2 research outputs found
Phthalocyanine-Based Single-Component Molecular Conductor [Mn<sup>III</sup>(Pc)(CN)]<sub>2</sub>O
A new
manganese complex, [MnĀ(Pc)Ā(CN)]<sub>2</sub>O, was prepared by an electrocrystallization
method. This material is a single-component molecular conductor that
displays semiconducting behavior with room temperature conductivity
of 4.5 Ć 10<sup>ā3</sup> S cm<sup>ā1</sup>. Furthermore,
we observed negative magnetoresistance at room temperature due to
interaction between conduction Ļ electrons and localized d spins.
X-ray structural analysis and IR absorption spectroscopy indicated
structural disorder. The magnetic susceptibility measurements suggested
the unequal spin states of two manganese atoms owing to this structural
disorder
Bistable Multifunctionality and Switchable Strong Ferromagnetic-to-Antiferromagnetic Coupling in a One-Dimensional Rhodium(I)āSemiquinonato Complex
We
present a comprehensive study of the synthesis, heat capacity,
crystal structures, UVāvisāNIR and mid-IR spectra, DFT
calculations, and magnetic and electrical properties of a one-dimensional
(1D) rhodiumĀ(I)āsemiquinonato complex, [RhĀ(3,6-DBSQ-4,5-(MeO)<sub>2</sub>)Ā(CO)<sub>2</sub>]<sub>ā</sub> (<b>3</b>), where
3,6-DBSQ-4,5-(MeO)<sub>2</sub><sup>ā¢ā</sup> represents
3,6-di-<i>tert</i>-butyl-4,5-dimethoxy-1,2-benzosemiquinonato
radical anion. The compound <b>3</b> comprises neutral 1D chains
of complex molecules stacked in a staggered arrangement with short
RhāRh distances of 3.0796(4) and 3.1045(4) Ć
at 226 K
and exhibits unprecedented bistable multifunctionality with respect
to its magnetic and conductive properties in the temperature range
of 228ā207 K. The observed bistability results from the thermal
hysteresis across a first-order phase transition, and the transition
accompanies the exchange of the interchain CāHĀ·Ā·Ā·O
hydrogen-bond partners between the semiquinonato ligands. The strong
overlaps of the complex molecules lead to unusually strong ferromagnetic
interactions in the low-temperature (LT) phase. Furthermore, the magnetic
interactions in the 1D chain drastically change from strongly ferromagnetic
in the LT phase to antiferromagnetic in the room-temperature (RT)
phase with hysteresis. In addition, the compound <b>3</b> exhibits
long-range antiferromagnetic ordering between the ferromagnetic chains
and spontaneous magnetization because of spin canting (canted antiferromagnetism)
at a transition temperature <i>T</i><sub>N</sub> of 14.2
K. The electrical conductivity of <b>3</b> at 300 K is 4.8 Ć
10<sup>ā4</sup> S cm<sup>ā1</sup>, which is relatively
high despite Rh not being in a mixed-valence state. The temperature
dependence of electrical resistivity also exhibits a clear hysteresis
across the first-order phase transition. Furthermore, the ferromagnetic
LT phase can be easily stabilized up to RT by the application of a
relatively weak applied pressure of 1.4 kbar, which reflects the bistable
characteristics and demonstrates the simultaneous control of multifunctionality
through external perturbation