Synthesis and spectroscopic characterization of a new family of Ni(4) spin clusters.
A new family of tetranuclear Ni complexes [Ni(4)(ROH)(4)L(4)] (H(2)L = salicylidene-2-ethanolamine; R = Me (1) or Et (2)) has been synthesized and studied. Complexes 1 and 2 possess a [Ni(4)O(4)] core comprising a distorted cubane arrangement. Magnetic susceptibility and inelastic neutron scattering studies indicate a combination of ferromagnetic and antiferromagnetic pairwise exchange interactions between the four Ni(II) centers, resulting in an S = 4 spin ground state. Magnetization measurements reveal an easy-axis-type magnetic anisotropy with D approximately -0.93 cm(-)(1) for both complexes. Despite the large magnetic anisotropy, no slow relaxation of the magnetization is observed down to 40 mK. To determine the origin of the low-temperature magnetic behavior, the magnetic anisotropy of complex 1 was probed in detail using inelastic neutron scattering and frequency domain magnetic resonance spectroscopy. The spectroscopic studies confirm the easy-axis-type anisotropy and indicate strong transverse interactions. These lead to rapid quantum tunneling of the magnetization, explaining the unexpected absence of slow magnetization relaxation for complex 1.
Sieber
Andreas
A
Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
Boskovic
Colette
C
Bircher
Roland
R
Waldmann
Oliver
O
Ochsenbein
Stefan T
ST
Chaboussant
Grégory
G
Güdel
Hans U
HU
Kirchner
Nadeschda
N
van Slageren
Joris
J
Wernsdorfer
Wolfgang
W
Neels
Antonia
A
Stoeckli-Evans
Helen
H
Janssen
Stefan
S
Juranyi
Fanni
F
Mutka
Hannu
H