Dinuclear Palladium, Nickel, And Rhodium Complexes Based On 1,3-bis[(2-(diphenylphosphino)benzylidene)-amino] Propan-2-ol

A new dinucleating ligand, 1,3-bis[(2-(diphenylphosphino)benzylidene)amino]-propan-2-ol (L1H), has been synthesized from 2-(diphenylphosphino)benzaldehyde and 1,3-diamino-propanol in 85% yield. Complexation with palladium, nickel, and rhodium salts gave the following dinuclear complexes: [M2(L1)(OAc)2](BF4) (6, M = Pd; 7, M = Ni), [Pd2(L1)Me2]-(BF4) (10), and [Rh2(L1)(CO)2](BF4) (11). In these complexes the two metals are bridged by the secondary alkoxy group of the ligand which keeps them at a fixed distance from each other. X-ray structure determinations of [Pd2(L1)(OAc)2](BF4) (6), [Pd2(L1)Me2](BF4) (10) and [Rh2(L1)(CO)2](BF4) (11) showed that both metals are in a square-planar environment and that the metal-metal distance varies from 3.5 to 3.7 Å. The related complex Pd2(L1H)Me2Cl2 (9) has also been characterized crystallographically. In palladium complex 9, the alkoxy group does not bridge the two metal centers and a much longer metal-metal distance of 7.5 Å is found. Furthermore, the ligand L1H is capable of forming heterodinuclear complexes. Reaction of L1H first with Pd(OAc)2 and subsequently with Rh2(CO)4Cl2 provided the heterodinuclear complex [PdRh(L1H)(Cl)(CO)](BF4).