2,2*-Biimidazoles

Neither of the parent 1,2 or 1,4 isomers, 60 or 61, is known. The 4, 5 -dihydro derivative of 60 has been prepared (90S561), as well as di- and trisubstituted derivatives of 60 [79JOC4243 82UC(B)945 89H(29)1325 91IJC(B)399]. Other substituted derivatives of both 60 and 61 have been prepared for bioactivity screening [84IJC(B)342 92MI3]. 

The 5 -amino derivative of 63 has been the subject of several studies in which it was cyclized to ethenoadenosines [70JCS(C)2206 73TL3087 75JOC1066 76CPB1561 80JA770.  

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Biguanide salts Biimidazole dimer Biisobutyryl [4388-87-8] Bilarcil Bile acids... 

The photopolymerization process taking place within a representative mixture of sensitizer, initiator, chain-transfer agent, and monomer, typical of positive Cromalin, has been studied in detail (41,42). The exact mechanism is still controversial, but a generalized reaction scheme can be postulated as follows, where L2 = biimidazole dimer, S = sensitizer, RH = chain-transfer agent, L2 = excited biimidazole dimer, L = biimidazole radical,... 

A number of tetraazafulvalenes 77 eontaining a p-quinoid substrueture have been synthesized they inelude phenylogous biimidazoles sueh as 1,4-... 

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... 

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. 

AyV -Carbonyl-2,2 -biimidazole (A V7-carbonyl-2,2 -biimidazyl) prepared from 2,2 -biimidazole and phosgene is relatively unreactive on hydrolysis, and shows reduced reactivity in reactions with carboxylic acids.[19],[2]... 

The synthesis of (80) from [Ircp Cl2]2 and 2,2 -biimidazole has been detailed.119 The X-ray structure of (80) shows the expected three-legged piano-stool arrangement round the Ir center. 

In the homodinuclear complex [ Pd(dppp) 2(//-biim)](OTf)2 (dppp = bis(diphenylphosphino)-propane, biim = 2,2 -biimidazole, 0Tf=0S02CF3) a biim2 ligand spans the two palladium(II) centers.535... 

The biphenyl ligand functionalized with two imidazoles (6) was used to produce distorted tetrahedral complexes of zinc.119 2,2 -Biimidazole can act as a bidentate ligand coordinating to one zinc ion (7) or as a bridging ligand in the formation of dimeric species (8) with X-ray structures of both binding motifs.120... 

Dinitroazetidine salts were studied as explosives nitrate, dinitroimidate, 2,4-dinitroimidazolate, 4,4, 5.5 -tctranitro-2.2 -biimidazolate, 5-nitro-l,2,4-triazolonate... 

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