Electronic Structure and Magnetic Properties of a Titanium(II) Coordination Complex

Zolnhofer E, Wijeratne GB, Jackson TA, Fortier S, Heinemann FW, Meyer K, Krzystek J, Ozarowski A, Mindiola DJ, Telser J (2020)

Publication Type: Journal article

Publication year: 2020

Journal

Inorganic Chemistry American Chemical Society

Book Volume: 59

Pages Range: 6187-6201

Journal Issue: 9

DOI: 10.1021/acs.inorgchem.0c00311

Abstract

Stable coordination complexes of TiII (3d2) are relatively uncommon, but are of interest as synthons for low oxidation state titanium complexes for application as potential catalysts and reagents for organic synthesis. Specifically, high-spin TiII ions supported by redox-inactive ligands are still quite rare due to the reducing power of this soft ion. Among such TiII complexes is trans-[TiCl2(tmeda)2], where tmeda = N,N,N′,N′-tetramethylethane-1,2-diamine. This complex was first reported by Gambarotta and co-workers almost 30 years ago, but it was not spectroscopically characterized and theoretical investigation by quantum chemical theory (QCT) was not feasible at that time. As part of our interest in low oxidation state early transition metal complexes, we have revisited this complex and report a modified synthesis and a low temperature (100 K) crystal structure that differs slightly from that originally reported at ambient temperature. We have used magnetometry, high-frequency and -field EPR (HFEPR), and variable-temperature variable-field magnetic circular dichroism (VTVH-MCD) spectroscopies to characterize trans-[TiCl2(tmeda)2]. These techniques yield the following S = 1 spin Hamiltonian parameters for the complex: D = -5.23(1) cm-1, E = -0.88(1) cm-1, (E/D = 0.17), g = [1.86(1), 1.94(2), 1.77(1)]. This information, in combination with electronic transitions from MCD, was used as input for both classical ligand-field theory (LFT) and detailed QCT studies, the latter including both density functional theory (DFT) and ab initio methods. These computational methods are seldom applied to paramagnetic early transition metal complexes, particularly those with S > 1/2. Our studies provide a complete picture of the electronic structure of this complex that can be put into context with the few other high-spin and mononuclear TiII species characterized to date.

Authors with CRIS profile

Eva Zolnhofer Lehrstuhl für Anorganische und Allgemeine Chemie Frank Wilhelm Heinemann Lehrstuhl für Anorganische und Allgemeine Chemie Karsten Meyer Lehrstuhl für Anorganische und Allgemeine Chemie

Involved external institutions

University of Kansas (KU) US United States (USA) (US) Indiana University US United States (USA) (US) Florida State University (FSU) US United States (USA) (US) University of Pennsylvania US United States (USA) (US) Roosevelt University US United States (USA) (US)

How to cite

APA:

Zolnhofer, E., Wijeratne, G.B., Jackson, T.A., Fortier, S., Heinemann, F.W., Meyer, K.,... Telser, J. (2020). Electronic Structure and Magnetic Properties of a Titanium(II) Coordination Complex. Inorganic Chemistry, 59(9), 6187-6201. https://dx.doi.org/10.1021/acs.inorgchem.0c00311

MLA:

Zolnhofer, Eva, et al. "Electronic Structure and Magnetic Properties of a Titanium(II) Coordination Complex." Inorganic Chemistry 59.9 (2020): 6187-6201.

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