Coordination geometry of lead carboxylates – spectroscopic and crystallographic evidence

Abstract

Despite their versatility, only a few single-crystal X-ray structures of lead carboxylates exist, due to difficulties with solubility. In particular, the structures of long-chain metal carboxylates have not been reported. The lone electron pair in Pb(ii) can be stereochemically active or inactive, leading to two types of coordination geometries commonly referred to as hemidirected and holodirected structures, respectively. We report (13)C and (207)Pb solid-state NMR and infrared spectra for a series of lead carboxylates, ranging from lead hexanoate (C6) to lead hexadecanoate (C18). The lead carboxylates based on consistent NMR parameters can be divided in two groups, shorter-chain (C6, C7, and C8) and longer-chain (C9, C10, C11, C12, C14, C16, and C18) carboxylates. This dichotomy suggests two modes of packing in these solids, one for the short-chain lead carboxylates and one for long-chain lead carboxylates. The consistency of the (13)C and (207)Pb NMR parameters, as well as the IR data, in each group suggests that each motif represents a structure characteristic of each subgroup. We also report the single-crystal X-ray diffraction structure of lead nonanoate (C9), the first single-crystal structure to have been reported for the longer-chain subgroup. Taken together the evidence suggests that the coordination geometry of C6-C8 lead carboxylates is hemidirected, and that of C9-C14, C16 and C18 lead carboxylates is holodirected.

Correlating Structural Features and 207Pb NMR Parameters with the Stereochemical Activity of PbII Lone Pairs in Birefringent Pb[2,6‐bis(benzimidazol‐2‐yl)pyridine] Complexes

“…Solid‐state NMR spectroscopy probes the local structure around an NMR‐active nucleus (spin quantum number, I ≥ 1/2) and is sensitive to coordination number, bond lengths and local asymmetry. As such, it can be used to measure lone‐pair activity . We have previously reported the 207 Pb magic‐angle spinning (MAS) NMR spectroscopic behaviour of Pb[Au(CN) 2 ] – coordination polymers containing various nitrogen‐donor capping ligands, for which it was demonstrated that the anisotropic nature of the chemical shift could be correlated with structural distortion parameters that are associated with lone‐pair activity , …”

“…As such, it can be used to measure lone-pair activity. [14][15][16] We have previously reported the 207 Pb magic-angle spinning (MAS) NMR spectroscopic behaviour of Pb[Au(CN) 2 ]coordination polymers containing various nitrogen-donor cap-ping ligands, for which it was demonstrated that the anisotropic nature of the chemical shift could be correlated with structural distortion parameters that are associated with lone-pair activity. [14,16] The chemical-shift tensor describes the orientational dependence of the magnetic shielding, which depends on the local electronic environment and is generally anisotropic if the site symmetry is not cubic.…”

Ionic Liquid Control Crystal Growth to Enhance Planar Perovskite Solar Cells Efficiency

“…Since HCOO -is known to form metal-organic complex with Pb 2+ ,our working hypothesis was that the HCOO -influences the crystal growth of the perovskite interacting with Pb 2+ . [18] In Figure 1b, we depict a schematic view of the proposed mechanism: STEP To investigate the impact of the MAF on the crystal growth, we prepared perovskite precursor solutions with and without 5mol% of MAF. Perovskite films were prepared on SnO 2 deposited FTO substrates by spin coating the precursor solution in a nitrogen filled glovebox using the one-step anti-solvent method.…”

Directionality of Pb2+ lone pair electrons dictated hemi‐directed coordination mode of methyl‐ and ferrocenylcarboxylate complexes

“…The exploring speciation of Pb 2+ gains the special interest from chemists for understanding its coordination chemistry and structural effects . The variation in coordination properties of Pb 2+ depends on the size of the ligands and the nature of donor atoms thus it dictates the structural arrangements in the entire globe of metal–ligand complex systems.…”

“…The exploring speciation of Pb 2+ gains the special interest from chemists for understanding its coordination chemistry and structural effects. [1][2][3][4][5][6][7][8][9][10][11][12] The variation in coordination properties of Pb 2+ depends on the size of the ligands and the nature of donor atoms thus it dictates the structural arrangements in the entire globe of metal-ligand complex systems. In general, the distribution of coordination bonds to bulky ligands would follow the structural rearrangements to avoid the steric repulsion between them and occupied entire globe.…”