CYCLOMETALATION OF 3,5 DISUBSTITUTED N-BENZYLIDENEAMINES BY PALLADIUM(II) - SYNTHESIS AND X-RAY CRYSTAL-STRUCTURE OF [PD(3,5-F2C6H2CH=NC6H5)BR(PPH(3))(2)]

The action of Pd(AcO)(2) on the imines C6R(5 . m)CH=N(CH2)(n)C6H5 have been studied. Five-membered endo metallacyles were obtained from the imines 1a (R=3,5-F-2, n=0), 1b (R=3,5-F-2, n=1), 1c (R=3,5-(MeO)(2), n=0) and 1d (R=3,5-(MeO)(2), n=1), by activation of a O(aromatic)-H bond, in spite of the presence of MeO or F substituents on the carbon atom adjacent to the metallation H-1 NMR spectra of the acetate bridged compounds [{Pd(C-N)(mu-AcO)}(2)] (2a-d) obtained show the existence of different isomers in solution. Complexes [PdBr(C-N)(PPh(3))] (4) and [PdBr(C-N)(PPh(3))(2)] (5) can be obtained by the action of PPh(3) on the new cyclometallated compounds. [Pd(3,5-F2C6H2CH=NC6H5)Br(PPh(3))(2)] crystallizes in the space group P2(1)/a with a=20.224(4), b=17.447(3), c=12.290(2) Angstrom, beta=110.12(3)degrees and Z=4. The dihedral angle between the metallated phenyl ring and the coordination plane is 86.6 degrees. An N=CH proton and a fluorine atom ortho to the Pd-C bond occupy the apical positions in the coordination sphere of the palladium atom.