Electronic Supporting Information

Homoleptic octahedral coordination of CH3CN to Mg2+

in the Mg[N(SO2CF3)2]2-CH3CN system

Gleb Veryasov, Kazuhiko Matsumoto,* Rika Hagiwara *

a Department of Fundamental Energy Science, Graduate School of Energy Science, Kyoto University, Sakyo-ku, Kyoto 606-8501, JAPAN

* e-mail: k-matsumoto@energy.kyoto-u.ac.jp, hagiwara@energy.kyoto-u.ac.jp

Electronic Supplementary Material (ESI) for Dalton Transactions.This journal is © The Royal Society of Chemistry 2016

Experimental details

Reagents and chemicals

The Mg[TFSA]2 powder (Kishida Chemicals, 99.9 %) was dried under vacuum at room temperature for 6 h and then for 24 h at 200˚C. Karl-Fischer titration indicated the water content of 200 ppm. Acetonitrile (Wako Chemicals, purity > 99.8%, H2O < 10 ppm) was used as received.

Synthesis

All the operations were carried out in a dry chamber. [Mg(AN)6][TFSA]2

(AN = acetonitrile) crystals were grown by the following approach. A portion of Mg[TFSA]2 (~30 mg) was placed in a glass tube (Pyrex, 12 mm) and CH3CN (0.5 mL) was carefully poured onto the Mg[TFSA]2 powder. The glass tube was connected to a Swagelok valve and transferred to the vacuum line. Removal of acetonitrile under dynamic vacuum resulted in the formation of good quality crystals of [Mg(AN)6][TFSA]2. Complete dissolution of Mg[TFSA]2 should be avoided and the supernatant should be kept in a low viscosity to obtain crystals with good quality. Once a homogeneous solution formed, the crystallization did not occur. The procedure was reproducible and gave crystals suitable for X-ray diffraction.

For the preparation of Mg[TFSA]2−acetonitrile solutions, portions of Mg[TFSA]2 were slowly dissolved in appropriate amounts of acetonitrile.

Crystallography

The crystal data and refinement results for [Mg(AN)6][TFSA]2 are given in Table S1. Transparent single crystals of [Mg(AN)6][TFSA]2 were collected from the glass tube and the selected crystal was glued to a quartz pin, using perfluoroether oil, transferred to the goniometer head (Rigaku R-AXIS RapidII diffractometer controlled by RAPID AUTO 2.401 software) under dry atmosphere and placed to the stream of cold nitrogen (-160 °C). The output of X-ray (Mo Kα, 0.71073 Å) was 40 mA at 50 kV. The measurements consisted of 12 ω scans (130–190°, 5°/frame) at the fixed χ (45°) and φ (0°) angles and 32 ω scans (0°–160°, 5°/frame) at the fixed χ (45°) and φ (180°) angles with the exposure time

was 600 s deg–1. Integration, scaling and absorption corrections were performed by RAPID AUTO 2.401 software. The structure was solved using SIR-20082 and refined by SHELXL-2014/73 in the WinGX4 software. For visualization of the obtained structure, ORTEP 35 was used.

Hydrogen atoms for the methyl groups involving C5 and C7 atoms were found during refinement; for the group involving C3 atom hydrogen atoms were placed on idealized positions using HFIX option.

Raman spectroscopy

The Raman spectra of the [Mg(AN)6][TFSA]2 crystal, acetonitrile and acetonitrile solutions of Mg[TFSA]2 were recorded using a Nanofinder 30 (Tokyo Instruments) microfocus Raman spectrometer with the 532 nm He-Ne laser. Samples were sealed in 0.5 mm wide (for crystal) and 1 mm wide (for liquids) glass capillaries under dry atmosphere to avoid water presence. The band of polycrystalline Si (520.6 cm-1) was used for calibration of the spectrometer.

Table S1. Crystal data and refinement results for [Mg(AN)6][TFSA]2

Crystal dataChemical formula C12H18MgN6·2(C2F6NO4S2)Mr 830.93Crystal system, space group Monoclinic, P21/nTemperature (K) 113a, b, c (Å) 8.8749 (5), 15.2823 (8), 12.9264 (7)β (°) 104.857 (2)V (Å3) 1694.58 (16)Z 2Radiation type Mo Kαµ (mm−1) 0.42Crystal size (mm) 0.55 × 0.45 × 0.25Diffractometer Rigaku R-AXIS RapidII diffractometerAbsorption correction Multi-scan

RAPID AUTO 2.40 (Rigaku 2006)Tmin, Tmax 0.802, 1.000No. of measured, independent and observed [I > 2σ(I)] reflections

16182, 3855, 3394

Rint 0.023(sin θ/λ)max (Å−1) 0.648RefinementRa, wR2

b, S 0.030, 0.083, 1.08No. of reflections 3855No. of parameters 248H-atom treatment H atoms treated by a mixture of independent and

constrained refinementΔρmax, Δρmin (e Å−3) 0.34, −0.31a R1 = ∑||Fo| – |Fc||/∑|Fo| for I > 2σ(I).b wR2 = (∑[w(Fo

2 – Fc2)2]/∑[w(Fo

2)2]) 1/2 for I > 2σ(I).

Table S2. Selected bond lengths (Å), distances (Å) and angles (˚) in the structure of [Mg(AN)6][TFSA]2

S2—O4 1.4273 (11) F4—C2 1.328 (2)S2—O3 1.4314 (11) N61—C6 1.1362 (19)S2—N1 1.5702 (13) N81—C8 1.1376 (18)S2—C2 1.8294 (17) F6—C2 1.3226 (19)S1—O1 1.4228 (12) F3—C1 1.3222 (18)S1—O2 1.4235 (13) C8—C7 1.456 (2)S1—N1 1.5809 (13) C4—C3 1.4568 (19)S1—C1 1.8266 (16) C6—C5 1.457 (2)Mg1∙∙∙N61 2.1439 (12) C7—H7A 0.99 (2)Mg1∙∙∙N41 2.1477 (12) C7—H7B 0.91 (2)Mg1∙∙∙N81 2.1549 (12) C7—H7C 0.93 (2)F2—C1 1.3382 (17) C5—H5B 0.86 (3)F5—C2 1.3330 (19) C5—H5C 0.93 (3)F1—C1 1.3232 (18) C5—H5A 0.96 (3)N41—C4 1.1363 (18)

O4—S2—O3 118.64 (7) N41—C4—C3 178.98 (16)O4—S2—N1 116.80 (7) F1—C1—F3 108.56 (13)O3—S2—N1 109.09 (7) F1—C1—F2 107.63 (13)O4—S2—C2 104.40 (7) F3—C1—F2 108.10 (12)O3—S2—C2 103.56 (8) F1—C1—S1 111.70 (11)N1—S2—C2 101.84 (8) F3—C1—S1 110.80 (11)O1—S1—O2 118.19 (9) F2—C1—S1 109.92 (10)O1—S1—N1 109.58 (7) F6—C2—F4 108.56 (15)O2—S1—N1 117.11 (7) F6—C2—F5 107.60 (14)O1—S1—C1 103.73 (8) F4—C2—F5 107.80 (14)O2—S1—C1 104.82 (8) F6—C2—S2 109.96 (12)N1—S1—C1 100.73 (7) F4—C2—S2 111.10 (11)N61i—Mg1—N61 180.0 F5—C2—S2 111.69 (12)N61i—Mg1—N41i 89.11 (5) C4—C3—H3A 109.5N61—Mg1—N41i 90.89 (4) C4—C3—H3B 109.5N61i—Mg1—N41 90.89 (4) H3A—C3—H3B 109.5N61—Mg1—N41 89.11 (5) C4—C3—H3C 109.5N41i—Mg1—N41 180.0 H3A—C3—H3C 109.5N61i—Mg1—N81 90.19 (5) H3B—C3—H3C 109.5N61—Mg1—N81 89.81 (5) N61—C6—C5 179.10 (18)N41i—Mg1—N81 89.67 (4) C8—C7—H7A 110.7 (12)N41—Mg1—N81 90.33 (4) C8—C7—H7B 107.7 (14)N61i—Mg1—N81i 89.81 (5) H7A—C7—H7B 113.5 (18)N61—Mg1—N81i 90.19 (5) C8—C7—H7C 107.0 (14)N41i—Mg1—N81i 90.33 (4) H7A—C7—H7C 107.6 (19)N41—Mg1—N81i 89.67 (4) H7B—C7—H7C 110 (2)N81—Mg1—N81i 180.0 C6—C5—H5B 106 (2)C4—N41—Mg1 173.15 (12) C6—C5—H5C 107 (2)C6—N61—Mg1 177.12 (12) H5B—C5—H5C 109 (2)C8—N81—Mg1 175.58 (11) C6—C5—H5A 114 (2)N81—C8—C7 179.67 (15) H5B—C5—H5A 112 (2)

S2—N1—S1 126.15 (8) H5C—C5—H5A 108 (2)Symmetry operations: (i) 1-x, -y, -z

Table S3. List of C–H···O interactions in [Mg(AN)6][TFSA]2

C–H···O H···O, Å C···O, Å ∠ C–H···O, ˚C3–H3c···O1 2.54 3.11 117.9C7–H7a···O2 2.50 3.48 169.3C7–H7b···O3 2.62 3.33 134.8C5–H5c···O4 2.67 3.16 113.9

Table S4. List of bands in the Raman spectrum of [Mg(AN)6][TFSA]2 with relative intensitiesa

Frequency, cm–1 Intensity, rel. Assignmentsb

117 40173 6213 4

τ

273 57 ρ(CF3)295 27 δ(FCS)313 47 ρ(SO2)338 41 τ(SO2)+ν(Mg···N)393 28 δ(CCN)408 23 ω(SO2)512 2 -533 5 -557 13 δs(SO2)569 10 δa(CF3)591 9 δa(SO2)638 2 δ(SNS)748 100 δ(CF3)+νs(SNS)801 3 νa(SNS)1130 37 ρ(CH3)1195 31222 11 νa(CF3)

1247 49 νs(CF3)1337 15 νs(SO2)1381 6 δs(CH3)+νa(SO2)2266 17 ν(C≡N)2293 19 ν(C≡N)+ ξ(C−H)+ ν(C−C)2318 12 ν(C≡N)2737 12953 793015 6

ν(C–H)

a relative intensities are calculated after subtracting the background. The intensities of the bands were normalized to the band at 748 cm–1 to be 100.b These assignments are based on a previous reports 6: ν – stretching, δ – bending, ω – wagging, ρ – rocking, τ – torsion, ξ – twisting, s –symmetric, a – asymmetric.

Table S5. List of bands in the Raman spectrum of Mg[TFSA]2 with relative intensitiesa

Frequency, cm–1 Intensity, rel. Assignmentsb

114 20134 37192 14209 17235 14

τ

259 23 ν(Mg···O)292 16 δ(FCS)310 17 ρ(SO2)325 27 τ(SO2)351 24 ω(SO2)428 15 ω(SO2)558 8 δs(SO2)581 12 δa(CF3)663 13 δ(SNS)754 100 δ(CF3)+νs(SNS)816 2 νa(SNS)

1119 111155 5 νs(SO2)

1235 191259 15 δs(CF3)

1379 11 νa(SO2)

a Relative intensities were calculated after subtracting the background. The intensities of the bands were normalized to the band at 755 cm–1 to be 100.b These assignments are based on a previous reports 6: ν – stretching, δ – bending, ω – wagging, ρ – rocking, τ – torsion, s –symmetric, a – asymmetric.

Fig. S1 C–H···O interactions between H atoms in Mg(AN)62+ and O

atoms in TFSA– in the surrounding of cation (top, symmetrically generated part is omitted for clarity) and the surrounding of anion (bottom). Thermal ellipsoids are shown at the 30% probability. Symmetry operations: (i) 1-x, -y, -z; (ii) x, y, -1+z; (iii) 3/2-x, 1/2+y, 1/2-z; (iv) 2-x, -y, 1-z.

Fig. S2 Packing diagram of [Mg(AN)6][TFSA]2 along the a-axis. Thermal ellipsoids are shown at the 30% probability.

Fig. S3 Raman spectrum of Mg[TFSA]2 powder.

Fig. S4 Raman spectrum of [Mg(AN)6][TFSA]2 in the liquid state.

Fig. S5 Full-scale Raman spectra of pure acetonitrile and Mg[TFSA]2 acetonitrile solutions.

Fig. S6 Raman spectra of pure acetonitrile, the acetonitrile solutions of Mg[TFSA]2 and [Mg(AN)6][TFSA]2 in the region between 100 - 800 cm-1.

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