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A Series of [Co(Mabiq)Cl2−n] (n = 0, 1, 2) Compounds and Evidence for the Elusive Bimetallic Form

DOI: 10.1021/acs.inorgchem.5b00636 DOI Help

Authors: Emma V. Puttock (Durham University) , Priyabrata Banerjee (Max-Planck-Institut für Chemische Energiekonversion) , Manuel Kaspar (Technische Universität München) , Liam Drennen (Durham University) , Dmitry Yufit (Durham University) , Eckhard Bill (Max-Planck-Institut für Chemische Energiekonversion) , Stephen Sproules (University of Glasgow) , Corinna R. Hess (Technische Universität München)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Inorganic Chemistry , VOL 54 (12) , PAGES 5864 - 5873

State: Published (Approved)
Published: June 2015
Diamond Proposal Number(s): 6749

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 CoII 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 CoI compounds. Spectroscopic and density functional theory computational data suggest that a CoII(Mabiq•) description may be a reasonable alternative to the CoI formalism for this compound.

Subject Areas: Chemistry, Materials

Instruments: I19-Small Molecule Single Crystal Diffraction