Magnetic property of 1:2 mixture of Co( p-tolsal) 2; p-tolsal = N- p-tolylsalicylideniminato, and cyclic pentacarbene–pyridine with S = 10/2 in dilute frozen solution

• Published in: Polyhedron Vol. 26; no. 9; pp. 1905 - 1911
• Main Authors: Tobinaga, Hiroyuki, Suehiro, Madoka, Ito, Tetsuji, Zhou, Guangyuan, Karasawa, Satoru, Koga, Noboru
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15-06-2007
• Subjects: Cobalt(II) complex; Heterospin system; Hysteresis loop; Pentacarbene; Single-molecule magnet; Cobalt(II) complex; Heterospin system; Hysteresis loop; Single-molecule magnet; Pentacarbene
• ISSN: 0277-5387
• DOI: 10.1016/j.poly.2006.09.036

A cyclic pentadiazo-pyridine derivative,
cD5py, was prepared. The 1:2 complex of Co(
p-tolsal)
2 with
cD5py in frozen solution after irradiation functions as the single-molecule magnet with
U
eff
=
72
K and
τ
0
=
2.0
×
10
−9
s. A hysteresis loop with
H
c
=
7.1
kOe at 1.9
K was also observed.
A cyclic pentadiazo-pyridine ligand,
cD5py, was prepared and its photoproduct,
cC5py, in a frozen solution was confirmed to be a high-spin polycarbene with
S
=
10/2. The magnetic property of the 1:2 mixture of Co(
p-tolsal)
2;
p-tolsal
=
N-
p-tolylsalicylideniminato, and
cD5py in a dilute frozen solution after irradiation was investigated by SQUID magneto/susceptometry. In the ac magnetic susceptibility measurements, the in-phase and out-of-phase components (
χ′ and
χ″, respectively) with frequency dependence were observed, indicating that the 1:2 complex, Co(
p-tolsal)
2-(
cC5py)
2, had slow magnetic relaxation characteristic of the single-molecule magnet (SMM). From the
χ″ versus
T plots with various frequencies, the values of activation barrier,
U
eff, for the reverse of the magnetism was estimated to be 72
K. In the dc magnetic susceptibility measurements, the magnetic hysteresis loops were observed below 3
K. The value of the coercive force,
H
c, depends on the temperature and increases on cooling. The hysteresis loop with
H
c
=
7.1
kOe was observed at 1.9
K.