A simple preparation for (η6-arene)(η4-cyclo-octa-1,5-diene)ruthenium-(<scp>0</scp>) complexes and their conversion into the corresponding arene–dichlororuthenium(<scp>II</scp>) complexes

A series of (η6-arene)(η4-cyclo-octa-1, 5-diene)ruthenium(0) complexes have been readily prepared by reaction of (η4-cyclo-octa-1,5-diene)(η6-cyclo-octa-1, 3, 5-triene)ruthenium(0) with arene compounds, under 1 atm H2[arene = C6H6, CH3 C6H5, 1, 4-Me2C6H4, 1,3,5-Me3C6H3, C2H5C6H5, Me2CHC6H5, Et2CHC6H5, C6H5(CH2)3 C6H5,C6H5C6H5, C2H5CH(Me)C6H5, Me2CHCH(Me)C6H5, NH2CH(Me)C6H5, CH3OC6H5, or CH3COC6H5]. These complexes react with aqueous HCI to give in almost quantitative yield the corresponding (η6-arene)-dichlororuthenium(II) complexes.