Dipyridine complexes

Dirheniumheptoxide 2154 is converted by TCS 14, in the presence of 2,2 -dipyri-dine, into the dipyridine complex 2160 [77]. Free ReCls, NbCls, and WCI5 react with HMDSO 7 and 2,2 -bipyridine to form bipyridine oxochloride complexes 2161 and TCS 14, with reversal of the hitherto described reactions of metal oxides with TCS 14. The analogous Mo complex 2162 undergoes silylahon-amination by N-trimethylsilyl-tert-butylamine 2163 to give the bis-imine complex 2164 and HMDSO 7 [77] (Scheme 13.22). 

Both the disilver derivative and its precursory dipyridine complex are highly explosive and extremely shock-sensitive when dry. 

Collin s oxidation with chromium trioxide-dipyridine complex, or by use of... 

Cobalt Ziegler catalysts were also used for the manufacture of 1.2-polybutadiene by Susa (48). He obtained syndiotactic 1.2-poIy-butadiene from catalysts of extremely high ratios of triethylaluminum to cobalt chloride-dipyridine complex. However, as the anionic character of the catalyst system was decreased by the introduction of diethylalumi-num chloride, the 1.2 syndiotactic polymer decreased and increasing... 

Blues, E. T. et al., J. Chem. Soc., Chem. Comm., 1974, 466—467 Both the disilver derivative and its precursory dipyridine complex are highly explosive and extremely shock-sensitive when dry. 

R. E. Arrick, D. C. Baker, and D. Horton, Chromium trioxide-dipyridine complex as an oxidant for partially protected sugar preparation of aldehydo and certain keto sugar derivatives, Carbohydr. Res., 26 (1973) 441 147. 

Perchlorates are unusual in that most are either extremely soluble or only sparingly soluble in water. Silver (I) perchlorate is one of the most soluble salts known, while its coordination compound with pyridine is so insoluble that pyridine can be precipitated quantitatively from aqueous solution by treatment with silver (I) perchlorate.1 Although several complexes of pyridine and silver (I) perchlorate have been described,1,2 the one in which silver(I) exhibits its common coordination number of two is the most stable. This compound provides a stable, nondeli-quescent starting material for synthesizing the perchlorates of the dipyridine complexes of unipositive bromine3 and iodine.4... 

The chroniium(VI) oxide-dipyridine complex also has beoi found to cause oxidative rearrangement of tertiary allylic alcohols to a,3-epoxy aldehydes and small amounts of a,3-unsaturated aldehydes (equation 6 and Table 3). This is potentially useful as a homologation sequence since the starting materials are readily available from vinyl metal addition to ketones. Use of pyridinium chlorochromate (PCC) for this transformation gives mosdy a,3 unsaturated aldehydes. 

Alkyl bromides and azides. Substitution of hydroxyl groups by bromine is readily performed with PhjP and 2,4,4,6-tetrabromo-2,5-cyclohexadienone. THP ethers and many silyl ethers are also converted to bromides directly. When zinc azide dipyridine complex is also present alcohols are transformed into azides. Inversion of configuration of the carbinolic center accompanies both transformations. 

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