Lanthanide-polyoxometalate complexes have recently shown unique magnetic, luminescent, and catalytic properties that can be readily exploited for new technological applications, such as infrared lasers, oxidative catalysis, energy storage, and single-molecule magnets. As POMs are chemically rich molecules, numerous chemical interactions dictate their properties, such as the identity of the metal species in their structure and the nature of the counter-cation. The current study seeks to clarify these chemical interactions by examining the electrochemical and spectroscopic behavior of Gd(OTf)3, sodium metatungstate (SMT, Na6[H2W12O40]), tungstosilicic acid (H4[Si(W12O40]), and concentrated LiCl in DMF. Concentrated LiCl was utilized to compare the electrochemistry of Gd 3+ -MT solutions to pure Gd 3+ , which was found to require non-aqueous, solvent-in-salt like solutions when experiments are performed outside of an air-free environment. It was found that Gd and MT weakly coordinated in solution without forming chemical bonds, as evidenced by UV-VIS. FTIR results found that concentrated Li + species shifted the O-H bending mode from asymmetric to symmetric, as well as disrupting the vibrational modes of C-H and C-N bonds in the DMF molecule. It was found that Gd 3+ and MT interacted via the terminal oxygen (Ot) of the POM as evidenced by suppression of the vibrational mode of the species. Additionally, the asymmetric stretching modes of the S-O bonds in the triflate anion were removed through the interaction of the two species, indicative of complex solution chemistry beyond Gd and MT interaction. Electrochemically, it was found that both Gd and MT 3-species were not active in neat DMF but exhibited both reduction and oxidation peaks, and only reduction peaks for Gd and MT, respectively. The interaction of the two species resulted in an additional electron transfer during reduction for Gd 3+ in the presence of MT 3-as well as shifting of oxidation peaks to a more negative potential. By modifying sweep rates, it was found that Gd 3+ exhibited quasi-reversible reductive electrochemistry but irreversible oxidation and that MT 3-exhibited irreversible oxidation and reduction behavior likely due to the extreme distortion of the molecule in high ionic-strength solution. When the two were combined it was found that both exhibited irreversible electrochemistry in both oxidative and reductive regimes. For the Si(W12O40) -POM, virtually no electrochemistry occurred in the presence of Gd 3+ and Li + . FTIR of the solution also found little interaction between the POM and Gd 3+ or Li + . The reason for this behavior is not entirely clear. The current work provides fundamental insight into the role of cationic and metallic species in the electrochemical behavior of lanthanide-POM complexes. Figure shows as schematic of the electrochemical system used in the current study. The solution is comprised of 30% salts by weight and 9.2% by volume, preventing the solution from being classified as 'solvent-in-salt'. It should be noted that while the schematic depicts electrodes in close proximity, they are evenly spaced within the cell. The working electrode was an evaporate Au thin film on silicon. FTIR spectra of the system with and without LiCl is also depicted in Figure . Spectra of the neat DMF solvent with and without LiCl are depicted in Figure . Tabulated references for each peak is in Table . In terms of changes in the solvent when LiCl is introduced, the O-H stretching mode shifts from asymmetric stretching to symmetric stretching. It was found in literature that O-H peaks typically shift higher in wavenumber as more LiCl is added, indicative of increased interaction between chlorine ions and water. Regarding LiCl in DMF, it was found that Li + bonds to the carbonyl oxygen on the DMF molecule, as evidenced by a shift in the bond at 660 cm -1 to 668 cm -1 , which was found in the current study. Peak shifts involved with CH3 stretching and rocking modes of the DMF molecule caused by LiCl solvation were found, indicative of either Cl -or Li + interaction with the C-N-C side of the molecule. No interaction peaks or peak shifts were noticed with Gd(OTf)3, or SMT addition, indicative of little interaction of the Gd 3+ ion with both the MT 6-anion, the OTf -ion, and with the LiCl/DMF solvent. It was found that Gd 3+ is solvated by 8 DMF molecules by EXAFS. The solvation of the molecule in concentrated LiCl DMF is unclear. In neat DMF solvent, Gd ions coordinate via the oxygen bond, which was found to be interact strongly with the Li + by FTIR, therefore the solvation of Gd 3+ by DMF must be disrupted in some way in the current system. While the solvation of SMT in DMF is unclear, studies have found that lanthanide species, such as Gd 3+ , readily form supramolecular networks with polyoxometalates that include 8 DMF molecules that readily exchange with the solution. While not seen directly using FTIR, the solutions appear slightly opaque, which could indicate the formation of 3-D structures suspended in solution. Studies have found that the W=Ot group of SMT binds to cationic species, which can been seen here as the intensity of the band greatly diminishes in the presence of Gd 3+ . As the intensity change in the W=O bond between the LiCl solution and the neat solvent do not differ greatly, it can be stated that Li + does not effect this bonding. The asymmetric SO3 stretch from the triflate molecule nearly disappears in the presence of SMT molecules, also indicative of interaction of MT 3-with OTf -anions. Due to their same charge, the nature of the interaction cannot be clarified. UV-VIS was also performed to verify the findings of FTIR, shown in Figure . It was found that in the low wavelength regime, minimal changed occurred in spectra related to Gd-POM interaction besides a region between 300 and 340nm. In literature, it was found that for the UV-VIS spectra for POMs in DMF, peaks around 324 to 300nm is associated with the pπ to dπ transition from Ot to W. Modifications in this region would make sense as cations in solution primarily interact with the terminal oxygen (Ot) of the POM, found both in literature and the current study using FTIR. For other regions, no electron-ligand charge transfer is found (no new peaks arise from the interaction of MT 3-and Gd 3+ ), indicative of no strong complexing of the two species. In typical lanthanide-POM complexes, strong oxidizing species such as H2O2 or HNO3 are required to chemically bond lanthanides within the POM complex. As the current study does not utilize any such species, weak, electrostatic bonding between the POM and cations in solution is expected. To study the electrochemical behavior of the system, cyclic voltammetry was used. Figure shows the cyclic voltammetry of Gd(OTf)3 and SMT in neat DMF and concentrated solutions. Measurements were performed at 25 mV/s using a Pt quasi-reference electrode. In concentrated LiCl/DMF, the potential difference between Ag/AgCl and the Pt reference was -300mV. It was found that without LiCl, Gd(OTf)3 in DMF exhibited a reduction plateau between -1.3 V (or -1V v.s. Ag/AgCl) and -3V. This behavior is similar to those found in literature where the plateau is attributed to mass-transfer limited proton diffusion. Additionally, a small slope is found between -0.5 and -1V. SMT exhibits a reduction peak around -0.7V and an oxidation peak around -0.8V. Studies have found LMT (lithium containing metatungstate) to undergo a 2 electron oxidation and reduction in DMF. In current study, it was found that only a one electron transfer is possible without Li + . The combination of SMT with Gd yields a broad slope starting at OCV, a small plateau between -1 and -1.5V, and a steep drop afterwards. No apparent reduction and oxidation peak appears for the combination of the two species. In the presence of LiCl, Gd 3+ solutions appear to have one broad peak around -1.5V and a plateau between -2 and -2.7V. The plateau shows two small reduction peaks. On the reverse scan, a large oxidation peak appears around -1.8V and -0.8V with a small shoulder around -0.7V. In molten salt solutions, Gd 3+ is reduced in a single electrochemical step around -2.3V (v.s. Ag/AgCl). Inset is a zoomed in portion of the Gd plateau between -2 and -2.7V. The two reduction peaks are located at -2.2 and -2.3V for Gd(OTf)3 and three at -2.2, -2.3, and -2.5V, indicative of a two and three electron transfer, respectively. For the SMT solution, four peaks at -0.8, -1.2, -1.5, and -2 can be seen. The first peak can be attributed to water break down while the other three can be attributed to 3 electron reduction steps. When Gd 3+ and MT 3-are combined, three peaks located at -1, -1.3, and -1.8V followed by the plateau between -2 and -2.5V seen with pure Gd(OTf)3. Going off the shape of the peaks, each one matches that of the MT 3-species but shifted by 200mV. The plateau shows a three-electron transfer appose to a two. The oxidation reverse scan shows a shoulder at -2.2 and two peaks at -2, and -1.3V. These peaks match those of the Gd 3+ peaks but are shifted by 300mV for the peak around -1.8V and 500mV for the peak around -0.8V. The shoulder around -0.7V diminishes and shifts to -0.9V. It was found that for actinide-POM complexes, reduction of the polyoxometalate aids in reduction of the actinide species by reducing the number of electrons required to change oxidation state, shifting from 1 to 0.72 electrons. The current study has shown that MT 3-allows for an additional electron to be transferred during reduction as well as changing the oxidation behavior of the material. To further probe the electrochemical mechanisms and their kinetics, each redox active species was run separately at different scan rates and compared to the combined solution. For the Gd(OTf)3 system, it was found that the plateau between -0.5 and -1V is not rate dependent, but all activity after -1.2V increases with scan rate. The peak around -1.7V increases at a faster rate than the multi-electron plateau between -2.1 and -2.5V. Assuming Gd 3+ , the electron transfer at -1.7V is more kinetically limited than the subsequent electron transfers at -2.2 and -2.3V. For the oxidation scan, a shoulder peak is seen at -2.3V for 50 and 100 mV/s that is not seen at 25 mV/s, indicative of a fast electron transfer. The peak at -1.8V first increases in current as the scan rate increases, and at 100 mV/s the peak shifts to -1.9V. Additionally, at 100 mV/s, a new peak appears at -1.6V. The peak around -0.8V increases in current and then shifts to -0.9V at 100 mV/s. The shoulder peak at -0.7V disappears at higher scan rate. In kinetics studies in literature for Gd 3+ deposited from molten salts, it was found that the reduction was quasi-reversible, or that the electron transfer rate was close to the rate of diffusion of Gd 3+ . Randles-Sevcik analysis was performed on the reduction peaks, found in Figure , where the first electron reduction in linear and the other two are linearly linear, indicative of a quasi-revisible, as found in literature. For the oxidation peaks, due to their non-linear current v.s. scan rate behavior, the oxidation of Gd deposited is deemed irreversible and kinetically limited. For SMT, it was found that all reduction peaks shifted in potential in a non-linear fashion, shifting towards more positive potentials at 50 mV/s then to more negative potentials at 100 mV/s. All peaks exhibited quasi-revisibility from Randles-Sevcik analysis. In literature, it was found that all electron transfers were reversible as well with little peak shifting until 100 mV/s. As the current system using a concentrated LiCl solution (3M compared to 0.1M) and a different metal basis (W versus Mo), the two exhibit different electrochemical behavior. Many recent studies have focused on the role of the counter ions in solutions, where it was found that electrostatic binding of alkali cations (Na and Li + ) interact strongly with the terminal oxo ligands of the polyoxometalate, which directly influences its electrochemical behavior. Based on this reasoning, the strong interaction between Li + and terminal oxo ligands result in kinetic limitations for electron transfer and different potentials for these reactions. For the combined system, it was found that all reactions before -1.5V are irreversible as the 100 mV/s scan lay between the other two scan rates in terms of peak current. The peak around -1.7V before the 3electron plateau between -2 and -2.5V, was found to show reversible behavior. Oxidation peaks showed a decrease in current with scan rate, indicative of a couple chemical-electrochemical reaction mechanism (CrEr). In the combined system, the oxo ligands of the MT -anion interact with both high charge Gd 3+ ions as well as Li + resulting in even more distorted electrochemical behavior. However, as was found using UV-VIS no direct bonding between Gd 3+ and MT 3-occurs, allowing for the two species to interchange electrons rather than directly bonding to one another.