Messanae Universitas Studiorum

Lew Acidity of Cations in Nonaqueous Solvents

Linert , Wolfgang and De Marco, Domenico (1998) Lew Acidity of Cations in Nonaqueous Solvents. Accademia Peloritana dei Pericolanti, Classe di Scienze FF. MM. NN., 76-77. pp. 37-58.

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The shift of the visible charge-transfer absorption bands of $Fe(phen)_2(CN)_2$ in various solvents that results from interaction of solvent molecules or of cationic species with the free electron pair on the -CN group(s) has been investigated and the results have been used to estabilish Acceptor Numbers $(AN_{M,NM})$ for cations, $M^n^+$, dissolved in various solvents of low donicity. Nitromethane (NM) has been used as a reference solvent because it is both a very weak donor and a relatively weak acceptor solvent. (The solvent must exhibit $some$ donor and acceptor properties in order to ensure solubility of the cationic species and the $Fe(phen)_2(CN)_2$ indicator). Apparent Acceptor Numbers $(AN_{M,solv})$ for cations dissolved in various solvents other than nitromethane are also given and used to show that the acceptor properties of cations vary in a way directly related to the Donor Number of the solvent (i.e. a decrease in the effective Acceptor Number of the cations is observed with increasing $DN_S_o_l_v$. This arises from competition between solvent and acceptor ion fot the $Fe(phen)_2(CN)_2$ used as the Lewis-acid indicator). The results are compared with the spectral shift of the analogous complex $Ru(phen)_2(CN)_2$. The relationship between the proposed AN scale for cations and other practical and theoretical measurements of the Lewis acidity of cations is discussed.

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Item Type: Article
Subjects: M.U.S. - Miscellanea > Atti Accademia Peloritana > Classe di Scienze Fisiche, Matematiche e Naturali > 1998-99
Depositing User: Dr A F
Date Deposited: 18 Sep 2012 07:58
Last Modified: 18 Sep 2012 07:58

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