Spectroscopic, structural, and thermodynamic aspects of the stereochemically active lone pair on lead(II): Structure of the lead(II) dota complex

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

“…A stereochemically active lone pair based on structural features has been previously identified by the presence of distorted geometries such as variable bond lengths and angles within the coordination sphere. As mentioned above, one such parameter is the bond length opposite the lone pair, which is typically shortened , , . For many of the aforementioned structures, the lone pair is proposed to be opposite the Pb–bbp(pyridine) bond, and therefore the difference in Pb–pyridine bond lengths between complexes can be related to the activity of the stereochemical lone pair.…”

“…Previous studies of lone‐pair stereochemical activity have mainly relied on X‐ray diffraction data, with asymmetric bond lengths and decreased coordination number reflecting increased stereochemical activity of the lone pair , , , . Some studies have attempted to qualitatively rank lone‐pair activity by investigating the degree of distortion in the coordination sphere as well as differences in the high‐energy UV absorptions and the stability of Pb II complexes . However, most studies only determine whether a structure is holo‐ or hemidirectional and not its degree of stereochemical activity.…”

Exciplex Formation and Aggregation Induced Emission in Di‐(N‐benzyl)cyclen and Its Complexes – Selective Fluorescence with Lead(II), and as the Cadmium(II) Complex, with the Chloride Ion

“…The nitrogen donors of the cyclen moiety form a plane with the Pb lying above it, while the two perchlorates are coordinated to the Pb, pushed to one side by the π contacted benzyl from an adjacent complex individual. The Pb–N bond lengths to the cyclen part of the macrocycle average 2.502 Å, somewhat shorter than the average of 2.65 ± 0.04 Å found in the CSD for Pb–N bonds in five structures containing Pb II bound to a cyclen moiety . The Pb–O bonds to the two perchlorates are rather long at 3.069(4) and 2.934(4) Å, which is typical of bonds near the stereochemically active lone pair on Pb II ,, , if the lone pair is located between the two Pb–O bonds.…”

“…The Pb–N bond lengths to the cyclen part of the macrocycle average 2.502 Å, somewhat shorter than the average of 2.65 ± 0.04 Å found in the CSD for Pb–N bonds in five structures containing Pb II bound to a cyclen moiety . The Pb–O bonds to the two perchlorates are rather long at 3.069(4) and 2.934(4) Å, which is typical of bonds near the stereochemically active lone pair on Pb II ,, , if the lone pair is located between the two Pb–O bonds. The difference appears to be due to the fact that the cyclen‐based ligands in the five reported structures all have pendent donor groups that raise the C.N.…”

“…The Pb–O bonds to the two perchlorates are rather long at 3.069(4) and 2.934(4) Å, which is typical of bonds near the stereochemically active lone pair on Pb II ,, , if the lone pair is located between the two Pb–O bonds. The difference appears to be due to the fact that the cyclen‐based ligands in the five reported structures all have pendent donor groups that raise the C.N. of the Pb II to 8, as compared with C.N.…”