# Seven-Coordinate Lanthanide Bis-Halide Bis-Tetrathiometallate Complexes: A Compelling Platform for Luminescent and Magnetic Properties

## TL;DR

Scientists created lanthanide complexes with unique optical and magnetic properties using inorganic ligands, offering new materials for advanced applications.

## Contribution

A novel approach using inorganic sulfur-based ligands to control lanthanide coordination and achieve low coordination numbers without bulky organic ligands.

## Key findings

- A series of 13 isostructural rare-earth complexes with coordination number 7 were synthesized.
- The complexes show potential for luminescent and single-molecule magnet applications.
- Buried volume analysis explained the stability of low coordination numbers.

## Abstract

To harness the unique luminescent and magnetic properties
of lanthanides,
precise control over their coordination sphere is essential, whether
to minimize deactivation processes or maximize magnetic anisotropy.
The traditional approaches rely on the use of large organic ligands
bearing strong atom donors to enforce low coordination numbers of
Ln ions. Herein we explored an alternative approach, constraining
low coordination numbers via a better control of the primary coordination
sphere of the Ln center using fully inorganic sulfur-based ligands,
tetrathiotungstates. This strategy led to the preparation of an isostructural
series of 13 rare-earth complexes, [NEt4]3[LnCl2(MeCN)­{(μ-S)2WS2}2]
(1Ln, Ln = Ce–Yb and Y). The unusually low coordination
numbers (CN = 7) observed here in the absence of sterically bulky
or rigid chelating ligands was rationalized using buried volume analysis.
We highlight the potential of this new ligand set for luminescent
and single-molecule magnets applications by investigating the properties
of 1Yb and 1Dy complexes, respectively.