Browsing by Author "Colston, Kyle J."

Now showing 1 - 6 of 6
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    Design, Synthesis, and Structure of Copper Dithione Complexes: Redox‐Dependent Charge Transfer
    (Wiley, 2019-12) Colston, Kyle J.; Dille, Sara A.; Mogesa, Benjamin; Astashkin, Andrei V.; Brant, Jacilynn A.; Zeller, Matthias; Basu, Partha; Chemistry and Chemical Biology, School of Science
    Redox‐active ligands impart versatility in transition metal complexes, which are attractive for photosensitizers, dye sensitized solar cells, photothermal therapy, etc. Dithiolene (Dt) ligands can transition between fully reduced and fully oxidized states. Herein, we report the syntheses, characterization, crystal structures and electronic properties of four [Cu(R2Dt0)2]+/2+ (R = Me, iPr) complexes, [Cu(iPr2Dt0)2][PF6] (1a), [Cu(iPr2Dt0)2][PF6]2 (1b), and [Cu(Me2Dt0)2][PF6] (2a), [Cu(Me2Dt0)2][PF6]2 (2b), where iPr2Dt0 = N,N′‐diisopropyl‐1,2‐piperazine dithione and Me2Dt0 = N,N′‐dimethyl‐1,2‐piperazine dithione. In addition, the molecular structure of [Cu(iPr2Dt0)2][BF4]2(1c) is also reported. Complexes 1a and 2a crystallized in the triclinic, P1 space group, and 1c crystallized in the monoclinic crystal system, space group C2/c. The single‐crystal X‐ray diffraction measurements show that the Cu(I) complexes have a distorted tetrahedral geometry, whereas the Cu(II) complex exhibits a true square‐planar geometry. Cu(I) complexes exhibit a low energy charge‐transfer band (450–650 nm), which are not observed in Cu(II) complexes. Electrochemical studies of these complexes show both ligand‐ and metal‐based redox couples.
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    Dithione, the antipodal redox partner of ene-1,2-dithiol ligands and their metal complexes
    (Elsevier, 2020) Basu, Partha; Colston, Kyle J.; Mogesa, Benjamin; Chemistry and Chemical Biology, School of Science
    Defining the oxidation state of the central atom in a coordination compound is fundamental in understanding the electronic structure and provides a starting point for elucidating molecular properties. The presence of non-innocent ligand(s) can obscure the oxidation state of the central atom as the ligand contribution to the electronic structure is difficult to ascertain. Redox-active ligands, such as dithiolene ligands, are well known non-innocent ligands that can exist in both a fully reduced (Dt2−) and fully oxidized (Dt0) states. Complexes containing the fully oxidized dithione state of the ligand are uncommon and only a few have been completely characterized. Dithione ligands are of interest due to their electron-deficient nature and ability to act as an electron acceptor for more electron-rich moieties, such as other dithiolene ligands or metal centers. This article focuses the syntheses, structures, and metal coordination, particularly coordination compounds, of dithione ligands. Various examples of mono, bis, and tris dithione complexes are discussed.
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    Interligand communication in a metal mediated LL′CT system – a case study
    (RSC, 2021) Dille, Sara A.; Colston, Kyle J.; Ratvasky, Stephen C.; Pu, Jingzhi; Basu, Partha; Chemistry and Chemical Biology, School of Science
    A series of oxo-Mo(IV) complexes, [MoO(Dt2−)(Dt0)] (where Dt2− = benzene-1,2-dithiol (bdt), toluene-3,4-dithiol (tdt), quinoxaline-2,3-dithiol (qdt), or 3,6-dichloro-benzene-1,2-dithiol (bdtCl2); Dt0 = N,N′-dimethylpiperazine-2,3-dithione (Me2Dt0) or N,N′-diisopropylpiperazine-2,3-dithione (iPr2Dt0)), possessing a fully oxidized and a fully reduced dithiolene ligand have been synthesized and characterized. The assigned oxidation states of coordinated dithiolene ligands are supported with spectral and crystallographic data. The molecular structure of [MoO(tdt)(iPr2Dt0)] (6) demonstrates a large ligand fold angle of 62.6° along the S⋯S vector of the Dt0 ligand. The electronic structure of this system is probed by density functional theory (DFT) calculations. The HOMO is largely localized on the Dt2− ligand while virtual orbitals are mostly Mo and Dt0 in character. Modeling the electronic spectrum of 6 with time dependent (TD) DFT calculations attributes the intense low energy transition at ∼18 000 cm−1 to a ligand-to-ligand charge transfer (LL′CT). The electron density difference map (EDDM) for the low energy transition depicts the electron rich Dt2− ligand donating charge density to the redox-active orbitals of the electron deficient Dt0 ligand. Electronic communication between dithiolene ligands is facilitated by a Mo-monooxo center and distortion about its primary coordination sphere.
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    Syntheses, spectroscopic, redox, and structural properties of homoleptic Iron(III/II) dithione complexes
    (Royal Society of Chemistry, 2020-10-16) Colston, Kyle J.; Dille, Sara A.; Mogesa, Benjamin; Brant, Jacilynn; Nemykin, Victor N.; Zeller, Matthias; Basu, Partha; Chemistry and Chemical Biology, School of Science
    Two sets of FeIII/II dithione complexes [FeII( i Pr2Dt0)3][PF6]2 ([1][PF6]2), [FeII(Me2Dt0)3][PF6]2 ([2][PF6]2), and [FeIII( i Pr2Dt0)3][PF6]3 ([3][PF6]3), [FeIII(Me2Dt0)3][PF6]3 ([4][PF6]3), and compound [FeIII( i Pr2Dt0)3][FeCl4][PF]2 ([3][FeCl4][PF6]2) were synthesized from N,N'-diisopropyl piperazine-2,3-dithione ( i Pr2Dt0) and N,N'-dimethyl piperazine-2,3-dithione (Me2Dt0) ligands. Complexes [1][PF6]2-[4][PF6]3 have been characterized by NMR, IR, and UV-visible spectroscopies, and by electrochemistry. The molecular structures of [2][PF6]2 and [3][FeCl4][PF6]2 have been determined by X-ray crystallography. Complexes [2][PF6]2 and [3][FeCl4][PF6]2 both crystallized in the monoclinic space group P21/n. Both complexes exhibit distorted octahedral geometry and the three coordinated ligands in each complex exhibit different dithione folding. Complexes [1][PF6]2-[4][PF6]3 exhibit a single FeIII/II based couple and three quasi-reversible ligand-based redox couples. The electronic spectra of [1][PF6]2-[4][PF6]3 show intense MLCT bands that indicate strong mixing between metal and ligand orbitals. DFT calculations were used to provide a framework for understanding the electronic origin of their redox chemistry and spectroscopic features.
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    Synthesis, Redox and Spectroscopic Properties of Pterin of Molybdenum Cofactors
    (MDPI, 2022-05-22) Colston, Kyle J.; Basu, Partha; Chemistry and Chemical Biology, School of Science
    Pterins are bicyclic heterocycles that are found widely across Nature and are involved in a variety of biological functions. Notably, pterins are found at the core of molybdenum cofactor (Moco) containing enzymes in the molybdopterin (MPT) ligand that coordinates molybdenum and facilitates cofactor activity. Pterins are diverse and can be widely functionalized to tune their properties. Herein, the general methods of synthesis, redox and spectroscopic properties of pterin are discussed to provide more insight into pterin chemistry and their importance to biological systems.
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    The Influence of Structure on the Donor-Acceptor Properties of Metallodithiolene Complexes
    (2024-08) Colston, Kyle J.; Basu, Partha; Deng, Yongming; Pu, Jingzhi; Laulhé, Sébastien
    The intrinsic charge transfer properties of a given system are dictated by their electronic structure. The movement of electrons from electron rich to electron deficient moieties of a system can spur useful photophysical properties that have been utilized in the development of materials science. Such systems take advantage of redox-active ligands, which can actively participate in electron transfer, and have the versatility to function as either electron donors or acceptors in charge transfer processes. One of the most widely used family of ligands in the development of such materials is dithiolene (Dt), which can exists in two redox extremes; reduced ene-1,2-dithiolate(2-) (Dt2-) and oxidized dithione (Dt0). Dt ligands draw inspiration from the molybdenum cofactor (Moco) found in molybdenum containing enzymes that are present in all phyla of life. The Dt2- and Dt0 ligands play contrasting roles in charge transfer, however, characterization of their electronic structure when both are incorporated into a coordination complex is underexplored. Detailed computational and experimental interrogation of such complexes are presented to highlight the importance of molecular and electronic structures on their charge transfer properties. Such complexes containing a Mo core are also relevant towards the comprehension of the electronic structure of Moco. This investigation focuses on the fundamental understanding of the charger transfer properties of metallodithiolene complexes containing both Dt2- and Dt0 ligands, and progress towards the synthesis of the closest Moco analogs.