## 3 Results  
### Synthesis and Characterization of the Complexes  
Manganese(III)-Schiff base complexes **1-7** were obtained in high yield as outlined in the experimental section. Characterization of complexes **2**[26], **4**[17] and **7**[27] has been already reported, so results and discussion of this section will be focused on compounds **1**, **3**, **5** and **6**. Elemental analysis establish a formula Mn\({}_{2}\)L\({}^{1}\)\({}_{2}\)(H\({}_{2}\)O)\({}_{2}\)(N(CN)\({}_{2}\))\({}_{2}\) for **1**, MnL\({}^{3}\)(H\({}_{2}\)O)\({}_{2}\)(ClO\({}_{4}\)) for **3**, Mn\({}_{2}\)L\({}^{4}\)\({}_{2}\)(H\({}_{2}\)O)\({}_{2}\)(N(CN)\({}_{2}\))\({}_{2}\) for **5**, and MnL\({}^{4}\)(H\({}_{2}\)O)\({}_{2}\)(ClO\({}_{4}\)) for **6**; other analytical and spectroscopic techniques support these formulations and give further insight into the structure of the complexes. Thus, the conductivity measurements in millimolar dimethylformamide solutions are in agreement with non-electrolyte behaviors of the Mn(III) complexes [33], and the magnetic moment values measured at room temperature are very close to the spin-value of 4.9 B.M., as expected for a high-spin magnetically diluted d\({}^{4}\) manganese(III) ions. IR spectra for all the complexes exhibit a strong band between 1612-1624 cm\({}^{-1}\) characteristic of the \(\
u\)(C=N) stretching mode of the Schiff base. This band in the Mn(III) coordinated complexes is shifted 5-14 cm\({}^{-1}\) lower with respect to the free Schiff base ligands, indicating the coordination to the manganese through nitrogen atoms of the imine group. The band attributed to the \(\
u\)(C-O) mode is shifted to higher frequencies with respect to the free ligands. Two new bands, at 2152-2147 and 2268-2260 cm\({}^{-1}\) in **1** and **5**, were observed and assigned to the symmetric and asymmetric dicyanamide modes, respectively [34]. The broad unsplit band at about 1120 cm\({}^{-1}\) in **3** and **6** is indicative of the presence of the uncoordinated perchlorate anion [35], its characteristic \(\
u_{4}\) stretching mode at ca. 630 cm\({}^{-1}\) can also easily be identified. Paramagnetic \({}^{1}\)H NMR spectra of **1-7** were registered using dimethylsulfoxide-d\({}_{6}\) as solvent. When applied to solutions of paramagnetic metal compounds, a significant line broadening and large paramagnetic chemical shifts are often observed in the NMR spectra providing evidence of paramagnetic metal-ligand coordination [36]. Our NMR spectra (Figure 1) show both paramagnetic signatures: the significant line broadening and the chemical shift range. For **1-7**, the spectra contain two upfield proton resonances (see Figure 1) from the protons in the aromatic phenoxy rings. The signals \begin{table}
\begin{tabular}{c c} \hline Empirical formula & C\({}_{22}\) H\({}_{24}\) Mn N\({}_{5}\) O\({}^{5}\) \\ Formula weight & 493.40 \\ Temperature [K] & 100 (2) \\ Wavelength [Å] & 0.71069 \\ Crystal system & Monoclinic \\ Space group & P21/c \\ a [Å] & 13.0012(3) \\ b [Å] & 13.1768(4) \\ c [Å] & 13.7748(4) \\ a [\({}^{\circ}\)] & 90 \\ g [\({}^{\circ}\)] & 110.325(2) \\ \(\gamma\) [\({}^{\circ}\)] & 90 \\ Volume [Å] & 2212.89(11) \\ Z & 4 \\ Density (calculated) [g cm\({}^{-3}\)] & 1.481 \\ Absorption coefficient [mm\({}^{-1}\)] & 0.641 \\ F(000) & 1024 \\ Theta range for data collection [\({}^{\circ}\)] & 1.67 to 27.87 \\ Reflections collected & 34,661 \\ Independent reflections & 5273 \\ Final R indices [I \(>\) 2 sigma(I)] & R1 = 0.0299; wR2 = 0.0689 \\ R indices (all data) & R1 = 0.0410; wR2 = 0.0722 \\ \hline \end{tabular}
\end{table} 
Table 2: Crystal data and structure refinement for **1**. appear outside the diamagnetic region (\(\delta\) = 0-14 ppm), due to the hyperfine couplings of the Schiff base ligand protons to high-spin d\({}^{4}\) manganese(III).