Tetra pyrazine ligands

Classic A/-heterocychc ligands, eg, bipyridyl (bipy), terpyridyl, imidazole, pyrazine, phenanthroline, piperazine (including alkyl- and aryl-substituted derivatives), and polypyrazol-l-yl-borates (bis, tris, and tetra), have all been found to coordinate Th(IV) chlorides, perchlorates, and nitrates. The tripodal hydrotris(pyrazolyl)borates, HBPz, have been used to stabilize organometaHic complexes (31). Bis-porphyrin Th(IV) "sandwich" complexes have been... 

The versatility of the quinolyl derivative (295) is exemplified in the complex [Ru(295-A,A )(295-A,A, A")C1]. The coordination behavior of (295) has been compared with those of (296) and (297) and factors influencing didentate vs. tridentate preferences have been examined. Perchlorate salts of [Ru(tpy)L)] " and [RUL2] where L = (298)-(300) have been synthesized and characterized, and their properties compared with those of [Ru(tpy)2] ". Complexation of Ru with 2,6-bis(4 -phenyl-2 -quinolyl)pyridine (L) affords [RUL2] , spectrosccmic properties of which have been discussed. " The bis(7 -methyl)-derivative of this ligand, L, has also been prepared and incorporated into the complexes [M(L )2f, [ (L CIs] (M = Ru, Os), and [Ru(L )(tppz)] + where tppz = 2,3,5,6-tetra(2 -pyridyl)pyrazine. Related cyclometallated complexes have also been studied. All the complexes luminesce at 77 K and [M(L )2] (M = Ru or Os), [Ru(L )(L )] , and two of the cyclometallated species are luminescent at room... 

The stepwise formation of quasi-octahedral macrocyclic complexes of iridium(lll) was observed for the reactions of [ Cp IrCl2 2] with bidentate ligands (L) such as l,4-diisocyano-2,5-dimethylbenzene a, l,4-diisocyano-2,3,5,6-tetra-methylbenzene b, pyrazine c, or 4,4 -dipyridyl d which gave the corresponding dinuclear complexes [Ir2Cl2(Cp )2(L)] 772, which were converted into tetranuclear complexes [( Cp Ir(jli-Cl) 2)2(L)2](OTf)4 773 on treatment with Ag(OTf). ... 

Polymers of the type shown in Figure 7 with pyrazine as the bridging ligand L can also be prepared using 5.10.15.20-tetra-phenylporphine (TPP ) or dihydrodibenzo [ b, i] -1,4,8,11-tetra-aza [14 ] annulene (taa ) as the macrocycle forming... 

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