Related Experiment Video
Updated: Aug 7, 2026
Combining Solid-state and Solution-based Techniques: Synthesis and Reactivity of Chalcogenidoplumbates(II or IV)
Published on: December 29, 2016
Structures of hexakis(antipyrine)lead(II) complexes: the first example of the stereochemically active and inactive
Krzysztof Łyczko1, Monika Łyczko1
1Institute of Nuclear Chemistry and Technology, Dorodna 16, 03-195 Warsaw, Poland.
Abstract:
Homoleptic lead(II) complexes with the monodentate O-donor ligand antipyrine (anti or 1,5-dimethyl-2-phenyl-2,3-dihydro-1H-pyrazol-3-one) were synthesized in the form of triflate (trifluoromethanesulfonate) and perchlorate salts, namely, hexakis(1,5-dimethyl-2-phenyl-2,3-dihydro-1H-pyrazol-3-one-κO)lead(II) bis(trifluoromethanesulfonate), [Pb(C11H12N2O)6](CF3SO3)2, and hexakis(1,5-dimethyl-2-phenyl-2,3-dihydro-1H-pyrazol-3-one-κO)lead(II) bis(perchlorate), [Pb(C11H12N2O)6](ClO4)2, abbreviated as [Pb(anti)6]X2 (X = OTf and ClO4). In the case of [Pb(anti)6](OTf)2, two polymorphic forms crystallizing in the monoclinic I2/a (1a) and triclinic P\overline 1 (1b) space groups were distinguished. [Pb(anti)6](ClO4)2 (2) crystallized in the trigonal space group P\overline 3. The crystal structures were determined by single-crystal X-ray diffraction. In all three structures, the metal ion is surrounded by six O atoms from the antipyrine molecules. Compounds 1a and 2 display regular and holodirected octahedral geometry with three similar [2.496 (1), 2.523 (1) and 2.539 (1) Å] or six equivalent Pb-O bond lengths [2.474 (2) Å]. Complex 1b has lower hemidirected symmetry, forming a ψ-pentagonal bipyramid, with six different Pb-O bond distances in the range 2.327 (2)-2.852 (2) Å and one position occupied by a lone electron pair. Shorter C-H...O contacts in 1b [2.998 (4) and 3.141 (4) Å] compared to those in 1a [3.354 (2) and 3.365 (2) Å] and 2 [3.360 (3) and 3.384 (3) Å] between the antipyrine molecules and the counter-ions seem to stabilize the active lone pair. In all three structures, the [Pb(anti)6]2+ cations organize into a hexagonal columnar packing, while the ordered counter-ions occupy the free cavities between them. Density functional theory (DFT) calculations reveal that the isolated [Pb(anti)6]2+ cation favours a distorted hemidirected geometry. The calculated eccentricity values [0.14 (1b) and 0 (1a and 2)] confirm the active and inert behaviour of the 6s2 lone pair, respectively. The distribution of the Pb-O bond lengths for the homoleptic lead(II) complexes with a PbO6 core was presented. Correlations between Pb-O bond lengths and cordination number (CN) for the selected lead(II) and lead(IV) complexes were analysed.
More Related Videos
Related Concept Videos
04:01VSEPR Theory and the Effect of Lone Pairs
02:42Valence Bond Theory
01:18Aromatic Hydrocarbon Cations: Structural Overview
Removing one hydrogen from the intervening CH2 group with both...
03:02Colors and Magnetism
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
02:34Structural Isomerism
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...