Two-dimensional holo- and hemidirected lead(II) coordination polymers: Synthetic, spectroscopic, thermal, and structural studies of [Pb(mu-SCN)(2)(mu-ebp)(1.5)](n) and {[Pb(mu-OAc)(mu-ebp)](ClO4)]}(n) (ebp=4,4 '-[(1E)-ethane-1,2-diyl]bis[pyridine]; OAc = acetato)

Abstract

Two new coordination polymers of Pb complexes with bridging 4,4 '-[(1E)-ethane-1,2-diyl]bis[pyridine] (ebp), thiocyanato, and acetato ligands, [Pb(mu-SCN)(2)(mu-ebp),(1.5)](n) (1) and {[Pb(mu-OAc)(mu-ebp)](ClO4)](n) (2), were synthesized and characterized by elemental analysis, FT IR, 'H- and 13C-NMR, thermal analysis, and single-crystal X-ray diffraction. In 1, the Pb2+ ions are doubly bridged by both the ebp and the SCN-ligands into a two-dimensional polymeric network. The seven-coordinate geometry around the Pb2+ ion in 1 is a distorted monocapped trigonal prism, in which the Pb2+ ions have a less-common holodirected geometry. In 2, the Pb2+ ions are bridged by ACO- ligands forming linear chains, which are also further bridged by the neutral ebp ligands into a two-dimensional polymeric framework. The Pb2+ ions have a five-coordinate geometry with two N-atoms from two cbp ligands and three O-atoms of AcO-. Although CkO(4)(-) acts as a counter-ion, it also makes weak interactions with the Pb2+ center. The arrangement of the ligands in 2 exhibits hemidirected geometry, and the coordination gap around the Pb2+ ion is possibly occupied by a configurationally active lone pair of electrons.