title: Unique mononuclear Mn(II) complexes of an end-off compartmental Schiff base ligand: experimental and theoretical studies on their bio-relevant catalytic promiscuity.
abstract: Three new mononuclear manganese(ii) complexes, namely [Mn(HL)2]·2ClO4 (1), [Mn(HL)(N(CN)2)(H2O)2]·ClO4 (2) and [Mn(HL)(SCN)2] (3) [LH = 4-tert-butyl-2,6-bis-[(2-pyridin-2-yl-ethylimino)-methyl]-phenol], have been synthesized and structurally characterized. An "end-off" compartmental ligand (LH) possesses two symmetrical compartments with N2O binding sites but accommodates only one manganese atom instead of two due to the protonation of the imine nitrogen of one compartment. Although all three complexes are mononuclear, complex 1 is unique as it has a 1 : 2 metal to ligand stoichiometry. The catalytic promiscuity of complexes 1-3 in terms of two different bio-relevant catalytic activities namely catecholase and phenoxazinone synthase has been thoroughly investigated. EPR and cyclic voltametric studies reveal that radical formation rather than metal centered redox participation is responsible for their catecholase-like and phenoxazinone synthase-like catalytic activity. A computational approach suggests that imine bond bound radical generation rather than phenoxo radical formation is most likely responsible for the oxidizing properties of the complexes.
authors.affiliation: Department of Chemistry, University of Calcutta, 92 A. P. C. Road, Kolkata 700 009, India. dasdebasis2001@yahoo.com.
authors.forename: Jaydeep
authors.initials: J
authors.lastname: Adhikary
authors.affiliation: Department of Chemistry, University of Calcutta, 92 A. P. C. Road, Kolkata 700 009, India. dasdebasis2001@yahoo.com.
authors.forename: Aratrika
authors.initials: A
authors.lastname: Chakraborty
authors.affiliation: Department of Chemistry, University of Calcutta, 92 A. P. C. Road, Kolkata 700 009, India. dasdebasis2001@yahoo.com.
authors.forename: Sanchari
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authors.lastname: Dasgupta
authors.affiliation: Department of Chemistry, Indian Institute of Engineering Science and Technology, Howrah 711 103, India.
authors.forename: Shyamal Kumar
authors.initials: SK
authors.lastname: Chattopadhyay
authors.affiliation: Department of X-Ray Crystallography and Crystal Chemistry, Institute of General and Ecological Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924 Lodz, Poland.
authors.forename: Rafał
authors.initials: R
authors.lastname: Kruszynski
authors.affiliation: Department of X-Ray Crystallography and Crystal Chemistry, Institute of General and Ecological Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924 Lodz, Poland.
authors.forename: Agata
authors.initials: A
authors.lastname: Trzesowska-Kruszynska
authors.affiliation: Center for Chemistry, IHTM, University of Belgrade, Studentski Trg 12-16, 11001 Belgrade, Serbia.
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authors.lastname: Stepanović
authors.affiliation: Faculty of Chemistry, University of Belgrade, Studentski Trg 12-16, 11001 Belgrade, Serbia.
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authors.lastname: Gruden-Pavlović
authors.affiliation: Institut de Química Computacionali Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, Facultat de Ciències, 17071 Girona, Spain and Institució Catalana de RecercaiEstudisAvançats (ICREA), Pg. LluísCompanys 23, 08010 Barcelona, Spain.
authors.forename: Marcel
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authors.lastname: Swart
authors.affiliation: Department of Chemistry, University of Calcutta, 92 A. P. C. Road, Kolkata 700 009, India. dasdebasis2001@yahoo.com.
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authors.lastname: Das