Photon Factory Activity Report 2019 #37 (2020)

AR-NW2A/2018G083

Redox-activity control in a conducting single-molecule magnet compound
Yongbing Shen1,* Cosquer Goulven1,* Takefumi Yoshida1 and Masahiro Yamashita1,2*1

Department of Chemistry, graduate School of Science, Tohoku University,
6-3 Aramaki Aza-Aoba, Aoba-ku, Sendai 980-8578, Japan
2
School of Materials Science and Engineering, Nankai University, Tianjin 300350, China
1 Introduction
Single-molecule magnets (SMMs) are molecularcompounds with a significant energy barrier for the spinreversal behaviour at the molecular level and can be used
for information storage, spin-valves or quantum computing,etc. Since the discovery of SMM, researchers haveperceived several potential applications, which havebecome key research topics in the area of molecularquantum spintronics. Combining SIM behavior andelectrical conductivity may bring about the giantmagnetoresistance and be advantageous for the next
generation of high-density information storage media.
Hybrids of SMM and electrical conductors with layered
structures have been reported, synergy between magnetic
lattice and conducting lattice is still challenging formaterials chemists. Herein, we introduce a strategy toincorporate strong interactions between π−conjugatedredox-active SIM and conducting sublattice with the use ofTTF molecule to afford the conductive SIM(TTF)2[Co(pdms)2] (2-Co) and the isostructural(TTF)2[Zn(pdms)2] (2-Zn). Introduction of redox-activity
on ligand is the first time to prepare conducting SIMmaterial. The H2pdms ligand is a σ and π electron donor
with quite similar redox activity to TTF upon formation ofmetal complex, causing the frontier orbitals of the ligand
and TTF to overlap, yielding electrical conductivity down
to 2 K. Moreover, the tetrahedrally coordination geometryof [M(pdms)2], combined with TTF, leads to an unusual
3D mixed stacking framework compared to those reported
2D layered conductive SMM compounds.
2 ExperimentH2pdms, CoCl2, ZnCl2, TTF and organic solvents were

The TTF●+ and Co(pdms)2 units electrocrystallized inthe C2/c space group with one TTF●+ and 0.5 Co(pdms)2molecules per asymmetric unit. The Co ion is coordinatedto two pdms ligands through the N atoms in a tetrahedral
geometry. Each TTF dimer is surrounded by six Co(pdms)2molecules (behaves as SMM) and interacts with themthrough several short contacts and weak hydrogen bonds,
forming a zig-zag structure along the [101] direction withthe Co(pdms)2 molecules at the corner and the TTF●+
dimer as segment (Figure 1a). The zig-zag chains interact
with each other in the (101̄) plane through hydrogen bonds
and O2···S3 (2.953 Å) and O2···C9 (2.887 Å) shortcontacts to form a 2D sheet. Finally, the sheets interact
with each other through various O···S, S···C and O···C
short contacts to give a fully interacting 3D structure(Figure 1b). Figure 1c shows the theoretical calculation ofcharge transfer between Co(pdms)2 and TTF dimer. 0.73eelectrons was transferred from pdms ligand to (TTF) 2+,
meanwhile, 0.76e- transferred from pdms ligand to Co ion,affording a total mix-valence state.[1]commercially purchased and used without furtherpurification. The precursors (HNEt3)2[Co(pdms)2] (1-Co)
and(HNEt3)2[Zn(pdms)2]

1-Zn

weresynthesisedfollowing a reported procedure.
Preparation of (TTF)2[M(pdms)2]: A solution of 20 mg
TTF and 80 mg of 1-Co (or 1-Zn) in 15 mL of dry
acetonitrile was filtered, and the resulting clear solution
was placed in an electrocrystallization cell under a N2 gas
atmosphere. A 0.5 μA dc current was then applied. Small
black needle-shaped crystals of size typically 50 m × 5
m × 5 m grew on the anode over 10 days, and then they
were collected, washed with a small amount of ethanol anddried in air. Yield: 20 mg (36% based on TTF).
3 Results and Discussion

Figure 1. a) crystal packing in ab plane b) crystal packing
in ac plane. c) charge transfer between Co(pdms)2 andTTF dimer.
References[1] Y. Shen et al., Angew. Chem. Int. Ed. 2020, 59, 23992406.
* shenyongbing17@gmail.com