The straightforward synthesis of tethered 畏5-oxocyclohexadienyl Ru(II) complexes is presented. Pioneering results in catalysis show that these original half-sandwich Ru(II) complexes allow the effective isomerization of allylic alcohols under mild conditions without further additives; 畏5-oxocyclohexadienyl ruthenium complexes may be considered as a new class of catalysts.