Magnetic properties of 1

4 complexes of Co IIX 2 (X = NCO -, NCS -, and Br -) with 4-(N-tert- butylaminoxyl)pyridine. Antiferromagnets in crystalline states and single-molecule magnets in frozen solutions

Shinji Kanegawa, Satoru Karasawa, Motohiro Nakano, Noboru Koga

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Three cobalt(II) complexes, [Co(X) 2(4NOpy) 4] (X = NCO -, NCS -, and Br -; 4NOpy = 4-(N-tert-butylaminoxyl)-pyridine) were prepared, and their molecular structures were characterized by X-ray structure analysis. The molecular geometry of [Co(X) 2(4NOpy) 4] (X = NCO - and NCS -) is a compressed octahedron, in which the counter ions occupy the apical positions with short bond distances of 2.064-2.098 Å. In the crystalline state, from plots of χ mol vs T and χ′ mol vs T, [Co(NCO) 2(4NOpy) 4] and [Co(NCS) 2(4NOpy) 4] are antiferromagnets with T N = 4.5 and 15 K, respectively. In frozen solution, on the other hand, both complexes and [Co(Br) 2(4NOpy) 4] functioned as single-molecule magnets. The χ″ mol vs T plot for [Co(Br) 2(4NOpy) 4] gave a effective activation barrier (U eff) of 20 K for the reorientation of the spin. From the field dependence of magnetization at various temperatures below 5 K for [Co(X) 2(4NOpy) 4] (X = NCO -, NCS -, and Br -) the values of the zero-field splitting parameters, D/k B, were estimated to be -14, -9.7, and -4.5 K with S = 5/2, respectively. Theoretical studies based on the ligand-field theory model for [Co(NCO) 2(4NOpy) 4] gave an exchange coupling parameter, J/k B, of 29 K and a thermodynamic activation barrier, U, of 60 K.

Original languageEnglish
Pages (from-to)1372-1382
Number of pages11
JournalBulletin of the Chemical Society of Japan
Volume79
Issue number9
DOIs
Publication statusPublished - 2006

Fingerprint

Magnets
Magnetic properties
Chemical activation
Crystalline materials
Exchange coupling
Molecules
Radiation counters
Cobalt
Molecular structure
Magnetization
Thermodynamics
Ligands
X rays
Geometry
Temperature
pyridine

All Science Journal Classification (ASJC) codes

  • Chemistry(all)

Cite this

@article{ab507ac24fae460894f606a1dae86573,
title = "Magnetic properties of 1: 4 complexes of Co IIX 2 (X = NCO -, NCS -, and Br -) with 4-(N-tert- butylaminoxyl)pyridine. Antiferromagnets in crystalline states and single-molecule magnets in frozen solutions",
abstract = "Three cobalt(II) complexes, [Co(X) 2(4NOpy) 4] (X = NCO -, NCS -, and Br -; 4NOpy = 4-(N-tert-butylaminoxyl)-pyridine) were prepared, and their molecular structures were characterized by X-ray structure analysis. The molecular geometry of [Co(X) 2(4NOpy) 4] (X = NCO - and NCS -) is a compressed octahedron, in which the counter ions occupy the apical positions with short bond distances of 2.064-2.098 {\AA}. In the crystalline state, from plots of χ mol vs T and χ′ mol vs T, [Co(NCO) 2(4NOpy) 4] and [Co(NCS) 2(4NOpy) 4] are antiferromagnets with T N = 4.5 and 15 K, respectively. In frozen solution, on the other hand, both complexes and [Co(Br) 2(4NOpy) 4] functioned as single-molecule magnets. The χ″ mol vs T plot for [Co(Br) 2(4NOpy) 4] gave a effective activation barrier (U eff) of 20 K for the reorientation of the spin. From the field dependence of magnetization at various temperatures below 5 K for [Co(X) 2(4NOpy) 4] (X = NCO -, NCS -, and Br -) the values of the zero-field splitting parameters, D/k B, were estimated to be -14, -9.7, and -4.5 K with S = 5/2, respectively. Theoretical studies based on the ligand-field theory model for [Co(NCO) 2(4NOpy) 4] gave an exchange coupling parameter, J/k B, of 29 K and a thermodynamic activation barrier, U, of 60 K.",
author = "Shinji Kanegawa and Satoru Karasawa and Motohiro Nakano and Noboru Koga",
year = "2006",
doi = "10.1246/bcsj.79.1372",
language = "English",
volume = "79",
pages = "1372--1382",
journal = "Bulletin of the Chemical Society of Japan",
issn = "0009-2673",
publisher = "The Chemical Society of Japan",
number = "9",

}

TY - JOUR

T1 - Magnetic properties of 1

T2 - 4 complexes of Co IIX 2 (X = NCO -, NCS -, and Br -) with 4-(N-tert- butylaminoxyl)pyridine. Antiferromagnets in crystalline states and single-molecule magnets in frozen solutions

AU - Kanegawa, Shinji

AU - Karasawa, Satoru

AU - Nakano, Motohiro

AU - Koga, Noboru

PY - 2006

Y1 - 2006

N2 - Three cobalt(II) complexes, [Co(X) 2(4NOpy) 4] (X = NCO -, NCS -, and Br -; 4NOpy = 4-(N-tert-butylaminoxyl)-pyridine) were prepared, and their molecular structures were characterized by X-ray structure analysis. The molecular geometry of [Co(X) 2(4NOpy) 4] (X = NCO - and NCS -) is a compressed octahedron, in which the counter ions occupy the apical positions with short bond distances of 2.064-2.098 Å. In the crystalline state, from plots of χ mol vs T and χ′ mol vs T, [Co(NCO) 2(4NOpy) 4] and [Co(NCS) 2(4NOpy) 4] are antiferromagnets with T N = 4.5 and 15 K, respectively. In frozen solution, on the other hand, both complexes and [Co(Br) 2(4NOpy) 4] functioned as single-molecule magnets. The χ″ mol vs T plot for [Co(Br) 2(4NOpy) 4] gave a effective activation barrier (U eff) of 20 K for the reorientation of the spin. From the field dependence of magnetization at various temperatures below 5 K for [Co(X) 2(4NOpy) 4] (X = NCO -, NCS -, and Br -) the values of the zero-field splitting parameters, D/k B, were estimated to be -14, -9.7, and -4.5 K with S = 5/2, respectively. Theoretical studies based on the ligand-field theory model for [Co(NCO) 2(4NOpy) 4] gave an exchange coupling parameter, J/k B, of 29 K and a thermodynamic activation barrier, U, of 60 K.

AB - Three cobalt(II) complexes, [Co(X) 2(4NOpy) 4] (X = NCO -, NCS -, and Br -; 4NOpy = 4-(N-tert-butylaminoxyl)-pyridine) were prepared, and their molecular structures were characterized by X-ray structure analysis. The molecular geometry of [Co(X) 2(4NOpy) 4] (X = NCO - and NCS -) is a compressed octahedron, in which the counter ions occupy the apical positions with short bond distances of 2.064-2.098 Å. In the crystalline state, from plots of χ mol vs T and χ′ mol vs T, [Co(NCO) 2(4NOpy) 4] and [Co(NCS) 2(4NOpy) 4] are antiferromagnets with T N = 4.5 and 15 K, respectively. In frozen solution, on the other hand, both complexes and [Co(Br) 2(4NOpy) 4] functioned as single-molecule magnets. The χ″ mol vs T plot for [Co(Br) 2(4NOpy) 4] gave a effective activation barrier (U eff) of 20 K for the reorientation of the spin. From the field dependence of magnetization at various temperatures below 5 K for [Co(X) 2(4NOpy) 4] (X = NCO -, NCS -, and Br -) the values of the zero-field splitting parameters, D/k B, were estimated to be -14, -9.7, and -4.5 K with S = 5/2, respectively. Theoretical studies based on the ligand-field theory model for [Co(NCO) 2(4NOpy) 4] gave an exchange coupling parameter, J/k B, of 29 K and a thermodynamic activation barrier, U, of 60 K.

UR - http://www.scopus.com/inward/record.url?scp=33750583733&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33750583733&partnerID=8YFLogxK

U2 - 10.1246/bcsj.79.1372

DO - 10.1246/bcsj.79.1372

M3 - Article

VL - 79

SP - 1372

EP - 1382

JO - Bulletin of the Chemical Society of Japan

JF - Bulletin of the Chemical Society of Japan

SN - 0009-2673

IS - 9

ER -