EPR Spectral Studies of Manganese(I) Based Molecular Squares
- PDF / 946,851 Bytes
- 8 Pages / 439.37 x 666.142 pts Page_size
- 7 Downloads / 192 Views
Applied Magnetic Resonance
ORIGINAL PAPER
EPR Spectral Studies of Manganese(I) Based Molecular Squares S. Karthikeyan1,3 · Bala. Manimaran1 · Velavan Kathirvelu2 Received: 3 September 2020 / Revised: 26 October 2020 / Accepted: 29 October 2020 © Springer-Verlag GmbH Austria, part of Springer Nature 2020, corrected publication 2020
Abstract Manganese(I) based molecular squares of type [Mn(CO)3Br(μ-L)]4 where L = pyrazine, 4,4′-bipyridine, trans-1,2-bis(4-pyridyl)ethylene were synthesized and studied in detail by EPR spectroscopy. The continuous wave electron paramagnetic resonance (CW EPR) spectrum of these compounds consists of a broad transition at g = 2.006 and 4.16 that corresponds to an interacting low spin Mn(II) center and a narrow transition at g = 2.004 that corresponds to a nitrogen center radical. These results are discussed in detail and the observation of these characteristic EPR spectral signals is attributed to a partial transfer of an electron from Mn(I) center to the nitrogenous ligand through MLCT.
1 Introduction Synthesis and characterization of polynuclear manganese compounds have become the interest for decades due to properties exhibited by them as single-molecule magnet [1–3], single-chain magnet [4, 5], and a tetranuclear Mn cluster being at the active site that catalyzes water oxidation in photosystem II in green plants and cyanobacteria [6]. In addition, tremendous efforts have been made to synthesize and characterize the manganese cyclophanes [7, 8] as molecular squares assembled from metallacorners and linear bridging ligands that are observed to have highly ordered structures of discrete size and shape. They were also found to exhibit enormous applications in molecular recognition, chemical sensing, gas separation, and storage [9–12]. Manganese(I) based compounds have become the interest of scientists due to their growing therapeutic application [13–17] and hence reports on the synthesis * Velavan Kathirvelu [email protected] 1
Department of Chemistry, Pondicherry University, Kalapet, Puducherry 605 014, India
2
Department of Applied Sciences, National Institute of Technology Goa, Ponda, Goa 403 401, India
3
Present Address: Department of Science and Humanities, University VOC College of Engineering, Thoothukudi 628 008, India
13
Vol.:(0123456789)
S. Karthikeyan et al.
and characterization of manganese(I) based metallacycles [15–17] have also been increased. Single pot synthesis of three manganese(I) based molecular squares (Scheme 1) of the type [Mn(CO)3Br(μ-L)]4 where L = pyrazine (1), 4,4′-bipyridine (2), trans-1,2-bis(4-pyridyl)ethylene (3) have been reported elsewhere [8] and the exclusive formation of the product was evident by monitoring the reaction by 1H NMR spectroscopy. The molecular structures of compounds 1 and 2 were also determined by single-crystal XRD. Herein, we report the study of the molecular squares 1–3 by EPR spectroscopy in detail including interesting results.
2 Experimental Compounds 1–3 were prepared as described in the literature [8].
Data Loading...
