pr u2032 2 ch 2 x pr u2033 2 type x 2 3 4 where r u2032 and r u2033 can be equal or different and are aliphatic or aromatic groups c an optically active diphosphine with m equal to 2 in the case of equal or different monodentate phosphines chosen from group a and equal to 1 if the phosphine is chosen from group b or c where r 4 r 5 can be equal or different and are h aliphatic or aromatic groups the complexes can present the two ligands x and y in trans or cis orientation by way of example the structures of two of the possible cis and trans isomers where r 4 u2550 r 5 u2550 h are given in the figure for the purposes of the present invention ruthenium ii complexes with the general formulas given below are obtained from combinations of the various meanings for x y l l u2032 and m l are monodentate phosphines equal or different chosen from group a l u2032 is a bidentate ligand of 2 aminomethyl pyridine type of formula ii l is a bidentate phosphine chosen from group b or an optically active diphosphine chosen from group c l u2032 is a bidentate ligand.