Redox Data of Tris(polypyridine)manganese(II) Complexes
Department of Chemistry, University of the Free State, Bloemfontein 9300, South Africa
*
Authors to whom correspondence should be addressed.
Data 2022, 7(9), 130; https://doi.org/10.3390/data7090130
Submission received: 30 July 2022
/
Revised: 3 September 2022
/
Accepted: 10 September 2022
/
Published: 13 September 2022
(This article belongs to the Section Chemoinformatics)
Abstract
:Abstract
Very little cyclic voltammetry data for tris(polypyridine)manganese(II) complexes, [MnII(N^N)3]2+, where N^N is bipyridine (bpy), phenanthroline (phen) or substituted bpy or phen ligands, respectively; are available in the literature. Cyclic voltammograms were found for tris(4,7-diphenyl-1,10-phenanthroline)manganese(II) perchlorate only. In addition to our recently published related research article, the data presented here provides cyclic voltammograms and corresponding voltage-current data obtained during electrochemical oxidation and the reduction of four [MnII(N^N)3]2+ complexes, using different scan rates and analyte concentrations. The results show increased concentration and scan rates resulting in higher Mn(II/III) peak oxidation potentials and increased peak current-voltage separations of the irreversible Mn(II/III) redox event. The average peak oxidation and peak reduction potentials of the Mn(II/III) redox events stayed constant within 0.01 V. Similarly, the average of the peak oxidation and reduction potentials of the ligand-based reduction events of [MnII(N^N)3]2+ were constant within 0.01 V.
Dataset
Supplementary file.
Dataset License
CC-BY
1. Summary
A comprehensive set of voltage-current related data obtained during the electrochemical oxidation and reduction of four tris(polypyridine)manganese(II) complexes are provided in this article. The oxidized tris(polypyridine)manganese(III) complexes, [MnIII(N^N)3]3+ (N^N = bipyridine (bpy), phenanthroline (phen) or substituted bpy or phen ligands), are unstable and have apparently never been isolated experimentally [1]. Only one related [MnIII(terpyridine)2]3+ complex has been isolated [2]. Experimental information on mononuclear [MnIII(N^N)3]3+ complexes was thus obtained through the electrochemical oxidation of [MnII(N^N)3]2+, using cyclic voltammetry experiments. Apart from our research article related to this dataset, “Electrochemical study of the Mn(II/III) oxidation of tris(polypyridine)manganese(II) complexes” [3], the literature on cyclic voltammetry experiments is limited, most probably due to the large peak current-voltage separation values of the Mn(II/III) oxidation process [4,5,6]. Only one cyclic voltammogram of the oxidation of a [MnII(N^N)3]2+ complex has been published [5], namely that of 0.001 M tris(4,7-diphenyl-1,10-phenanthroline)manganese(II) perchlorate in acetonitrile, at a scan rate of 0.10 V s−1. Similarly, the literature on the reduction of [MnII(N^N)3]2+ complexes was also limited [4,7,8,9], i.e., only one cyclic voltammogram of the reduction of tris(4,7-diphenyl-1,10-phenanthroline)manganese(II) perchlorate complex in acetonitrile, at a scan rate of 0.00125 V s−1 [9].
The relevance of scan rate studies is to establish how redox behavior changes with scan rate, as well as to analyze the type of redox processes observed [10,11]. The present article provides, in addition to data provided in the related research article [3], redox data of four [MnII(N^N)3]2+ complexes containing the bidentate ligands N^N = bipyridine, 4,4′-di-methoxy-2,2′-dipyridyl, 4,4′-di-tetra-butyl-2,2′-dipyridyl and 3,4,7,8-tetramethyl-1,10-phenanthroline, each coordinated through two N atoms to Mn (see Scheme 1). Cyclic voltammograms were obtained at scan rates ranging over more than two orders of magnitude (0.05 to 5.12 Vs−1) and concentrations varying over one order of magnitude (0.001 to 0.010 mol dm−3), using acetonitrile as a solvent. The redox data of the tris(polypyridine)manganese(II) complexes were added to the published redox data of related complexes of Fe [12], Ru [13], Os [14] and Co [15,16]. The information herein is helpful to researchers who design complexes with specific redox properties, for example, as may be required in studies of redox mediators in dye-sensitized solar cells [17,18], antimicrobial activity [19,20] or molecular catalysts for CO2 and/or H2O reduction [21].
2. Data Description
Results obtained from voltage-current data of the cyclic voltammograms (Figure 1, Figure 2, Figure 3 and Figure 4 for oxidation, Figure 5 for reduction) of four Mn(II) complexes are presented in Table 1, Table 2, Table 3, Table 4, Table 5, Table 6, Table 7 and Table 8 of this article. These four complexes, 1–4, contain different polypyridine ligands, namely, bipyridine, substituted bipyridine and substituted phenanthroline ligands (see Scheme 1). The cyclic voltammograms presented herein provide more detailed electrochemical data for 1–4 (i.e., at different scan rates and concentrations) than presented in the related research article [3], wherein only data from one scan rate (0.10 V s−1) and concentration (0.005 mol dm−3) were presented. A full electrochemical dataset of the related [Mn(phen)3](PF6)2 complex is available in the related research article [3].
2.1. Oxidation Data
Figure 1, Figure 2, Figure 3 and Figure 4 show the CVs obtained during electrochemical oxidation of complexes 1–4, at different scan rates (0.05–5.12 V s−1) and different analyte concentrations (0.001–0.01 mol dm−3 at a scan rate of 0.10 Vs−1). Table 1, Table 2, Table 3 and Table 4 list the electrochemical data of the complexes corresponding to Figure 1, Figure 2, Figure 3 and Figure 4. The metal-based oxidations [3] are representative of the Mn(II/III) redox process. The CV data illustrate increased concentrations and scan rates resulting in increased peak oxidation potentials of the irreversible Mn(II/III) redox transitions. The average of the peak oxidation (Epa) and peak reduction potentials (Epc), namely ½(Epa + Epc) of the Mn(II/III) redox couple, however, stayed within 0.01 V of the average value, irrespective of the increase in the peak current voltage separations upon increases in the scan rate and analyte concentration (e.g., see Figure 1a). The large peak current voltage separations (ΔEp) and small peak current ratios clearly indicate the Mn(II/III) oxidation process to be chemically and electrochemically irreversible [10,11].
Figure 1.
Cyclic voltammograms of tris(bipyridine)manganese(II) hexafluorophosphate (1), (a) at indicated scan rates in V/s and concentration 0.0042 mol dm−3 and (b) at a scan rate of 0.01 V/s and the indicated concentrations in moles per cubic decimeter, scanned in the positive direction. Data in Table 1. The Epa and Epc of the 5.12 V/s scan and the average E1/2 value are indicated in (a).
Figure 1.
Cyclic voltammograms of tris(bipyridine)manganese(II) hexafluorophosphate (1), (a) at indicated scan rates in V/s and concentration 0.0042 mol dm−3 and (b) at a scan rate of 0.01 V/s and the indicated concentrations in moles per cubic decimeter, scanned in the positive direction. Data in Table 1. The Epa and Epc of the 5.12 V/s scan and the average E1/2 value are indicated in (a).
Table 1.
Electrochemical oxidation data (potential in V vs. Fc/Fc+) obtained from the CV of tris(bipyridine)manganese(II) hexafluorophosphate (1), in acetonitrile (CH3CN) as solvent at the indicated scan rates ν (Vs−1) and concentrations C (mol dm−3).
Table 1.
Electrochemical oxidation data (potential in V vs. Fc/Fc+) obtained from the CV of tris(bipyridine)manganese(II) hexafluorophosphate (1), in acetonitrile (CH3CN) as solvent at the indicated scan rates ν (Vs−1) and concentrations C (mol dm−3).
| ν (Vs−1) | C (mol dm−3) | Epa/V | Epc/V | ΔEp/V | ½(Epa + Epc)/V |
|---|---|---|---|---|---|
| 0.050 | 0.0042 | 1.069 | 0.848 | 0.221 | 0.959 |
| 0.100 | 0.0042 | 1.075 | 0.847 | 0.228 | 0.961 |
| 0.150 | 0.0042 | 1.087 | 0.830 | 0.257 | 0.959 |
| 0.200 | 0.0042 | 1.098 | 0.820 | 0.278 | 0.959 |
| 0.250 | 0.0042 | 1.110 | 0.815 | 0.295 | 0.963 |
| 0.300 | 0.0042 | 1.123 | 0.805 | 0.318 | 0.964 |
| 0.500 | 0.0042 | 1.134 | 0.790 | 0.344 | 0.962 |
| 1.003 | 0.0042 | 1.200 | 0.720 | 0.480 | 0.960 |
| 5.120 | 0.0042 | 1.356 | 0.547 | 0.809 | 0.952 |
| 0.100 | 0.0012 | 1.070 | 0.830 | 0.240 | 0.950 |
| 0.100 | 0.0023 | 1.100 | 0.820 | 0.280 | 0.960 |
| 0.100 | 0.0035 | 1.110 | 0.820 | 0.290 | 0.965 |
| 0.100 | 0.0047 | 1.110 | 0.819 | 0.291 | 0.965 |
| 0.100 | 0.0058 | 1.115 | 0.818 | 0.297 | 0.967 |
| 0.100 | 0.0082 | 1.120 | 0.816 | 0.304 | 0.968 |
| 0.100 | 0.0117 | 1.130 | 0.815 | 0.315 | 0.973 |
| Average | 0.961(4) |
Figure 2.
Cyclic voltammograms of tris(4,4′-di-methoxy-2,2′-dipyridyl)manganese(II) hexafluorophosphate (2), (a) at the indicated scan rates in V/s and concentration 0.0034 mol dm−3 and (b) at a scan rate of 0.01 V/s and the indicated concentrations in moles per cubic decimeter, scanned in the positive direction. Data in Table 2. Average E1/2 value is indicated in (a).
Figure 2.
Cyclic voltammograms of tris(4,4′-di-methoxy-2,2′-dipyridyl)manganese(II) hexafluorophosphate (2), (a) at the indicated scan rates in V/s and concentration 0.0034 mol dm−3 and (b) at a scan rate of 0.01 V/s and the indicated concentrations in moles per cubic decimeter, scanned in the positive direction. Data in Table 2. Average E1/2 value is indicated in (a).
Table 2.
Electrochemical oxidation data (potential in V vs. Fc/Fc+) obtained from the CV of tris(4,4′-di-methoxy-2,2′-dipyridyl)manganese(II) hexafluorophosphate (2), in acetonitrile (CH3CN) as solvent at the indicated scan rates ν (Vs−1) and concentrations C (mol dm−3).
Table 2.
Electrochemical oxidation data (potential in V vs. Fc/Fc+) obtained from the CV of tris(4,4′-di-methoxy-2,2′-dipyridyl)manganese(II) hexafluorophosphate (2), in acetonitrile (CH3CN) as solvent at the indicated scan rates ν (Vs−1) and concentrations C (mol dm−3).
| ν (Vs−1) | C (mol dm−3) | Epa/V | Epc/V | ΔEp/V | ½(Epa + Epc)/V |
|---|---|---|---|---|---|
| 0.050 | 0.0034 | 0.858 | 0.494 | 0.364 | 0.676 |
| 0.100 | 0.0034 | 0.900 | 0.450 | 0.450 | 0.675 |
| 0.150 | 0.0034 | 0.927 | 0.420 | 0.507 | 0.674 |
| 0.200 | 0.0034 | 0.963 | 0.390 | 0.573 | 0.677 |
| 0.250 | 0.0034 | 0.967 | 0.388 | 0.579 | 0.678 |
| 0.300 | 0.0034 | 0.973 | 0.376 | 0.597 | 0.675 |
| 0.500 | 0.0034 | 0.987 | 0.372 | 0.615 | 0.680 |
| 1.003 | 0.0034 | 1.042 | 0.370 | 0.672 | 0.706 |
| 5.120 | 0.0034 | 1.145 | 0.270 | 0.875 | 0.708 |
| 0.100 | 0.0010 | 0.885 | 0.455 | 0.430 | 0.670 |
| 0.100 | 0.0020 | 0.890 | 0.455 | 0.435 | 0.673 |
| 0.100 | 0.0030 | 0.895 | 0.455 | 0.440 | 0.675 |
| 0.100 | 0.0040 | 0.896 | 0.455 | 0.441 | 0.676 |
| 0.100 | 0.0050 | 0.898 | 0.450 | 0.448 | 0.674 |
| 0.100 | 0.0070 | 0.905 | 0.444 | 0.461 | 0.675 |
| 0.100 | 0.0101 | 0.905 | 0.441 | 0.464 | 0.673 |
| Average a | 0.675(4) |
a Data of 1.003 and 5.120 Vs−1 scan not included in average.
Figure 3.
Cyclic voltammograms of tris(4,4′-di-tetra-butyl-2,2′-dipyridyl)manganese(II) hexafluorophosphate (3), (a) at the indicated scan rates in V/s and concentration 0.0027 mol dm−3 and (b) at a scan rate of 0.01 V/s and the indicated concentrations in moles per cubic decimeter, scanned in the positive direction. Data in Table 3. Average E1/2 value is indicated in (a).
Figure 3.
Cyclic voltammograms of tris(4,4′-di-tetra-butyl-2,2′-dipyridyl)manganese(II) hexafluorophosphate (3), (a) at the indicated scan rates in V/s and concentration 0.0027 mol dm−3 and (b) at a scan rate of 0.01 V/s and the indicated concentrations in moles per cubic decimeter, scanned in the positive direction. Data in Table 3. Average E1/2 value is indicated in (a).
Table 3.
Electrochemical oxidation data (potential in V vs. Fc/Fc+) obtained from the CV of tris(4,4′-di-tetra-butyl-2,2′-dipyridyl)manganese(II) hexafluorophosphate (3), in acetonitrile (CH3CN) as solvent at the indicated scan rates ν (Vs−1) and concentrations C (mol dm−3).
Table 3.
Electrochemical oxidation data (potential in V vs. Fc/Fc+) obtained from the CV of tris(4,4′-di-tetra-butyl-2,2′-dipyridyl)manganese(II) hexafluorophosphate (3), in acetonitrile (CH3CN) as solvent at the indicated scan rates ν (Vs−1) and concentrations C (mol dm−3).
| ν (Vs−1) | C (mol dm−3) | Epa/V | Epc/V | ΔEp/V | ½(Epa + Epc)/V |
|---|---|---|---|---|---|
| 0.050 | 0.0027 | 1.203 | 0.331 | 0.872 | 0.767 |
| 0.100 | 0.0027 | 1.246 | 0.290 | 0.956 | 0.768 |
| 0.150 | 0.0027 | 1.251 | 0.279 | 0.972 | 0.765 |
| 0.200 | 0.0027 | 1.272 | 0.262 | 1.010 | 0.767 |
| 0.250 | 0.0027 | 1.296 | 0.237 | 1.059 | 0.767 |
| 0.300 | 0.0027 | 1.300 | 0.229 | 1.071 | 0.765 |
| 0.500 | 0.0027 | 1.310 | 0.220 | 1.090 | 0.765 |
| 1.003 | 0.0027 | 1.340 | 0.190 | 1.150 | 0.765 |
| 5.120 | 0.0027 | 1.450 | 0.080 | 1.370 | 0.765 |
| 0.100 | 0.0009 | 1.200 | 0.360 | 0.840 | 0.780 |
| 0.100 | 0.0017 | 1.200 | 0.355 | 0.845 | 0.778 |
| 0.100 | 0.0026 | 1.205 | 0.350 | 0.855 | 0.778 |
| 0.100 | 0.0035 | 1.210 | 0.340 | 0.870 | 0.775 |
| 0.100 | 0.0043 | 1.210 | 0.330 | 0.880 | 0.770 |
| 0.100 | 0.0061 | 1.220 | 0.320 | 0.900 | 0.770 |
| 0.100 | 0.0087 | 1.230 | 0.310 | 0.920 | 0.770 |
| Average | 0.770(4) |
Figure 4.
Cyclic voltammograms of tris(3,4,7,8-tetramethyl-1,10 phenanthroline)manganese(II) hexafluorophosphate (4), (a) at the indicated scan rates in V/s and concentration 0.0011 mol dm−3 and (b) at a scan rate of 0.01 V/s and the indicated concentrations in moles per cubic decimeter, scanned in the positive direction. The solution was saturated at 0.0030 mol dm−3. Data in Table 4. Average E1/2 value is indicated in (a).
Figure 4.
Cyclic voltammograms of tris(3,4,7,8-tetramethyl-1,10 phenanthroline)manganese(II) hexafluorophosphate (4), (a) at the indicated scan rates in V/s and concentration 0.0011 mol dm−3 and (b) at a scan rate of 0.01 V/s and the indicated concentrations in moles per cubic decimeter, scanned in the positive direction. The solution was saturated at 0.0030 mol dm−3. Data in Table 4. Average E1/2 value is indicated in (a).
Table 4.
Electrochemical oxidation data (potential in V vs. Fc/Fc+) obtained from the CV of tris(3,4,7,8-tetramethyl-1,10 phenanthroline)manganese(II) hexafluorophosphate (4), in acetonitrile (CH3CN) as solvent at the indicated scan rates ν (Vs−1) and concentrations C (mol dm−3). The solution was saturated at 0.0030 mol dm−3.
Table 4.
Electrochemical oxidation data (potential in V vs. Fc/Fc+) obtained from the CV of tris(3,4,7,8-tetramethyl-1,10 phenanthroline)manganese(II) hexafluorophosphate (4), in acetonitrile (CH3CN) as solvent at the indicated scan rates ν (Vs−1) and concentrations C (mol dm−3). The solution was saturated at 0.0030 mol dm−3.
| ν (Vs−1) | C (mol dm−3) | Epa/V | Epc/V | ΔEp/V | ½(Epa + Epc)/V |
|---|---|---|---|---|---|
| 0.050 | 0.0011 | 0.920 | 0.479 | 0.441 | 0.700 |
| 0.100 | 0.0011 | 0.954 | 0.449 | 0.505 | 0.702 |
| 0.150 | 0.0011 | 0.970 | 0.430 | 0.540 | 0.700 |
| 0.200 | 0.0011 | 0.980 | 0.420 | 0.560 | 0.700 |
| 0.250 | 0.0011 | 1.000 | 0.400 | 0.600 | 0.700 |
| 0.300 | 0.0011 | 1.000 | 0.400 | 0.600 | 0.700 |
| 0.500 | 0.0011 | 1.000 | 0.400 | 0.600 | 0.700 |
| 1.003 | 0.0011 | 1.050 | 0.350 | 0.700 | 0.700 |
| 5.120 | 0.0011 | 1.162 | 0.296 | 0.866 | 0.729 |
| 0.100 | 0.0010 | 0.925 | 0.468 | 0.457 | 0.697 |
| 0.100 | 0.0020 | 0.925 | 0.484 | 0.441 | 0.705 |
| 0.100 | 0.0030 | 0.945 | 0.455 | 0.490 | 0.700 |
| Average a | 0.700(3) |
a Data of 5.120 Vs−1 scan not included in average.
2.2. Reduction Data
Figure 5 shows the CVs obtained during the electrochemical reduction of complexes 1–4, using different scan rates. Table 5, Table 6, Table 7 and Table 8 list the electrochemical data of the reduction of the complexes corresponding to Figure 5a–d, respectively. The reduction is ligand-based [3]. Complexes 1–3 each show three reduction peaks, corresponding to consecutive reductions in the three coordinated N^N ligands. Data of only the first 2 reduction peaks of 4 are shown, since the reduction of 4 is irreversible. The data illustrate that with the increased scan rate, the peak current voltage separations increase for 1–3, but the average of the peak oxidation (Epa) and peak reduction potentials (Epc) of each reduction peak, namely ½(Epa + Epc), stayed within 0.01 V of the average value.
Figure 5.
Cyclic voltammograms of (1)–(4) at the indicated scan rates in V/s, scanned in the negative direction. (a) tris(bipyridine)manganese(II) hexafluorophosphate (1) (b) tris(4,4′-di-methoxy-2,2′-dipyridyl)manganese(II) hexafluorophosphate (2), (c) tris(4,4′-di-tetra-butyl-2,2′-dipyridyl)manganese(II) hexafluorophosphate (3) (d) tris(3,4,7,8-tetramethyl-1,10 phenanthroline)manganese(II) hexafluorophosphate (4). Data Table 5, Table 6, Table 7 and Table 8, respectively.
Figure 5.
Cyclic voltammograms of (1)–(4) at the indicated scan rates in V/s, scanned in the negative direction. (a) tris(bipyridine)manganese(II) hexafluorophosphate (1) (b) tris(4,4′-di-methoxy-2,2′-dipyridyl)manganese(II) hexafluorophosphate (2), (c) tris(4,4′-di-tetra-butyl-2,2′-dipyridyl)manganese(II) hexafluorophosphate (3) (d) tris(3,4,7,8-tetramethyl-1,10 phenanthroline)manganese(II) hexafluorophosphate (4). Data Table 5, Table 6, Table 7 and Table 8, respectively.
Table 5.
Electrochemical reduction data (potential in V vs. Fc/Fc+) obtained from the CV tris(bipyridine)manganese(II) hexafluorophosphate (1), in acetonitrile (CH3CN) as solvent at the indicated scan rates ν (Vs−1). Analyte concentration = 0.0044 mol dm−3.
Table 5.
Electrochemical reduction data (potential in V vs. Fc/Fc+) obtained from the CV tris(bipyridine)manganese(II) hexafluorophosphate (1), in acetonitrile (CH3CN) as solvent at the indicated scan rates ν (Vs−1). Analyte concentration = 0.0044 mol dm−3.
| Peak 1 | Peak 2 | Peak 3 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ν (Vs−1) | Epa/V | Epc/V | ΔEp/V | ½(Epa + Epc)/V | Epa/V | Epc/V | ΔEp/V | ½(Epa + Epc)/V | Epa/V | Epc/V | ΔEp/V | ½(Epa + Epc)/V |
| 0.100 | −1.729 | −1.794 | 0.065 | −1.762 | −1.903 | −1.983 | 0.080 | −1.943 | −2.127 | −2.192 | 0.065 | −2.160 |
| 0.200 | −1.727 | −1.793 | 0.066 | −1.760 | −1.900 | −1.985 | 0.085 | −1.943 | −2.120 | −2.190 | 0.070 | −2.155 |
| 0.300 | −1.733 | −1.806 | 0.073 | −1.770 | −1.887 | −1.990 | 0.103 | −1.939 | −2.105 | −2.214 | 0.109 | −2.160 |
| 0.400 | −1.712 | −1.804 | 0.092 | −1.758 | −1.889 | −1.996 | 0.107 | −1.943 | −2.100 | −2.212 | 0.112 | −2.156 |
| 0.500 | −1.703 | −1.814 | 0.111 | −1.759 | −1.893 | −2.001 | 0.108 | −1.947 | −2.098 | −2.211 | 0.113 | −2.155 |
| 5.120 | −1.681 | −1.863 | 0.182 | −1.772 | −1.855 | −2.075 | 0.220 | −1.965 | −2.047 | −2.288 | 0.241 | −2.168 |
| Average a | −1.763(5) | −1.943(4) | −2.159(2) |
a Data of 5.120 Vs−1 scan not included in average for peak 2.
Table 6.
Electrochemical reduction data (potential in V vs. Fc/Fc+) obtained from the CV of tris(4,4′-di-methoxy-2,2′-dipyridyl)manganese(II) hexafluorophosphate (2), in acetonitrile (CH3CN) as solvent at the indicated scan rates ν (Vs−1). Analyte concentration = 0.0033 mol dm−3.
Table 6.
Electrochemical reduction data (potential in V vs. Fc/Fc+) obtained from the CV of tris(4,4′-di-methoxy-2,2′-dipyridyl)manganese(II) hexafluorophosphate (2), in acetonitrile (CH3CN) as solvent at the indicated scan rates ν (Vs−1). Analyte concentration = 0.0033 mol dm−3.
| Peak 1 | Peak 2 | Peak 3 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ν (Vs−1) | Epa/V | Epc/V | ΔEp/V | ½(Epa + Epc)/V | Epa/V | Epc/V | ΔEp/V | ½(Epa + Epc)/V | Epa/V | Epc/V | ΔEp/V | ½(Epa + Epc)/V |
| 0.050 | −1.880 | −1.956 | 0.076 | −1.918 | −2.032 | −2.089 | 0.057 | −2.061 | −2.195 | −2.257 | 0.062 | −2.226 |
| 0.100 | −1.881 | −1.958 | 0.077 | −1.920 | −2.036 | −2.093 | 0.057 | −2.065 | −2.193 | −2.251 | 0.058 | −2.222 |
| 0.150 | −1.882 | −1.960 | 0.078 | −1.921 | −2.032 | −2.092 | 0.060 | −2.062 | −2.194 | −2.257 | 0.063 | −2.226 |
| 0.200 | −1.884 | −1.962 | 0.078 | −1.923 | −2.014 | −2.097 | 0.083 | −2.056 | −2.195 | −2.262 | 0.067 | −2.229 |
| 0.250 | −1.888 | −1.967 | 0.079 | −1.928 | −2.032 | −2.105 | 0.073 | −2.069 | −2.182 | −2.263 | 0.081 | −2.223 |
| 0.300 | −1.890 | −1.969 | 0.079 | −1.930 | −2.027 | −2.103 | 0.076 | −2.065 | −2.181 | −2.267 | 0.086 | −2.224 |
| 0.500 | −1.873 | −1.976 | 0.103 | −1.925 | −2.026 | −2.112 | 0.086 | −2.069 | −2.174 | −2.270 | 0.096 | −2.222 |
| 0.700 | −1.873 | −1.977 | 0.104 | −1.925 | −2.025 | −2.111 | 0.086 | −2.068 | −2.174 | −2.274 | 0.100 | −2.224 |
| 1.003 | −1.870 | −1.976 | 0.106 | −1.923 | −2.000 | −2.121 | 0.121 | −2.061 | −2.174 | −2.284 | 0.110 | −2.229 |
| 2.007 | −1.866 | −1.975 | 0.109 | −1.921 | −1.998 | −2.130 | 0.132 | −2.064 | −2.168 | −2.295 | 0.127 | −2.232 |
| 5.120 | −1.851 | −1.989 | 0.138 | −1.920 | −1.985 | −2.164 | 0.179 | −2.075 | −2.161 | −2.314 | 0.153 | −2.238 |
| Average | −1.923(3) | −2.065(4) | −2.227(4) |
Table 7.
Electrochemical reduction data (potential in V vs. Fc/Fc+) obtained from the CV of tris(4,4′-di-tetra-butyl-2,2′-dipyridyl)manganese(II) hexafluorophosphate (3), in acetonitrile (CH3CN) as solvent at the indicated scan rates ν (Vs−1). Analyte concentration = 0.0028 mol dm−3.
Table 7.
Electrochemical reduction data (potential in V vs. Fc/Fc+) obtained from the CV of tris(4,4′-di-tetra-butyl-2,2′-dipyridyl)manganese(II) hexafluorophosphate (3), in acetonitrile (CH3CN) as solvent at the indicated scan rates ν (Vs−1). Analyte concentration = 0.0028 mol dm−3.
| Peak 1 | Peak 2 | Peak 3 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ν (Vs−1) | Epa/V | Epc/V | ΔEp/V | ½(Epa + Epc)/V | Epa/V | Epc/V | ΔEp/V | ½(Epa + Epc)/V | Epa/V | Epc/V | ΔEp/V | ½(Epa + Epc)/V |
| 0.050 | −1.797 | −1.885 | 0.088 | −1.841 | −1.989 | −2.048 | 0.059 | −2.019 | −2.174 | −2.255 | 0.081 | −2.215 |
| 0.100 | −1.798 | −1.884 | 0.086 | −1.841 | −1.984 | −2.051 | 0.067 | −2.018 | −2.174 | −2.257 | 0.083 | −2.216 |
| 0.150 | −1.793 | −1.885 | 0.092 | −1.839 | −1.978 | −2.058 | 0.080 | −2.018 | −2.170 | −2.265 | 0.095 | −2.218 |
| 0.200 | −1.788 | −1.885 | 0.097 | −1.837 | −1.978 | −2.058 | 0.080 | −2.018 | −2.170 | −2.267 | 0.097 | −2.219 |
| 0.250 | −1.788 | −1.884 | 0.096 | −1.836 | −1.978 | −2.058 | 0.080 | −2.018 | −2.169 | −2.269 | 0.100 | −2.219 |
| 0.300 | −1.777 | −1.903 | 0.126 | −1.840 | −1.968 | −2.064 | 0.096 | −2.016 | −2.164 | −2.271 | 0.107 | −2.218 |
| Average | −1.839(2) | −2.018(1) | −2.217(1) |
Table 8.
Electrochemical reduction data (potential in V vs. Fc/Fc+) obtained from the CV of tris(3,4,7,8-tetramethyl-1,10 phenanthroline)manganese(II) hexafluorophosphate (4), in acetonitrile (CH3CN) as solvent at the indicated scan rates ν (Vs−1). Concentration of analyte = 0.0011 mol dm−3.
Table 8.
Electrochemical reduction data (potential in V vs. Fc/Fc+) obtained from the CV of tris(3,4,7,8-tetramethyl-1,10 phenanthroline)manganese(II) hexafluorophosphate (4), in acetonitrile (CH3CN) as solvent at the indicated scan rates ν (Vs−1). Concentration of analyte = 0.0011 mol dm−3.
| Peak 1 | Peak 2 | |||||||
|---|---|---|---|---|---|---|---|---|
| ν (Vs−1) | Epa/V | Epc/V | ΔEp/V | ½(Epa + Epc)/V | Epa/V | Epc/V | ΔEp/V | ½(Epa + Epc)/V |
| 0.100 | −1.911 | −1.991 | 0.080 | −1.951 | −2.040 | −2.120 | 0.080 | −2.080 |
| 0.200 | −1.911 | −1.993 | 0.082 | −1.952 | −2.040 | −2.120 | 0.080 | −2.080 |
| 0.300 | −1.911 | −1.997 | 0.086 | −1.954 | −2.040 | −2.126 | 0.086 | −2.083 |
| 0.400 | −1.911 | −2.003 | 0.092 | −1.957 | −2.040 | −2.133 | 0.093 | −2.086 |
| 0.500 | −1.911 | −2.011 | 0.100 | −1.961 | −2.040 | −2.141 | 0.101 | −2.091 |
| Average | −1.955(3) | −2.084(4) |
3. Methods
Complexes 1–4 were synthesized, purified and characterized as described in the related research article [3]. The cyclic voltammetry (CV) scans were obtained under similar conditions as described therein, as well as in our previous work [22,23]. The CV experiments were performed on a BAS100B Electrochemical Analyzer connected to a desktop computer containing the BAS100W version 2.3 software. The software provides current-voltage and peak current--voltage data. The obtained current-voltage data were exported to Excel for further evaluation and visualization.
The temperature was kept constant at 298 K. The electrochemical cell contained three electrodes; a glassy carbon (surface area 1.257 × 10−5 m2) working electrode, a Pt wire auxiliary electrode and an Ag/Ag+ (0.010 mol dm−3 AgNO3 in acetonitrile) reference electrode, mounted on a Luggin capillary. Ferrocene was used as the internal standard. Electrochemical measurements were carried out in anhydrous acetonitrile (anhydrous, ≥ 99.8%) containing the analyte and 0.1 mol dm−3 tetrabutylammonium hexafluorophosphate as the supporting electrolyte. Care was taken to exclude water from the cell, since the presence of trace amounts of water may lead to the formation of mixed-valent di-μ-oxo bridged binuclear complexes, [Mn2III,IV(O)2(L)4]3+ (N^N = bpy, phen, 4,4′-Me-bpy, 4,4′-Ph-bpy, 4,7-Ph-phen), upon oxidation of [MnII(N^N)3]2+ [5].
The analyte solution in a three-electrode cell was purged with argon gas before and throughout the CV experiment. Care was taken to keep the volume of the analyte solution constant, since the obtained current-voltage data depends on the analyte concentration as well as scan rate.
For the purpose of obtaining reproducible results, firm polishing of the working electrode before each CV scan was necessary, since electrode poisoning occurs during CV scans. Polishing of the working electrode was done on a Bühler polishing mat, moving the flat tip of the electrode in a figure-eight motion, at first using 1-micron diamond paste. The electrode was then rinsed with ethanol, water and acetonitrile, and dried. The polishing procedure was then repeated using ¼-micron diamond paste.
Supplementary Materials
The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/data7090130/s1, Excel files with current-voltage data.
Author Contributions
Conceptualization, J.C. and K.G.v.E.; methodology, J.C. and K.G.v.E.; validation, J.C.; formal analysis, J.C. and Z.M.; investigation, Z.M.; resources, J.C.; data curation, Z.M.; writing—original draft preparation, Z.M.; writing—review and editing, J.C. and K.G.v.E.; visualization, J.C. and Z.M.; supervision, J.C.; project administration, J.C.; funding acquisition, J.C. and K.G.v.E. All authors have read and agreed to the published version of the manuscript.
Funding
This research was funded by the South African National Research Foundation, grant numbers 129270 and 132504, and the Central Research Fund of the University of the Free State, Bloemfontein. The APC was funded by the Open Access Publications Fund (OAPF) of the University of the Free State.
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
Within the article and the Supplementary Material.
Conflicts of Interest
The authors declare no conflict of interest.
References
- Wang, M.; England, J.; Weyhermüller, T.; Wieghardt, K. Electronic structures of “low-valent” neutral complexes [NiL2]0 (S = 0; L = bpy, phen, tpy)—An experimental and DFT computational study. Eur. J. Inorg. Chem. 2015, 2015, 1511–1523. [Google Scholar] [CrossRef]
- Romain, S.; Duboc, C.; Neese, F.; Rivière, E.; Hanton, L.R.; Blackman, A.G.; Philouze, C.; Leprêtre, J.C.; Deronzier, A.; Collomb, M.N. An unusual stable mononuclear MnIII bis-terpyridine complex exhibiting Jahn-Teller compression: Electrochemical synthesis, physical characterisation and theoretical study. Chem. Eur. J. 2009, 15, 980–988. [Google Scholar] [CrossRef] [PubMed]
- Mtshali, Z.; von Eschwege, K.G.; Conradie, J. Electrochemical study of the Mn(II/III) oxidation of tris(polypyridine)manganese(II) complexes. Electrochim. Acta 2021, 391, 138965. [Google Scholar] [CrossRef]
- Richert, S.A.; Tsang, P.K.S.; Sawyer, D.T. Ligand-centered redox processes for manganese, iron and cobalt, MnL3, FeL3, and CoL3, complexes (L = acetylacetonate, 8-quinolinate, picolinate, 2,2′-bipyridyl, 1,10-phenanthroline) and for their tetrakis(2,6-dichlorophenyl)porphinato complexes [M(Por)]. Inorg. Chem. 1989, 28, 2471–2475. [Google Scholar] [CrossRef]
- Morrison, M.M.; Sawyer, D.T. Redox chemistry of the polyimine complexes of manganese(II), -(III), and -(IV) in acetonitrile. Inorg. Chem. 1978, 17, 333–337. [Google Scholar] [CrossRef]
- Richert, S.A.; Tsang, P.K.S.; Sawyer, D.T. Ligand-centered oxidation of manganese(II) complexes. Inorg. Chem. 1988, 27, 1814–1818. [Google Scholar] [CrossRef]
- Wang, M.; England, J.; Weyhermüller, T.; Wieghardt, K. Molecular and Electronic Structures of the Members of the Electron Transfer Series [Mn(bpy)3]n ( n = 2+, 1+, 0, 1−) and [Mn(tpy)2]m ( m = 4+, 3+, 2+, 1+, 0). An Experimental and Density Functional Theory Study. Inorg. Chem. 2014, 53, 2276–2287. [Google Scholar] [CrossRef] [PubMed]
- Sato, Y.; Tanaka, N. Polarographic Behavior of Tris(2,2′-bipyridine)manganese(II) in Acetonitrile Solutions. Bull. Chem. Soc. Jpn. 1968, 41, 2064–2066. [Google Scholar] [CrossRef]
- Hughes, M.C.; Rao, J.M.; Macero, D.J. Further studies on the stabilization of high and low oxidation states in aromatic imine ligand complexes of first row transition metals. II. Substituted bipyridine complexes of manganese(II) and chromium(III). Inorganica Chim. Acta 1979, 35, L321–L324. [Google Scholar] [CrossRef]
- Elgrishi, N.; Rountree, K.J.; McCarthy, B.D.; Rountree, E.S.; Eisenhart, T.T.; Dempsey, J.L. A Practical Beginner’s Guide to Cyclic Voltammetry. J. Chem. Educ. 2018, 95, 197–206. [Google Scholar] [CrossRef]
- Kissinger, P.T.; Heineman, W.R. Cyclic voltammetry. J. Chem. Educ. 1983, 60, 702–706. [Google Scholar] [CrossRef]
- Ferreira, H.; von Eschwege, K.G.; Conradie, J. Electronic properties of Fe charge transfer complexes—A combined experimental and theoretical approach. Electrochim. Acta 2016, 216, 339–346. [Google Scholar] [CrossRef]
- van der Westhuizen, D.; von Eschwege, K.G.; Conradie, J. Electrochemistry and spectroscopy of substituted [Ru(phen)3]2+ and [Ru(bpy)3]2+ complexes. Electrochim. Acta 2019, 320, 134540. [Google Scholar] [CrossRef]
- Westhuizen, D.; Conradie, J.; Eschwege, K.G. Electrochemistry of Os Bipyridyl and Phenanthroline Complexes, Comparison with Ru and Fe. Electroanalysis 2020, 32, 2838–2851. [Google Scholar] [CrossRef]
- Ferreira, H.; Conradie, M.M.; Conradie, J. Electrochemical properties of a series of Co(II) complexes, containing substituted phenanthrolines. Electrochim. Acta 2018, 292, 489–501. [Google Scholar] [CrossRef]
- Ferreira, H.; Conradie, M.M.; Conradie, J. Electrochemical and electronic properties of a series of substituted polypyridine ligands and their Co(II) complexes. Inorganica Chim. Acta 2019, 486, 26–35. [Google Scholar] [CrossRef]
- Saygili, Y.; Stojanovic, M.; Flores-Díaz, N.; Zakeeruddin, S.M.; Vlachopoulos, N.; Grätzel, M.; Hagfeldt, A. Metal Coordination Complexes as Redox Mediators in Regenerative Dye-Sensitized Solar Cells. Inorganics 2019, 7, 30. [Google Scholar] [CrossRef]
- Feldt, S.M.; Gibson, E.A.; Gabrielsson, E.; Sun, L.; Boschloo, G.; Hagfeldt, A. Design of Organic Dyes and Cobalt Polypyridine Redox Mediators for High-Efficiency Dye-Sensitized Solar Cells. J. Am. Chem. Soc. 2010, 132, 16714–16724. [Google Scholar] [CrossRef]
- Hamdani, H.E.; Amane, M.E.; Duhayon, C. Synthesis, spectroscopic properties, crystal structure, antimicrobial properties and molecular docking studies of the complex (1) 3(C36H24MnN6)·6(PF6).0.5H2O. J. Mol. Struct. 2019, 1180, 438–446. [Google Scholar] [CrossRef]
- Kani, I.; Atlier, Ö.; Güven, K. Mn(II) complexes with bipyridine, phenanthroline and benzoic acid: Biological and catalase-like activity. J. Chem. Sci. 2016, 128, 523–536. [Google Scholar] [CrossRef] [Green Version]
- Elgrishi, N.; Chambers, M.B.; Wang, X.; Fontecave, M. Molecular polypyridine-based metal complexes as catalysts for the reduction of CO2. Chem. Soc. Rev. 2017, 46, 761–796. [Google Scholar] [CrossRef] [PubMed]
- Conradie, M.M.; Conradie, J. Electrochemical behaviour of Tris(β-diketonato)iron(III) complexes: A DFT and experimental study. Electrochim. Acta 2015, 152, 512–519. [Google Scholar] [CrossRef]
- Freitag, R.; Conradie, J. Electrochemical and Computational Chemistry Study of Mn(β-diketonato)3 complexes. Electrochim. Acta 2015, 158, 418–426. [Google Scholar] [CrossRef]
Scheme 1.
Complex numbering and structure of Mn(II) polypyridine complexes.
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. |
© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
Share and Cite
MDPI and ACS Style
Mtshali, Z.; von Eschwege, K.G.; Conradie, J. Redox Data of Tris(polypyridine)manganese(II) Complexes. Data 2022, 7, 130. https://doi.org/10.3390/data7090130
AMA Style
Mtshali Z, von Eschwege KG, Conradie J. Redox Data of Tris(polypyridine)manganese(II) Complexes. Data. 2022; 7(9):130. https://doi.org/10.3390/data7090130
Chicago/Turabian StyleMtshali, Zinhle, Karel G. von Eschwege, and Jeanet Conradie. 2022. "Redox Data of Tris(polypyridine)manganese(II) Complexes" Data 7, no. 9: 130. https://doi.org/10.3390/data7090130
