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]-propane-2-ol ((LH)-H-1), has been synthesized from 2-(diphenylphosphino)benzaldehyde and 1,3-diaminopropanol in 85% yield. Complexation with palladium, nickel, and rhodium salts gave the following dinuclear complexes: [M-2(L-1)(OAc)(2)](BF4) (6, M = Pd; 7, M = Ni), [Pd-2(L-1)Me-2]-(BF4) (10), and [Rh-2(L-1)(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 [Pd-2(L-1)(OAc)(2)](BF4) (6), [Pd-2(L-1)Me-2](BF4) (10) and [Rh-2(L-1)(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 Angstrom. The related complex Pd-2((LH)-H-1)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 Angstrom is found. Furthermore, the ligand (LH)-H-1 is capable of forming heterodinuclear complexes. Reaction of (LH)-H-1 first with Pd(OAc)(2) and subsequently with Rh-2(CO)(4)Cl-2 provided the heterodinuclear complex [PdRh((LH)-H-1)(Cl)(CO)](BF4).