FIRST BIS(ALLENYLIDENE)DIRUTHENIUM DERIVATIVES [(PH(3)P)(4)(MU-CL)(3)RU-2(=C=C=CAR2)(2)]PF6 AND ACCESS TO [(PH(2)PCH(2)CH(2)PPH(2))(2)CLRU(=C=C=CAR2)]PF6 COMPLEXES

RuCl2(PPh(3))(3) reacts with HC=CC(OH)Ar-2 derivatives in the presence of NaPF6 to selectively afford only one isomer of the cationic bis(al lenylidene) binuclear complexes [(Ph(3)P)(4)(mu-Cl)(3)Ru-2(=C=C=CAr2)( 2)]PF6[3; Ar=C6H5 (a), p-C6H4Cl (b), p-C6H4F (c)]. Complex 3a on treat ment with an excess of Ph(2)PCH(2)CH(2)PPh(2) (dppe) gives access to t he new mononuclear complex trans-[(dppe)(2)ClRu(=C=C=CAr2)]PF6 (4a). T he direct reaction. of cis-RuCl2(dppe)(2) with the alcohols HC=CC(OH)- Ar-2 and NaPF6 also readily gives the allenylidene complexes 4a-c.