COORDINATION MODES OF THE NOVEL BIFUNCTIONAL NITROGEN LIGANDS 8-(2-PYRIDYL) QUINOLINE AND 8-(6-METHYL-2-PYRIDYL)QUINOLINE TOWARDS PALLADIUM AND PLATINUM - X-RAY CRYSTAL STRUCTURES OF (8-(2-PYRIDYL)QUINOLINE)PD(ME)CL, (8-(2-PYRIDYL)QUINOLINE)PD(C(O)ME

摘要

The coordination chemistry of the new bidentate nitrogen ligands 8-(2-pyridyl)quinoline (8-PQ) and 8-(6-methyl-2-pyridyl) quinoline) (Me-8-PQ) towards palladium and platinum has been studied. Several ((NN)-N-boolean AND)Pd(R)Cl and ((NN)-N-boolean AND)Pd(alkene) complexes have been synthesised. The complex (8-PQ)Pd(Me)Cl has been characterised by a single crystal X-ray determination (crystal data: triclinic space group P (1) over bar with a = 8.513(5), b = 9.338(4), c = 10.219(2) Angstrom, alpha = 108.11(2), beta = 89.82(3), gamma = 116.81(4)degrees, V = 680.1(6) Angstrom(3), R = 0.033, Z = 2). A fast CO insertion occurs into the palladium-carbon bond of the complexes ((NN)-N-boolean AND)Pd(Me)Cl providing the ((NN)-N-boolean AND)Pd(C(O)Me)Cl complexes. For (8-PQ)Pd(C(O)Me)Cl an X-ray structure determination has been carried out (crystal data: monoclinic space group P2(1)/c with a = 9.084(4), b = 10.179(3), c = 16.400(3) Angstrom, beta = 95.59(2)degrees V = 1509.2(9) Angstrom(3), R = 0.043, Z = 4). Unexpected in both molecular structures is the large dihedral angle between the plane of the bidentate nitrogen ligand and the coordination plane of the palladium. Both bidentate coordinating ligands 8-PQ and Me-8-PQ show a relatively large bite angle. A monodentate coordination mode has been observed for the complexes ((NN)-N-boolean AND)M(PEt(3))Cl-2 (M = Pd, Pt), as the pyridyl group of the ligand is coordinated to the metal while the quinoline group is dissociated from the metal, which is shown in the X-ray structure determination for the complex (8-PQ)Pd(PEt(3))Cl-2 (crystal data: monoclinic space group P2(1)/a with a = 15.736(2), b =7.782(1), c = 18.255(3) Angstrom, beta = 102.98(1)degrees, V = 2178.3(6) Angstrom(3), R = 0.062, Z = 4). [References: 51]