The interaction of vanadate (V04H11-) with a variety of alkyl alcohol's (ROH) covering about seven pK, units of acidity have been studied in aqueous solution by ''v nuclear magnetic resonance spectroscopy. A linear free energy relationship between the equilibrium constant for the formation of the vanadate monoester ( H O V O~R '~) and the acidity of the alcohol was established at 23'C. The correlation was found to be log I/K = -(0.09 ? 0 . 0 2 )~~:~~ + 2.1 k 0.3 where. This correlation was shown not to extend to ligands with T-bonding capability such as phenols or phosphates, where the products are highly favoured relative to the alkyl esters. An interesting correlation between pK, values of the product esters and the pK, of the parent alcohols was also observed. It was found that below a p~:OH of about 15 the pK, values of the esters were essentially constant. However, above this value of 15 the pK, of the ester was found to increase rapidly with an increase in pK, of the alcohol. This result may indicate that the electron accepting ability of the metal is exhausted with the higher pK, alcohols, and the extra electron density is transferred to the oxygens, thus causing an increase in pK, of the ester. On a trouvt que la corrilation prend la forme de log 1/K = -(0,09 k 0 , 0 2 )~~:[ROH]. On a dCmontrC que cette corrClation ne s'ttend pas aux ligands prCsentant une capacitt de liaison par des Clectrons T, comme les phCnols ou les phosphates; dans ces cas, les produits sont trks favorisCs par rapport aux esters d'alkyles. On a aussi observC une corrtlation inttressante entre les valeurs des pK, des esters qui se foment comme produits et les pK, des alcools qui leur donnent naissance. On a trouvt qu'en-dessous d'une valeur de 15 pour le p~:OH, les ialeurs des p~, des esters augmentent rapidement avec une augmentation du pK, des alcools. Ce rtsultat semble indiquer que la facilitt du mCtal i accepter des Clectrons est CpuisCe avec les alcools de pK, ClevC et que la densitt Clectronique additionnelle est transferee aux oxygknes; ceci provoque une augmentation du pK, de I'ester.[Traduit par la revue]

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In the reaction of V2O5 with aqueous or alcoholic solutions of tetraalkylammoniumhydroxide the orange decavanadates (NR4)3H3Vio028; (NR4)4H2VIO028> (NR4)5HVio028, (NR4)6VLO028 and colourless metavanadates can be obtained. The tetrabutylammoniumsalt [N(C4H9)4]3HV40i2 is the first known metavanadate with discrete polyanion. Its molecular weight was determined by vapor pressure osmometry in chloroform. The Raman spectrum is identical with the spectrum of a sodium metavanadate solution. The vibration spectra of the compounds are discussed and partial assignments were made.

Ein Molybdän‐Polyanion, das nebeneinander oktaedrische MoO6‐ und tetraedrische MoO4‐Baugruppen enthält, wurde erstmals als kristallines Ammoniumsalz isoliert. Es hat die Struktur (1) und die Summenformel [Mo10O34]8−.

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