Work

Solid-State Transformation (Stotal = 0, 1, and 2) in a Ni2+ Chelate with Two tert-Butyl 5-(p-Biphenylyl)-2-pyridyl Nitroxides

Year: 2025

Type: article

Abstract: A novel S = 1/2 paramagnetic chelating ligand tert-butyl 5-(p-biphenylyl)-2-pyridyl nitroxide (bppyNO) and its S = 1 nickel(II) ion complex [Ni(bppyNO)2Br2] were synthesized. X-ray crystallography revealed a 2p–3d–2p heterospin triad, with half of the molecule being crystallographically independent. A relatively planar chelate geometry with the torsion angle ϕ(Ni-O-N-C2py) = −10.6(5)° at 300 K becomes significantly out-of-plane distorted with ϕ = −46.9(8) and 26.1(11)° at 90 K accompanied by disorder at the oxygen site. The torsion angle changes, Δϕ = 36° and 37°, are among the largest reported for related compounds. Magnetic measurements indicate gradual and incomplete spin transition-like behavior around 143(2) K. A three-state model involving an intermediate-spin (Stotal = 1) state is proposed to explain non-zero χmT plateau in a low-temperature region. Density functional theory calculations using the determined structures support the proposed mechanism. Furthermore, geometry optimizations assuming Stotal = 0, 1, and 2 are in good agreement with the present model.

Source: Materials

DOI: 10.3390/ma18122793

Authors: Masataka Mitsui, Takayuki Ishida

Institution: University of Electro-Communications

Language: English

Topic: Magnetism in coordination complexes

Subfield: Electronic, Optical and Magnetic Materials

Field: Materials Science

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $3,137

Funder: Ministry of Education, Culture, Sports, Science and Technology