title: A Series of [Co(Mabiq)Cl2-n] (n = 0, 1, 2) Compounds and Evidence for the Elusive Bimetallic Form.
abstract: The synthesis and characterization of a series of cobalt compounds, coordinated by the redox-active macrocyclic biquinazoline ligand, Mabiq [2-4:6-8-bis(3,3,4,4-tetramethyldihydropyrrolo)-10-15-(2,2'-biquinazolino)-[15]-1,3,5,8,10,14-hexaene-1,3,7,9,11,14-N6], is presented. The series includes the monometallic Co(Mabiq)Cl2 (1), Co(Mabiq)Cl (2), and Co(Mabiq) (4), with formal metal oxidation states of 3+ → 1+. A binuclear cobaltous compound, Co2(Mabiq)Cl3 (3), also was obtained, providing the first evidence for the ability of the Mabiq ligand to coordinate two metal ions. The electronic structures of the paramagnetic 2 and 3 were examined by electron paramagnetic resonance spectroscopy and magnetic susceptibility studies. The Co(II) ion that resides in the N4-macrocylic cavity of 2 and 3 adopts a low-spin S = (1)/2 configuration. The bypirimidine functionality in 3 additionally coordinates a high-spin S = (3)/2 cobaltous ion in a tetrahedral environment. The two metal ions in 3 are weakly coupled by magnetometry. The square-planar, low-valent 4 offers one of a limited number of examples of structurally characterized N4-macrocyclic Co(I) compounds. Spectroscopic and density functional theory computational data suggest that a Co(II)(Mabiq(•)) description may be a reasonable alternative to the Co(I) formalism for this compound.
authors.affiliation: †Department of Chemistry, Durham University, South Road, Durham, DH1 3LE, United Kingdom.
authors.forename: Emma V
authors.initials: EV
authors.lastname: Puttock
authors.affiliation: ‡Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany.
authors.forename: Priyabrata
authors.initials: P
authors.lastname: Banerjee
authors.affiliation: ⊥Department of Chemistry and Catalysis Research Center, Technische Universität München (TUM), Lichtenbergstrasse 4, D-85747 Garching, Germany.
authors.forename: Manuel
authors.initials: M
authors.lastname: Kaspar
authors.affiliation: †Department of Chemistry, Durham University, South Road, Durham, DH1 3LE, United Kingdom.
authors.forename: Liam
authors.initials: L
authors.lastname: Drennen
authors.affiliation: †Department of Chemistry, Durham University, South Road, Durham, DH1 3LE, United Kingdom.
authors.forename: Dmitry S
authors.initials: DS
authors.lastname: Yufit
authors.affiliation: ‡Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany.
authors.forename: Eckhard
authors.initials: E
authors.lastname: Bill
authors.affiliation: ∥WestCHEM, School of Chemistry, University of Glasgow, Glasgow, G12 8QQ, United Kingdom.
authors.forename: Stephen
authors.initials: S
authors.lastname: Sproules
authors.affiliation: ⊥Department of Chemistry and Catalysis Research Center, Technische Universität München (TUM), Lichtenbergstrasse 4, D-85747 Garching, Germany.
authors.forename: Corinna R
authors.initials: CR
authors.lastname: Hess