Reactivity of 9-anthracenecarboxylate in the presence of Mn(II) and Mn(III) ions: Biomimetic aerobic oxidative decarboxylation catalysed by a manganese(III) 2,2′-bipyridine complex

Incorporation of Manganese Complexes within Hybrid Resol-Silica and Carbon-Silica Nanoparticles

“…We chose two manganese complexes possessing 2,2′-bipyridne (bpy) and 9-antracenecarboxylate (AntCO 2 ) as ligands in order to incorporate them into different types of nanoparticles. One of the complexes is a tetranuclear Mn III cluster [Mn III 4 (μ-O) 2 (μ-AntCO 2 ) 6 (bpy) 2 (ClO 4 ) 2 ] with a butterfly core [ 24 , 26 ]. The second is a dinuclear Mn(II) complex, where the two Mn centers are bridged by two carboxylate groups and one water molecule [{Mn II (bpy)(AntCO 2 )} 2 (μ-AntCO 2 ) 2 (μ-OH 2 )].…”

“…For the latter, the dinuclear species is the main compound in solution. However, depending on the synthesis conditions, a 1D molecular chain can also form and be isolated as a solid [ 24 ].…”

“…Therefore, both parameters were necessary to obtain a good simulation. From the different simulations we can propose that: (1) the magnetic data of the [Mn III ] system inside the RSNP suggests that the tetranuclear entity was broken and a dinuclear entity was likely formed ( Scheme 1 ) since a weak antiferromagnetic coupling typical of Mn III dinuclear species was observed [ 44 ] instead the expected magnetic behaviour of the Mn III 4 butterfly complex [ 24 ]; (2) in both cases (Mn II and Mn III ) a dinuclear entity was considered as the main species and a weak magnetic interaction was found between the Mn ions for both [Mn II ]@RSNP and [Mn III ]@RSNP samples; (3) for the [Mn III ]@RSNP system a dinuclear unit was considered and typical values of ZFS of the Mn III ions were used, obtaining a weak antiferromagnetic magnetic exchange between the Mn sites (2J = −1.2 cm −1 ) and a D Mn quite important (D Mn = −3 cm −1 ), as usual for Mn III complexes [ 44 , 45 ]; (4) the simulation of [Mn II ]@RSNP did not reproduce well the behaviour of experimental data at low temperatures, suggesting a weak magnetic coupling constant (2J = −1.2 cm −1 ) [ 46 ] and an orthogonal distortion higher than expected for Mn II ions (D Mn = 1 cm −1 ). As a conclusion, from these results we can expect that a dinuclear entity was present inside the nanoparticles in all the cases.…”

“…All the reactants and solvents were used as received without any further purification. The two manganese complexes, [Mn III 4 (μ-O) 2 (μ-AntCO 2 ) 6 (bpy) 2 (ClO 4 ) 2 ] and [{Mn II (bpy)(AntCO 2 )} 2 (μ-AntCO 2 ) 2 (μ-OH 2 )], with AntCO 2 = 9-anthracene carboxylate, were synthesized as described elsewhere [ 24 ]. They are called [Mn III ] and [Mn II ], respectively, in the following sections.…”