Document Type

Article

Language

eng

Format of Original

11 p.

Publication Date

8-31-2011

Publisher

The Royal Society of Chemistry

Source Publication

Dalton Transactions

Source ISSN

1477-9226

Original Item ID

DOI: 10.1039/C1DT10712G

Abstract

A series of iron(II) chloride complexes of pentadentate ligands related to α,α,α′,α′-tetra(pyrazolyl)-2,6-lutidine, pz4lut, has been prepared to evaluate whether pyrazolyl substitution has any systematic impact on the electronic properties of the complexes. For this purpose, the new tetrakis(3,4,5-trimethylpyrazolyl)lutidine ligand, pz**4lut, was prepared via a CoCl2-catalyzed rearrangement reaction. The equimolar combination of ligand and FeCl2 in methanol gives the appropriate 1:1 complexes [FeCl(pzR4lut)]Cl that are each isolated in the solid state as a hygroscopic solvate. In solution, the iron(II) complexes have been fully characterized by several spectroscopic methods and cyclic voltammetry. In the solid state, the complexes have been characterized by X-ray diffraction, and, in some cases, by Mössbauer spectroscopy. The Mössbauer studies show that the complexes remain high spin to 4 K and exclude spin-state changes as the cause of the surprising solid-state thermochromic properties of the complexes. Non-intuitive results of spectroscopic and structural studies showed that methyl substitution at the 3- and 5- positions of the pyrazolyl rings reduces the ligand field strength through steric effects whereas methyl substitution at the 4-position of the pyrazolyl rings increases the ligand field strength through inductive effects.

Comments

Accepted version. Dalton Transactions, Vol. 40, No. 31 (August 31, 2011): 8024-8034. DOI. © 2011 The Royal Society of Chemistry. Used with permission.

Brian Bennett was affiliated with the Medical College of Wisconsin at the time of publication.

Download

Included in

Physics Commons

Share

COinS