Syntheses, Structures, and Characterizations of Four New Lead(II) 5-Sulfosalicylate Complexes with Both Chelating and Bridging Neutral Ligands

Abstract

Four structurally diverse complexes, {[Pb(Hssal)(2,2′-bipy)](4,4′-bipy) 0.5 } n (1), [Pb 2 (Hssal) 2 (2,2′-bipy) 2 (4,4′-bipy)-(H 2 O) 2 ] (2), [Pb(Hssal)(phen)(4,4′-bipy) 0.5 ] n (3), and [Pb(Hssal)(2,2′-bipy)(bpe) 0.5 ] n (4), have been synthesized and characterized by elemental analyses, IR, thermogravimetric analyses, fluorescent spectra, and single-crystal X-ray analyses, where Hssal 2is doubly deprotonated 5-sulfosalicylate, 2,2′-bipy is 2,2′-bipyridine, phen is 1,10phenanthroline, 4,4′-bipy is 4,4′-bipyridine, and bpe is trans-1,2-bis(4-pyridyl)ethylene. The structure of complex 1 possesses a one-dimensional ladderlike chain with guest 4,4′-bipy molecules, while the molecular structure of complex 2 is a dimeric species with a coordinating 4,4′-bipy ligand. Complex 3 consists of a one-dimensional ladderlike chain with monodentate 4,4′-bipyridine but somewhat different from that of complex 1. Complex 4 is a two-dimensional layer structure. In 1−4, all 5-sulfosalicylates are doubly deprotonated, and all carboxylate groups of Hssal 2chelate to Pb II ions; however, the coordination modes of sulfonyl groups are different: syn−syn bridging in 1, noncoordinating in 2, syn-skew bridging in 3, and one-atom bridging in 4. The noncoordinating mode of sulfonate in Pb II complexes containing 5-sulfosalicylate is first reported in this presentation. The 4,4′-bipy ligands act as guest molecules in 1, dimeric linkers in 2, and monodentates in 3. The π−π stacking interactions can be observed in complexes 1−3, whereas there is no such interaction in complex 4. The coordination spheres of Pb II ions in 1−4 are controlled by three factors: the activity of a lone pair of electrons, weak Pb−O interactions, and π−π stacking interactions. The Pb II lone pair in 4 is inactive, whereas in 1−3, they are stereochemically active. The thermal stability and fluorescent property of complexes 1−4 are different from those of Pb II complexes only containing chelating ligands, [Pb(Hssal)(2,2′-bipy)(DMF)] n (5), and [Pb(Hssal)(2,2′-bipy)(H 2 O)] n (6), and [Pb(Hssal)-(phen)(DMF)] n (7).

Two new lead(II) coordination polymer and discrete complex containing bipyridine ligands with different positioned methyl substituents: synthesis, characterization, crystal structure determination, and luminescent properties

“…However, the bond lengths Pb1-O2, Pb1-O2a (symmetry code: 2 -x, y, 1/2 -z), Pb1-O3b (symmetry code: 2 -x, -1 -y, -z), Pb1-O3d (symmetry code: x, -1 -y, 1/2 ? z) are longer than the sum of the ionic radii [54] but significantly shorter than the sum of the van der Waals radii (3.54 Å ) [19,55], which can be explained by the presence of an active lone pair in the proximity of the nitrate (O2, O3b) atoms, indicating a hemidirected geometry of the Pb centers. In addition, the Pb-N distances in 1, located in the opposite site of the lone pair are significantly shorter than the observed range for complexes with an inactive lone pair [56] and these distances are similar to most of the previously reported complexes containing a 2,2 0 -bipyridine with an active lone pair [19,23].…”

“…z) are longer than the sum of the ionic radii [54] but significantly shorter than the sum of the van der Waals radii (3.54 Å ) [19,55], which can be explained by the presence of an active lone pair in the proximity of the nitrate (O2, O3b) atoms, indicating a hemidirected geometry of the Pb centers. In addition, the Pb-N distances in 1, located in the opposite site of the lone pair are significantly shorter than the observed range for complexes with an inactive lone pair [56] and these distances are similar to most of the previously reported complexes containing a 2,2 0 -bipyridine with an active lone pair [19,23]. Hence, the geometry of the nearest coordination environment of Pb1 is likely to be caused by the geometrical constraints of coordinated O-and N-atoms, and by the influence of a stereochemically ''active'' electron pair of the metal ion.…”

“…Pb(II) complexes with 2,2 0 -bipyridine and 4,4 0 -bipyridine ligands [18][19][20] were subject to frequent studies. Since 4,4 0 -bipyridine can potentially act as a spacer ligand, a vast number of coordination polymers of its metal ions (e.g., with Pb(II), [20,21]) have been previously reported.…”

Crystal structure of poly[(4,5-imidazoledicarboxylato)lead(II)], [Pb3(C10H2N4O8)]n

“…Lead is a toxic metal, so the study of Pb(II) model complexes in biological systems and removal of lead by chelating agents through coordination is very important [1]. Lead(II) possesses a large radius, avariable stereochemical activity, and a flexible coordination environment, which provides unique opportunities for the construction of novel metal-organic frameworks (MOFs) [2].…”

Crystal structure of poly[(4,5-imidazoledicarboxylato)lead(II)], [Pb3(C10H2N4O8)]n

“…Lead is atoxic metal, so the study of Pb(II) model complexes in biological systems and removal of lead by chelating agents through coordination is very important [1]. Lead(II) possesses a large radius, avariable stereochemical activity, and aflexible coordination environment, which provides unique opportunities for the construction of novel metal-organic frameworks (MOFs) [2].…”