title: Theoretical study of the interaction between molecular oxygen and tetraaza macrocyclic manganese complexes.
abstract: Theoretical chemistry calculations using the Density Functional Theory (DFT) were carried out to understand the interaction between oxygen (O2) and MnN4 type manganese-based complexes during the formation of MnN4-O2 adducts. In order to understand how this interaction is affected by different macrocyclic ligands, O2 was bonded to manganese-porphyrin (MnP), manganese-octamethylporphyrin (MnOMP), manganese-tetraaza[14]annulene (MnTAA), manganese-dibenzo [b,i] [1, 4, 8, 11]-tetraaza [14] annulene (MnDBTAA), manganese-2,3,9,10-tetramethyl-1,4,8,11-tetraazacyclotetradeca-1,3,8,10-tetraene ([(tim)Mn](2+)), and manganese-2,3,9,10-tetraphenyl-1,4,8,11-tetraazacyclotetradeca-1,3,8,10-tetraene ([(ph-tim)Mn](2+)). The binding and activation of the oxygen molecule was facilitated by an increasing trend in the O-O bond lengths and a decreasing one in the O-O vibrational frequency, with preference for the O2 side-on interaction among MnN4 macrocycles. The catalytic activities of the MnN4 complexes toward the O2 binding process increased in the following order: [(ph-tim)Mn](2+) < MnP < MnOMP < MnDBTAA < MnTAA < [(tim)Mn](2+). Therefore, it was concluded that the [(tim)Mn](2+)complex was the most active for the binding and activation of molecular oxygen.
authors.affiliation: Universidade Federal do Maranhão, 65080-805, São Luís, MA, Brazil.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Costa
authors.affiliation: Universidade Estadual do Maranhão, 65055-970, São Luís, MA, Brazil.
authors.forename: Adilson Luís Pereira
authors.initials: AL
authors.lastname: Silva
authors.affiliation: Instituto de Química de São Carlos, Universidade São Paulo, CP 780, 13560-970, São Carlos, SP, Brazil.
authors.forename: Rommel Bezerra
authors.initials: RB
authors.lastname: Viana
authors.affiliation: Universidade Federal do Maranhão, 65080-805, São Luís, MA, Brazil.
authors.forename: Auro Atsushi
authors.initials: AA
authors.lastname: Tanaka
authors.affiliation: Universidade Federal do Maranhão, 65080-805, São Luís, MA, Brazil. jaldyr.varela@ufma.br.
authors.forename: Jaldyr de Jesus Gomes
authors.initials: Jde J
authors.lastname: Varela
keywords: Density Functional Theory; Oxygen reduction reaction; Transition metal macrocyclic complex