SYNTHESIS AND STRUCTURE OF PALLADACYCLOPENTADIENYL COMPLEX WITH ACENAPHTHENE-1,2-DIIMINE LIGAND

Abstract

The organometallic complex [Pd(dpp-bian)(C4(COOMe)4)]·(C2H5)2O (1·(C2H5)2O) is obtained by the interaction of [Pd2(dba)3] (dba = dibenzylideneacetone) with dimethyl ether of acetylenedicarboxylic acid and 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-bian) in the 1:4:2 molar ratio. During the oxidative addition reaction the 1,2,3,4-tetrakis(methoxycarbonyl)buta-1,3-dienyl dianion is formed from two molecules of dimethyl ether of acetylenedicarboxylic acid. This dianion is coordinated to palladium(II) via 1 and 4 carbon atoms with the formation of the palladacyclopentadienyl moiety. The crystal structure is determined by the single crystal X-ray diffraction analysis. The 1·(C2H5)2O compound crystallizes in the orthorhombic crystal system (Pbca) with unit cell parameters a = 16.9069(3) Å, b = 23.5618(6) Å, c = 23.8902(7) Å, V = 9516.83(40) Å3. Each palladium atom has an almost square planar environment composed of two dpp-bian nitrogen atoms and two carbon atoms of the (C4(COOMe)4)2– anion. The cyclic voltammogram of 1 in acetonitrile reveals irreversible oxidation at Ea = 1.43 V, reversible reduction at E1/2 = 0.62 V, and irreversible reduction at Eb = 1.52 V. The electronic structure of complex 1 is studied within the density functional theory.