The mononuclear arene-ruthenium(II) derivatives [RuCl2(eta(6)-arene)(PTA-Me)] (arene = C6H6 (3a), p-cymene (3b), 1,3,5-C6H3Me3 (3c), C6Me6 (3d)), containing the ionic phosphine ligand 1-methyl-3,5-diaza-1-azonia-7-phosphaadamantane chloride (PTA-Me), have been synthesized and fully characterized. These complexes were evaluated as potential catalysts for the redox isomerization of allylic alcohols. Among them, best results in terms of activity were obtained with complex [RuCl2(eta(6)-C6H6)(PTA-Me)] (3a) which, in combination with K2CO3 (2.5 equiv. per Ru), was able to selectively isomerize a number of allylic alcohols RCH(OH)CH=CH2 (R = H, aryl, alkyl or heteroaryl group) into the corresponding carbonyl compounds RC(=O)CH2CH3 in refluxing THF (TOF values up to 800 h(-1)). Complex [RuCl2(eta(6)-C6H6)(PTA-Me)] (3a) was adsorbed onto the Montmorillonite K-10 clay, and the resulting solid proved also active in the isomerization of the model substrate 1-octen-3-ol. In addition, it could be easily separated from the reaction media by simple filtration and reused several times (up to 11 consecutive runs) with retention of its efficiency. (c) 2012 Elsevier B.V. All rights reserved.