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Acta Cryst. (2013). E69, m387-m388    [ doi:10.1107/S1600536813016085 ]

(4,7,13,16,21,24-Hexaoxa-1,10-di­aza­bicyclo­[8.8.8]hexa­cosa­ne)sodium iodide-1,1,2,2,tetra­fluoro-1,2-diiodo­ethane (2/3)

G. Cavallo, P. Metrangolo, T. Pilati, G. Resnati, M. Ursini and G. Terraneo

Abstract top

The title complex (CX1), [Na(C18H36N2O6)]I·1.5C2F4I2, is a three-component adduct containing a [2.2.2]-cryptand, sodium iodide and 1,1,2,2-tetra­fluoro-1,2-di­iodo­ethane. The di­iodo­ethane works as a bidentate halogen-bonding (XB) donor, the [2.2.2]-cryptand chelates the sodium cation, and the iodide counter-ion acts as a tridentate XB acceptor. A (6,3) network is formed in which iodide anions are the nodes and halocarbons the sides. The network symmetry is C3i and the I...I- XB distance is 3.4492 (5) Å. This network is strongly deformed and wrinkled. It forms a layer 9.6686 (18) Å high and the inter-layer distance is 4.4889 (10) Å. The cations, inter­acting with each other via weak O...H hydrogen bonds, are confined between two anionic layers and also form a (6,3) net. The structure of CX1 is closely related to that of the KI homologue (CX2). The 1,1,2,2,-tetrafluoro-1,2-diiodoethane molecule is rotationally disordered around the I...I axis, resulting in an 1:1 disorder of the C2F4 moiety.

Comment top

(4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo(8.8.8)hexacosane (K2.2.2) is one of the most popular cryptands in supramolecular chemistry and crystal engineering. Our group has used this [2.2.2] cryptand to generate naked halide anions from their alkali and alkali earth salts and to promote the formation of halogen bonding (XB) with diiodoperfluoroalkanes (DIPFAn, where n is the alkyl chain length). Different structures were obtained as a function of the cation and of the haloalkane length. For instance, in the complex with BaI2 and DIPFA2 the ratios K2.2.2/BaI2/DIPFA2 are 1:1:1, iodide anions function as monodentate XB acceptors and form the trimer I-···DIPFA2···I- (Fox, et al., 2004). This is probably related to the fact that the iodide anions are hydrogen bonded to a water molecule and the resulting decrease of electron density on the anion may limit the number of XB's it gives rise to. The K2.2.2/BaI2/DIPFA8 adduct presents a quite different stoichiometry and interaction pattern (Metrangolo, et al., 2004). Here, the ratios among the three component are 1:1:3 and an infinite comb-like supramolecular anion is formed in which iodide anions in the main chain and in the prongs function as tridentate and bidentate XB acceptors, respectively. Here too the cryptand does not saturate the cation coordination sphere and two methanol molecules are bound to barium. In the K2.2.2/KI/DIPFAn adducts (n = 2,6 (Liantonio, et al., 2006) and n=4,8 (Liantonio, et al., 2003) the ratios among the three components is 2:2:3. The cryptand completes the coordination sphere of K+ cation and no water or alcohol molecules are present in the crystals. The iodide anions are free to function as tridentate XB acceptors and unlimited (6,3) anionic networks are formed in all four cases. This net is not planar but strongly wrinkled as the (C—I)3···I- group is pyramidal. The six iodide nodes are the vertices of a trigonal anti-prism whose dimension can be fully described by the mean distance between two iodide anions on the same side of the layer, and by the distance between the planes through the iodide nodes on the two layer sides. The hole dimension increases with n and for n=6,8 it is so large that the cation cannot fulfill the voids and three different (6,3) nets interpenetrate to give an intriguing borromean system (Liantonio, et al., 2006). In all four structures, two layers are faced vertex to vertex, hole to hole, as two egg trays where the cations are hosted. In the K2.2.2/NaI/DIPFA2 adducts (CX1) described here, I- anions are tridentate XB acceptors, DIPFA2 are bidentate XB donors and a (6,3) net is formed which is closely similar to that of the KI analogue (CX2). Figure 1 shows the molecular geometry, with the numbering scheme. The Na+ cation is small relative to the cryptand cavity and is therefore not exactly in the middle of the [2.2.2] cryptand cavity, as was the case for K+ in CX2. As a consequence, the two independent Na+—N distances are very different. Table 1 reports some geometric details of the supramolecular anion hosting cavity and of the supramolecular cation dimensions in CX1 and CX2. Table 2 shows the halogen and hydrogen bonds of CX1. The 'egg tray' here is too small to isolate completely the 'eggs', namely the supramolecular cations, which are linked to each other by a couple of symmetry equivalent weak hydrogen bonds between the methylene hydrogen atom and ether oxygen forming a layer with the same topology of the anion network. Both the anion and cation layers are shown in Figure 2 and 3.

Related literature top

For other K2.2.2./salt/haloperfluorocarbon complexes, see: Fox et al. (2004); Metrangolo et al. (2004); Liantonio et al. (2003, 2006).

Experimental top

The complex was prepared in two steps. Equimolar amounts of [2.2.2] cryptand and NaI in ethanol solution were mixed and refluxed for 5 min. After cooling, the solution was added to a chloroform solution of DIPFA2 (1.5 equivalents). A glass vial containg the resulting mixture was put in a wide mouth flask containing vaseline oil. Vapour exchange at room temperature afforded colourless, thin, hexagonal crystals of good quality after a few days.

Refinement top

The tetrafluorodiiodoethane molecule was rotationally disordered. The split model was refined with restraints on geometric parameters and ADPs. The rotation of this molecule around the I···I axis, was so large that SHELXL suggested a second splitting of two F atoms. We considered this suggestion not useful and even dangerous to refinement stability in view of the high correlations between split atoms parameters (already up to 0.87). Hydrogen atoms were positioned geometrically and refined using a riding model, with C—H = 0.95–0.99 Å and with Uiso(H) = 1.2 times Ueq(C).

Computing details top

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SIR2002 (Burla et al., 2003); program(s) used to refine structure: SHELXL2012 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXL2012 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The three components of CX1, with numbering scheme of the indepent atoms. The disordered atoms of DIPFA2, generated by the twofold axis are omitted for clarity. Probability level at 50%.
[Figure 2] Fig. 2. A layer of cations and two layers of anions, are shown along the a* axis, only partial overposition is adopted for sake of clarity. One hexagonal ring of supramolecular cations and of supramolecular anions are the topologic units of the layers and are shown in spacefilling style.
[Figure 3] Fig. 3. The same molecular assembly as shown in Figure 2, projected down the c axis
(4,7,13,16,21,24-Hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane)sodium iodide–1,1,2,2,tetrafluoro-1,2-diiodoethane (2/3) top
Crystal data top
[Na(C18H36N2O6)]I·1.5C2F4I2Dx = 2.116 Mg m3
Mr = 1057.11Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3cCell parameters from 20222 reflections
a = 11.634 (2) Åθ = 2.2–29.8°
c = 84.945 (15) ŵ = 3.84 mm1
V = 9957 (4) Å3T = 93 K
Z = 12Hexagonal table, colourless
F(000) = 60120.28 × 0.25 × 0.03 mm
Data collection top
2604 reflections with I > 2σ(I)
Radiation source: sealed tubeRint = 0.035
ϕ and ω scansθmax = 30.0°, θmin = 1.4°
Absorption correction: multi-scan
(SADABS; Bruker, 2008)
h = 1515
Tmin = 0.676, Tmax = 1.000k = 1515
47282 measured reflectionsl = 114114
2994 independent reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.032Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.076H-atom parameters constrained
S = 1.07 w = 1/[σ2(Fo2) + (0.040P)2]
where P = (Fo2 + 2Fc2)/3
2994 reflections(Δ/σ)max = 0.001
148 parametersΔρmax = 1.64 e Å3
44 restraintsΔρmin = 0.58 e Å3
Crystal data top
[Na(C18H36N2O6)]I·1.5C2F4I2Z = 12
Mr = 1057.11Mo Kα radiation
Trigonal, R3cµ = 3.84 mm1
a = 11.634 (2) ÅT = 93 K
c = 84.945 (15) Å0.28 × 0.25 × 0.03 mm
V = 9957 (4) Å3
Data collection top
2994 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2008)
2604 reflections with I > 2σ(I)
Tmin = 0.676, Tmax = 1.000Rint = 0.035
47282 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.03244 restraints
wR(F2) = 0.076H-atom parameters constrained
S = 1.07Δρmax = 1.64 e Å3
2994 reflectionsΔρmin = 0.58 e Å3
148 parameters
Special details top

Experimental. OXFORD low temperature device.

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

Refinement. The tetrafluorodiiodoethane molecule was rotationally disordered. The split model was refined with restraints on geometric parameters and ADPs. The rotation of this molecule around the I···I axis, was so large that SHELXL suggested a second splitting of two F atoms. We considered not useful and even dangerous the suggestion, because the largest correlations between split atoms parameters, already high (<0.87), would be larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
I20.00000.00000.47358 (2)0.01498 (10)
I10.22447 (2)0.05878 (2)0.44381 (2)0.02001 (9)
C70.3618 (9)0.1058 (7)0.42456 (12)0.029 (2)0.5
F10.4634 (7)0.2274 (9)0.42658 (10)0.065 (3)0.5
F20.4115 (9)0.0252 (9)0.42395 (11)0.080 (3)0.5
C80.3016 (8)0.1016 (6)0.40861 (12)0.028 (2)0.5
F30.2439 (9)0.1750 (10)0.40947 (12)0.074 (3)0.5
F40.2054 (7)0.0222 (8)0.40618 (10)0.083 (4)0.5
Na0.33330.66670.48841 (2)0.0176 (4)
N10.33330.66670.52071 (5)0.0147 (9)
C10.2462 (3)0.5297 (3)0.52603 (3)0.0167 (6)
C20.2684 (3)0.4311 (3)0.51696 (4)0.0174 (6)
O10.2542 (2)0.44777 (19)0.50055 (2)0.0159 (4)
C30.2593 (3)0.3468 (3)0.49158 (3)0.0186 (6)
C40.2632 (3)0.3789 (3)0.47452 (4)0.0186 (6)
O20.3838 (2)0.5009 (2)0.47155 (3)0.0180 (5)
C50.4235 (3)0.5180 (3)0.45540 (4)0.0198 (6)
C60.3357 (3)0.5475 (3)0.44487 (3)0.0191 (6)
N20.33330.66670.44990 (5)0.0173 (9)
Atomic displacement parameters (Å2) top
I20.01522 (13)0.01522 (13)0.01451 (17)0.00761 (6)0.0000.000
I10.01636 (13)0.02578 (14)0.01665 (12)0.00961 (9)0.00183 (7)0.00086 (8)
C70.028 (5)0.051 (6)0.021 (5)0.030 (5)0.005 (4)0.002 (4)
F10.025 (3)0.080 (6)0.025 (3)0.022 (4)0.007 (2)0.019 (5)
F20.114 (8)0.145 (7)0.058 (6)0.122 (7)0.058 (5)0.066 (5)
C80.017 (5)0.048 (6)0.020 (5)0.017 (4)0.004 (4)0.003 (4)
F30.086 (7)0.137 (7)0.060 (6)0.101 (6)0.046 (5)0.063 (6)
F40.033 (4)0.089 (7)0.028 (3)0.043 (4)0.009 (3)0.022 (5)
Na0.0162 (7)0.0162 (7)0.0204 (10)0.0081 (3)0.0000.000
N10.0115 (13)0.0115 (13)0.021 (2)0.0057 (6)0.0000.000
C10.0148 (14)0.0158 (15)0.0172 (14)0.0058 (13)0.0007 (11)0.0012 (11)
C20.0184 (16)0.0147 (15)0.0184 (15)0.0078 (13)0.0009 (12)0.0023 (11)
O10.0194 (11)0.0140 (11)0.0163 (10)0.0099 (9)0.0001 (8)0.0004 (8)
C30.0219 (16)0.0120 (15)0.0211 (15)0.0079 (13)0.0002 (12)0.0011 (11)
C40.0167 (15)0.0135 (15)0.0221 (15)0.0049 (13)0.0016 (12)0.0015 (12)
O20.0182 (11)0.0143 (11)0.0185 (11)0.0058 (9)0.0000 (8)0.0003 (8)
C50.0192 (16)0.0188 (16)0.0207 (15)0.0091 (13)0.0038 (13)0.0002 (12)
C60.0197 (16)0.0195 (16)0.0168 (14)0.0089 (13)0.0001 (12)0.0016 (12)
N20.0167 (14)0.0167 (14)0.018 (2)0.0084 (7)0.0000.000
Geometric parameters (Å, º) top
I1—C8i2.153 (11)O1—C31.427 (4)
I1—C72.156 (11)C3—C41.492 (4)
C7—F11.325 (5)C3—H3A0.9900
C7—F21.327 (5)C3—H3B0.9900
C7—C81.514 (7)C4—O21.434 (4)
C8—F41.325 (5)C4—H4A0.9900
C8—F31.327 (5)C4—H4B0.9900
N1—C1ii1.468 (3)O2—C51.430 (4)
N1—C11.468 (3)C5—C61.520 (4)
N1—C1iii1.468 (3)C5—H5A0.9900
C1—C21.508 (4)C5—H5B0.9900
C1—H1A0.9900C6—N21.464 (3)
C2—O11.428 (4)C6—H6B0.9900
C2—H2A0.9900N2—C6iii1.464 (3)
C2—H2B0.9900N2—C6ii1.464 (4)
F1—C7—F2106.7 (7)O1—C3—C4108.7 (2)
F1—C7—C8107.6 (5)O1—C3—H3A109.9
F2—C7—C8107.4 (5)C4—C3—H3A109.9
F1—C7—I1109.0 (5)O1—C3—H3B109.9
F2—C7—I1112.3 (6)C4—C3—H3B109.9
C8—C7—I1113.5 (4)H3A—C3—H3B108.3
F4—C8—F3106.5 (7)O2—C4—C3108.1 (2)
F4—C8—C7107.5 (5)O2—C4—H4A110.1
F3—C8—C7107.7 (5)C3—C4—H4A110.1
F1i—C8—I1i118.8 (9)O2—C4—H4B110.1
F4—C8—I1i110.4 (6)C3—C4—H4B110.1
F3—C8—I1i110.5 (6)H4A—C4—H4B108.4
C7—C8—I1i114.0 (4)C5—O2—C4113.2 (2)
C1ii—N1—C1110.97 (18)O2—C5—C6112.9 (3)
C1ii—N1—C1iii110.97 (18)O2—C5—H5A109.0
C1—N1—C1iii110.97 (18)C6—C5—H5A109.0
N1—C1—C2112.3 (2)O2—C5—H5B109.0
N1—C1—H1B109.1N2—C6—C5112.0 (3)
O1—C2—C1108.6 (2)N2—C6—H6B109.2
O1—C2—H2B110.0C6iii—N2—C6ii111.84 (19)
C1—C2—H2B110.0C6iii—N2—C6111.84 (19)
H2A—C2—H2B108.3C6ii—N2—C6111.84 (18)
C3—O1—C2110.8 (2)
F1—C7—C8—F4176.1 (9)C1iii—N1—C1—C2162.6 (3)
F2—C7—C8—F461.5 (8)N1—C1—C2—O154.8 (3)
I1—C7—C8—F463.3 (8)C1—C2—O1—C3173.3 (2)
F1—C7—C8—F369.6 (8)C2—O1—C3—C4172.2 (2)
F2—C7—C8—F3175.9 (7)O1—C3—C4—O263.8 (3)
I1—C7—C8—F351.1 (7)C3—C4—O2—C5158.4 (2)
F1—C7—C8—I1i53.4 (8)C4—O2—C5—C671.9 (3)
F2—C7—C8—I1i61.2 (7)O2—C5—C6—N258.0 (3)
I1—C7—C8—I1i174.0 (2)C5—C6—N2—C6iii154.9 (3)
C1ii—N1—C1—C273.6 (4)C5—C6—N2—C6ii78.7 (4)
Symmetry codes: (i) x+2/3, x+y+1/3, z+5/6; (ii) y+1, xy+1, z; (iii) x+y, x+1, z.

Experimental details

Crystal data
Chemical formula[Na(C18H36N2O6)]I·1.5C2F4I2
Crystal system, space groupTrigonal, R3c
Temperature (K)93
a, c (Å)11.634 (2), 84.945 (15)
V3)9957 (4)
Radiation typeMo Kα
µ (mm1)3.84
Crystal size (mm)0.28 × 0.25 × 0.03
Data collection
DiffractometerBruker APEXII CCD
Absorption correctionMulti-scan
(SADABS; Bruker, 2008)
Tmin, Tmax0.676, 1.000
No. of measured, independent and
observed [I > 2σ(I)] reflections
47282, 2994, 2604
(sin θ/λ)max1)0.702
R[F2 > 2σ(F2)], wR(F2), S 0.032, 0.076, 1.07
No. of reflections2994
No. of parameters148
No. of restraints44
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)1.64, 0.58

Computer programs: APEX2 (Bruker, 2008), SAINT (Bruker, 2008), SIR2002 (Burla et al., 2003), SHELXL2012 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 2012) and Mercury (Macrae et al., 2006).

Some parameters (Å, Å3) of the anionic layer and of the cation in the structures CX1 and CX2. top
Hole side111.634 (2)11.7478 (15)
Layer height29.6686 (18)9.6380 (13)
h34.4889 (10)4.5343 (7)
V3303.79 (7)312.89 (6)
M+—O12.460 (2)2.6650 (12)
M+—O22.692 (2)2.7737 (13)
M+—N12.744 (5)2.941 (2)
M+—N23.271 (5)2.985 (3)
Notes: (1) Distance between the nearest iodide anions on the same side of the anionic layer, equal to the cell parameter a; (2) distance between the planes through the iodide anions on the opposite sides of the anionic layer; (3) h = distance between the nearest planes through iodide anions of contiguous layers. (4) V = a2h/2, volume of the trigonal prism whose vertices are the three iodide anions on a layer and the same faced on the contiguous one.
Halogen and hydrogen bonds (Å, °) in CX1 and CX2. top
In CX2, the cell origin and the atom numbering are different, so that atom labels and symmetry code refer only to CX1; for CX2 the reported values refer to the equivalent atoms and values.
X···Y—CCX1 X···YCX1 C—X···YCX2 X···YCX2 C—X···Y
I2···I1—C73.4492 (5)175.99 (17)3.4492 (5)176.30 (16)
I2···I1—C8i3.4492 (5)168.30 (16)3.4492 (5)166.40 (16)
Symmetry codes: (i) 2/3-x, 1/3-x+y, 5/6-z; (ii) x-y,x, 1-z.
Acknowledgements top

GC, PM, GR and GT acknowledge the Fondazione Cariplo (project 2010–1351) and "5x1000 junior project" for financial support.