Synthesis and Magnetic Studies of Two Neutral, Bis-Ligand Fe(II) Complexes Containing Carbazole- Bis(tetrazole) Ligands

Leah Gajecki; Barbara Sawicka; David J Berg; Allen G Oliver

doi:10.1021/acs.inorgchem.3c01167

Synthesis and Magnetic Studies of Two Neutral, Bis-Ligand Fe(II) Complexes Containing Carbazole- Bis(tetrazole) Ligands

Inorg Chem. 2023 Aug 7;62(31):12372-12382. doi: 10.1021/acs.inorgchem.3c01167. Epub 2023 Jul 21.

Authors

Leah Gajecki¹, Barbara Sawicka², David J Berg¹, Allen G Oliver³

Affiliations

¹ Department of Chemistry, University of Victoria, P.O. Box 3065, Victoria, British Columbia, Canada V8W 3V6.
² Department of Mechanical Engineering, University of Victoria, P.O. Box 1700 STN CSC, Victoria, British Columbia, Canada V8W 2Y2.
³ Department of Chemistry & Biochemistry, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana 46556, United States.

PMID: 37478316
DOI: 10.1021/acs.inorgchem.3c01167

Abstract

Previously reported carbazole-bis(tetrazole) (CzT^R) ligands (where R = iPr and CH₂-2,4,6-C₆H₂Me₃) were used to synthesize air-stable, six-coordinate, octahedral bis-ligand Fe(II) complexes (CzT^R)₂Fe. The synthesis and characterization of these complexes using ¹H nuclear magnetic resonance (NMR), X-ray crystallography, Mössbauer spectroscopy, and density functional theory (DFT) calculations are reported. Analysis of the magnetic properties revealed that the isopropyl derivative displays thermally induced spin crossover (SCO) over a temperature range of 150-350 K. This transition appears as an abrupt two-step transition in the solid state but simplifies to a smooth one-step transition in solution. The two-step transition in the solid state has been postulated to be due to lattice and solvation effects. In contrast, the slightly bulkier substituted CH₂-2,4,6-C₆H₂Me₃ (CH₂Mes) Fe complex displays dramatically different magnetic behavior with no SCO and magnetic data suggesting low-spin Fe(II) with a possible TIP contribution. DFT calculations support the postulate that the change in magnetic behavior is primarily due to the nature of the ligand substituents.