title: 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.
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.
authors.affiliation: Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, FL 32611, USA. veige@chem.ufl.edu.
authors.forename: M E
authors.initials: ME
authors.lastname: Pascualini
authors.affiliation: National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA. sebastian.stoian@magnet.fsu.edu.
authors.forename: S A
authors.initials: SA
authors.lastname: Stoian
authors.affiliation: National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA. sebastian.stoian@magnet.fsu.edu.
authors.forename: A
authors.initials: A
authors.lastname: Ozarowski
authors.affiliation: Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, FL 32611, USA. veige@chem.ufl.edu.
authors.forename: N V
authors.initials: NV
authors.lastname: Di Russo
authors.affiliation: Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, FL 32611, USA. veige@chem.ufl.edu.
authors.forename: A E
authors.initials: AE
authors.lastname: Thuijs
authors.affiliation: Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, FL 32611, USA. veige@chem.ufl.edu.
authors.forename: K A
authors.initials: KA
authors.lastname: Abboud
authors.affiliation: Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, FL 32611, USA. veige@chem.ufl.edu.
authors.forename: G
authors.initials: G
authors.lastname: Christou
authors.affiliation: Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, FL 32611, USA. veige@chem.ufl.edu.
authors.forename: A S
authors.initials: AS
authors.lastname: Veige
mesh_terms: D000838:Anions / Q000737:chemistry; D003035:Cobalt / Q000737:chemistry*; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D004583:Electrons; D008024:Ligands; D008958:Models, Molecular; D011789:Quantum Theory
chemical_list: D000838:Anions; D056831:Coordination Complexes; D008024:Ligands; D003035:Cobalt