealt with in Section 46.4.4.6.iii. 

Table 9 Properties of Bipyridyl, Pbenanthroline and Terpyridyl Complexes...

As a tridentate conjugated ligand this would be expected, like 2,2 -bipyridyl and 1,10-phenanth-roline, to stabilize osmium(II) and this is indeed the case, with most of the reported complexes containing divalent osmium. The unsubstituted bis complex [Os(terpy)2]2+ is remarkably stable. It seems likely that terpyridyl complexes of osmium(II) are good candidates for further investigation as photosensitizers, having so far received less attention than the corresponding bipyridyl or phenanthroline species. 

A number of substituted terpyridyl complexes have been reported, most of them made by Dwyer and co-workers in 1964.192 Preparative routes are given in Scheme 5. 

A number of substituted osmium(III) terpyridyl complexes are known (see Scheme 5). 

Reduction of [V(bipy)3]l2 with the metals Mg or Zn yields the complex [V(bipy)3], which will undergo ftulher reduction by lithium aluminum hydride to Li[V(bipy)3] 4THF, which formally contains V". Similarly, reduction of [V(phen)3] with dUithium naphthalenide or dihthium benzophenone in THF yields [V(phen)3]l2. Further reduction with dilithium benzophenone gives the V complex Li[V(phen)3] 3.5THF. The terpyridyl complex [V(terpy)2] can be obtained as black crystals by reduction of DMF solutions of [V(terpy)2]l2 with Mg or LiAlH. Such low oxidation state complexes are highly air sensitive and decompose if heated to 100 - 200 °C in a vacuum. In these systems, the ligands may have an anion radical character. ... 

Another advance seems likely through the use of zeolites as enzyme mimics.This centers on the reactions of organometallics with zeolite internal surfaces. The best-known example is the production of a [Co (bipyridyl)(terpyridyl)] + complex inside the main cavity of zeohte Y that can selectively and reversibly absorb oxygen from the air. The catalytic potential of a Co phthalocyanine moiety prepared in the Y cavity has also been demonstrated. 

In a further step, Yam and coworkers constructed helical superstructures emplo5nng chiral alkynylplatiniun(II)-terpyridyl complexes, obtaining metallogels that show helical fibrous nanostructures. The chiral supramolecular structiue and the spectroscopic properties depend on the extent of aggregation through Pt- Pt and n-n interactions, which can be influenced by varying the nature of counteranions, as revealed by UV/vis, circular dichroism, and luminescence studies (221). 

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