Alkaline earth, lead(II), and cadmium(II) complexes of a nitrogen analogue of [18]annulene; X-ray crystal structure of the lead and cadmium complexes

Abstract

CaII, SrII, BaII, and PbII are effective templates ALTHOUGH it has not previously been synthesised, the for the synthesis of a conjugated, 18-membered, hexaconjugated macrocycle L (1) containing the 18-membered dentate 'N6' macrocycle; the crystal and molecular inner large ring, has been the subject of theoretical calculastructures of a PbII complex, and of a CdII complex tions by Honeybournel who predicted that (i) the six prepared by metal exchange, have been determined.nitrogen atoms would define a hexagon with a face dimension of ca. 2.8 A, (ii) when co-ordinated, the length of any

Comparison of Zinc and Cadmium Coordination Environments in Synthetic Analogues of Carbonic Anhydrase: Synthesis and Structure of {[PimPri,But]Cd(OH2)(OClO3)}(ClO4)

“…Although commonly viewed as a “noncoordinating” anion, perchlorate is nonetheless known to bind to certain metal centers, including cadmium. − Interestingly, however, the Cd−OClO 3 bond length of 2.203(8) Å in {[Pim Pr i ,Bu t ]Cd(OH 2 )(OClO 3 )} + is close to the sum of the covalent radii of Cd and O (2.14 Å) and is considerably shorter than the range previously established for cadmium complexes listed in the Cambridge Structural Database (2.33 Å−2.65 Å). − For example, the Cd−OClO 3 interaction in the related cis aqua−perchlorate complex {[η 5 -(C 2 H 4 S) 5 ]Cd(OH 2 )(OClO 3 )} + is sufficiently long [2.653(5) Å] that it may be considered to be effectively nonbonding. , In contrast to the different Cd−OClO 3 interactions in the above complexes, however, the Cd−OH 2 bond lengths in {[Pim Pr i ,Bu t ]Cd(OH 2 )(OClO 3 )} + [2.297(9) Å] and {[η 5 -(C 2 H 4 S) 5 ]Cd(OH 2 )(OClO 3 )} + [2.253(4) Å] 12 are comparable.…”

“…The Cd−OClO 3 [2.33(3) Å] and Cd−OH 2 [2.24(3) Å] bond lengths in a hexagonal bipyramidal [(L N 6 )Cd(OH 2 )(OClO 3 )] + trans aqua−perchlorate complex are, however, comparable to those in {[Pim Pr i ,Bu t ]Cd(OH 2 )(OClO 3 )} + . See ref .…”

Pb2+—N Bonding Chemistry: Recycling of Polyaniline–Pb Nanocrystals Waste for Generating High-Performance Supercapacitor Electrodes

“…In fact, whether the electrons reside in the 6s orbital or in a hybrid 6s-6p orbital is still an item of ongoing research and not yet firmly entered into textbooks. , The so-called inert-pair effect explains not only the liquidity of Hg, but also helps to rationalize the superior stability of Tl, Pb, and Bi ions in the lower-oxidation states of +1, + 2, and +3, respectively. ,, Apart from chemical stability, the stereochemical activity of the inert-pair, specifically of Pb 2+ ion, could adversely affect the functions of biological channels involving Mg 2+ , Ca 2+ , Fe 2+ , or Zn 2+ ions, commonly referred to as lead-poisoning or saturnism . Although the stereochemical implications of the inert-pair on the structure of Pb 2+ complexes were demonstrated crystallographically long ago, molecular level understanding of lead poisoning appeared only recently with computational modeling experiments using density functional theory. − …”

Synthesis, crystal structure and spectroscopic characterization of silver(I), cadmium(II) complexes with the Schiff base derived from pyridine-2-carboxaldehyde and 4-[(E)-2-phenyldiazenyl]aniline

“…Similar to 1, the Schiff-base chelates cadmium(II) through the pyridyl N and imine N atoms to form a stable five-membered ring with bite angles of N(2)-Cd(1)-N(1) (73.24(13)8) and N(5)-Cd(1)-N(6) (73.71(13)8), which are larger than found in aqua-perchlorate-(bis(o-phenylene)-bis (pyridine-2,6-dialdimino))-cadmium(II) perchlorate methanol solvate [18]. In 2, the bond distances of Cd-N py ¼ 2.3000(4)-2.325(4) and Cd-N imine ¼ 2.304(4)-2.319(4) Å are shorter than corresponding bonds found in the literature [19] …”