RIGID BIDENTATE NITROGEN LIGANDS IN ORGANOMETALLIC-CHEMISTRY AND HOMOGENEOUS CATALYSIS, 14 - MONODENTATE AND BRIDGING COORDINATION OF 3,3'-ANNELATED 2,2'-BIPYRIDINES IN ZERO-VALENT PALLADIUM-P-QUINONE AND PLATINUM-P-QUINONE COMPLEXES

Compounds of the type M(N boolean AND N-kappa N)(nq)(2) and M-2(mu(2)- N boolean AND N)-(mu(2)-pbq)(2), in which nq = 1,4-naphthoquinone, pbq = 1,4-benzoquinone, and N boolean AND N is a monodentate or bridging Ligand of the alpha-diimine type, were obtained from reactions of Pd(d ba)(2) in toluene with the 3,3'-annelated-2,2'-bipyridines: 4,5-diazaf luoren-9-one (dafo) and 4,5-diazafluorene (dafe) in the presence of th e appropriate p-quinone. In the corresponding reactions with 2,2'-bipy ridine (bpy), 1,10-phenanthroline (phen), 2,2'-bipyrimidine (bpym), N, N'-dicyclohexyl-1,4-diaza-1,3-butadiene (chex-dab), bis[N-(o,o'-diiso propyl)phenylimino]acenaphthene (o,o'-iPr(2)-bian) and 5,6-dihydro1,10 -phenanthroline (dh-phen) only complexes of the type M(N boolean AND N -kappa(2)N)(Q) were formed (Q = nq, pbq). The structures of the comple xes have been established by NMR in solution and by X-ray diffraction in the solid state; crystal structures of Pd(bpy-kappa(2)N)(eta(2)-pbq ) (1) Pd(dafo-kappa N)(eta(2)-nq)(2) (14) and Pd-2(mu(2)-dafo) (mu(2), eta(2):eta(2)-pbq)(2) (16) have been determined. Of the Ligands, dafo and dafe are the only ones apt to form complexes containing a monodent ate or bridging N boolean AND N ligand. This behaviour is ascribed to the geometrical constraints of dafo and dafe; the annelation by one ca rbon atom at the 3,3'-positions in these Ligands causes an increase in bite angle from approximately 77 degrees to 82 degrees.