ARTICLE pubs.acs.org/crystal
Strong Iodine 3 3 3 Oxygen Interactions in Molecular Conductors Incorporating Sulfonate Anions Published as part of the Crystal Growth & Design virtual special issue on Halogen Bonding in Crystal Engineering: Fundamentals and Applications". Kyung-Soon Shin,† Mariya Brezgunova,‡ Olivier Jeannin,† Thierry Roisnel,† Franck Camerel,† Pascale Auban-Senzier,§ and Marc Fourmigue*,† †
Sciences Chimiques de Rennes, Universite Rennes 1, UMR CNRS 6226, Campus de Beaulieu 35042, Rennes, France Laboratoire CR2M, UMR CNRS 7036, Institut Jean Barriol, Nancy Universite, BP 70239, 54506 Vandoeuvre-les-Nancy, France § Laboratoire de Physique des Solides, Universite Paris-Sud, UMR CNRS 8502, B^at. 510, 91405 Orsay, France ‡
bS Supporting Information ABSTRACT: Strong I 3 3 3 O halogen bonds are identified in a series of cation radical salts of the donor molecule 3,4-diiodo-30 ,40 -ethylenedithiotetrathiafulvalene (EDT-TTFI2, 1) with ClO4 and various organic sulfonates, such as racemic camphor sulfonate, 1,5- and 2,6naphtalene bis(sulfonate), and 2,6-anthracene bis(sulfonate). In all compounds, oxygen atoms of sulfonate moieties appear thus as powerful halogen bonding acceptors with I 3 3 3 O distance much shorter than the van der Waals contacts (down to 77%). A full charge transfer (F = 1) is found in (1)ClO4 and (1)2[2,6-Napth(SO3)2], with a dimerization of the stacks of 1•+ cation radicals and a diamagnetic behavior. The mixed-valence (F = 1/2) salts (1)2[(rac)-camph(SO3)] 3 Solv, (1)5[2,6-Anthr(SO3)2], and (1)4[1,5-Napht(SO3)2] form conducting stacks with semiconducting behavior. Band structure calculations and magnetic measurements performed on (1)4[1,5-Napht(SO3)2] show a strongly one-dimensional electronic structure, at the origin of the semiconducting behavior.
’ INTRODUCTION Anion recognition and coordination has gained an important role from a fundamental and applicative point of view in the last decades,1 based on various types of nonbonding interactions, particularly hydrogen bonding,2 electrostatic interactions,3 or coordination to metal ions.4 More recently, halogen bonding has also been investigated as a powerful tool toward anion coordination.5,6 Indeed, besides the CHal 3 3 3 HalC interactions extensively investigated in the last years7 and characterized with various structural motifs8 (type I, type II, triangular motifs),9,10 the electrophilic part of the halogen atom located in the extension of the CHal bond11 can also interact with any donor of electron density (Lewis base) and, hence, essentially any anionic species, halides, polyhalo anions, polycyanometallates, etc. Anions appear now as particularly robust halogen bonding acceptors for the elaboration of a wide variety of complex supramolecular architectures.5,6 This ability has been successfully exploited in the field of molecular conductors since 1995.12 Crystalline organic metals are based on the oxidation of electron-rich molecules such as tetrathiafulvalenes (TTF) to the radical cation state and their association with anions into mixed-valence systems formulated as (TTF)2X.13 The stacking of these partially oxidized donor molecules leads to the formation of a partially filled conduction r 2011 American Chemical Society
band (in one dimension), with associated metallic behavior. Actually, the electronic structure of such conductors is highly sensitive to the details of the respective organization of radical cations and anions, and weak interactions such as CH 3 3 3 X contacts at the organic/inorganic interface were shown to play a crucial role on the conducting properties of such salts.14 These early observations have served as an incentive to further control or manipulate the organicinorganic interface with more predictable nonbonding interactions such as hydrogen bonding,15,16 based on TTF derivatives bearing hydroxyl,17 carboxylic acid,18 phosphonic acid,19 amide,20,21 and thioamide22 substituents. Halogen bonding was first introduced with the same aim by Kato and Imakubo,12 who showed that the oxidation of iodinated TTFs affords cation radical salts where the counterion [Br, Ag(CN)2, ...] is associated by halogen bonding to the iodine atom of the TTF derivative through very short CTTFI 3 3 3 Hal or CTTFI 3 3 3 N contacts. Indeed, this interaction is particularly strong, as the cationic state of the TTF core “activates” the positive hole on the iodine atom,16 in interaction with the charged anion. Following this work, many salts were described Received: July 20, 2011 Revised: September 22, 2011 Published: October 07, 2011 5337
dx.doi.org/10.1021/cg200934r | Cryst. Growth Des. 2011, 11, 5337–5345
Crystal Growth & Design Scheme 1
ARTICLE
Table 1. Evolution of Intramolecular Bond Lengths within the TTF Core in Salts with 1
F
a (Å)
b (Å)
c (Å)
(1)ClO4
1
1.388(5)
1.726(3) 1.735(8)
1.727(3) 1.720(8)
(1)2[2,6-Napht(SO3)2]
1
1.388(4)
(1)2[(rac)-CamphSO3]
0.5 ≈0.5
1.373(6)
1.745(5)
1.733(6)
mol. 2
≈0.5
1.356(6)
1.754(6)
1.756(6)
1.742(6) 1.743(4)
1.741(4) 1.737(6)
0.5
mol. 1
≈0.5
1.365(6)
mol. 2
≈0.5
1.356(5)
(1)5[Anthr(SO3)2] mol. 1 (2) mol. 2 (2) mol. 3
b
a
EDT-TTF a
1.726(3) 1.736(3)
mol. 1 (1)4[1,5-Napht(SO3)2]
involving halogenated TTFs on the one hand, with anionic species acting as halogen bonding acceptor on the other hand, (i) with CTTFHal 3 3 3 Hal interactions with halides,12,23 polyhalides (I3, IBr2),24,25 or polyhalometallates such as FeCl4,26 (Pb2.5I6)∞,27 PbI3,28 or Mo3S7Cl6229 and (ii) with CTTFHal 3 3 3 N interactions with cyanometallates,30,31 thiocyanatometallates,32 or [M(mnt)2] dithiolene complexes.33 By comparison, CTTFHal 3 3 3 O interactions with oxygen atoms were limited to the inorganic ClO4 (ref 34) or HSO4 anions.35 In the search for chiral molecular conductors,36 we recently described a cation radical salt of the iodinated EDT-TTFI2 donor molecule with the chiral enantiopure Dcamphorsulfonate anion, a salt formulated as [EDT-TTFI2]2(D-camphorsulfonate) 3 H2O37 and characterized by the presence of CTTFI 3 3 3 O halogen bonding. It was hoped that the chiral structure of the anion will influence the solid state organization of the conducting stacks toward chiral supramolecular arrangements. Actually, the charge distribution in the two crystallographically independent EDT-TTFI2 molecules in this salt was far from uniform, with the most oxidized molecule strongly associated by CTTFI 3 3 3 O halogen bonding to the sulfonate anion while the less oxidized one was only interacting with a neutral water molecule. This salt demonstrated for the first time that organic sulfonates were most probably very good halogen bonding acceptors and that other organic sulfonates than the camphor derivative could lead to novel attractive conducting phases with iodinated tetrathiafulvalenes, based on CTTFI 3 3 3 O interactions. Actually, by comparison with inorganic anions, the use of organic anions in conducting cation radical salts has been much less documented.38 It essentially concerns carboxylates, sulfonates, and phenolate anions. While the carboxylate group suffers from intrinsic instability toward oxidative decomposition unless stabilized by added hydrogen bonds,39 the sulfonates have much greater stability and a few conducting salts with nonhalogenated TTFs were described with sulfonate anions, NO radical substituents,40 aromatic sulfonates,41,42 or fluorinated sulfonates such as F3CSO341b,43 or F5SCH2CF2SO3, which leads to the formation of superconducting salts with BEDT-TTF.38,44 The D-camphorsulfonate salt mentioned above37 with EDTTTFI2 is to our knowledge the only one where halogen bonding interactions involve purely organic counterions since all reported
1.729(3) 1.732(3)
1.757(4)
1.745(5)
1.755(5)
1.753(4)
0.4 ≈0.5 ≈0.5
1.369(13)
1.747(9)
1.728(7)
1.741(9)
1.741(8)
1.365(11)
1.755(7)
1.737(8)
≈0.0
1.329(14)
1.737(8) 1.766(9)
1.751(7) 1.766(9)
1.762(9)
1.762(9)
0
1.335(4)
1.756(4)
1.759(3)
Reference 46. b The molecule is disordered on an inversion center.
examples of organic conductors with halogen bonding interactions concentrated on halides, polyhalides, and polyhalo- and polycyanometallates as halogen bond acceptors (see above). The availability of aliphatic and aromatic sulfonates, as mono-, di-, or trisulfonate45 anions opens wide perspectives for the elaboration of novel solid state associations based on halogen bonding with sulfonates as halogen bonding acceptors. Accordingly, we describe here a series of novel cation radical salts derived from the iodinated tetrathiafulvalene EDT-TTFI2 (1) as halogen bonding donor, with different oxo anions (Scheme 1), the inorganic perchlorate on the one hand and organic sulfonates on the other hand, such as the racemic camphorsulfonate [(rac)Camph(SO3)]—for comparison with the salt obtained earlier with the enantiopure anion—and three aromatic disulfonates, namely 1,5- and 2,6-naphtalene bis(sulfonate) and 2,6-anthracene bis(sulfonate).
’ RESULTS AND DISCUSSION Electrocrystallization of EDT-TTF-I2 (1) in the presence of [(n-Bu)4N]ClO4, [(n-Bu)4N][(rac)-CamphSO3)], [(n-Bu)4N]2[1, 5-Napht(SO3)2], [(n-Bu)4N]2[2,6-Napht(SO3)2], or [(n-Bu)4N][2,6-Anthr(SO3 )2] systematically afforded black crystals on the anode which analyze respectively as (1)ClO4, (1)2[(rac)camphSO3] 3 Solv, (1)4[1,5-Napht(SO3)2], (1)2[2,6-Napht(SO3)2], and (1)5[Anthr(SO3)2]. It follows from the stoichiometry that the ClO4 salt is therefore a so-called 1:1 salt with full charge transfer where every EDT-TTFI2 molecule 1 oxidized to the cation radical. The same F = 1 charge transfer is observed in the [2,6-Napht(SO3)2]2 5338
dx.doi.org/10.1021/cg200934r |Cryst. Growth Des. 2011, 11, 5337–5345
Crystal Growth & Design
ARTICLE
salt, with two donor molecules for one dianionic counterion. On the other hand, the three other salts with [(rac)-camphSO3], [1,5Napht(SO3)2]2, and [2,6-Anthr(SO3)2]2 have a mixed-valence character, with an averaged usual oxidation state F = 0.5 in (1)2[(rac)camphSO3] and (1)4[1,5-Napht(SO3)2] while F equals 0.4 in the anthracenedisulfonate salt, with five donor molecules for one dianionic counterion. These extensive series provide therefore also a beautiful opportunity to evaluate if the strength of the halogen bonding, which settles between the iodine atoms of 1 and the sulfonate anions, varies with the degree of charge transfer, as one could anticipate from the electrostatic nature of the interaction. Halogen Bonding in the EDT-TTFI2 (1) Salts. (1)ClO4 crystallizes in the monoclinic system, space group P21/n, with both donor and ClO4 moieties in a general position in the unit
cell. Intramolecular bond distances within the TTF core are in accordance with a F =1 charge transfer, with a marked lengthening of the central CidCi bond (noted a in Table 1) and associated shortening of the CiS bonds (noted b and c in Table 1), when compared with less oxidized (see below) or neutral EDT-TTF derivatives. In (1)ClO4, halogen bonding interactions take place between the two iodine atoms of the EDT-TTFI2 molecule and the ClO4 anion, with I 3 3 3 O distances (Figure 1, Table 2) shorter than those reported earlier in the 2:1 (EDO-TTFI2)2ClO4 salt with the same ClO4 anion. This shortening might be tentatively attributed to the actual stoichiometry of our salt (F = 1). The +1 positive charge on the TTF core can indeed enhance the +δ positive part of the iodine atoms to a larger extent than in the mixed valence EDO-TTFI2 salt with F = 0.5. Such an effect was already noticed in the enantiopure camphorsulfonate salt, where two crystallographically independent EDT-TTFI2 molecules were engaged in different halogen bonding interactions (with the SO3 moiety or with the H2O molecule), depending on their actual partial charge. In (EDT-TTFI2)2ClO4, the two halogen bonds lead to the formation of a linear motif linking alternatively cations and anions along (a + c) (Figure 1). Considering the other salt with full charge transfer, that is (1)2[2,6-Napht(SO3)2], it crystallizes in the triclinic system space group P1 with the donor molecule in the general position and the [2,6-napht(SO3)2]2 dianion on the inversion center. Examination of intramolecular bond length with the TTF core (Table 1) confirms unambiguously the full charge transfer (F = 1). The halogen bonding pattern is shown in Figure 2 and is characterized by the formation of a cyclic motif involving two sulfonate moieties and two donor molecules. I 3 3 3 O interactions are particularly strong (see Table 2), with a shortening of
Figure 1. Halogen bond pattern observed in (1)ClO4. See also Table 2.
Table 2. Geometrical Features of the Halogen Bond Interactionsa F
I 3 3 3 O (Å)
reduction ratio
CI 3 3 3 O (deg)
I 3 3 3 OX (deg)
In (1)ClO4 I1 3 3 I2 3 3
3 O4
1
3.191(3)
0.91
149.5(1)
109.2(1)
3 O3
1
2.940(11)
0.84
172.2(1)
115.1(1)
I1 3 3 I2 3 3
3 O2A
1
2.773(4)
0.79
179.11(7)
121.4(1)
3 O1A
1
2.780(4)
0.79
176.2(7)
119.2(1)
0.5
2.89(2)
131(2)
In (1)2[2,6-Napht(SO3)2]
In (1)2[(rac)-CamphSO3) I1 3 3 3 O4B(dC)b I1 3 3 3 O4C(dC)b I2 3 3 3 O1B I1A 3 3 3 O2B
0.82
174.7(6)
0.5
2.87(3)
0.82
171.7(6)
135(2)
0.5 0.5
3.159(4) 2.809(5)
0.90 0.80
148.2(1) 175.3(1)
144.3(2) 121.0(2)
I2A 3 3 3 O3B
0.5
2.873(4)
0.82
172.0(2)
131.9(2)
I1 3 3 I2 3 3
3 O21
0.5
2.781(4)
0.79
175.5(1)
123.8(2)
3 O23
0.5
2.728(3)
0.78
173.1(1)
119.1(2)
I12 3 3 3 O22
0.5
2.972(4)
0.85
159.4(1)
129.9(2)
I2 3 3 3 O1C I1A 3 3 3 O3C
0.5
2.704(6)
0.77
170.3(2)
131.5(3)
0.5
2.855(7)
0.81
169.2(2)
136.5(3)
In (1)4[1,5-Napht(SO3)2]
In (1)5[Anthr(SO3)2]
F is the charge transfer on the EDT-TTFI2 (1) molecule bearing the iodine atom involved in the interaction, as deduced from the analysis of intramolecular bond length with the TTF core in Table 1. The reduction ratio is calculated relative to the van der Waals I 3 3 3 O contact (1.52 + 1.98 = 3.50 Å. b This carbonyl oxygen atom is disordered on two sites. a
5339
dx.doi.org/10.1021/cg200934r |Cryst. Growth Des. 2011, 11, 5337–5345
Crystal Growth & Design
ARTICLE
Figure 2. Halogen bong motif observed in the full charge transfer salt (1)2[2,6-Napht(SO3)2].
Figure 4. Projection view along a of the unit cell of (1)2[(rac)CamphSO3] 3 (TCE)x, showing the halogen bonding pattern. See also Table 2. The voids in the structure are occupied by disordered TCE solvent molecules.
Figure 3. Disorder model adopted by one of the two enantiomers of camphorsulfonate in its EDT-TTFI2 salt. The D-isomer is in light gray; the L-isomer, in dark gray.
0.79. Preliminary comparison with the above-mentioned ClO4 salt seems to indicate that the oxygen atoms in the sulfonate group appear as better halogen bond acceptors than in the perchlorate anion. In the following, we will describe the three other salts with partial charge transfer. The racemic camphor sulfonate salt crystallizes in the triclinic system, space group P1, with two crystallographically independent donor molecules, together with one (rac)-camphorsulfonate anion, as a racemic mixture and disordered solvent molecules which proved difficult to localize properly. Note that the two enantiomers of the anion are actually sitting on the same site in the structure, as detailed in Figure 3, but with the sulfonate moiety fixed on one single position for the two enantiomers, as if it was anchored by the halogen bonding interactions it develops with the EDT-TTFI2 (1) molecules. Indeed, as shown in Figure 4, the three oxygen atoms of the sulfonate moiety are engaged in short O 3 3 3 I contacts (Table 2) with three different iodine atoms while the fourth iodine atom is linked to the carbonyl oxygen atom. Note also that the intramolecular bond lengths within the TTF core in the two crystallographically independent molecules are comparable and indicate a similar partial charge (F = 0.5), correlated here with comparable halogen bonding ability. The 1,5-naphthalene bis(sulfonate) salt, (1)4[1,5-Napht(SO3)2], crystallizes in the triclinic system, space group P1, with two EDT-TTFI2 (1) molecules in the general position and one naphthalene on the inversion center, hence the stoichiometry of four donor molecules for one dianion and the (1)4[1,5-Napht(SO3)2] formulation with an averaged F = 0.5. The intramolecular bond lengths with the TTF core in the two donor molecules are comparable and do not indicate a noticeable charge differentiation. As shown in Figure 5, each oxygen atom of the SO3 group is engaged in a halogen bonding interaction, leaving only
Figure 5. Projection view, along the stacking axis, of the unit cell of (1)4[Napht(SO3)2], showing the halogen bond interactions (dotted lines).
one iodine atom (I11) free, close to sulfur atoms. The I 3 3 3 O distances (Table 2) are particularly short, down to a 0.78 fraction of the contact distance. The 2,6-anthracene disulfonate salt is more complex than the other salts described above, as it crystallizes in the triclinic system, space group P1, with two EDT-TTFI2 (1) donor molecules in general position, one EDT-TTFI2 (1) disordered on an inversion center, and one anthracene bis(sulfonate) on an inversion center, together with TCE solvent molecules, leading to the formulation of five donor molecules for one dianion, that is (1)5[Anthr(SO3)2] 3 (TCE)x. Note that such a disorder pattern of the donor molecule has already been encountered once with the monoiodo derivative EDT-TTFI.31 A projection view of the unit cell is shown in Figure 6, with the disordered molecule (darkened) at the corners of the cell. Analysis of the intramolecular bond distances within the TTF core of the three donor molecules (Table 1) shows that only the two independent molecules are actually oxidized while the disordered one appears to be essentially neutral. As a consequence, this salt would rather be described as a mixed valence (F = 0.5) salt, cocrystallizing with 5340
dx.doi.org/10.1021/cg200934r |Cryst. Growth Des. 2011, 11, 5337–5345
Crystal Growth & Design
ARTICLE
Figure 6. Projection view along a of the unit cell of (1)5[Anthr(SO3)2] 3 S. The dotted lines indicate the halogen bond interactions. The darkened disordered donor molecule at the unit cell corner is essentially neutral.
a neutral donor molecule. This charge ordering clearly affects the halogen bonding pattern, as only the two oxidized molecules are indeed engaged in halogen bonding interactions with the sulfonate anion, with particularly short distances (Table 2), down to 0.77, the contact distance, while the neutral molecule disordered on the inversion center is not engaged in halogen bonding interactions. Several important conclusions arise from the five examples described above. First of all, the sulfonate moiety appears as a powerful halogen bond acceptor, characterized with short I 3 3 3 O intermolecular distances and associated systematically with a linear geometry and CI 3 3 3 O angles close to 180°, particularly with the shortest interactions (Table 2). The influence of the halogen bonding on the SO intramolecular bond lengths has also been examined in the four compounds. Among them, only two oxygen atoms, in (1)4[2,6-Napht(SO3)2] and (1)5[Anthr(SO3)2], are not involved in halogen bonding. They exhibit SO bond lengths slightly shorter than the other ones, demonstrating that the halogen bonding partially weakens the SO bond. The influence of the oxidation state of the TTF core on the halogen bond interaction should be considered cautiously. The fully oxidized salt (F = 1) obtained with [2,6-Napht(SO3)2]2 exhibits indeed a strong I 3 3 3 O shortening (0.79), while the partially oxidized molecules (F = 0.5) give a broader dispersion (0.770.90). A larger set of salts would be necessary to identify a clear discrimination. A more definitive result is given by the anthracene bis(sulfonate) salt, where the larger size of the anion allows for the inclusion of an essentially neutral donor molecule. Concomitantly, this molecule is not engaged in any halogen bond which would fix its orientation, but instead it is disordered on an inversion center. Electronic Properties of the EDT-TTFI2 Salts. Besides the halogen bonding interactions taking place between cations and anions, these salts are also characterized with strong interactions between the fully or partially oxidized donor molecules, which explain their conducting and magnetic properties. As shown in Figure 7 for (1)ClO4, the radical cations associate into face-toface dyads with short intradyad S 3 3 3 S (2 3.58 Å, 2 3.59 Å) distances, while the fewer interdyad S 3 3 3 S contacts along the a axis are much longer (3.75 Å, 4.16 Å). It is therefore anticipated that the two radical species are associated into the bonding combination of the two radical SOMOs. Calculations of the βHOMOHOMO interaction energy for the intra- and interdimer
Figure 7. Solid state organization of the radical cations in (1)[ClO4].
Figure 8. Projection view along a of the unit cell of (1)2[2,6Napht(SO3)2].
interactions give βintra = 0.67 eV and βinter = 0.14 eV, allowing us to describe these spin chains as strongly dimerized. The temperature dependence of the magnetic susceptibility of this salt confirms this analysis, with only a Curie-type contribution encompassing 0.3% paramagnetic defaults. Considering now the other salt with full charge transfer, that is (1)2[2,6-Napht(SO3)2], its solid state structure also shows chains running along a and isolated from each other by the 2,6-naphtalene bis(sulfonate) anions (Figure 8) with two different overlap interactions within the chains. Calculations of the βHOMOHOMO interaction energies for the intra- and interdimer interactions give here βintra = 0.44 eV and βinter = 0.23 eV. The temperature dependence of the magnetic susceptibility follows a Curie-type law encompassing only 1.3% paramagnetic defaults, a behavior which reflects the dimerization of the cation radicals. On the other hand, the mixed valence salts derived from the (rac)camphorsulfonate, 1,5-naphthalene bis(sulfonate), and 2,6-anthracene bis(sulfonate) anions exhibit a different behavior with a medium to high room temperature conductivity, 630 103 S cm1 in (1)2[(rac)-Camph(SO3)], 2 S cm1 in (1)5[2,6-Anthr(SO3)2], 5341
dx.doi.org/10.1021/cg200934r |Cryst. Growth Des. 2011, 11, 5337–5345
Crystal Growth & Design
ARTICLE
Figure 11. Calculated band structure for (1)4[1,5-Napht(SO3)2]. The dotted line indicates the Fermi level for a hypothetical metallic behavior. Figure 9. Temperature dependence of the resistivity in the three mixedvalence salts vs 1000/T, showing the activated behavior, with Eact/k = 310 K in (1)2[(rac)-Camph(SO3)], Eact/k = 1100 K in (1)5[2,6-Anthr(SO3)2], and (1)4[1,5-Napht(SO3)2].
Figure 12. Calculated Fermi surface for (1)4[1,5-Napht(SO3)2].
Figure 10. Projection view of the conducting slab in (1)4[1,5-Napht(SO3)2]. The two crystallographically independent molecules have been differentiated with dark gray and light gray colors for carbon atoms and bonds. The calculated βij interaction energies (eV) for the different intermolecular interactions are as follows: a1 = 0.3645, a2 = 0.4117, b1 = 0.0159, b2 = 0.0042, ab1 = 0.0049, ab2 = 0.0255, ab3 = 0.0045, ab4 = 0.0241.
and up to 8 S cm1 in (1)4[1,5-Napht(SO3)2]. The temperature dependence of the resistivity (Figure 9) shows an activated (semiconducting) behavior with F = F0 exp(Eact/kT) with Eact = 27 meV (310 K) in (1)2[(rac)-Camph(SO3)] and 95 meV (1100 K) in both (1)5[2,6-Anthr(SO3)2] and (1)4[1,5Napht(SO3)2]. Among these three salts, the (rac)-camphorsulfonate and 2,6-anthracene bis(sulfonate) ones are affected by disorder, on the anion or on the donor stacks, making a detailed analysis of their electronic structure difficult. In the following, we will therefore concentrate on the 1,5-naphtalene bis sulfonate salt (1)4[1,5-Napht(SO3)2], which also exhibits the highest conductivity. A projection view of the conducting slab in (1)4[1,5-Napht(SO3)2], viewed along the long molecular axis, is shown in Figure 10, with the calculated β interaction energies within and
Figure 13. Temperature dependence of the magnetic susceptibility for (1)4[1,5-Napht(SO3)2]. The red line is a fit to the uniform spin chain model for a (1)2•+ radical species together with a Curie tail: χ = χ0 + xχCurie + (1 x)χBF, with χ0 = 1.11 103 cm3 mol1, x = 0.5%, and JBF/k = 980(50) K.
between the stacks. Large values are found within the stacks (βa1 = 0.36 eV, βa2 = 0.41 eV) while the largest interstack interactions do not exceed 0.016 eV, indicating a probable onedimensional electronic structure. The calculated band structure (Figure 11) confirms this assumption. The Fermi level, determined for a hypothetical metallic behavior and a F = 0.5 band filling, does not cut any band in the Γ f Y direction, and the calculated Fermi surface 5342
dx.doi.org/10.1021/cg200934r |Cryst. Growth Des. 2011, 11, 5337–5345
Crystal Growth & Design
ARTICLE
Table 3. Electrocrystallization Conditions isolated phase
a
electrolyte
solvent
T (°C)
current (μA)
(1)ClO4
(Bu4N)ClO4
CH2Cl2
20(2)
1
(1)2[(rac)-CamphSO3]
(Bu4N)[(rac)-CamphSO3]
CH2Cl2
20(2)
4
(1)4[1,5-Napht(SO3)2]
(PPh4)2[1,5-Napht(SO3)]
CH2Cl2
20(2)
0.5
(1)2[2,6-Napht(SO3)2]
(PPh4)2[2,6-Napht(SO3)2]
TCEa
40(2)
2
(1)5[2,6-Anthr(SO3)2]
(PPh4)2[2,6-Anthr(SO3)2]
TCEa
30(2)
0.5
TCE: 1,1,2-trichloroethane.
Table 4. Crystallographic Data for the EDT-TTFI2 (1) Salts with Different Anions compd
(1)ClO4
(1)2[(rac)-CamphSO3]
(1)4[1,5-Napht(SO3)]
(1)2[2,6-Napht(SO3)2]
(1)5[2,6-Anthr(SO3)2]
formula
C8H4Cl1I2O4S6
C26H23IO4S13
C42H22I8O6S26
C26H14I4O6S14
C54H28I10O6S32
FW (g 3 mol1) crystal color
645.72 black
1323.82 black
2471.36 black
1378.95 black
3067.68 black
crystal size (mm)
0.3 0.15 0.05
0.41 0.26 0.09
0.19 0.05 0.04
0.12 0.08 0.03
0.11 0.08 0.04
crystal system
monoclinic
triclinic
triclinic
triclinic
triclinic
space group
P21/n
P1
P1
P1
P1
T (K)
293(2)
100(2)
100(2)
150(2)
100(2)
a (Å)
7.6417(4)
7.7550(3)
7.7713(2)
7.9840(7)
8.2897(5)
b (Å)
23.3523(9)
17.4439(5)
14.1238(4)
10.7355(9)
16.5934(10)
c (Å) α (deg)
9.7987(6) 90.00
18.3384(6) 67.622(2)
17.1337(5) 112.569(1)
11.4398(10) 101.320(3)
17.3822(9) 69.717(2)
β (deg)
108.017(7)
85.438(2)
94.867(1)
96.260(3)
87.867(2)
γ (deg)
90.00
77.4080(10)
105.053(1)
99.933(3)
79.992(2)
V (Å3)
1662.85(15)
2238.76(13)
1640.69(8)
936.62(14)
2207.9(2)
Z
4
2
1
1
1
Dcalc (g 3 cm3) μ (mm1)
2.579
1.964
2.501
2.445
2.307
4.704
3.420
4.654
4.150
4.310
total refls abs corr
18690 multiscan
30280 multiscan
13508 multiscan
15421 multiscan
24995 multiscan
Tmin, Tmax
0.433, 0.790
0.358, 0.735
0.567, 0.830
0.678, 0.883
0.668, 0.842
unique refls
3798
10127
7375
4209
10123
Rint
0.0241
0.0308
0.0307
0.0319
0.0432
unique refls
a
I > 2σ(I)
3428
9573
6633
3898
7224
refined param
190
528
370
226
516
R1a (I > 2σ(I)) wR2 (all data)
0.0272 0.0609
0.0300 0.0904
0.0273 0.0664
0.0189 0.0458
0.0500 0.1450
GOF
1.166
1.317
1.167
1.086
1.104
res. dens (e Å3)
1.18, +0.67
0.760, 0.831
0.98, 0.15
0.38, 1.47
1.44, 2.40
R1 = ∑||Fo| |Fc||/∑|Fo|; wR2 = [Σw(Fo2 Fc2)2/ΣwFo4]1/2.
(Figure 12) exhibits a 1D open character. Note also that this Fermi surface can be efficiently nested by one single nesting vector (q). The magnetic susceptibility (Figure 13) shows a weak temperature dependence with a rounded maximum around 250 K. On the basis of the structure description (Figure 10), it is fitted with a uniform BonnerFisher spin chain model47,48 for (1)2•+ radical dimers, most probably interacting along the stacking a direction. This salt can therefore be described as a Mott insulator, a situation often found with such systems where the upper band (Figure 12) is actually half-filled, while the nesting properties of the Fermi surface for the hypothetical metallic state are correlated to the directionality of the strongest magnetic interactions.49
’ CONCLUSIONS Inspired by our first result on a conducting salt of EDTTTFI2 (1) with the enantiopure camphorsulfonate anion which revealed a halogen bonding interaction between iodine and the sulfonate group,37 we have investigated here a variety of sulfonate anions as counterions in the electrocrystallization process with the iodinated tetrathiafulvalene 1, affording in every case cation radical salts with CI 3 3 3 O halogen bonds. Because of its essentially electrostatic character, the strength of halogen bonding appears to follow the oxidation state (F) of the TTF. Interactions with the ClO4 anion are indeed shorter in the fully oxidized (F = 1) salt (1)ClO4 than in the previously reported mixed-valence (F = 0.5) salt (EDO-TTFI2)2ClO4. 5343
dx.doi.org/10.1021/cg200934r |Cryst. Growth Des. 2011, 11, 5337–5345
Crystal Growth & Design Organic sulfonates appear here as powerful halogen bonding acceptors, with even shorter I 3 3 3 O interactions (down to 0.77 shortening ratio), opening perspectives not only for the synthesis of novel organic conductors but also as a more general tool in supramolecular chemistry.
’ EXPERIMENTAL SECTION Crystal Growth. EDT-TTFI2 (1) was prepared as described previously.25 The tetrabutylammonium salt of the (rac)-camphorsulfonate anion was prepared from the commercially available sulfonic acid and nBu4NOH as described for the enantiopure compound.37 Bis(tetraphenylphosphonium) salts of 1,5-naphthalene-, 2,6-naphtalene-, and 2,6-anthracenedisulfonic acids were prepared by metathesis reaction from the commercially available sodium sulfonate salts and PPh4Br in water. Crystal growth was performed by electrocrystallization50 in twocompartment cells with Pt electrodes (diameter 1 mm, length 2 cm), containing 1 (510 mg) and electrolyte (100 mg, see Table 3), at a constant current, as detailed in Table 3. X-ray Diffraction Studies. Data were collected on a Nonius KappaCCD diffractometer with graphite-monochromated Mo Kα radiation (λ = 0.71073 Å). Structures were solved by direct methods (SHELXS-97) and refined (SHELXL-97) by full-matrix least-squares methods,51 as implemented in the WinGX software package.52 Absorption corrections were applied. Hydrogen atoms were introduced at calculated positions (riding model), included in structure factor calculations, and not refined. Crystallographic data are summarized in Table 4. Band Structure Calculations. The tight-binding band structure calculations and βHOMOHOMO interaction energies were based upon the effective one-electron Hamiltonian of the extended H€uckel method,53 as implemented in the Caesar 1.0 chain of programs.54 The off-diagonal matrix elements of the Hamiltonian were calculated according to the modified WolfsbergHelmholz formula.55 All valence electrons were explicitly taken into account in the calculations, and the basis set consisted of double-ζ Slater-type orbitals for C, S, Br, and I and single-ζ Slater-type orbitals for H. The exponents, contraction coefficients, and atomic parameters for C, S, I, and H were taken from previous work.25
’ ASSOCIATED CONTENT
bS
Supporting Information. Crystallographic data in cif format for the five reported salts. This material is available free of charge via the Internet at http://pubs.acs.org.
’ AUTHOR INFORMATION Corresponding Author
*Phone: +33-223235243. E-mail:
[email protected].
’ ACKNOWLEDGMENT This work was made possible with financial support from ANR (France) under Contracts ANR-08-BLAN-0140-02 and ANR08-BLAN-0091-02. ’ REFERENCES (1) (a) Bianchi, A.; Bowman-James, K.; Garcia-Espanaed, E. Supramolecular Chemistry of Anions; Wiley-VCH: New York, 1997. (b) Anion Receptor Chemistry; Sessler, J. L., Gale, P. A., Cho, W. S., Eds.; Royal Society of Chemistry: Cambridge, U.K., 2006. (2) (a) Park, C. H.; Simmons, H. E. J. Am. Chem. Soc. 1968, 90, 2431. (b) Graf, E.; Lehn, J.-M. J. Am. Chem. Soc. 1976, 98, 6403.
ARTICLE
(3) (a) Gale, P. A. Chem. Commun. 2011, 47, 82. (b) Worm, K.; Schmidtchen, F. P. Angew. Chem., Int. Ed. Engl. 1995, 34, 65. (4) O’Neil, E. J.; Smith, B. D. Coord. Chem. Rev. 2006, 250, 3068. (5) Metrangolo, P.; Pilati, T.; Terraneo, G.; Biella, S.; Resnati, G. CrystEngComm 2009, 11, 1187. (6) Cavallo, G.; Metrangolo, P.; Pilati, T.; Resnati, G.; Sansotera, M.; Terraneo, G. Chem. Soc. Rev. 2010, 39, 3772. (7) Halogen Bonding, Fundamentals and Applications; Metrangolo, P., Resnati, G., Eds.; Structure and Bonding Vol. 126; Springer Verlag: Berlin Heidelberg, 2008. (8) (a) Ramasubbu, N.; Parthasarathy, R.; Murray-Rust, P. J. Am. Chem. Soc. 1986, 108, 4308. (b) Pedireddi, V. R.; Reddy, D. S.; Goud, B. S.; Craig, D. C.; Rae, A. D.; Desiraju, G. R. J. Chem. Soc., Perkin Trans. 2 1994, 2353. (c) Sakurai, T.; Sundaralingam, M.; Jeffrey, G. A. Acta Crystallogr. 1963, 16, 354–363. (d) Desiraju, G. R.; Parthasarathy, R. J. Am. Chem. Soc. 1989, 111, 8725. (9) Reddy, C. M.; Kirchner, M. T.; Gundakaram, R. C.; Padmanabhan, K. A.; Desiraju, G. R. Chem.—Eur. J. 2006, 12, 2222. (10) Bui, T. T. T.; Dahaoui, S.; Lecomte, C.; Desiraju, G. R.; Espinosa, E. Angew. Chem., Int. Ed. 2009, 48, 3838. (11) (a) Nyburg, S. C.; Wong-Ng, W. Inorg. Chem. 1979, 18, 2790. (b) Nyburg, S. C.; Wong-Ng, W. Proc. R. Soc. London, Ser. A 1979, 367, 29. (12) Imakubo, T.; Sawa, H.; Kato, R. Synth. Met. 1995, 73, 117. (13) For a general review, see for example: Chem. Rev. 2004, 104 (11), Special Issue on Molecular Conductors. (14) Whangbo, M.-H.; Williams, J. M.; Schultz, A. J.; Emge, T. J.; Beno, M. A. J. Am. Chem. Soc. 1987, 109, 90. (15) Bryce, M. R. J. Mater. Chem. 1995, 5, 1481. (16) Fourmigue, M.; Batail, P. Chem. Rev. 2004, 104, 5379. (17) Dolbecq, A.; Fourmigue, M.; Batail, P.; Coulon, C. Chem. Mater. 1994, 6, 1413. (18) Heuze, K.; Fourmigue, M.; Batail, P. J. Mater. Chem. 1999, 9, 2373. (19) Dolbecq, A.; Fourmigue, M.; Krebs, F. C.; Batail, P.; Canadell, E.; Clerac, R.; Coulon, C. Chem.—Eur. J. 1996, 2, 1275. (20) (a) Ono, G.; Izuoka, A.; Sugawara, T.; Sugawara, Y. J. Mater. Chem. 1998, 8, 1703. (b) Heuze, K.; Fourmigue, M.; Batail, P.; Canadell, E.; Auban-Senzier, P. Chem.—Eur. J. 1999, 5, 2971. (c) Heuze, K.; Meziere, C.; Fourmigue, M.; Batail, P.; Coulon, C.; Canadell, E.; AubanSenzier, P.; Jerome, D. Chem. Mater. 2000, 12, 1898. (21) (a) Baudron, S. A.; Batail, P.; Coulon, C.; Clerac, R.; Canadell, E.; Laukhin, V.; Melzi, R.; Wzietek, P.; Jerome, D.; Auban-Senzier, P.; Ravy, S. J. Am. Chem. Soc. 2005, 127, 11785. (b) Baudron, S. A.; Avarvari, N.; Canadell, E.; Auban-Senzier, P.; Batail, P. Chem.—Eur. J. 2004, 10, 4498. (c) Baudron, S. A.; Batail, P.; Rovira, C.; Canadell, E.; Clerac, R. Chem. Commun 2003, 1820. (d) Baudron, S. A.; Avarvari, N.; Batail, P.; Coulon, C.; Clerac, R.; Canadell, E.; Auban-Senzier, P. J. Am. Chem. Soc. 2003, 125, 11583. (22) Moore, A. J.; Bryce, M. R.; Batsanov, A. S.; Heaton, J. N.; Lehmann, C. W.; Howard, J. A. K.; Robertson, N.; Underhill, A. E.; Perepichka, I. F. J. Mater. Chem. 1998, 8, 1541. (b) Batsanov, A. S.; Bryce, M. R.; Cooke, G.; Heaton, J. N.; Howard, J. A. K. J. Chem. Soc., Chem. Commun. 1993, 1701. (c) Batsanov, A. S.; Bryce, M. R.; Cooke, G.; Dhindsa, A. S.; Heaton, J. N.; Howard, J. A. K.; Moore, A. J.; Petty, M. C. Chem. Mater. 1994, 6, 1419. (23) Imakubo, T.; Shirahata, T.; Herve, K.; Ouahab, L. J. Mater. Chem. 2006, 16, 162. (24) Iyoda, M.; Ogura, E.; Takano, T.; Hara, K.; Kuwatani, Y.; Kato, T.; Yoneyama, N.; Nishijo, J.; Miyazaki, A.; Enoki, T. Chem. Lett. 2000, 680. (25) Domercq, B.; Devic, T.; Fourmigue, M.; Auban-Senzier, P.; Canadell, E. J. Mater. Chem. 2001, 11, 1570. (26) Enoki, T.; Yamazaki, H.; Nishijo, J.; Miyazaki, A.; Ugawa, K.; Ogura, E.; Kuwatani, Y.; Iyoda, M.; Sushko, Y. V. Synth. Met. 2003, 137, 1173. (27) Devic, T.; Evain, M.; Mo€elo, Y.; Canadell, E.; Auban-Senzier, P.; Fourmigue, M.; Batail, P. J. Am. Chem. Soc. 2003, 125, 3295. 5344
dx.doi.org/10.1021/cg200934r |Cryst. Growth Des. 2011, 11, 5337–5345
Crystal Growth & Design (28) Devic, T.; Canadell, E.; Auban-Senzier, P.; Batail, P. J. Mater. Chem. 2004, 14, 135. (29) Alberola, A.; Fourmigue, M.; Gomez-García, C. J.; Llusar, R.; Triguero, S. New J. Chem. 2008, 32, 1103. (30) (a) Thoyon, D.; Okabe, K.; Imakubo, T.; Golhen, S.; Miyazaki, A.; Enoki, T.; Ouahab, L. Mol. Cryst. Liq. Cryst. 2002, 376, 25. (b) Ueda, K.; Sugimoto, T.; Faulmann, C.; Cassoux, P. Eur. J. Inorg. Chem. 2003, 2333. (c) Imakubo, T.; Sawa, H.; Kato, R. Synth. Met. 1997, 86, 1847. (d) Imakubo, T.; Sawa, H.; Kato, R. J. Chem. Soc., Chem. Commun. 1995, 1667. (e) Imakubo, T.; Miyake, A.; Sawa, H.; Kato, R. Synth. Met. 2001, 120, 927. (31) Ranganathan, A.; El-Ghayoury, A.; Meziere, C.; Harte, E.; Clerac, R.; Batail, P. Chem. Commun. 2006, 2878. (32) (a) Fourmigue, M.; Auban-Senzier, P. Inorg. Chem. 2008, 47, 9979. (b) Herve, K.; Cador, O.; Golhen, S.; Costuas, K.; Halet, J.-F.; Shirahata, T.; Muto, T.; Imakubo, T.; Miyazaki, A.; Ouahab, L. Chem. Mater. 2006, 18, 790. (33) (a) Nishijo, J.; Ogura, E.; Yamaura, J.; Miyazaki, A.; Enoki, T.; Takano, T.; Kuwatani, Y.; Iyoda, M. Solid State Commun. 2000, 116, 661. (b) Devic, T.; Domercq, B.; Auban-Senzier, P.; Molinie, P.; Fourmigue, M. Eur. J. Inorg. Chem. 2002, 2844. (34) Kuwatani, Y.; Ogura, E.; Nishikawa, H.; Ikemoto, I.; Iyoda, M. Chem. Lett. 1997, 817. (35) Batsanov, A. S.; Moore, A. J.; Robertson, N.; Green, A.; Bryce, M. R.; Howard, J. A. K.; Underhill, A. E. J. Mater. Chem. 1997, 7, 387. (36) For a review see:Avarvari, N.; Wallis, J. D. J. Mater. Chem. 2009, 19, 4061. (37) Brezgunova, M.; Shin, K. S.; Auban-Senzier, P.; Jeannin, O.; Fourmigue, M. Chem. Commun. 2010, 3926. (38) Geiser, U.; Schlueter, J. A. Chem. Rev. 2004, 104, 5203. (39) Giffard, M.; Riou, A.; Mabon, G.; Mercier, N.; Molinie, P.; Nguyen, T. P. J. Mater. Chem. 1999, 9, 851. (40) (a) Akutsu, H.; Yamada, J.; Nakatsuji, S.; Turner, S. S. Solid State Commun. 2006, 140, 256. (b) Akutsu, H.; Sato, K.; Yamashita, S.; Yamada, J.; Nakatsuji, S.; Turner, S. S. J. Mater. Chem. 2008, 18, 3313. (c) Akutsu, H.; Yamashita, S.; Yamada, J.; Nakatsuji, S.; Hosokoshi, Y.; Turner, S. S. Chem. Mater. 2011, 23, 762. (d) Akutsu, H.; Kawamura, A.; Yamada, J.; Nakatsuji, S.; Turner, S. S. CrystEngComm 2011, 13, 5281. (41) (a) Wang, H. H.; Geiser, U.; Schlueter, J. A.; Ward, B. H.; Parakka, J. P.; Kini, A. M.; O’Malley, J. L.; Thomas, S. Y.; Morales, E.; Dudek, J. D.; Williams, J. M.; Garda, G. L. Synth. Met. 1999, 102, 1666. (b) Chasseau, D.; Watkin, D.; Rosseinsky, M. J.; Kurmoo, M.; Talham, D. R.; Day, P. Synth. Met. 1988, 24, 117. (42) Lakhdar, Y.; El-Ghayoury, A.; Zorina, L.; Mercier, N.; Allain, M.; Meziere, C.; Auban-Senzier, P.; Batail, P.; Giffard, M. Eur. J. Inorg. Chem. 2010, 3338. (43) Jia, C.; Zhang, D.; Xu, W.; Zhu, D. Synth. Met. 2004, 140, 9. (44) Geiser, U.; Schlueter, J. A.; Wang, H. H.; Kini, A. M.; Williams, J. M.; Sche, P. P.; Zakowicz, H. I.; Vanzile, M. L.; Dudek, J. D.; Nixon, P. G.; Winter, R. W.; Gard, G. L.; Ren, J.; Whangbo, M.-H. J. Am. Chem. Soc. 1996, 118, 9996. (45) (a) Russell, V. A.; Evans, C. C.; Li, W.; Ward, M. D. Science 1997, 276, 575. (b) Horner, M. J.; Holman, K. T.; Ward, M. D. J. Am. Chem. Soc. 2007, 129, 14640. (46) Garreau, B.; De Montauzon, D.; Cassoux, P.; Legros, J.-P.; Fabre, J.-M.; Saoud, K.; Chakroune, S. New J. Chem. 1995, 19, 161. (47) Bonner, J. C.; Fisher, M. E. Phys. Rev. A 1964, 135, 640. (48) (a) Kahn, O. Molecular Magnetism; VCH: New York, 1993; Chapter 11, pp 251286. (b) Estes, W.; Gavel, D. P.; Hatfield, W. E.; Hogdson, D. Inorg. Chem. 1978, 17, 1415. (49) Fourmigue, M.; Reinheimer, E. W.; Assaf, A.; Jeannin, O.; Saad, A.; Auban-Senzier, P.; Alemany, P.; Rodríguez-Fortea, A.; Canadell, E. Inorg. Chem. 2011, 50, 4171. (50) Batail, P.; Boubekeur, K.; Fourmigue, M.; Gabriel, J.-C. P. Chem. Mater. 1998, 10, 3005. (51) SHELX97—Programs for Crystal Structure Analysis (Release 972); Sheldrick, G. M., 1998.
ARTICLE
(52) Farrugia, L. J. J. Appl. Crystallogr. 1999, 32, 837. (53) Whangbo, M.-H.; Hoffmann, H. J. Am. Chem. Soc. 1978, 100, 6093. (54) Ren, J.; Liang, W.; Whangbo, M.-H. Crystal and Electronic Structure Analysis Using CAESAR; 1998. (55) Ammeter, J.; B€urgi, H.-B.; Thibeault, J.; Hoffmann, R. J. Am. Chem. Soc. 1978, 100, 3686.
5345
dx.doi.org/10.1021/cg200934r |Cryst. Growth Des. 2011, 11, 5337–5345
