Cobalticinium salts

Even more intriguing was the observation that the same products were formed upon pyrolysis of ionic cobalticinium salts of commo-metallocar-... 

The discovery of the thermal metal transfer reaction (27) afforded a third preparative route to bimetallic twelve-vertex metallocarboranes. This method involves the pyrolysis of eleven-vertex cfoso-metallocarboranes or cobalticinium salts of eleven-vertex cowimo-metallocarboranes and results in the production of several isomeric, closed, neutral, twelve-vertex bimetallocarboranes [Eqs. (9) and (10) Fig. 7]. Yields are reasonable in... 

An interesting reducing agent is cobaltocene (37), although its use is somewhat limited by the low solubility of the cobalticinium salts. 

Penta(isopropyl)- and penta(neopentyl)-Cp cobalticinium salts, on the other hand, have a high enough barrier to interconversion (AG% 17.1 and 19.4 kcal/mol, respectively) with coalescence temperatures of 65° and 100°C, respectively, in the NMR (14). Thus, both enantiomers can coexist at 20°C with only a slow interconversion between them. In tricarbonyl-methyl-penta(isopropyl)cyclopentadienyl molybdenum the activation energy has been estimated to 13 1 kcal/mol (211) (cf. comment in Section IV, C, 2). 

G. Wilkinson, The Preparation and Some Properties of the Cobalticinium Salts, J. Am. 

Chemical Shifts (ppm) of the Various Ring Protons OF Substituted Cobalticinium Salts"... 

All four organometallic cyclopentadienyl systems discussed heretofore have had their homoannular electronic effects examined by PMR spectroscopy. Of the four, only the cobalticinium salts exhibited shielding for the... 

More recently, UV data for a related system, substituted cobalticinium salts (77) have been tabulated. A similarity in the positions of the absorption bands in this system and the analogous substituted ferrocenes was observed. A decrease in the absorbance of the band at 260-275 m/x with both donating and withdrawing groups was the only electronic effect of note. 

In this manner benzil was converted to benzoic acid quantitatively and acenaphthene quinone was oxidized to naphthalene-1,8-dicarboxylic acid in 80% yield. Although these reactions are very facile and occur at a very low temperature (—50 to 15 °C) cobaltocene was irreversibly oxidized to a cobalticinium salt and a catalytic system was apparently not developed. 

A number of Cp derivatives of Ti exist. Titanocene dichloride exists as a distorted tetrahedron, with the planes of the Cp rings facing the titanium metal. This is unlike ferrocene and cobalticinium salts for which the metal atoms are sandwiched between the parallel Cp rings. The structure of titanocene dichloride is similar to that of many of the other n-bonded Cp structures. Numerous derivatives of the titanocene moiety exist. These derivatives consist of various substituents, including alkyl, aryl,... 

Our cooperation with Sheats also extended into the area of condensation polymers of cobalticinum salts.92 Ionic polyesters were prepared by melt-phase transesterification of 1,1 bis(carbethoxy)cobalticinium hexafluorophosphate with various diols. Low molecular-weight polysters were formed. However, attempts to prepare polyamides by melt condensations of alkylene diammonium salts of l,l -bis(carboxy)cobalticinium PFg salts resulted in decomposition.92... 

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