Annulenes dianion salts

The solid aromatic dianion salt of l,2-di-[ C][8]annulene has not been found to scramble the Cs even on heating to over 600 °C for 2hs. ° This behaviour of the cyclooctatetraene dianion is in contrast with that of neutral aromatic systems, which readily automerize in the gas phase. Apparently, when sufficient energy is applied... 

Treatment of 2 with two equivalents of potassium gives the corresponding [8]annulene dianion. 1,1, 3,3, 5,5, 7,7 -Octamethylthorocene,20 -uranocene,-neptunocenei, 21 and -protactinocene2i have all been synthesized by the addition of I,3,5,7-tetramethyl[8]annuIene dianion to the appropriate actinide salt. 

Attempts to make the octamethylplutonocene derivative by addition of tetramethyl[8]annulene dianion to the tetrachloride resulted in the reduction of Pu(IV) by the tetramethyl[8]annulene dianion to Pu(III).i When the borohydride complexes of neptunium and plutonium are used in place of the halide salts acceptable yields of the bis(tetra-roethyl[8]annulene) complexes were obtained.21... 

Other substituted bis([8]annulene)actinide(IV) complexes of uranium,3-13 thorium,20 neptunium and plutonium have been prepared by the reaction of the substituted [8]annulene dianion with the appropriate actinide(IV) salt. X-ray diffraction data suggest that the alkyl-substituted neptunium(lV) and plutonium(IV) complexes are isomorphous with the corresponding uranium(IV) complex but none of the structures of these complexes has yet been determined from single crystal x-ray diffraction. 

The potassium salts of bis([8]annulene)uranate(III),2 -neptunatedll). s -plutonatedll) and -americiatedll) anions have all been reported. These complexes have been synthesized by the reaction of two moles of [8]annulene dianion with one mole of the actinide trihalide. 

The two classes of complexes containing a bis(f8]annulene)-lanthanate(III) anion are those that contain an alkali cation and those that contain the complex [8]annulenelanthanatedII) cation. One of the classes, the alkali salts of the bis([8lannulene)lanthanate(III) anions, have been prepared by a variety of methods. The first of the methods, and the one which is of the roost synthetic utility, is the direct reaction of the di-alkali salt of (8]annulene dianion with the anhydrous lanthanide trichloride. The synthesis can be accomplished either by the addition of a suspension of the lanthanide salt in THF to a THF solution of the dianion.or by the reverse method, the addition of a solution of dianion to a suspension of the lanthanide (III) salt. 0... 

Hydrolysis in wet THF is rather slow but can be followed kinetically by the change in color the products are a mixture of cyclooctatrienes and uranium oxides. An interesting feature of this hydrolysis is proportion of cyclooctatriene isomers formed. Hydrolysis of the dipotassium salt of [8]annulene dianion in THF gives a 3 1 ratio of 1,3,5-cyclooctatriene to 1,3,6-cyclooctatriene, in the same direction as but a smaller magnitude than the equilibrium ratio 97 3 hydrolysis of uranocene, however, gives the opposite regiospecificity, a 1 2 ratio of 1,3,5 to 1,3,6.73... 

In order to study a bis[8]annulene compound with a divalent central metal atom we have synthesized and characterized the divalent ytterbium complex K2[Yb(CgHg)2]F K2[Yb(CgHg)2]r and its calcium analogue, K2[Ca(CgHg)2].51 These compounds were prepared by a reaction which utilizes the solubility of ytterbium and calcium metals in liquid ammonia. Reaction of cyclooctatetraene, potassium and either ytterbium or calcium, in liquid ammonia solution, gives the desired potassium salt of the complex dianion. 

---