Solution studies of the cobalt(II) N-rac- and N-meso-CoL2+ isomers and molecular and crystal structures of the low-spin, five-coordinate cobalt(II) macrocyclic complexes N-rac-[CoL(H2O)](ClO4)2·0.6H 2O (1) and N-rac-CoL(OClO3)ClO4 (2) (L = 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene)

David J. Szalda, Carolyn L. Schwarz, John F. Endicott, Etsuko Fujita, Carol Creutz

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Abstract

The title cobalt(II) complexes were prepared from the reaction of CoL(Cl)H2O2+ with Cr2+(aq) in 1.0 M HClO4, and crystals of 1 and 2 were obtained from acetone. Structures were determined from single-crystal X-ray diffraction data collected with use of Cu Ka radiation. Crystallographic data: 1, N-rac-[CoL(H2O)](ClO4)2·0.6H 2O, Pbcn, a = 15.654 (4) Å, b = 14.623 (2) Å, c = 55.221 (11) Å, V = 12640 (7) Å3, Z = 20 (R = 0.113, Rw = 0.135); 2, N-rac-[CoL(OClO3)]ClO4, P21/c, a = 10.336 (3) Å, b = 17.094 (1) Å, c = 13.890 (2) Å, β = 105.59 (2)°, V = 2363 (1) Å3, Z = 4 (R = 0.061, Rw = 0.087). Both 1 and 2 contain a five-coordinate cobalt(II) center with the four nitrogen atoms of N-rac-L forming the base of a square pyramid and axial water (1, Co-OH2 = 2.25 (5) Å) or axial perchlorate ion (2, Co-OClO3 = 2.305 (5) Å) forming the apex of the square pyramid. Studies of N-rac- and N-meso-CoL2+ in solution (perchlorate salts) are described: the lowest energy d-d band (1400-1700 nm, depending upon solvent) provides a probe of the isomeric composition of the solutions, since this band is 2-3 times more intense for the N-rac than for the N-meso isomer. Equilibration of the two isomers is slow at room temperature (-7 s-1) in organic solvents and in acidic aqueous solutions; it is, however, rapid in alkaline media, and the N-rac isomer is favored at equilibrium.

Original languageEnglish
Pages (from-to)3214-3219
Number of pages6
JournalInorganic Chemistry
Volume28
Issue number16
Publication statusPublished - 1989

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dienes
Cobalt
Isomers
Molecular structure
molecular structure
cobalt
isomers
Crystal structure
perchlorates
pyramids
crystal structure
nitrogen atoms
acetone
apexes
Acetone
Organic solvents
aqueous solutions
salts
Nitrogen
Salts

ASJC Scopus subject areas

  • Inorganic Chemistry

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@article{7e6bf4cdb7a340c683831e9f6cfd3011,
title = "Solution studies of the cobalt(II) N-rac- and N-meso-CoL2+ isomers and molecular and crystal structures of the low-spin, five-coordinate cobalt(II) macrocyclic complexes N-rac-[CoL(H2O)](ClO4)2·0.6H 2O (1) and N-rac-CoL(OClO3)ClO4 (2) (L = 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene)",
abstract = "The title cobalt(II) complexes were prepared from the reaction of CoL(Cl)H2O2+ with Cr2+(aq) in 1.0 M HClO4, and crystals of 1 and 2 were obtained from acetone. Structures were determined from single-crystal X-ray diffraction data collected with use of Cu Ka radiation. Crystallographic data: 1, N-rac-[CoL(H2O)](ClO4)2·0.6H 2O, Pbcn, a = 15.654 (4) {\AA}, b = 14.623 (2) {\AA}, c = 55.221 (11) {\AA}, V = 12640 (7) {\AA}3, Z = 20 (R = 0.113, Rw = 0.135); 2, N-rac-[CoL(OClO3)]ClO4, P21/c, a = 10.336 (3) {\AA}, b = 17.094 (1) {\AA}, c = 13.890 (2) {\AA}, β = 105.59 (2)°, V = 2363 (1) {\AA}3, Z = 4 (R = 0.061, Rw = 0.087). Both 1 and 2 contain a five-coordinate cobalt(II) center with the four nitrogen atoms of N-rac-L forming the base of a square pyramid and axial water (1, Co-OH2 = 2.25 (5) {\AA}) or axial perchlorate ion (2, Co-OClO3 = 2.305 (5) {\AA}) forming the apex of the square pyramid. Studies of N-rac- and N-meso-CoL2+ in solution (perchlorate salts) are described: the lowest energy d-d band (1400-1700 nm, depending upon solvent) provides a probe of the isomeric composition of the solutions, since this band is 2-3 times more intense for the N-rac than for the N-meso isomer. Equilibration of the two isomers is slow at room temperature (-7 s-1) in organic solvents and in acidic aqueous solutions; it is, however, rapid in alkaline media, and the N-rac isomer is favored at equilibrium.",
author = "Szalda, {David J.} and Schwarz, {Carolyn L.} and Endicott, {John F.} and Etsuko Fujita and Carol Creutz",
year = "1989",
language = "English",
volume = "28",
pages = "3214--3219",
journal = "Inorganic Chemistry",
issn = "0020-1669",
publisher = "American Chemical Society",
number = "16",

}

TY - JOUR

T1 - Solution studies of the cobalt(II) N-rac- and N-meso-CoL2+ isomers and molecular and crystal structures of the low-spin, five-coordinate cobalt(II) macrocyclic complexes N-rac-[CoL(H2O)](ClO4)2·0.6H 2O (1) and N-rac-CoL(OClO3)ClO4 (2) (L = 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene)

AU - Szalda, David J.

AU - Schwarz, Carolyn L.

AU - Endicott, John F.

AU - Fujita, Etsuko

AU - Creutz, Carol

PY - 1989

Y1 - 1989

N2 - The title cobalt(II) complexes were prepared from the reaction of CoL(Cl)H2O2+ with Cr2+(aq) in 1.0 M HClO4, and crystals of 1 and 2 were obtained from acetone. Structures were determined from single-crystal X-ray diffraction data collected with use of Cu Ka radiation. Crystallographic data: 1, N-rac-[CoL(H2O)](ClO4)2·0.6H 2O, Pbcn, a = 15.654 (4) Å, b = 14.623 (2) Å, c = 55.221 (11) Å, V = 12640 (7) Å3, Z = 20 (R = 0.113, Rw = 0.135); 2, N-rac-[CoL(OClO3)]ClO4, P21/c, a = 10.336 (3) Å, b = 17.094 (1) Å, c = 13.890 (2) Å, β = 105.59 (2)°, V = 2363 (1) Å3, Z = 4 (R = 0.061, Rw = 0.087). Both 1 and 2 contain a five-coordinate cobalt(II) center with the four nitrogen atoms of N-rac-L forming the base of a square pyramid and axial water (1, Co-OH2 = 2.25 (5) Å) or axial perchlorate ion (2, Co-OClO3 = 2.305 (5) Å) forming the apex of the square pyramid. Studies of N-rac- and N-meso-CoL2+ in solution (perchlorate salts) are described: the lowest energy d-d band (1400-1700 nm, depending upon solvent) provides a probe of the isomeric composition of the solutions, since this band is 2-3 times more intense for the N-rac than for the N-meso isomer. Equilibration of the two isomers is slow at room temperature (-7 s-1) in organic solvents and in acidic aqueous solutions; it is, however, rapid in alkaline media, and the N-rac isomer is favored at equilibrium.

AB - The title cobalt(II) complexes were prepared from the reaction of CoL(Cl)H2O2+ with Cr2+(aq) in 1.0 M HClO4, and crystals of 1 and 2 were obtained from acetone. Structures were determined from single-crystal X-ray diffraction data collected with use of Cu Ka radiation. Crystallographic data: 1, N-rac-[CoL(H2O)](ClO4)2·0.6H 2O, Pbcn, a = 15.654 (4) Å, b = 14.623 (2) Å, c = 55.221 (11) Å, V = 12640 (7) Å3, Z = 20 (R = 0.113, Rw = 0.135); 2, N-rac-[CoL(OClO3)]ClO4, P21/c, a = 10.336 (3) Å, b = 17.094 (1) Å, c = 13.890 (2) Å, β = 105.59 (2)°, V = 2363 (1) Å3, Z = 4 (R = 0.061, Rw = 0.087). Both 1 and 2 contain a five-coordinate cobalt(II) center with the four nitrogen atoms of N-rac-L forming the base of a square pyramid and axial water (1, Co-OH2 = 2.25 (5) Å) or axial perchlorate ion (2, Co-OClO3 = 2.305 (5) Å) forming the apex of the square pyramid. Studies of N-rac- and N-meso-CoL2+ in solution (perchlorate salts) are described: the lowest energy d-d band (1400-1700 nm, depending upon solvent) provides a probe of the isomeric composition of the solutions, since this band is 2-3 times more intense for the N-rac than for the N-meso isomer. Equilibration of the two isomers is slow at room temperature (-7 s-1) in organic solvents and in acidic aqueous solutions; it is, however, rapid in alkaline media, and the N-rac isomer is favored at equilibrium.

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JF - Inorganic Chemistry

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