Synthesis, structure and reactivity of Pd-II complexes with the terdentateimino alcohol ligand C6H3-3,4-(OMe)(2)-C(H)= N-CH2CH2OH

The reaction of the imino alcohol C6H3-3,4-(OMe)(2)-C(H)=NCH2CH2OH, 1, with Pd(OAc)(2) yields the dinuclear orthometallated compound [Pd(mu -OAc){C6H2 -4,5-(OMe)(2)-2-C(H)=NCH2CH2OH-kappa (2)- C,N}](2), 2, which, by reaction w ith excess LiCl in MeOH, can be transformed into the halide-bridged complex [Pd(mu -Cl){C6H2-4,5-(OMe)(2)-2-C(H)=NCH2CH2OH-kappa (2)-C,N}](2), 3. Comp lex 3 reacts with neutral monodentate ligands L that promote the cleavage o f the halide bridging system to give the mononuclear [Pd(Cl){C6H2-4,5-(OMe) (2)-2-C(H)=NCH2CH2OH-kappa (2)-C,N}(L)] (L=PPh3 4; py 5) complexes. The OH group does not interact with the Pd atom in complexes 2-5. The reaction of 3 with AgClO4 in NCMe gives the cationic monosolvate [Pd{C6H2-4,5-(OMe)(2)- 2-C(H)=NCH2CH2OH-kappa (3)- C,N,O}(NCMe)](ClO4), 6, in which the orthometal lated ligand is now C,N,O-terdentate through coordination of the OH group. The strength of the Pd-O(H) bond has been studied. Complex 6 reacts with an excess of a neutral monodentate ligand L to give [Pd{C6H2-4,5-(OMe)(2)-2-C (H)2</BO>NCH2CH2OH-kappa (3)-C,N,O}(L)](ClO4) (L=PPh3 7; py 8), in which th e incoming ligand L replaces the NCMe but does not cleave the Pd-O(H) bond. Alternatively, complexes 7 and 8 can be obtained by reaction of 3 with AgC lO4 and L. Complex 6 reacts with bidentate N-donor ligands, yielding [Pd{C6 H2-4,5-(OMe)(2)-2-C(H)=NCH2CH2OH-kappa (3)-C,N,O}(L-L-kappa (1)-N)](ClO4) ( L-L=bipy 9; N,N,N',N'-tmeda 10), in which the bipy or tmeda ligand is coord inated through only one N atom. The rupture of the Pd-O(H) bond can be acco mplished by reacting 6 with diphosphine ligands, such as dppe, giving [Pd{C 6H2-4,5-(OMe)(2)-2-C(H)=NCH2CH2OH-kappa (2)- C,N}(dppe-P,P)](ClO4), 11. Com plexes 4 . CHCl3 and 7 have been characterized by X-ray diffraction.