2,2 -Bibenzimidazole

Biimidazole and bibenzimidazole with [(ri -2-RC3H )Pd(p-Cl)]2 (R = H, Me) taken in the 2 1 molar ratio in the presence of methanolic potassium hydroxide give complexes of the type 146 (83JCS(D)1729) and with [(ti -2-RC3H ) Pd(Mc2C0) ](C10 ) - 147. When the ratio of 2,2 -biimidazole or 2,2 -bibenz-imidazole and [(Ti -2-RC3H )Pd(p-Cl)]2 (R = H, Me) is 1 1, the homo-tetranuclear species 148 result. Heterotetranuclear palladium(II)-rhodium(I) complexes 149 (L2 = cod) follow from [(TiLcod)Rh(Hbim)] and [(ri -2-R-C3H )Pd(acac)]. They are readily carbonylated with complete substitution of... 

Interaction of the latter with triphenylphosphine in the presence of sodium perchlorate leads to the cationic complex [(dppm)Au2(li-L)Pd(C Fj)(PPh3)]C10. Reactions of [L Au(p-L)AuL ] (L = bibenzimidazolate L = PPh, dppm)] with [Pd(0C103)(C Fj)(PPh3)2] do not lead to the tetranuclear products. Only the bibenzimidazolate (L) dinuclear product [(PPh3)(C F3)Pd(p-L)Pd(C, F3)(PPh3)] could be isolated in both cases. 

Imidazole is characterized mainly by the T) (N) coordination mode, where N is the nitrogen atom of the pyridine type. The rare coordination modes are T) - (jt-) realized in the ruthenium complexes, I-ti (C,N)- in organoruthenium and organoosmium chemistry. Imidazolium salts and stable 1,3-disubsti-tuted imidazol-2-ylidenes give a vast group of mono-, bis-, and tris-carbene complexes characterized by stability and prominent catalytic activity. Benzimidazole follows the same trends. Biimidazoles and bibenzimidazoles are ligands as the neutral molecules, mono- and dianions. A variety of the coordination situations is, therefore, broad, but there are practically no deviations from the expected classical trends for the mono-, di-, and polynuclear A -complexes. 

PPh3) 2(p.-bbzim)] and [ Au(PPh3) 4 (p.-bbzim)][C104]2 (bbzim = 2, 2 -Bibenzimidazolate). Journal of the Chemical Society, Dalton Transactions, 2365-2371. 

Neutral complexes with azolate ligands of the type [AuL(PPh3)], with L representing differently substituted pyrazolates,2251,2366 imidazolates,365,2 69 2370 benzidimidazolates, 71 2372 triazolate,2373 tetraazolate (403),536 or 2,2 -bibenzimidazolates (404),2374,2375 have been prepared. The structure of the [Au(l,2,4-triaz)(PPh3)] is a dimer with Au-,Au interactions (405).23 3 The antimicrobial... 

Non-luminescent, octahedral Ru(ii) complexes bearing two 4,4 -di(/ r/-butyl)bipyridine and one bibenzimidazole ligand become luminescent upon coordination of diethylzinc to the bibenzimidazole 39, as shown in Scheme 34.85... 

Martin-Bertram H, Hartl P, Winkler C (1984) Unpaired bases in phage DNA after gamma-radiation in-situ and in-vitro. Radiat Environ Biophys 23 95-105 Martin RF (1998) DNA-binding bibenzimidazoles as radioprotectors. In Bump EA, Malaker K (eds) Radioprotectors. Chemical, biological, and clinical perspectives. CRC Press, Boca Raton, pp 151-166... 

Poly-2-2 -(w-phenylene)-5,5 -bibenzimidazole, commonly called polybenzimidazole (PBI), was developed under the aegis of the U.S. Air Force Materials Laboratory in cooperation with the then-existing Celanese Corporation. The fiber went into commercial production in the United States in 1983. It is a condensation polymer obtained from the reaction of tetra-aminobiphenyl and diphenylisophthalate in a nitrogen atmosphere at temperatures that may reach 400°C in the final stages.29 The structure of a repeating unit is shown below. 

Whenpoly(2,2 -(m-phenylene)-5,5-bibenzimidazole)havingaMnOf2.0 x 10" daltons was crosslinked with tetrahydrothiophene-1,1-dioxide, (11), or 1,4-phenylene, (111), by Young [2] and Jorgensen [3], respectively, each membrane was selective for hydrogen, carbon dioxide, nitrogen, and methane. 

In the formation of the l,l -bibenzimidazole (16) the second benzimidazole ring is formed by cyclization of a monoacylated o-phenylenediamine (8UCS(Pl)403), while thermolysis of the anils (17) derived from 2-azidoaniline also gives good yields of 2-aryl-substituted... 

FIGURE 27.70 Chemical structure of poly[2,20-(w-phenylene)-5,50-bibenzimidazole]. 

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