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Pascualini ME, Stoian SA, Ozarowski A, Di Russo NV, Thuijs AE, Abboud KA, Christou G, Veige AS. Synthesis and characterization of a family of M(2+) complexes supported by a trianionic ONO(3-) pincer-type ligand: towards the stabilization of high-spin square-planar complexes. Dalton Trans 2015; 44:20207-15. [PMID: 26537572 DOI: 10.1039/c5dt03960f] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
High-spin square-planar molecular compounds are rare. In an effort to access this unique combination of geometry and spin state, we report the synthesis of a series of M(II) compounds stabilized by a trianionic pincer-type ligand, highlighting the formation of a high-spin square-planar Co(II) complex. Low-temperature, variable-frequency EPR measurements reveal that the ground electronic state of the Co(II) analogue is a highly anisotropic Kramers doublet (effective g values 7.35, 2.51, 1.48). This doublet can be identified with the lowest doublet of a quartet, S = 3/2 spin state that exhibits a very large ZFS, D ≥ 50 cm(-1). The observation of an effective g value considerably greater than the largest spin-only value 6, demonstrates that the orbital angular moment is essentially unquenched along one spatial direction. Density Functional Theory (DFT) and time-dependent DFT calculations reveal the electronic configurations of the ground and excited orbital states. A qualitative crystal field description of the geff tensor shows that it originates from the spin-orbit coupling acting on states obtained through the transfer of a β electron from the doubly occupied xy to the singly-occupied {xz/yz} orbitals.
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Affiliation(s)
- M E Pascualini
- Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, FL 32611, USA.
| | - S A Stoian
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA.
| | - A Ozarowski
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA.
| | - N V Di Russo
- Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, FL 32611, USA.
| | - A E Thuijs
- Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, FL 32611, USA.
| | - K A Abboud
- Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, FL 32611, USA.
| | - G Christou
- Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, FL 32611, USA.
| | - A S Veige
- Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, FL 32611, USA.
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Pascualini ME, Di Russo NV, Thuijs AE, Ozarowski A, Stoian SA, Abboud KA, Christou G, Veige AS. A high-spin square-planar Fe(ii) complex stabilized by a trianionic pincer-type ligand and conclusive evidence for retention of geometry and spin state in solution. Chem Sci 2014; 6:608-612. [PMID: 28706628 PMCID: PMC5491960 DOI: 10.1039/c4sc02634a] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 10/15/2014] [Indexed: 12/02/2022] Open
Abstract
Extensive spectroscopic evaluation of a novel ONO3– trianionic pincer Fe(ii) complex indicates the rare square-planar geometry and S = 2 spin state are retained in solution.
Square-planar high-spin Fe(ii) molecular compounds are rare and the only three non-macrocyclic or sterically-driven examples reported share a common FeO4 core. Using an easily modifiable pincer-type ligand, the successful synthesis of the first compound of this type that breaks the FeO4 motif was achieved. In addition, we present the first evidence that geometry and spin state persist in solution. Extensive characterization includes the first high-field EPR and variable field/temperature Mössbauer spectra for this class of compounds. Analysis of the spectroscopic data indicates this complex exhibits a large and positive zero-field splitting tensor. Furthermore, the unusually small ΔEQ value determined for this compound is rationalized on the basis of DFT calculations.
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Affiliation(s)
- M E Pascualini
- Department of Chemistry , Center for Catalysis , University of Florida , Gainesville , FL 32611 , USA .
| | - N V Di Russo
- Department of Chemistry , Center for Catalysis , University of Florida , Gainesville , FL 32611 , USA .
| | - A E Thuijs
- Department of Chemistry , Center for Catalysis , University of Florida , Gainesville , FL 32611 , USA .
| | - A Ozarowski
- National High Magnetic Field Laboratory , Florida State University , Tallahassee , FL 32310 , USA
| | - S A Stoian
- National High Magnetic Field Laboratory , Florida State University , Tallahassee , FL 32310 , USA
| | - K A Abboud
- Department of Chemistry , Center for Catalysis , University of Florida , Gainesville , FL 32611 , USA .
| | - G Christou
- Department of Chemistry , Center for Catalysis , University of Florida , Gainesville , FL 32611 , USA .
| | - A S Veige
- Department of Chemistry , Center for Catalysis , University of Florida , Gainesville , FL 32611 , USA .
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