Inorganic Chemistry, Vol.35, No.8, 2287-2291, 1996
Palladium Complexes with the Tridentate Dianionic Ligand Pyridine-2,6-Dicarboxylate, Dipic - Crystal-Structure of (Pd(Dipic)(Pbu(3)))(2)
The reactions of [Pd(acac)(2)] or [Pd(OAc)(2)](3) with pyridine-2,6-dicarboxylic acid (H(2)dipic) in acetonitrile afford [Pd(dipic)(NCMe)] in high yield. This complex has been used as starting material in the preparation of a variety of neutral an anionic complexes. The dipicolinate anion behaves as a tridentate ligand in all cases, but two modes of coordination are found, depending on the ligand : as a pincer ligand O,N,O-bonded to the same palladium, giving mononuclear complexes, and as an O,N-chelate N,O’-bridging ligand in dinuclear complexes. An X-ray determination of the structure of a dimer, [Pd(dipic)(PBu(3))](2) (monoclinic, space group P2(1)/n, a = 18.144(4) Angstrom, b = 13.191(2) Angstrom, c = 19.571(3) Angstrom, beta = 113.45(2)degrees, Z = 4, R = 0.050, R(w) = 0.054) shows that the ligand is coordinated to one palladium in a eta(2)-N,O chelate fashion and one oxygen atom of the other carboxylate group makes a bridge to the other palladium atom, in a novel bonding mode for the dipic ligand.
Keywords:MOLECULAR-STRUCTURE;BIS(PYRIDINE-2;6-DICARBOXYLATE) MONOHYDRATE;COORDINATION CHEMISTRY;DIMETHYL-SULFOXIDE;LIQUID-CRYSTALS;DIVALENT COBALT;ACID;METALLOMESOGENS;PLATINUM(II);RESONANCE