Gajecki L, Sawicka B, Berg DJ, Oliver AG. Synthesis and Magnetic Studies of Two Neutral,
Bis-Ligand Fe(II) Complexes Containing Carbazole-
Bis(tetrazole) Ligands.
Inorg Chem 2023. [PMID:
37478316 DOI:
10.1021/acs.inorgchem.3c01167]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/23/2023]
Abstract
Previously reported carbazole-bis(tetrazole) (CzTR) ligands (where R = iPr and CH2-2,4,6-C6H2Me3) were used to synthesize air-stable, six-coordinate, octahedral bis-ligand Fe(II) complexes (CzTR)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.
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