Mn-Containing Paramagnetic Conductors with Bis ( ethylenedithio ) tetrathiafulvalene ( BEDT-TTF )

Two novel paramagnetic conductors have been prepared with the organic donor bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF = ET) and paramagnetic Mn-containing metallic complexes: κ-ET4[KMn(C2O4)3]·PhCN (1) and ET[MnCl4]·H2O (2). Compound 1 represents the first Mn-containing ET salt of the large Day’s series of oxalato-based molecular conductors and superconductors formulated as (ET)4[AM(C2O4)3]·G (A+ = H3O, NH4, K+, ...; MIII = Fe, Cr, Al, Co, ...; G = PhCN, PhNO2, PhF, PhCl, PhBr, ...). It crystallizes in the orthorhombic pseudo-κ phase where dimers of ET molecules are surrounded by six isolated ET molecules in the cationic layers. The anionic layers contain the well-known hexagonal honey-comb lattice with Mn(III) and H3O ions connected by C2O4 anions. Compound 2 is one of the very few examples of ET salts containing ET2+. It also presents alternating cationic-anionic layers although the ET molecules lie parallel to the layers instead of the typical almost perpendicular orientation. Both salts are semiconductors with room temperature conductivities of ca. 2 × 10−5 and 8 × 10−5 S/cm and activation energies of 180 and 210 meV, respectively. The magnetic properties are dominated by the paramagnetic contributions of the high spin Mn(III) (S = 2) and Mn(II) (S = 5/2) ions.


Introduction
The design and synthesis of multifunctional molecular materials combining electrical and magnetic properties is one of the main challenges in the field of molecular materials [1][2][3][4].An advantage of these materials is that they offer the possibility to study the competition and interplay of these two properties.So far, a large number of molecular materials combining magnetism with conductivity has been obtained.These examples include superconductors with paramagnetic complexes [1,[5][6][7][8][9] or with antiferromagnetic lattices [10][11][12][13][14][15] and ferromagnetic conductors [4,16].
Although many different guest molecules have been used (see Tables 1-4), the number of trivalent metals used to date is quite limited.Thus, most of the reported salts contain Fe (30 salts), Cr (16 salts) or Ga (6 salts).There are also two reported examples with Ru, two with Al and one with Co. Surprisingly, no radical salts with other trivalent metal ions have been reported to date.In order to investigate the effect of other trivalent metal ions on the final structure and on the physical properties, we have used the [Mn(C 2 O 4 ) 3 ] 3− anion with ET under different synthetic conditions.Here, we present the synthesis, structure, magnetic and electrical properties of the first example of radical salt of the Day's series obtained with Mn(III): κ -(ET) 4 [KMn III (C 2 O 4 ) 3 ]•PhCN (1) and of a very original salt obtained with the same [Mn(C 2 O 4 ) 3 ] 3− anion but using different synthetic conditions: (ET)[MnCl 4 ]•H 2 O (2).

Syntheses of the Complexes
The synthesis of the two radical salts was performed using the same precursor K 3 [Mn(C 2 O 4 ) 3 ] salt (and 18-crown-6 in order to solubilize this salt, see the Experimental section).The main difference is the use of different solvents: a 10:1 (v/v) mixture of PhCN and MeOH for compound 1 and a 10:1 (v/v) mixture of 1,1,2-trichloroethane (TCE) and MeOH for 2.An additional difference is the use of benzoic acid in the synthesis of compound 1.Interestingly, benzoic acid does not enter in the structure, but it seems to facilitate the crystallization of the final salt.In fact, attempts to obtain compound 1 without the use of benzoic acid failed.In summary, the use of PhCN gives rise to compound (ET) 4 [KMn III (C 2 O 4 ) 3 ]•PhCN (1), whereas TCE results in a totally different compound (ET)[MnCl 4 ]•H 2 O (2) with ET 2+ instead of ET +0.5 and with [Mn II Cl 4 ] 2− instead of [Mn III (C 2 O 4 ) 3 ] 3− .The question is straightforward: why is the solvent so important in the final product?The answer seems to be related with the much lower solubility of the precursor K 3 [Mn(C 2 O 4 ) 3 ] in TCE.This lower solubility increases the resistance of the electrochemical cell since the concentration of anions is lower.The higher resistance increases the potential of the source needed to apply the desired constant intensity since the electrochemical synthesis is performed under constant current.The higher voltage results in the cathode in the oxidation of ET to ET 2+ and in the anode in the reduction of Mn(III) to Mn(II).Additionally, the intensity and time used for compound 2 were higher than for 1 (see experimental section).Finally, the partial decomposition of TCE liberates chloride anions that coordinate to Mn(II) to form the observed [MnCl 4 ] 2− anion.Note that the release of chloride anions from the decomposition of chlorinated solvents is quite common in the synthetic conditions of the electrochemical cells and has been observed in other ET salts [62][63][64].

Description of the Structures
Structure of (ET) 4 [KMn III (C 2 O 4 ) 3 ]•PhCN (1).Compound 1 crystallizes in the orthorhombic space group Pbcn (Table 5) and is isostructural to those obtained with other trivalent metal ions as Fe, Cr, Co and Al and different monovalent cations as H 3 O + , NH 4 + and K + (Table 2).Interestingly, there is only one reported example with K + as monovalent cation and there is no example with Mn(III) as a trivalent cation.The asymmetric unit contains two independent ET molecules (labelled as A and B) lying on general positions, half [Mn(C 2 O 4 ) 3 ] 3− anion, half benzonitrile molecule and half K + cation, all lying on a two-fold rotation axis.Figure 1 shows the ellipsoid diagram of the molecules in 1 together with the atom-labelling scheme.
The crystal structure consists of alternating layers of ET molecules adopting the pseudo-κ phase and anionic layers containing [Mn(C 2 O 4 ) 3 ] 3− anions, K + cations and the guest benzonitrile molecule (Figure 2).The anionic layers form a honeycomb structure with hexagonal cavities that are occupied by the benzonitrile guest molecules (Figure 3a).The -CN group of the benzonitrile molecule presents a disorder over two positions related by the C2 axis passing through the centre of the aromatic ring.The -CN group in both positions lies very close to a K + cation (K1-N100 = 3.055(15) Å) and, therefore, we can consider that the K + ions present a 6 + 2 coordination.This double orientation of the -CN groups and the close distance from the N atom to the monovalent cation is also observed in all the other reported orthorhombic structures with PhCN as solvent (Table 2) [7,32,47].The Mn•••K distances (6.308, 6.239 and 6.308 Å) reflect a slight elongation of the hexagonal cavities parallel to the C2 axis to accommodate the -CN group of the PhCN guest molecule.Similar elongations are also observed in all the reported orthorhombic (ET)4[AM(C2O4)3]•G phases except in the Al-NH4 + and Ru-H3O + /K + compounds.The anionic layers form a honeycomb structure with hexagonal cavities that are occupied by the benzonitrile guest molecules (Figure 3a).The -CN group of the benzonitrile molecule presents a disorder over two positions related by the C 2 axis passing through the centre of the aromatic ring.The -CN group in both positions lies very close to a K + cation (K1-N100 = 3.055(15) Å) and, therefore, we can consider that the K + ions present a 6 + 2 coordination.This double orientation of the -CN groups and the close distance from the N atom to the monovalent cation is also observed in all the other reported orthorhombic structures with PhCN as solvent (Table 2) [7,32,47] The anionic layers form a honeycomb structure with hexagonal cavities that are occupied by the benzonitrile guest molecules (Figure 3a).The -CN group of the benzonitrile molecule presents a disorder over two positions related by the C2 axis passing through the centre of the aromatic ring.The -CN group in both positions lies very close to a K + cation (K1-N100 = 3.055(15) Å) and, therefore, we can consider that the K + ions present a 6 + 2 coordination.This double orientation of the -CN groups and the close distance from the N atom to the monovalent cation is also observed in all the other reported orthorhombic structures with PhCN as solvent (Table 2) [7,32,47].The Mn•••K distances (6.308, 6.239 and 6.308 Å) reflect a slight elongation of the hexagonal cavities parallel to the C2 axis to accommodate the -CN group of the PhCN guest molecule.Similar elongations are also observed in all the reported orthorhombic (ET)4[AM(C2O4)3]•G phases except in the Al-NH4 + and Ru-H3O + /K + compounds.The cationic layers are formed by ET dimers surrounded by six ET monomers in the so-called pseudo-κ phase (Figure 3b).The ET dimers are formed by A-type ET molecules, whereas the isolated ET molecules correspond to the B-type ones.As observed in other similar pseudo-κ phases, there are several short S•••S contacts shorter that the sum of the Van der Waals radii (3.60 Å) (Table 6).
The estimation of the charge on the ET molecules in compound 1 using the formula proposed by Guionneau et al. [65] gives values of ca.+1 and ca.0 for A-and B-type ET molecules (Table 7), respectively, as also found in all the reported orthorhombic (ET) 4 [AM(C 2 O 4 ) 3 ]•G phases [7,32,34,47,51].The cationic layers are formed by ET dimers surrounded by six ET monomers in the so-called pseudo-κ phase (Figure 3b).The ET dimers are formed by A-type ET molecules, whereas the isolated ET molecules correspond to the B-type ones.As observed in other similar pseudo-κ phases, there are several short S•••S contacts shorter that the sum of the Van der Waals radii (3.60 Å) (Table 6).

Atoms
Distance (Å) Atoms Distance (Å) The estimation of the charge on the ET molecules in compound 1 using the formula proposed by Guionneau et al. [65] gives values of ca.+1 and ca.0 for A-and B-type ET molecules (Table 7), respectively, as also found in all the reported orthorhombic (ET)4[AM(C2O4)3]•G phases [7,32,34,47,51].Structure of (ET)[Mn II Cl4]•H2O (2).Compound 2 crystallizes in the orthorhombic space group Pnna (Table 5).The asymmetric unit contains a half ET molecule, half [MnCl4] 2− anion and half water molecule lying on special positions.Figure 4 shows the ellipsoid diagram of the molecules in 2 together with the atom-labelling scheme.Structure of (ET)[Mn II Cl 4 ]•H 2 O (2).Compound 2 crystallizes in the orthorhombic space group Pnna (Table 5).The asymmetric unit contains a half ET molecule, half [MnCl 4 ] 2− anion and half water molecule lying on special positions.Figure 4 shows the ellipsoid diagram of the molecules in 2 together with the atom-labelling scheme.

Compound
Magnetochemistry 2017, 3, 7 7 of 16 The cationic layers are formed by ET dimers surrounded by six ET monomers in the so-called pseudo-κ phase (Figure 3b).The ET dimers are formed by A-type ET molecules, whereas the isolated ET molecules correspond to the B-type ones.As observed in other similar pseudo-κ phases, there are several short S•••S contacts shorter that the sum of the Van der Waals radii (3.60 Å) (Table 6).

Atoms
Distance (Å) Atoms Distance (Å) The estimation of the charge on the ET molecules in compound 1 using the formula proposed by Guionneau et al. [65] gives values of ca.+1 and ca.0 for A-and B-type ET molecules (Table 7), respectively, as also found in all the reported orthorhombic (ET)4[AM(C2O4)3]•G phases [7,32,34,47,51].Structure of (ET)[Mn II Cl4]•H2O (2).Compound 2 crystallizes in the orthorhombic space group Pnna (Table 5).The asymmetric unit contains a half ET molecule, half [MnCl4] 2− anion and half water molecule lying on special positions.Figure 4 shows the ellipsoid diagram of the molecules in 2 together with the atom-labelling scheme.The crystal structure of compound 2 consists of layers of ET molecules lying parallel to the plane alternating with layers of [MnCl 4 ] 2− anions (Figure 5a,d).The anions adopt a square lattice with Mn•••Mn distances of 8.321 Å (Figure 5b) and with a shortest Cl•••Cl intermolecular contact of 4.877 Å, well above the sum of the Van der Waals radii (3.50 Å).The cationic layer contains ET molecules lying parallel to the layer forming double layers.The ET molecules are parallel to each other inside the double layers but are orthogonal to the ET molecules of consecutive double layers (Figure 5c).This very unusual packing of the ET molecules parallel to the layer may be due to the +2 charge of the ET molecules (Table 7), precluding the usual packing in columns or dimers due to the coulombic repulsions.The short anion-cation contacts in 2 (Table 8) are also a consequence of this double charge on the ET molecules.Additionally, there is a Cl very unusual packing of the ET molecules parallel to the layer may be due to the +2 charge of the ET molecules (Table 7), precluding the usual packing in columns or dimers due to the coulombic repulsions.The short anion-cation contacts in 2 (Table 8) are also a consequence of this double charge on the ET molecules.Additionally, there is a Cl The presence of ET 2+ di-cations is very unusual.In fact, only six ET salts with ET 2+ di-cations have been reported to date [66][67][68][69].Its presence in 2 implies that the anion must be [MnCl4] 2− , i.e., that the precursor Mn(III) salt has been reduced to Mn(II).The oxidation state of the Mn ion in this anion is confirmed by the magnetic measurements (see below) and by the Mn-Cl bond distances in the anion (Mn1-Cl1 = 2.3724 (15) Å and Mn1-Cl2 = 2.3638 (15) Å).These distances are very similar to those reported for the [Mn II Cl4] 2− dianion in all the reported ET salts with this anion (2.348-2.363Å, Table 9).Furthermore, the hypothetical [Mn III Cl4] − monoanion has never been reported and the Mn-Cl bond distances should be ca.0.2 Å shorter, (i.e., around 2.15-2.17Å).
The presence of ET 2+ di-cations is very unusual.In fact, only six ET salts with ET 2+ di-cations have been reported to date [66][67][68][69].Its presence in 2 implies that the anion must be [MnCl 4 ] 2− , i.e., that the precursor Mn(III) salt has been reduced to Mn(II).The oxidation state of the Mn ion in this anion is confirmed by the magnetic measurements (see below) and by the Mn-Cl bond distances in the anion (Mn1-Cl1 = 2.3724 (15) Å and Mn1-Cl2 = 2.3638 (15) Å).These distances are very similar to those reported for the [Mn II Cl 4 ] 2− dianion in all the reported ET salts with this anion (2.348-2.363Å, Table 9).Furthermore, the hypothetical [Mn III  Cl 4 ] − monoanion has never been reported and the Mn-Cl bond distances should be ca.0.2 Å shorter, (i.e., around 2.15-2.17Å).

Magnetic Properties
The product of the magnetic susceptibility times the temperature (χ m T) per Mn(III) ion for compound 1 shows a value of ca.3.2 cm 3 •K•mol −1 , close to the expected one (3.0cm 3 •K•mol −1 ) for an S = 2 isolated Mn(III) ion with g = 2 (Figure 6).When the temperature is lowered, χ m T remains constant down to ca.50 K where a progressive decrease starts to reach a value of ca.1.0 cm 3 •K•mol −1 at 2 K.This behaviour indicates that compound 1 is essentially paramagnetic and presents the contribution expected for the anionic lattice, in agreement with the crystal structure that shows magnetically isolated [Mn(C 2 O 4 ) 3 ] 3− anions since the K + ions are diamagnetic.The decrease at low temperatures is simply due to the presence of a zero field splitting of the S = 2 spin ground state.The lack of magnetic contribution of the cationic lattice indicates that the spins on the ET molecules of the (ET 2 2+ dimers are strongly antiferromagnetically coupled and the neutral isolated ET monomers are also diamagnetic.

Magnetic Properties
The product of the magnetic susceptibility times the temperature (χmT) per Mn(III) ion for compound 1 shows a value of ca.3.2 cm 3 •K•mol −1 , close to the expected one (3.0cm 3 •K•mol −1 ) for an S = 2 isolated Mn(III) ion with g = 2 (Figure 6).When the temperature is lowered, χmT remains constant down to ca.50 K where a progressive decrease starts to reach a value of ca.1.0 cm 3 •K•mol −1 at 2 K.This behaviour indicates that compound 1 is essentially paramagnetic and presents the contribution expected for the anionic lattice, in agreement with the crystal structure that shows magnetically isolated [Mn(C2O4)3] 3− anions since the K + ions are diamagnetic.The decrease at low temperatures is simply due to the presence of a zero field splitting of the S = 2 spin ground state.The lack of magnetic contribution of the cationic lattice indicates that the spins on the ET molecules of the (ET2) 2+ dimers are strongly antiferromagnetically coupled and the neutral isolated ET monomers are also diamagnetic.For compound 2, the χmT product per [MnCl4] 2− anion shows a value of ca.4.5 cm 3 •K•mol −1 , close to the expected one (4.375cm 3 •K•mol −1 ) for an S = 5/2 isolated Mn(II) ion with g = 2 (Figure 7).When the sample is cooled, χmT shows a progressive decrease to reach a value of ca.1.0 cm 3 •K•mol −1 at 2 K.This behaviour indicates that compound 2 presents a weak antiferromagnetic coupling that might be attributed to a relatively short intermolecular Cl•••Cl contact (4.877 Å) or to the short O-H•••Cl H-bonds present in the anionic layer.Note that weak antiferromagnetic couplings through Cl•••H-N contacts with similar distances have already been observed and confirmed with theoretical calculations [72].Accordingly, we have fit the magnetic properties to a simple Curie-Weiss law [χ = C/(T − θ)] in order to estimate the weak magnetic coupling in 1.Thus, the χm −1 vs. T plot can be fit in the 30-300 K range with a Curie constant, C = 4.57 cm 3 •K•mol −1 and a Weiss temperature, θ = −9.4cm −1 (solid line in insert in Figure 7), confirming the presence of a weak antiferromagnetic coupling.As in 1, we do not observe any magnetic contribution of the cationic lattice, suggesting that, as expected, the ET 2+ cations are diamagnetic.For compound 2, the χ m T product per [MnCl 4 ] 2− anion shows a value of ca.4.5 cm 3 •K•mol −1 , close to the expected one (4.375cm 3 •K•mol −1 ) for an S = 5/2 isolated Mn(II) ion with g = 2 (Figure 7).When the sample is cooled, χ m T shows a progressive decrease to reach a value of ca.1.0 cm 3 •K•mol −1 at 2 K.This behaviour indicates that compound 2 presents a weak antiferromagnetic coupling that might be attributed to a relatively short intermolecular Cl•••Cl contact (4.877 Å) or to the short O-H•••Cl H-bonds present in the anionic layer.Note that weak antiferromagnetic couplings through Cl•••H-N contacts with similar distances have already been observed and confirmed with theoretical calculations [72].Accordingly, we have fit the magnetic properties to a simple Curie-Weiss law [χ = C/(T − θ)] in order to estimate the weak magnetic coupling in 1.Thus, the χ m −1 vs. T plot can be fit in the 30-300 K range with a Curie constant, C = 4.57 cm 3 •K•mol −1 and a Weiss temperature, θ = −9.4cm −1 (solid line in insert in Figure 7), confirming the presence of a weak antiferromagnetic coupling.As in 1, we do not observe any magnetic contribution of the cationic lattice, suggesting that, as expected, the ET 2+ cations are diamagnetic.

Electrical Properties
Compound 1 is a semiconductor with a room temperature conductivity value of ca. 2 × 10 −5 S/cm and an activation energy of ca.180 meV (Figure 8).This behaviour is very similar to that observed in all the similar orthorhombic salts of the type (ET)4[AM(C2O4)3]•G that are semiconductors with activation energies in the range 140-225 meV (Table 2).The semiconducting behaviour is attributed to the presence of completely ionized (ET2) 2+ dimers surrounded by neutral ET monomers.
Compound 2 is also a semiconductor with a conductivity at room temperature of ca. 8 × 10 −5 S/cm and an activation energy of ca.210 meV (Figure 8).Note that this behaviour can be attributed to two possible reasons: (i) a charge transfer between the Cl ligands of the [MnCl4] 2− anion through the six short Cl•••S contacts (see Table 8); and (ii) the presence of a small degree of mixed valence in the ET molecules due to the presence of neutral or (most probably) mono-cationic ET molecules.Although most of the ET molecules are doubly oxidized, we cannot discard that, during the electrocrystallization process, some mono cationic ET + molecules enter in the structure.This is in agreement with the average charge of ca.1.8 found for the ET molecules in 2 (see Table 7).The weak electron delocalization would take place through the two short S•••S intermolecular contacts present in compound 2 (Figure 5d and Table 8).

Starting Materials
The organic donor bis(ethylenedithio)tetrathiafulvalene (ET), the 18-crown-6 ether, benzoic acid and all the solvents used in this work are commercially available and were used as received.The potassium salt K3[Mn(C2O4)3] was prepared as previously reported [73] and was recrystallized several times from water.The radical salts were prepared by electrochemical oxidation of ET on

Electrical Properties
Compound 1 is a semiconductor with a room temperature conductivity value of ca. 2 × 10 −5 S/cm and an activation energy of ca.180 meV (Figure 8).This behaviour is very similar to that observed in all the similar orthorhombic salts of the type (ET) 4 [AM(C 2 O 4 ) 3 ]•G that are semiconductors with activation energies in the range 140-225 meV (Table 2).The semiconducting behaviour is attributed to the presence of completely ionized (ET 2 ) 2+ dimers surrounded by neutral ET monomers.
Compound 2 is also a semiconductor with a conductivity at room temperature of ca. 8 × 10 −5 S/cm and an activation energy of ca.210 meV (Figure 8).Note that this behaviour can be attributed to two possible reasons: (i) a charge transfer between the Cl ligands of the [MnCl 4 ] 2− anion through the six short Cl•••S contacts (see Table 8); and (ii) the presence of a small degree of mixed valence in the ET molecules due to the presence of neutral or (most probably) mono-cationic ET molecules.Although most of the ET molecules are doubly oxidized, we cannot discard that, during the electro-crystallization process, some mono cationic ET + molecules enter in the structure.This is in agreement with the average charge of ca.1.8 found for the ET molecules in 2 (see Table 7).The weak electron delocalization would take place through the two short S•••S intermolecular contacts present in compound 2 (Figure 5d and Table 8).

Electrical Properties
Compound 1 is a semiconductor with a room temperature conductivity value of ca. 2 × 10 −5 S/cm and an activation energy of ca.180 meV (Figure 8).This behaviour is very similar to that observed in all the similar orthorhombic salts of the type (ET)4[AM(C2O4)3]•G that are semiconductors with activation energies in the range 140-225 meV (Table 2).The semiconducting behaviour is attributed to the presence of completely ionized (ET2) 2+ dimers surrounded by neutral ET monomers.
Compound 2 is also a semiconductor with a conductivity at room temperature of ca. 8 × 10 −5 S/cm and an activation energy of ca.210 meV (Figure 8).Note that this behaviour can be attributed to two possible reasons: (i) a charge transfer between the Cl ligands of the [MnCl4] 2− anion through the six short Cl•••S contacts (see Table 8); and (ii) the presence of a small degree of mixed valence in the ET molecules due to the presence of neutral or (most probably) mono-cationic ET molecules.Although most of the ET molecules are doubly oxidized, we cannot discard that, during the electrocrystallization process, some mono cationic ET + molecules enter in the structure.This is in agreement with the average charge of ca.1.8 found for the ET molecules in 2 (see Table 7).The weak electron delocalization would take place through the two short S•••S intermolecular contacts present in compound 2 (Figure 5d and Table 8).

Starting Materials
The organic donor bis(ethylenedithio)tetrathiafulvalene (ET), the 18-crown-6 ether, benzoic acid and all the solvents used in this work are commercially available and were used as received.The potassium salt K3[Mn(C2O4)3] was prepared as previously reported [73] and was recrystallized several times from water.The radical salts were prepared by electrochemical oxidation of ET on

Starting Materials
The organic donor bis(ethylenedithio)tetrathiafulvalene (ET), the 18-crown-6 ether, benzoic acid and all the solvents used in this work are commercially available and were used as received.
The potassium salt K 3 [Mn(C 2 O 4 ) 3 ] was prepared as previously reported [73] and was recrystallized several times from water.The radical salts were prepared by electrochemical oxidation of ET on platinum wire electrodes (1 mm diameter) in U-shaped cells under low constant current (Table 10).The anodic and cathodic compartments are separated by a porous glass frit.The exact conditions for the synthesis of each particular radical salt are described in Table 10.

Synthesis of (ET
A solution of racemic K 3 [Mn(C 2 O 4 ) 3 ] (43.6 mg, 0.1 mmol), PhCOOH (18 mg, 0.15 mmol) and 18-crown-6 ether (90 mg, 0.35 mmol) in a mixture of 10 mL of PhCN and 1.5 mL of MeOH was placed in the cathode of a U-shaped electrochemical cell.A solution of ET (10 mg, 0.026 mmol) in a mixture of 10 mL of PhCN and 1.5 mL of MeOH was placed in the anode of the U-shaped cell and a constant current of 3 µA was applied.Black plate single crystals were collected from the anode after one week.

Synthesis of (ET)[MnCl 4 ]•H 2 O (2)
A solution of racemic K 3 [Mn(C 2 O 4 ) 3 ] (43.6 mg, 0.1 mmol) and 18-crown-6 ether (90 mg, 0.35 mmol) in a mixture of 10 mL of 1,1,2-trichloroethane and 1.5 mL of MeOH was placed in the cathode of a U-shaped electrochemical cell.A solution of ET (10 mg, 0.026 mmol) in a mixture of 10 mL of 1,1,2-trichloroethane and 1.5 mL of MeOH was placed in the anode of the U-shaped cell and a constant current of 2 µA was applied during three weeks.The intensity was increased to 4 µA for one week more and finally to 5 µA.Dark green prismatic crystals were collected from the anode after one week at 5 µA.

Physical Measurements
Magnetic susceptibility measurements were carried out in the temperature range 2-300 K with an applied magnetic field of 0.5 T on polycrystalline samples of compounds 1 and 2 with a MPMS-XL-5 SQUID susceptometer (Quantum Desing, San Diego, CA, USA).The susceptibility data were corrected for the sample holders previously measured using the same conditions and for the diamagnetic contributions of the salt as deduced by using Pascal's constant tables [74].
The temperature dependence of the DC electrical conductivity was measured with the four contact method on different single crystals of compounds 1 and 2 in cooling and warming scans with similar results within experimental errors.The contacts were made with Pt wires (25 µm diameter) using graphite paste.The samples were measured in a PPMS-9 equipment (Quantum Desing, San Diego, CA, USA) connected to an external voltage source model 2450 source-meter (Keithley, Cleveland, OH, USA) and amperometer model 6514 electrometer (Keithley, Cleveland, OH, USA).The conductivity quoted values have been measured in the voltage range where the crystals are Ohmic conductors.The cooling and warming rates were 1 and 2 K•min −1 .

Crystallographic Data Collection and Refinement
Suitable single crystals of compounds 1 and 2 were mounted on a glass fibre using a viscous hydrocarbon oil to coat the crystal and then transferred directly to the cold nitrogen stream for data collection.X-ray data were collected at 120 K on a Supernova diffractometer (Agilent, Santa Clara, CA, USA) equipped with a graphite-monochromated Enhance (Mo) X-ray Source (λ = 0.71073 Å).The program CrysAlisPro v38.43, (Rigaku, Tokyo, Japan), was used for unit cell determinations and data reduction.Empirical absorption correction was performed using spherical harmonics, implemented in the SCALE3 ABSPACK scaling algorithm.Crystal structures were solved with direct methods with the SIR97 program [75], and refined against all F 2 values with the SHELXL-2014 program [76], using the WinGX graphical user interface [77].All non-hydrogen atoms were refined anisotropically, and hydrogen atoms were placed in calculated positions and refined isotropically with a riding model.There is a disorder in the CH 3 CN solvent molecules that appears with two possible orientations with a common N atom located on a C 2 axis.Data collection and refinement parameters are given in Table 5.
CCDC-1527866 and 1527859 contain the supplementary crystallographic data for compounds 1 and 2, respectively.These data can be obtained free of charge from The Cambridge Crystallographic Data Centre at www.ccdc.cam.ac.uk/data_request/cif.

Conclusions
The combination of the magnetic anion [Mn(C 2 O 4 ) 3 ] 3− with the organic donor ET under different synthetic conditions has resulted in the synthesis of two very original magnetic and conducting radical salts: (ET .Both salts are semiconductors (with activation energies of ca.180 and ca.210 meV, respectively) and paramagnetic with magnetic moments corresponding to the anionic complexes, since the organic lattices do not contribute to the magnetic moment.

Figure 2 .
Figure 2. View of the cationic and anionic layers alternating along the c-direction in 1.

Figure 3 .
Figure 3. Structure of compound 1: (a) view of the anionic layer showing the two possible positions of the -CN groups and the K-N bond.(b) view of the pseudo-κ packing of the bis(ethylenedithio)tetrathiafulvalene (ET) molecules in the cationic layer showing the A-type dimers (in red) surrounded by six B-type monomers (in blue).H atoms have been omitted for clarity.

Figure 2 .
Figure 2. View of the cationic and anionic layers alternating along the c-direction in 1.

16 Figure 2 .
Figure 2. View of the cationic and anionic layers alternating along the c-direction in 1.

Figure 3 .
Figure 3. Structure of compound 1: (a) view of the anionic layer showing the two possible positions of the -CN groups and the K-N bond.(b) view of the pseudo-κ packing of the bis(ethylenedithio)tetrathiafulvalene (ET) molecules in the cationic layer showing the A-type dimers (in red) surrounded by six B-type monomers (in blue).H atoms have been omitted for clarity.

Figure 3 .
Figure 3. Structure of compound 1: (a) view of the anionic layer showing the two possible positions of the -CN groups and the K-N bond.(b) view of the pseudo-κ packing of the bis(ethylenedithio)tetrathiafulvalene (ET) molecules in the cationic layer showing the A-type dimers (in red) surrounded by six B-type monomers (in blue).H atoms have been omitted for clarity.
•••O short contact (3.336 Å) that suggests the presence of hydrogen bonds of the type O-H•••Cl connecting neighbouring [MnCl 4 ] 2− anions.Unfortunately, the H atoms of the water molecules could not be located in the single crystal structural analysis.
•••O short contact (3.336 Å) that suggests the presence of hydrogen bonds of the type O-H•••Cl connecting neighbouring [MnCl4] 2− anions.Unfortunately, the H atoms of the water molecules could not be located in the single crystal structural analysis.

Figure 5 .
Figure 5. Structure of compound 2: (a) view of the cationic and anionic layers alternating along the c direction in 2. Green and blue (or red and yellow) ET molecules form one double layer.(b) view of the anionic layer.(c) view of two consecutive double ET and anionic layers down the c direction.(d) view of the zigzag chains in the ab plane showing the short S•••S intermolecular contacts.

Figure 5 .
Figure 5. Structure of compound 2: (a) view of the cationic and anionic layers alternating along the c direction in 2. Green and blue (or red and yellow) ET molecules form one double layer; (b) view of the anionic layer; (c) view of two consecutive double ET and anionic layers down the c direction; (d) view of the zigzag chains in the ab plane showing the short S•••S intermolecular contacts.

Figure 6 .
Figure 6.Thermal variation of the χmT product per Mn(III) ion for compound 1.

Figure 6 .
Figure 6.Thermal variation of the χ m T product per Mn(III) ion for compound 1.

Figure 8 .
Figure 8. Thermal variation of the electrical resistivity of compounds 1 and 2.

Figure 8 .
Figure 8. Thermal variation of the electrical resistivity of compounds 1 and 2.

1 Figure 8 .
Figure 8. Thermal variation of the electrical resistivity of compounds 1 and 2.

Table 1 .
Structural and electrical properties of the monoclinic (ET) 4 [A I M III (C 2 O 4 ) 3 ]•G salts.

Table 2 .
Structural and electrical properties of the orthorhombic (ET) 4 [A I M III (C 2 O 4 ) 3 ]•G salts.

Table 3 .
Structural and electrical properties of the triclinic (ET) 4 [A I M III (C 2 O 4 ) 3 ]•G salts.
T MI = metal insulator temperature.

Table 5 .
Crystal data and structure refinement of compounds 1 and 2.

Table 6 .
Intermolecular S•••S contacts shorter that the sum of the Van der Waals radii in 1.

Table 7 .
Bond distances (Å) and calculated charges of the ET molecules in 1 and 2.

Table 6 .
Intermolecular S•••S contacts shorter that the sum of the Van der Waals radii in 1.

Table 7 .
Bond distances (Å) and calculated charges of the ET molecules in 1 and 2.

Table 6 .
Intermolecular S•••S contacts shorter that the sum of the Van der Waals radii in 1.

Table 7 .
Bond distances (Å) and calculated charges of the ET molecules in 1 and 2.

Table 8 .
Cation-anion contacts shorter than the sum of the Van der Waals radii in 2.

Table 8 .
Cation-anion contacts shorter than the sum of the Van der Waals radii in 2.

Table 10 .
Synthetic conditions used for salts 1 and 2.