7.7.8.8- Tetrakis -quinodimethane

Fig. 3. Isolatable y)-xylylene derivatives (12), Thiele s hydrocarbon - 1904 [26392-12-1] (13), tetracyanoquiuodimethane [1518-16-7] (TCNQ) (14), tetrakis(methoxycarbonyl)-quiaodimethan [65649-20-9]-, (15), tetrakis(ethy1sii1fony1)quinodimethan [84928-90-5].

Tetracyano ligands have been used to bridge between four Ru(NH3)5 moieties. The complexes [ Ru(NH3)5 4(/i-L)] + (L = tetracyanoethene, tetracyano-p-quinodimethane, 1,2,4,5-tetracyano-benzene, 2,3,5,6-tetracyanopyrazine) exhibit intense, long-wavelength electronic absorptions. Oxidation to [ Ru(NH3)5 4(yU-L)] °" " and reduction to [ Ru(NH3)5 4(//-L)] + and [ Ru(NH3)5 4-(/i-L)] + can readily be achieved. The species are fully delocalized with partially reduced ligands or partially oxidized Ru centers. Treatment of [5,10,15,20-tetrakis(4-cyanophenyl)porphyrinato] cobalt(II) or [5,10,15,20-tetrakis(4-cyano-2,6,-dimethylphenyl)porphyrinato]cobalt(II) with [Ru-(NH3)5(0S02CF3)] introduces cyano-bound pendant Ru (NH3)5 groups to the porphyrinato complexes. ... 

Keywords tetrakis(ethoxycarbonyl)quinodimethane, molecular oxygen... 

C5 sHs 3CI3F6NO8P, 1,1 -Binaphthylmacrocyclicpolyether (R)-phenylgly-cine methyl ester hexafluorophosphate chloroform, 43B, 426 C60H3 iiN2 2Pd, Tetrakis (methyl isocyanide )palladium( 11) tetrakis-(7,7,8,8-tetracyano-p-quinodimethane) diacetonitrile solvate, 42B, 499... 

CsoH ,6Ni8r [N,N,N,N , N, N -Hexamethylhexamethylenediammonium] tetra-kis[tetracyanoquinodimethane), 45B, 683 Cs1H32N18 f 1,3-Di(N-pyridinium)propane tetrakis(7,7,8,8-tetracyano-quinodimethane), 43B, 796... 

C62H34N18 f 1,2-Di(N-methyl-4-pyridiniurn)ethane tetrakis(7,7,8,8-tetracyanoquinodimethane, 43B, 798 Cs2H65ClsN9Nb3, Tris((di-M chloro)(hexamethylbenzene)niobium) bis(7,7,8,8-tetracyano-p-quinodimethane) acetonitrile solvate, 43B, 799... 

Bis(dicyanomethylene)-2,5-dihydropyridine (18), so-called 2-azaTCNQ, is a more intriguing candidate for the real pyridine-TCNQ, because it can formally take the quinodimethane structure with no ylide bond. The synthesis of 18 [41,42] has been carried out by using a nucleophilic substitution reaction of 2,5-dihalopyridine (16) with sodium dicyanomethanide in the presence of a catalytic amount of tetrakis(triphe-nylphosphine)palladium(O) in refluxing 1,2-dimethox-yethane as developed for a facile preparation of TCNQ by Takahashi and co-workers [43] (Scheme 4.4). 

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