# Magnetic and EPR Spectroscopic Studies of Thiolate Bridged Divalent Ni, Pd, and Pt Ions Capped with VO(N 2 S 2 ) Metalloligands

## TL;DR

Scientists studied how different metals affect magnetic interactions in compounds made with vanadium and sulfur-based ligands.

## Contribution

The study reveals how varying the central metal ion in trimetallic complexes influences magnetic coupling through thiolate bridges.

## Key findings

- X-ray analysis showed a consistent C2h structure in all three compounds.
- Ferromagnetic coupling strength increased with the order Ni < Pd < Pt.
- DFT calculations confirmed an S = 1 ground state for all complexes.

## Abstract

Reactions of the
metallodithiolate complex VO­(bme-dach) (hereafter
abbreviated as V, where bme-dach = N,N′-bis­(2-mercaptoethyl)-1,4-diazacycloheptane) with [PdII(CH3CN)4]­(BF4)2 and [PtII(CH3CN)4]­(BF4)2 yield the V–M–V trimetallic
compounds [VPdV]­(BF

4
)
2

(2) and [VPtV]­(BF

4
)
2

(3). Reaction
of a similar metalloligand, VO­(bme-daco) (hereafter abbreviated as
V′ where bme-daco = N,N′-bis­(2-mercaptoethyl)-1,5-diazacyclooctane)
with [NiII(CH3CN)6]­(BF4)2 afforded the related salt [V′NiV′]­(BF

4
)
2

(1). X-ray structural analyses revealed that cations in 1, 2, and 3 adopt a stairstep C2h structure consisting of two terminal VO­(N2S2) moieties bridged via thiolate sulfur to the group 10 metal ions.
Weak ferromagnetic superexchange coupling (J = 0.282
cm–1 for 1, 0.954 cm–1 for 2, and 1.372 cm–1 for 3) was observed between the two S = 1/2 VIV centers separated by distances in the range of 5.9–6.3 Å,
with J values varying following the order Ni <
Pd < Pt. Frozen-solution EPR spectra measured on the more soluble
[BArF24]− (BArF24
– = tetrakis­((3,5-trifluoromethyl)­phenyl)­borate) analogues revealed
that the [VPtV]2

+
cation
exhibits a 15-line hyperfine splitting of 225 MHz at g = 4 in parallel mode, confirming exchange coupling between the two 51V, I = 7/2 nuclei. Density-functional theory
(DFT) calculations indicate an S = 1 ground state
for 1–3. These results demonstrate
that the choice of paramagnetic metallodithiolate ligand and diamagnetic
bridge in such trimetallic species influences the sign and magnitude
of magnetic interactions.