The present invention relates to the field of one step process for the preparation of monomeric or dimeric [Ru(diene)(OOCR)2]n complexes from [(diene)Ru Cl2]n, as well as a new class of [Ru(diene)(OOCR)2]n complexes and their use to prepare [Ru(PP)(OOCR)2] complexes, which are good catalysts.
