Novel Pb(II), Zn(II), and Cd(II) coordination polymers constructed from ferrocenyl-substituted carboxylate and bipyridine-based ligands

Treatment of two kinds of ferrocenyl-substituted carboxylate ligands (3-ferrocenyl-2-crotonic acid, HOOC-CH= (CH3)CFc (Fc=(eta(5)-C5H5)Fe(eta(5)-C5H4)) or o-ferrocecarbonyl benzoic acid, O-HOOCC(6)H(4)COFc with Pb(OAc)(2) . 3H(2)O, Zn(OAc)(2) . 2H(2)O, or Cd(OAC)(2) . 2H(2)O) resulted in four novel ferrocene-containing coordination polymers {[Pb(mu(2)-eta- OOCCH=(CH3)CFc)(2)].MeOH}(n) (1), {[Zn(o-OOCC(6)H(4)COFc)(2)(4,4'-bipy)(H2O)(2)].2MeOH.2H(2)O}(n) (4,4'-bipy = 4,4'-bipyridine) (2), {[Cd(o-OOCC(6)H(4)COFc)(2)(bpe)(MeOH)]-2H(2)O}(n) (bpe = 1,2-bis(4-pyridyl)ethene) (3), and [Pb(o-OOCC(6)H(4)COFc)(eta(2) -o-OOCC(6)H(4)COFc)(bpe)](n) (4). Their crystal structures have been characterized by single X-ray determinations. In polymer 1, Pb(II) ions are bridged by tridentate FcC(CH3)=CHCOO- anions, forming an infinite chain [Pb(mu(2)-eta(2)-OOC=CH(CH3)CFc)(2))](n). In polymers 2-4, there are three kinds of components, metal ions, o-FcCOC(6)H(4)COO(-) units, and organic bridging ligands. The bipyridine-based ligands connect metal ions leading to a one-dimensional chain with o-FcCOC(6)H(4)COO(-) Units acting as monodentate or chelate ligands in the side chain. Such coordination polymers containing ferrocenyl-substituted carboxylate and bipyridine-based ligands are very rare. The solution-state differential pulse voltammetries of polymers 1-4 were determined. The results indicate that the half-wave potential of the ferrocenyl moieties is influenced by the Pb(II) ions in polymer 1 and strongly influenced by Zn(II), Cd(II), or Pb(II) ions in polymers 2-4. The thermal properties of the four polymers were also investigated.