metal-organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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Poly[(μ4-5,7-di­hydro-1H,3H-dithieno[3,4-b:3′,4′-e]pyrazine-κ4N:N′:S:S′)tetra-μ3-iodido-tetra­copper]: a three-dimensional copper(I) coordination polymer

aInstitute of Chemistry, University of Neuchâtel, Av. de Bellevax 51, CH-2000 Neuchâtel, Switzerland, and bInstitute of Physics, University of Neuchâtel, rue Emile-Argand 11, CH-2000 Neuchâtel, Switzerland
*Correspondence e-mail: helen.stoeckli-evans@unine.ch

Edited by A. J. Lough, University of Toronto, Canada (Received 17 March 2020; accepted 21 March 2020; online 27 March 2020)

The reaction of ligand 5,7-di­hydro-1H,3H-dithieno[3,4-b:3′,4′-e]pyrazine (L) with CuI lead to the formation of a three-dimensional coordination polymer, incorporating the well known [CuxIx]n staircase motif (x = 4). These polymer [Cu4I4]n chains are linked via the N and S atoms of the ligand to form the three-dimensional coordination polymer poly[(μ4-5,7-di­hydro-1H,3H-dithieno[3,4-b:3′,4′-e]pyrazine-κ4N:N′:S:S′)tetra-μ3-iodido-tetra­copper], [Cu4I4(C8H8N2S2)]n (I). The asymmetric unit is composed of half a ligand mol­ecule, with the pyrazine ring located about a center of symmetry, and two independent copper(I) atoms and two independent I ions forming the staircase motif via centers of inversion symmetry. The framework is consolidated by C—H⋯I hydrogen bonds.

3D view (loading...)
[Scheme 3D1]
Chemical scheme
[Scheme 1]

Structure description

We have recently shown that the reaction of the ligand 5,7-di­hydro-1H,3H-dithieno[3,4-b:3′,4′-e]pyrazine (L), with silver(I) nitrate leads to the formation of a two-dimensional coordination polymer, with the silver atom coordinating only to the S atoms of the ligand so forming chains. The nitrato anion bridges two equivalent silver atoms and so generates the network structure (Assoumatine & Stoeckli-Evans, 2020a[Assoumatine, T. & Stoeckli-Evans, H. (2020a). Acta Cryst. E76, 539-546.]). Ligand L is one of a series of pyrazine­thio­phanes synthesized to study their coordination chemistry with various transition metals (Assoumatine, 1999[Assoumatine, T. (1999). PhD Thesis. University of Neuchâtel, Switzerland.]). The reaction of L with CuCl2 and CuBr2 lead to the formation of isostructural one-dimensional coordination polymers with the ligand coordinating to the copper atom via the N atoms only (Assoumatine & Stoeckli-Evans, 2020b[Assoumatine, T. & Stoeckli-Evans, H. (2020b). Private communications (deposition numbers 1988248 and 1988249). CCDC, Cambridge, England.]).

The reaction of L with CuI has lead to the formation of a three-dimensional coordination polymer, incorporating the well known [CuxIx]n staircase motif (x = 4; Fig. 1[link]). The asymmetric unit is composed of half a ligand mol­ecule, with the pyrazine ring located about a center of symmetry, and two independent copper(I) atoms and two independent I ions forming the staircase motif via centers of inversion symmetry. The polymer [Cu4I4]n chains are linked via the N and S atoms of the ligand to form the three-dimensional framework of complex I (Fig. 2[link]).

[Figure 1]
Figure 1
A partial view of the mol­ecular structure of complex I, with atom labelling for the atoms of the asymmetric unit. Displacement ellipsoids are drawn at the 30% probability level. Colour code: Cu1 orange, Cu2 green, I1 purple, I2 violet.
[Figure 2]
Figure 2
A view along the a axis of the crystal packing of complex I. For clarity, the H atoms have been omitted.

In the ligand, the five-membered thio­phene rings are not planar, but have envelope configurations with the S atom as the flap. Atom S1 deviates by 0.5076 (14) Å from the mean plane of the four C atoms (C1–C4). This is considerably more than in the silver(I) nitrate two-dimensional coordination polymer or the ligand itself (Assoumatine & Stoeckli-Evans, 2020a[Assoumatine, T. & Stoeckli-Evans, H. (2020a). Acta Cryst. E76, 539-546.]). In the former, the S atom deviates from the mean plane of the four C atoms by 0.170 (15) Å, and in the latter by only 0.0256 (8) Å.

Selected bond lengths and bond angles involving the copper(I) atoms in I are given in Table 1[link]. In I, both copper(I) atoms are fourfold coordinate; the Cu⋯Cu distances are not considered as bonds. Hence, atom Cu1 has a fourfold CuSI3 coord­ination geometry with the fourfold index parameter τ4 = 0.91 (τ4 = 1 for a perfect tetra­hedral geometry, 0 for a perfect square-planar geometry and 0.85 for perfect trigonal–pyramidal geometry; Yang et al., 2007[Yang, L., Powell, D. R. & Houser, R. P. (2007). Dalton Trans. pp. 955-964.]). Atom Cu2 has a CuNI3 coordination geometry with a fourfold index parameter τ4 = 0.88. Hence, both atoms have similar distorted shapes, neither perfect tetra­hedral nor perfect trigonal–pyramidal. The Cu—N, Cu—S and Cu—I bond lengths are within normal values and are discussed below.

Table 1
Selected geometric parameters (Å, °)

Cu1—Cu1i 2.7355 (16) I2—Cu1ii 2.6617 (10)
Cu1—Cu2ii 2.9030 (14) Cu2—N1iv 2.059 (4)
Cu1—S1 2.3393 (16) I1—Cu2ii 2.6786 (9)
I1—Cu1 2.6477 (9) I1—Cu2 2.7142 (9)
I2—Cu1iii 2.6478 (11) I2—Cu2 2.6418 (8)
       
S1—Cu1—I1 104.34 (4) N1iv—Cu2—I2 107.06 (12)
S1—Cu1—I2v 108.74 (5) N1iv—Cu2—I1ii 122.19 (13)
I1—Cu1—I2v 107.06 (3) I2—Cu2—I1ii 113.30 (3)
S1—Cu1—I2ii 104.10 (5) N1iv—Cu2—I1 110.69 (13)
I1—Cu1—I2ii 113.66 (3) I2—Cu2—I1 108.98 (3)
I2v—Cu1—I2ii 117.98 (3) I1ii—Cu2—I1 93.48 (3)
Symmetry codes: (i) -x+2, -y, -z+2; (ii) -x+1, -y, -z+2; (iii) x-1, y, z; (iv) -x+2, -y+1, -z+2; (v) x+1, y, z.

In the crystal of I, the three-dimensional structure is consolidated by C—H⋯I hydrogen bonds (Table 2[link]).

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
C3—H3B⋯I1 0.97 3.01 3.808 (6) 140
C3—H3A⋯I1vi 0.97 2.91 3.767 (5) 149
C4—H4A⋯I1iv 0.97 3.00 3.641 (5) 124
Symmetry codes: (iv) -x+2, -y+1, -z+2; (vi) -x+1, -y, -z+1.

There are less than 15 polymeric structures in the Cambridge Structural Database (CSD; Version 5.41, last update November 2019; Groom et al., 2016[Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171-179.]) that concern pyrazine ligands and the [CuxIx]n staircase motif (see file S1 in the supporting information). The majority form two-dimensional coordination polymers with the pyrazine ligand bridg­ing the [CuxIx]n chains. For example, catena-[bis­(μ3-iodo)(μ2-pyrazine-N,N′)dicopper(I)] (CSD refcode AGIYEU01 at 203 K; Blake et al., 1999[Blake, A. J., Brooks, N. R., Champness, N. R., Cooke, P. A., Crew, M., Deveson, A. M., Hanton, L. R., Hubberstey, P., Fenske, D. & Schröder, M. (1999). Cryst. Eng. 2, 181-195.]) and catena-[bis­(μ3-iodo)(μ3-bis­(6-methyl­pyrazin-2-ylmeth­yl)thio­ether-N,N′,N′′,S)(μ2-iodo)­tri­copper(I)] (RABBUS at 123 K; Amoore et al., 2003[Amoore, J. J. M., Hanton, L. R. & Spicer, M. D. (2003). Dalton Trans. pp. 1056-1058.]). In AGIYEU01, the copper atom has a CuNI3 fourfold coordin­ation geometry with a τ4 index parameter of 0.90. In the case of RABBUS, there are three copper(I) atoms. Two of the copper atoms have CuNI3 fourfold coordination geometries with τ4 index parameters of 0.92 and 0.89. The third copper atom has a CuNSI2 fourfold coordination geometry with a τ4 index parameter of 0.73. In comparison, the τ4 index parameters for the two copper atoms in I are 0.91 and 0.85.

In AGIYEU01, the Cu—Npyrazine bond length is 2.028 (9) Å. In RABBUS the copper(I) atoms coordinate to the pyrazine N atoms and the S atom of the ligand. Here, the Cu—Npyrazine bond lengths are 2.053 (4), 2.070 (4) and 2.071 (4) Å and the Cu—S bond length is 2.3574 (15) Å. In I, the Cu2—Niv and Cu1—S1 bond lengths of 2.059 (4) and 2.3393 (16) Å, respectively, are very similar to those sited above. The Cu—I bond lengths involving the [CuxIx]n staircase motifs are very similar in all three compounds; they vary from 2.6131 (15) to 2.6485 (15) Å in AGIYEU01, from 2.5993 (7) to 2.8348 (7) Å in RABBUS, and from 2.6418 (8) to 2.7142 (9) Å in I. The Cu⋯Cu distances in I, Cu1—Cu1i = 2.7355 (16) Å and Cu1—Cu2ii = 2.9030 (14) Å, are similar to those in AGIYEU01 [2.7562 (19) Å] and RABUSS [2.6546 (8), 2.7565 (9) and 2.9256 (8) Å].

Synthesis and crystallization

The synthesis and crystal structure of the ligand 5,7-di­hydro-1H,3H-dithieno[3,4-b:3′,4′-e]pyrazine (L), have been reported (Assoumatine & Stoeckli-Evans, 2020a[Assoumatine, T. & Stoeckli-Evans, H. (2020a). Acta Cryst. E76, 539-546.]).

Synthesis of compound I: A solution of L (15 mg, 0.08 mmol) in CH2Cl2 (10 ml) was introduced into a 16 mm diameter glass tube and layered with MeCN (2 ml) as a buffer zone. Then a solution of CuI (15 mg, 0.08 mmol) in MeCN (5 ml) was added very gently to avoid possible mixing. The glass tube was sealed under an atmosphere of nitro­gen and left in the dark at room temperature for at least 2 weeks, whereupon deep-orange plate-like crystals of the title compound, (I), were isolated in the buffer zone. Analysis for C8H8N2S2Cu4I4 (Mr = 958.14 g mol−1): calculated (%): C 10.03, H 0.84, N 2.92, S 6.69; found (%): C 10.12, H 0.80, N 2.82, S 6.67. The IR spectrum is shown in Fig. S1 of the supporting information.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3[link]. A Stoe IPDS-I one-circle diffractometer was used for the data collection at RT. With this instrument for the triclinic system often a small cusp of data is inaccessible; here 176 reflections which gives the alert diffrn_reflns_laue_measured_fraction_full value (0.889) below minimum (0.95). The effect here appears to be limited if one compares the bond lengths in the structure of the pure ligand (Assoumatine & Stoeckli-Evans, 2020a[Assoumatine, T. & Stoeckli-Evans, H. (2020a). Acta Cryst. E76, 539-546.]) with those of the ligand in complex I; they are the same within 3 s.u.s.

Table 3
Experimental details

Crystal data
Chemical formula [Cu4I4(C8H8N2S2)]
Mr 958.04
Crystal system, space group Triclinic, P[\overline{1}]
Temperature (K) 293
a, b, c (Å) 7.0082 (8), 8.378 (1), 8.8162 (10)
α, β, γ (°) 102.808 (13), 104.607 (13), 109.369 (13)
V3) 445.35 (10)
Z 1
Radiation type Mo Kα
μ (mm−1) 11.87
Crystal size (mm) 0.50 × 0.35 × 0.13
 
Data collection
Diffractometer Stoe IPDS1
Absorption correction Multi-scan (MULABS; Spek, 2020[Spek, A. L. (2020). Acta Cryst. E76, 1-11.])
Tmin, Tmax 0.188, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections 3272, 1515, 1452
Rint 0.038
(sin θ/λ)max−1) 0.612
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.040, 0.103, 1.10
No. of reflections 1515
No. of parameters 92
H-atom treatment H-atom parameters constrained
Δρmax, Δρmin (e Å−3) 1.73, −1.58
Computer programs: EXPOSE, CELL and INTEGRATE in IPDS-I (Stoe & Cie, 1998[Stoe & Cie (1998). IPDS-1 Software. Stoe & Cie GmbH, Darmstadt, Germany.]), SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]), Mercury (Macrae et al., 2020[Macrae, C. F., Sovago, I., Cottrell, S. J., Galek, P. T. A., McCabe, P., Pidcock, E., Platings, M., Shields, G. P., Stevens, J. S., Towler, M. & Wood, P. A. (2020). J. Appl. Cryst. 53, 226-235.]), SHELXL2018 (Sheldrick, 2015[Sheldrick, G. M. (2015). Acta Cryst. C71, 3-8.]), PLATON (Spek, 2020[Spek, A. L. (2020). Acta Cryst. E76, 1-11.]) and publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).

The residual electron-density peaks, Δρmax = 1.73 e Å−3, and Δρmin = −1.58 e Å−3, are located near the iodine atoms (within 0.80 to 1.13 Å). As stated by Spek (2018[Spek, A. L. (2018). Inorg. Chim. Acta, 470, 232-237.]): `they can be inter­preted as absorption artefacts due to insufficient or incorrect correction for absorption'; the Tmin and Tmax values of 0.188 and 1.000, respectively, are rather extreme. However, in our experience high residual electron-density peaks are often observed for compounds containing heavy atoms such as iodine.

Structural data


Computing details top

Data collection: EXPOSE in IPDS-I (Stoe & Cie, 1998); cell refinement: CELL in IPDS-I (Stoe & Cie, 1998); data reduction: INTEGRATE in IPDS-I (Stoe & Cie, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2018 (Sheldrick, 2015); molecular graphics: Mercury (Macrae et al., 2020); software used to prepare material for publication: SHELXL2018 (Sheldrick, 2015), PLATON (Spek, 2020) and publCIF (Westrip, 2010).

Poly[(µ4-5,7-dihydro-1H,3H-dithieno[3,4-b:3',4'-e]pyrazine-κ4N:N':S:S')tetra-µ3-iodido-tetracopper] top
Crystal data top
[Cu4I4(C8H8N2S2)]Z = 1
Mr = 958.04F(000) = 430
Triclinic, P1Dx = 3.572 Mg m3
a = 7.0082 (8) ÅMo Kα radiation, λ = 0.71073 Å
b = 8.378 (1) ÅCell parameters from 5000 reflections
c = 8.8162 (10) Åθ = 3.3–25.8°
α = 102.808 (13)°µ = 11.87 mm1
β = 104.607 (13)°T = 293 K
γ = 109.369 (13)°Plate, orange
V = 445.35 (10) Å30.50 × 0.35 × 0.13 mm
Data collection top
Stoe IPDS-1
diffractometer
1515 independent reflections
Radiation source: fine-focus sealed tube1452 reflections with I > 2σ(I)
Plane graphite monochromatorRint = 0.038
φ rotation scansθmax = 25.8°, θmin = 3.3°
Absorption correction: multi-scan
(MULABS; Spek, 2020)
h = 88
Tmin = 0.188, Tmax = 1.000k = 1010
3272 measured reflectionsl = 1010
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.040H-atom parameters constrained
wR(F2) = 0.103 w = 1/[σ2(Fo2) + (0.0717P)2 + 0.7287P]
where P = (Fo2 + 2Fc2)/3
S = 1.10(Δ/σ)max < 0.001
1515 reflectionsΔρmax = 1.73 e Å3
92 parametersΔρmin = 1.58 e Å3
0 restraintsExtinction correction: (SHELXL2018; Sheldrick, 2015), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.016 (3)
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
I10.57925 (5)0.17176 (5)0.88315 (4)0.0210 (2)
I20.21064 (6)0.27610 (5)1.19497 (4)0.0241 (2)
Cu10.90704 (13)0.07739 (12)0.89969 (10)0.0309 (3)
Cu20.53098 (11)0.18093 (10)1.18047 (9)0.0261 (2)
S11.0313 (2)0.16243 (17)0.69503 (15)0.0198 (3)
N11.1948 (7)0.6290 (6)0.6269 (5)0.0153 (9)
C10.9013 (8)0.3374 (7)0.5075 (6)0.0157 (10)
C21.0949 (8)0.4665 (7)0.6316 (6)0.0173 (10)
C30.8095 (8)0.1646 (8)0.5351 (6)0.0227 (12)
H3A0.7596860.0645570.4335630.027*
H3B0.6891230.1572780.5726130.027*
C41.1768 (9)0.4053 (7)0.7736 (6)0.0235 (11)
H4A1.1469350.4573090.8698830.028*
H4B1.3314930.4395650.8047630.028*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
I10.0227 (3)0.0192 (3)0.0175 (3)0.00881 (19)0.00387 (17)0.00296 (18)
I20.0207 (3)0.0222 (3)0.0265 (3)0.0103 (2)0.00545 (18)0.00384 (18)
Cu10.0322 (4)0.0328 (5)0.0296 (4)0.0143 (4)0.0077 (3)0.0158 (3)
Cu20.0223 (4)0.0226 (4)0.0229 (4)0.0062 (3)0.0000 (3)0.0025 (3)
S10.0224 (6)0.0158 (7)0.0185 (6)0.0074 (5)0.0034 (5)0.0057 (5)
N10.0137 (18)0.018 (2)0.0127 (19)0.0066 (17)0.0032 (15)0.0036 (16)
C10.015 (2)0.015 (2)0.016 (2)0.005 (2)0.0047 (18)0.0048 (19)
C20.017 (2)0.020 (3)0.014 (2)0.010 (2)0.0030 (19)0.004 (2)
C30.020 (3)0.026 (3)0.016 (2)0.009 (2)0.0015 (19)0.005 (2)
C40.027 (3)0.016 (3)0.018 (2)0.004 (2)0.002 (2)0.006 (2)
Geometric parameters (Å, º) top
Cu1—Cu1i2.7355 (16)S1—C31.825 (5)
Cu1—Cu2ii2.9030 (14)N1—C21.324 (7)
Cu1—S12.3393 (16)N1—C1v1.345 (6)
I1—Cu12.6477 (9)C1—C21.400 (7)
I2—Cu1iii2.6478 (11)C1—C31.478 (8)
I2—Cu1ii2.6617 (10)C2—C41.509 (7)
Cu2—N1iv2.059 (4)C3—H3A0.9700
I1—Cu2ii2.6786 (9)C3—H3B0.9700
I1—Cu22.7142 (9)C4—H4A0.9700
I2—Cu22.6418 (8)C4—H4B0.9700
S1—C41.817 (6)
Cu1—I1—Cu2ii66.05 (3)I2—Cu2—Cu1ii57.14 (3)
Cu1—I1—Cu2103.29 (3)I1ii—Cu2—Cu1ii56.46 (3)
Cu2ii—I1—Cu286.52 (3)I1—Cu2—Cu1ii105.41 (3)
Cu2—I2—Cu1iii102.73 (3)C4—S1—C393.7 (2)
Cu2—I2—Cu1ii66.37 (3)C4—S1—Cu1107.46 (19)
Cu1iii—I2—Cu1ii62.02 (3)C3—S1—Cu1109.11 (19)
S1—Cu1—I1104.34 (4)C2—N1—C1v115.3 (4)
S1—Cu1—I2vi108.74 (5)C2—N1—Cu2iv121.6 (3)
I1—Cu1—I2vi107.06 (3)C1v—N1—Cu2iv123.0 (4)
S1—Cu1—I2ii104.10 (5)N1v—C1—C2121.5 (5)
I1—Cu1—I2ii113.66 (3)N1v—C1—C3122.6 (4)
I2vi—Cu1—I2ii117.98 (3)C2—C1—C3115.9 (4)
S1—Cu1—Cu1i123.23 (6)N1—C2—C1123.2 (5)
I1—Cu1—Cu1i132.41 (5)N1—C2—C4122.9 (5)
I2vi—Cu1—Cu1i59.24 (3)C1—C2—C4113.9 (5)
I2ii—Cu1—Cu1i58.74 (4)C1—C3—S1105.0 (3)
S1—Cu1—Cu2ii121.87 (5)C1—C3—H3A110.7
I1—Cu1—Cu2ii57.49 (3)S1—C3—H3A110.7
I2vi—Cu1—Cu2ii129.10 (4)C1—C3—H3B110.7
I2ii—Cu1—Cu2ii56.48 (3)S1—C3—H3B110.7
Cu1i—Cu1—Cu2ii94.20 (5)H3A—C3—H3B108.8
N1iv—Cu2—I2107.06 (12)C2—C4—S1105.1 (4)
N1iv—Cu2—I1ii122.19 (13)C2—C4—H4A110.7
I2—Cu2—I1ii113.30 (3)S1—C4—H4A110.7
N1iv—Cu2—I1110.69 (13)C2—C4—H4B110.7
I2—Cu2—I1108.98 (3)S1—C4—H4B110.7
I1ii—Cu2—I193.48 (3)H4A—C4—H4B108.8
N1iv—Cu2—Cu1ii143.81 (13)
C1v—N1—C2—C10.7 (8)N1v—C1—C3—S1164.0 (4)
Cu2iv—N1—C2—C1176.2 (4)C2—C1—C3—S116.8 (6)
C1v—N1—C2—C4179.2 (5)C4—S1—C3—C122.5 (4)
Cu2iv—N1—C2—C42.3 (7)Cu1—S1—C3—C1132.4 (3)
N1v—C1—C2—N10.7 (8)N1—C2—C4—S1164.6 (4)
C3—C1—C2—N1178.6 (5)C1—C2—C4—S116.7 (6)
N1v—C1—C2—C4179.3 (4)C3—S1—C4—C222.5 (4)
C3—C1—C2—C40.1 (7)Cu1—S1—C4—C2133.8 (3)
Symmetry codes: (i) x+2, y, z+2; (ii) x+1, y, z+2; (iii) x1, y, z; (iv) x+2, y+1, z+2; (v) x+2, y+1, z+1; (vi) x+1, y, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C3—H3B···I10.973.013.808 (6)140
C3—H3A···I1vii0.972.913.767 (5)149
C4—H4A···I1iv0.973.003.641 (5)124
Symmetry codes: (iv) x+2, y+1, z+2; (vii) x+1, y, z+1.
 

Acknowledgements

HSE is grateful to the University of Neuchâtel for their support over the years.

Funding information

Funding for this research was provided by: Swiss National Science Foundation and the University of Neuchâtel.

References

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