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Title: Structural investigation into the steric control of polyether complexation in the lanthanide series: Macrocyclic 18-crown-6 versus acyclic pentaethylene glycol

Abstract

The complexation reactions of MCl[sub 3][center dot]nH[sub 2]O (M = Y, La-Pr, Sm-Lu) with pentaethylene glycol (EO5) and MCl[sub 3][center dot]nH[sub 2]O (M = La, Ce, Pr, Eu, Gd) with 18-crown-6 in 1:1 molar ratios in 3:1 CH[sub 3]CN:CH[sub 3]OH were investigated. X-ray structural analysis of 21 crystalline complexes were carried out. Comparison of all the crystalline complexes studied reveals that polyethylene glycols exhibit a helical wrapping pattern around the lanthanide ions, while the crown ethers attempt to fold around these cations. This feature of polyether complexation of the lanthanide(III) chlorides may be responsible for the ready isolation of EO5 complexes for all lanthanides and the lack of direct coordination of 18-crown-6 past M = Tb in normal 1:1 complexation reactions.

Authors:
; ; ; ;  [1]
  1. (Northern Illinois Univ., DeKalb, IL (United States))
Publication Date:
OSTI Identifier:
5088593
Resource Type:
Journal Article
Resource Relation:
Journal Name: Inorganic Chemistry; (United States); Journal Volume: 32:16
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; RARE EARTH COMPLEXES; CRYSTAL STRUCTURE; YTTRIUM COMPLEXES; CHELATING AGENTS; CROWN ETHERS; HYDRATES; POLYETHYLENE GLYCOLS; X-RAY DIFFRACTION; ALCOHOLS; COHERENT SCATTERING; COMPLEXES; DIFFRACTION; ETHERS; GLYCOLS; HYDROXY COMPOUNDS; ORGANIC COMPOUNDS; ORGANIC OXYGEN COMPOUNDS; ORGANIC POLYMERS; POLYMERS; SCATTERING; TRANSITION ELEMENT COMPLEXES; 400201* - Chemical & Physicochemical Properties

Citation Formats

Rogers, R.D., Rollins, A.N., Etzenhouser, R.D., Voss, E.J., and Bauer, C.B. Structural investigation into the steric control of polyether complexation in the lanthanide series: Macrocyclic 18-crown-6 versus acyclic pentaethylene glycol. United States: N. p., 1993. Web. doi:10.1021/ic00068a013.
Rogers, R.D., Rollins, A.N., Etzenhouser, R.D., Voss, E.J., & Bauer, C.B. Structural investigation into the steric control of polyether complexation in the lanthanide series: Macrocyclic 18-crown-6 versus acyclic pentaethylene glycol. United States. doi:10.1021/ic00068a013.
Rogers, R.D., Rollins, A.N., Etzenhouser, R.D., Voss, E.J., and Bauer, C.B. 1993. "Structural investigation into the steric control of polyether complexation in the lanthanide series: Macrocyclic 18-crown-6 versus acyclic pentaethylene glycol". United States. doi:10.1021/ic00068a013.
@article{osti_5088593,
title = {Structural investigation into the steric control of polyether complexation in the lanthanide series: Macrocyclic 18-crown-6 versus acyclic pentaethylene glycol},
author = {Rogers, R.D. and Rollins, A.N. and Etzenhouser, R.D. and Voss, E.J. and Bauer, C.B.},
abstractNote = {The complexation reactions of MCl[sub 3][center dot]nH[sub 2]O (M = Y, La-Pr, Sm-Lu) with pentaethylene glycol (EO5) and MCl[sub 3][center dot]nH[sub 2]O (M = La, Ce, Pr, Eu, Gd) with 18-crown-6 in 1:1 molar ratios in 3:1 CH[sub 3]CN:CH[sub 3]OH were investigated. X-ray structural analysis of 21 crystalline complexes were carried out. Comparison of all the crystalline complexes studied reveals that polyethylene glycols exhibit a helical wrapping pattern around the lanthanide ions, while the crown ethers attempt to fold around these cations. This feature of polyether complexation of the lanthanide(III) chlorides may be responsible for the ready isolation of EO5 complexes for all lanthanides and the lack of direct coordination of 18-crown-6 past M = Tb in normal 1:1 complexation reactions.},
doi = {10.1021/ic00068a013},
journal = {Inorganic Chemistry; (United States)},
number = ,
volume = 32:16,
place = {United States},
year = 1993,
month = 8
}
  • A series of macrocyclic polyether-diester ligands containing a proton-ionizable triazole subcyclic unit has been prepared. The crystal structure of one ligand shows that it forms a hydrate with the water molecule located in the macrocyclic cavity. The water is coordinated by hydrogen bonding to two oxygen atoms of the macrocycle and to the NH group of the triazole moiety. These macrocycles also form complexes with amines. These amine complexes are kinetically more stable than complexes formed by the triazole ligands with the corresponding alkylammonium perchlorate salts. The crystal structure of one of these complexes shows that the triazole ring hasmore » donated a proton to the amine group. 41 references, 4 figures, 2 tables.« less
  • A series of macrocyclic polyether-diester ligands containing a proton-ionizable 4-hydroxypyridine subcyclic unit has been prepared. These new macrocyclic ligands form stable complexes with both alkylammonium perchlorate salts and with alkylamines. The crystal structure for one of these complexes with an alkylamine shows that the hydroxy proton has been donated to the amine with the resultant formation of a 4-pyridone unit. Chiral dimethyl- and diphenyl-substituted macrocycles containing the 4-hydroxpyridine subcyclic unit exhibit chiral recognition for the enantiomers of 2-(1-naphthyl)ethylamine and their hydrogen perchlorate salts. 15 references, 6 figures, 4 tables.
  • The reaction of anhydrous UO[sub 2]Cl[sub 2] with 12-crown-4 or hexaethylene glycol (EO6) in THF with low water content resulted in the crystallization of [UO[sub 2]Cl[sub 2](OH[sub 2])[sub 2](12-crown-4)][center dot]12-crown-4 and UO[sub 2]Cl[sub 2](OH[sub 2])[sub 2](EO6). The crystal structures of both complexes were determined. Each complex consists of a uranyl ion coordinated to two chloride anions, two water molecules, and one oxygen of the polyether. Most of the uncoordinated ether oxygen atoms participate in hydrogen bonding. The hydrogen bonding in the 12-crown-4 complex produces a dimer, while the hydrogen bonding in the EO6 complex is polymeric. The etheric U-O separationmore » of 2.546(4) [angstrom] in the 12-crown-4 complex is the longest U-O contact in either complex, while the alcoholic U-O distance in the EO6 complex is a much shorter 2.433(5) [angstrom].« less
  • The direct reaction of hydrated lanthanide nitrate salts with 18-crown-6 in 3:1 CH{sub 3}CN:CH{sub 3}OH has resulted in the isolation and structural characterization of [Pr(NO{sub 3}){sub 3}(18-crown-6)] and [M(NO{sub 3}){sub 3}(OH{sub 2}){sub 3}]{center_dot}18-crown-6 (M=Y, Eu, Tb-Lu). (The Eu and Yb analogs were confirmed with preliminary cell data only). [Pr(NO{sub 3}){sub 3}(18-crown-6)] is 12-coordinate icosahedral and crystallizes in the orthorhombic space group Pbca with (at 20{degrees}C) a = 12.230(2), b = 15.598(4), c = 21.777(9) {angstrom} and D{sub calc} = 1.89 g cm{sup -3} for Z = 8. The seven isostructural [Pr(NO{sub 3}){sub 3}(18-crown-6)] complexes all contain 9-coordinate capped square antiprismaticmore » metal centers hydrogen bonded via the bound water molecules to D{sub 3d} 18-crown-6 within the lattice to form hydrogen bonded polymeric chains.« less
  • Complexes of LaCl{sub 3}{center_dot}7H{sub 2}O and CeCl{sub 3} {center_dot} 7H{sub 2}O directly coordinated to 15-crown-5 were prepared by placing the reactants in 3:1 CH{sub 3}CN:CH{sub 3}OH on opposite sides of a fine porosity glass frit in a U-shaped cell and passing a 10 {mu}A current through the cell. The crystal structures of the two anhydrous 8-coordinate complexes, [MCl{sub 3}(15-crown-5)] (M = La, Ce) have been determined. Each contains the lanthanide in a bicapped trigonal prismatic geometry. The two complexes are isostructural crystallizing in the monoclinic space group P2{sub 1}/c with (at 20{degrees}C) for M = La: a =8.217(8), b =more » 14.298(2), c = 14.341(9){angstrom}, {beta} = 104.79(8){degrees}, and D{sub calc} = 1.90 g cm{sup {minus}3} for Z = 4; for M = Ce: a = 8.208(9), b = 14.263(6), c = 14.270(8){angstrom}, {beta} = 104.74(7){degrees}, and D{sub calc} = 1.92 g cm{sup {minus}3} for Z = 4. Direct reaction of ErCl{sub 3}{center_dot}6H{sub 2}O with 15-crown-5 in 3:1 CH{sub 3}CN:CH{sub 3}OH resulted in the crystallization of the second sphere hydrogen bonded complex [Er(OH{sub 2}){sub 8}]Cl{sub 3}{center_dot}15-crown-5. This complex is monoclinic, P2{sub 1}/n with (at 18{degrees}C) a = 9.193(3), b = 17.235(9), c = 15.216(5){angstrom}, {beta} = 92.48(3){degrees}, and D{sub calc} = 1.76 g cm{sup {minus}3} for Z = 4. The Er{sup 3+} ion is dodecahedral.« less