Cyclometallation of 3,5-disubstituted N-benzylideneamines by palladium(II). Synthesis and X-ray crystal structure of

Article abstract of DOI:10.1016/0022-328X(94)05365-I

The action of Pd(AcO)2 on the imines C6RmH5-mCH=N(CH2)nC6H5 have been studied.Five-membered endo metallacycles were obtained from the imines 1a (R = 3,5-F2, n = 0), 1b (R = 3,5-F2, n = 1), 1c (R = 3,5-(MeO)2, n = 0) and 1d (R = 3,5-(MeO)2, n = 1), by activation of a C(aromatic)-H bond, in spite of the presence of MeO or F substituents on the carbon atom adjacent to the metallation position. 1H NMR spectra of the acetate bridged compounds (2a-d) obtained show the existence of different isomers in solution.Complexes (4) and (5) can be obtained by the action of PPh3 on the new cyclometallated compounds. crystallizes in the space group P2₁/a with a = 20.224(4), b = 17.447(3), c = 12.290(2) Angstroem, β = 110.12(3) deg and Z = 4.The dihedral angle between the metallated phenyl ring and the coordination plane is 86.6 deg.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.Keywords: Palladium; Cyclometallation; Benzylideneamine complexes; Dinuclear complexes; X-ray structure; Imine