Unusual centrosymmetric structure of [M(18-crown-6)]⁺ (M = Rb, Cs and NH₄) complexes stabilized in an environment of hexa­chlorido­antimonate(V) anions

In (1,4,7,10,13,16-hexa­oxa­cyclo­octa­decane)rubidium hexa­chlorido­antimon­ate(V), [Rb(C₁₂H₂₄O₆)][SbCl₆], (1), and its isomorphous caesium {(1,4,7,10,13,16-hexa­oxa­cyclo­octa­decane)caesium hexa­chlorido­antimon­ate(V), [Cs(C₁₂H₂₄O₆)][SbCl₆]}, (2), and ammonium {ammonium hexa­chlorido­antimon­ate(V)–1,4,7,10,13,16-hexa­oxa­cyclo­octa­decane (1/1), (NH₄)[SbCl₆]·C₁₂H₂₄O₆}, (3), ana­logues, the hexa­chlorido­antimonate(V) anions and 18-crown-6 mol­ecules reside across axes passing through the Sb atoms and the centroids of the 18-crown-6 groups, both of which coincide with centres of inversion. The Rb⁺ [in (1)], Cs⁺ [in (2)] and NH₄⁺ [in (3)] cations are situated inside the cavity of the 18-crown-6 ring; they are situated on axes and are equally disordered about centres of inversion, deviating from the centroid of the 18-crown-6 mol­ecule by 0.4808 (13), 0.9344 (7) and 0.515 (8) Å, respectively. Inter­action of the ammonium cation and the 18-crown-6 group is supported by three equivalent hydrogen bonds [N...O = 2.928 (3) Å and N—H...O = 162°]. The centrosymmetric structure of [Cs(18-crown-6)]⁺, with the large Cs⁺ cation approaching the centre of the ligand cavity, is unprecedented and accompanied by unusually short Cs—O bonds [2.939 (2) and 3.091 (2) Å]. For all three compounds, the [M(18-crown-6)]⁺ cations and [SbCl₆]⁻ anions afford linear stacks along the c axis, with the cationic complexes embedded between pairs of inversion-related anions.

S1. Introduction

Chemical and steric constraints imposed by the crystal lattice often result in the stabilization of peculiar and unusual molecular and coordination geometries, such as perfectly tetra­hedral CuX₄^2- (X = Cl, Br) anions in high-symmetry lattice clathrates (Kahwa et al., 1992), or, in contrast, tetra­gonal distortion of Ni²⁺ o­cta­hedra in La₂NiO₄ (Brown, 1992). These effects may be referred to as `pressure of the crystal environment', but their prediction, evaluation and utilization for crystal design are not straightforward. From this point of view, univalent metal complexes with the macrocyclic polyether 18-crown-6 (1,4,7,10,13,16-hexaoxa­cyclo­octa­decane) can be regarded as especially suitable and structurally simple molecular models. It is well known that large cations, such as Rb⁺, Cs⁺, Tl⁺ and NH₄⁺, do not fit the size of the 18-crown-6 cavity (Steed, 2001). In their crystal structures, they usually reside above the ligand plane, with the most significant deviations (up to d = 2.40 Å) observed for the largest caesium cations (Domasevitch et al., 1997). In fact, the importance of ion-dipole inter­actions with the counteranions is particularly dominant for the present systems, which appear to be very sensitive to the crystal environment (Steed, 2001). The forced centrosymmetric structure of the [M(18-crown-6)]⁺ group, with the large metal cation situated exactly in the centre of the ligand cavity, may presumably be constrained with a set of equivalent supra­molecular inter­actions from both axial sides. The usefulness of this approach was suggested by the structure of coordination chains –([M(18-crown-6)]-A–)_n– supported by centrosymmetric singly charged anionic linkers. A series of such compounds, based upon hydrogen oximate anions [H{ONC(CN)—R}₂]^- (R = COPh, benzo­thia­zol-2-yl), revealed the first examples for a perfect fit of Rb⁺, Tl⁺ and NH₄⁺ cations inside the 18-crown-6 cavity (Domasevitch et al., 1996, 1998; Ponomarova & Domasevitch, 2002). The inorganic tetra­chloridoaurate(III) anion [AuCl₄]^- could also be applied: it stabilizes the centrosymmetric structure of [Rb(18-crown-6)]⁺ (with the Rb⁺ cation equally disordered above and below the ligand plane at d = 0.40 Å), being integrated within {[Rb(18-crown-6)][AuCl₄]}_n chains (Manskaya et al., 1998).

These observations raise further inter­est in the structure of the caesium systems. Due to the large ionic radius of Cs⁺ (1.67 Å), they exhibit no isomorphism with the related complexes of lighter alkali metal and ammonium ions, and thus the centrosymmetric structure of [Cs(18-crown-6)]⁺ does not appear to have been considered. In the present work, we illustrate this very uncommon possibility, with a rational combination of cationic and anionic counterparts of the structure. As was revealed by the prototypic structures of the oxonium compounds, [H₃O(18-crown-6)][SbCl₆] (Neumüller et al., 1994) and [H₃O(18-crown-6)][TaCl₆] (Bulychev & Bel'sky, 1995), singly charged o­cta­hedral hexachloridometallate anions [M^VCl₆]^- are complementary with [H₃O(18-crown-6)]⁺ from the point of view of charge and local symmetry, and they generate infinite stacks with [H₃O(18-crown-6)]⁺ embedded between pairs of inversion-related anions. Following this structural paradigm, we have prepared a series of new compounds, [M(18-crown-6)][SbCl₆] [M = Rb, (1), Cs, (2), and NH₄, (3)] and here report their structures.

S2. Experimental

S2.1. Synthesis and crystallization

The hexachlorido­anti­monate(V) complexes [M(18-crown-6)][SbCl₆] were prepared by reacting M[SbCl₆] [M = Rb, Cs and NH₄] and 18-crown-6 in di­methyl­formamide (DMF) solutions. Thus, a solution of RbCl (1.706 g, 14.1 mmol) in warm HCl (30%, 10 ml) was added to a 0.98 M solution (14.3 ml) of SbCl₅ in 30% HCl. The colourless precipitate of Rb[SbCl₆] (5.33 g, 90%) was filtered off, washed with 30% HCl (5 ml) and dried. A solution of this material (0.290 g, 0.69 mmol) in warm DMF (5 ml) was added to a solution of 18-crown-6 (0.185 g, 0.70 mmol) in DMF (5 ml) with stirring. The colourless crystalline product, [Rb(18-crown-6)][SbCl₆], (1), was filtered off, washed with DMF (5 ml) and dried in vacuo. Large colourless prism crystals of the complex grew from the DMF filtrate over a period of 2 d (combined yield 0.305 g, 65%). The isomorphous complexes [Cs(18-crown-6)][SbCl₆], (2), and [NH₄(18-crown-6)][SbCl₆], (3) (both also colourless prisms), were prepared in a similar fashion starting with the caesium and ammonium chlorides, respectively.

Elemental analysis, calculated for (1): C 21.06, H 3.54; found: C 20.92, H 3.60%; calculated for (2): C 19.70, H, 3.31; found: C 19.91, H 3.47%; calculated for (3): C 23.37, H 4.58, N 2.27; found: C 23.51, H 4.64, N 2.03%.

S2.2. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. All H atoms were located from difference Fourier maps but refined as riding, with C—H = 0.98 Å and ammonium N—H = 0.90 Å, and with U_iso(H) = 1.2U_eq(C) or 1.5U_eq(N). In all three structures, the metal (Rb and Cs) and ammonium cations are disordered about a centre of inversion. The corresponding Rb, Cs and N atoms were freely refined with anisotropic displacement parameters and with occupancy factors of 0.5. Tentative structure solutions in the noncentrosymmetric subgroup R3 did not provide ordered models, and the subsequent refinements equally suggested disorder of the cations above and below the 18-crown-6 plane.

S3. Results and discussion

In the isomorphous compounds (1)–(3) (Table 1), the hexachlorido­anti­monate(V) anions reside on a 3 axis, with the central Sb atoms situated on a centre of inversion. The [M(18-crown-6)]⁺ groups are also centrosymmetric and located about a 3 axis; it passes through the centroid of the 18-crown-6 molecule which lies on a centre of inversion. In all three structures, the crown ether adopts the D_3d conformation, with 1/6 of the molecule being symmetrically independent. All O—C—C—O torsion angles are gauche, whereas all C—O—C—C angles are trans, and the sequence of torsion angles is [(tg⁺t)(tg^-t)]₃. This geometry is identical to that observed for centrosymmetric metal ion complexes of 18-crown-6 (Bajaj & Poonia, 1988).

The Rb⁺ [in (1)], Cs⁺ [in (2)] and NH₄⁺ [in (3)] cations reside on a 3 axis and appear to be disordered about a centre of inversion, above and below the mean plane defined by the six O atoms of the 18-crown-6 ligand. Inside the ligand cavity, the Rb⁺ and Cs⁺ cations form six nearly equidistant bonds with donor O atoms (Fig. 1), whereas the ammonium cation is held there by three equivalent moderately strong hydrogen bonds [N···O = 2.928 (3) Å and N—H···O = 162°] (Fig. 2). These bonds are very similar to those found for [NH₄(18-crown-6)][PF₆] (Wu & Wu, 2010).

In spite of the fact that the positions of the metal and, in the case of ammonium, of the N atom do not coincide with the centre of the crown ether cavity, the corresponding deviations are only minor and amount to d = 0.4808 (13) Å for Rb⁺, 0.515 (8) Å for NH₄⁺ and 0.9344 (8) Å for Cs⁺. These numbers are significantly smaller than typical values observed earlier. For example, in [NH₄(18-crown-6)]⁺ compounds the essential size mismatch of the components is commonly reflected by pronounced dislocations of the ammonium cation from the ring centroid, such as d = 1.03 Å for the hydrogen sulfate complex (Braga et al., 2007) and d = 0.98 Å for the hydrated bromide complex (Nagano et al., 1978). The forced geometry of the NH₄⁺ cation exactly inside the 18-crown-6 cavity has only one precedent (Ponomarova & Domasevitch, 2002), while the centrosymmetric structure of the [Cs(18-crown-6)]⁺ aggregate is entirely unprecedented. In (2), the deviation of the caesium cation from the ring centroid is much smaller than the characteristic values of 1.50–2.40 Å (Steed, 2001; Domasevitch et al., 1997) and even smaller than the previous lower limit of 1.18 Å for the η²-fluorenyl complex (Neander et al., 2000). The forced geometry of the [M(18-crown-6)]⁺ groups is also reflected in unusually short coordination bonds [for (1), Rb—O = 2.839 (2) and 2.917 (2) Å; for (2), Cs—O = 2.939 (2) and 3.091 (2) Å], which may be compared with typical values for 18-crown-6 complexes in the ranges 2.92–3.13 and 3.05–3.35 Å, respectively (Bajaj & Poonia, 1988; Steed, 2001). The location of the large cations almost in the centre of the 18-crown-6 cavity is facilitated by a certain conformational flexibility of the ligand. In all three cases, the torsion angles O—C—C—O exceed the standard for 18-crown-6 molecule values of 66° (Bajaj & Poonia, 1988), with the maximum value observed for the complex of the largest cation, Cs⁺ [70.0 (4)° in (1), 70.9 (4)° in (2) and 68.8 (3)° in (3)].

The supra­molecular structures of these three compounds are completely uniform. They arrange in infinite linear chains along the c axis in which [M(18-crown-6)]⁺ and [SbCl₆]^- groups alternate (Figs. 3 and 4). The shortest contacts between the chains, formed by each of the six Cl atoms of the anion, indicate very weak C–H···Cl hydrogen bonds [for (2), C1···Cl1^vi = 3.805 (3) Å; C1—H···Cl1^vi = 130°; symmetry code: (vi) 2/3 - x + y, 1/3 - x, 1/3 + z]. Inter-ion bonding within the chains is at first sight counterintuitive: the shortest contacts with the Cl atoms are observed for the largest Cs cations. The three symmetrically equivalent Cs1—Cl1 separations [3.5938 (12) Å] in (2) agree well with the standard value in the CsCl structure [3.56 Å; Wells, 1991], but the corresponding Rb1—Cl1 distances in (1) are significantly longer [3.7353 (16) Å, versus 3.28 Å in RbCl]. This parallels the weak inter­actions in the NH₄⁺ complex, (3): strong inter-ion hydrogen bonds do not exist, and the distal N—H···[SbCl₆]^- contacts [N1···Cl1 = 3.746 (7) Å and N1—H···Cl1 = 140°] can be ascribed either to a very weak trifurcated hydrogen bond or to dispersion forces (Fig. 2). It is worth noting that the chain periodicity for all three structures (half of the lattice parameter c) is very similar and insensitive to the nature of the encapsulated cation. This is primarily caused by tight packing of the 18-crown-6 units and the bulky [SbCl₆]^- anions, resulting in uniform inter-ion separations for (1)–(3). Therefore, when passing from Cs⁺ to Rb⁺, the slightly larger deviation of the metal cation from the mean plane through the 18-crown-6 ring leads to shorter ion-dipole bonding with the anions, as demonstrated by structures (1) and (2). The [SbCl₆]^- anions play a crucial role in sustaining such stacks, since the structures of closely related singly charged o­cta­hedral hexa­fluoro­phosphates are completely different: stronger ion-dipole inter­actions or hydrogen bonding with the more electronegative F atoms results in significant displacement of the cations from the ligand cavity, disintegration of the stacks and generation of molecular arrays, for example in [Tl(18-crown-6)][PF₆] (Liu, 2003) and [NH₄(18-crown-6)][PF₆] (Wu & Wu, 2010).

The supra­molecular structures presented here are likely predetermined by a perfect match between charge, shape, size and symmetry of the [M(18-crown-6)]+ and [SbCl₆]^- components which facilitates favourable and very tight packing. This idea is supported by their unusually high packing indices of 77.8% [in (1)] and 76.4% [in (2)], as calculated by PLATON (Spek, 2009), assuming ordered positions of the cations at the centre of the 18-crown-6 cavity. The encapsulated cations thus appear in a constrained crystal environment: the behaviour of the large caesium cation towards the 18-crown-6 ligand in (2) is unprecedented and similar to that of the common K⁺, Rb⁺ and NH₄⁺ systems. This is best illustrated by the isomorphism of the Rb⁺, NH₄⁺ and Cs⁺ derivatives (1)–(3). The previously reported oxonium complexes [H₃O(18-crown-6)][SbCl₆] (Neumüller et al., 1994) and [H₃O(18-crown-6)][TaCl₆] (Bulychev & Bel'sky, 1995) afford closely related structures, even without any strong inter­actions between the cationic and anionic residues: all three H atoms of the oxonium cations are bonded to crown ether O acceptors and not accessible for inter­molecular bonding. This relationship provides the first example of isomorphism between caesium and oxonium 18-crown-6 complexes. It is even more inter­esting that the product obtained via reduction of perrhenate in a liquid clathrating medium (18-crown-6/H₂O/HCl) is also isomorphous (Barbour et al., 1996). This finding suggests that crystallization affords the compound [H₃O(18-crown-6)][ReCl₆], containing the unusual [Re^VCl₆]^- anion (Arp & Preetz, 1994), rather than the originally assumed [H₃O(18-crown-6)]₂[Re^IVCl₆], with `remarkably short Re—Cl bonds' (Barbour et al., 1996). The stabilization of the partially reduced chloridorhenate(V) anion may also be related to the specific and favourable supra­molecular structure reported here, predetermining the very low solubility of the solid. The [M^I(18-crown-6)][M^VCl₆] lattice can thus be proposed as a suitable form for the synthesis and isolation of unstable or unusual hexachloridometallate(V) (M = Re, W, U etc.) derivatives.

In brief, the present study is important for new structural features of 18-crown-6 complexes, in particular those formed by the large caesium cation, as well as for providing reliable chemical targets for the evaluation of unusual molecular geometries constrained in the specific crystal environment.

Related literature

For related literature, see: Arp & Preetz (1994); Bajaj & Poonia (1988); Barbour et al. (1996); Braga et al. (2007); Brown (1992); Bulychev & Bel'sky (1995); Domasevitch et al. (1996, 1997, 1998); Kahwa et al. (1992); Liu (2003); Manskaya et al. (1998); Nagano et al. (1978); Neander et al. (2000); Neumüller et al. (1994); Ponomarova & Domasevitch (2002); Spek (2009); Steed (2001); Wells (1991); Wu & Wu (2010).

Computing details

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994) for (1), (3); APEX2 (Bruker, 2008) for (2). Cell refinement: CAD-4 EXPRESS (Enraf–Nonius, 1994) for (1), (3); SAINT (Bruker, 2008) for (2). Data reduction: XCAD4 (Harms & Wocadlo, 1995) for (1), (3); SAINT (Bruker, 2008) for (2). For all compounds, program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 1999). Software used to prepare material for publication: WinGX (Farrugia, 2012) for (1), (2); SHELXL97 (Sheldrick, 2008) for (3).

Figures

	Fig. 1. The structure of (2), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 35% probability level. Complex (1) is isomorphous with the same atom-labelling scheme, with atom Rb1 instead of Cs1. [Symmetry codes: (i) y, -x + y, 1 - z; (ii) -x + y, -x, z; (iii) -x, -y, 1 - z; (iv) -y, x-y, z; (v) x-y, x, 1 - z.]
	Fig. 2. The structure of (3), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 40% probability level and dashed lines indicate hydrogen bonds. [Symmetry codes: (i) y, -x + y, 1 - z; (ii) -x + y, -x, z; (iii) -x, -y, 1 - z; (iv) -y, x-y, z; (v) x-y, x, 1 - z.] [Symop (v) not visible originally - has it been added correctly (O1v label)?]
	Fig. 3. A fragment of the structure of (2), showing the chains composed of [Cs(18-crown-6)]^+ (with the Cs atoms disordered over two positions) and [SbCl6] groups. The latter are represented as octahedra, and dashed lines indicate possible C—H···Cl bonding. [Symmetry codes: (iii) -x, -y, 1 - z; (vi) 2/3 - x + y, 1/3 - x, 1/3 + z.]
	Fig. 4. A projection of the structure of (2) on the ab plane, showing the arrangement of [Cs(18-crown-6)][SbCl6] stacks.

(1) (1,4,7,10,13,16-Hexaoxacyclooctadecane)rubidium hexachloridoantimonate(V)

Crystal data

[Rb(C12H24O6)]·[SbCl6]	Dx = 1.963 Mg m^−3
Mr = 684.23	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3	Cell parameters from 24 reflections
a = 14.1011 (10) Å	θ = 12.1–17.8°
c = 10.0850 (9) Å	µ = 4.00 mm^−1
V = 1736.7 (2) Å^3	T = 223 K
Z = 3	Prism, colourless
F(000) = 1002	0.26 × 0.22 × 0.20 mm

Data collection

Enraf–Nonius CAD4 diffractometer	635 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.073
Graphite monochromator	θmax = 25.2°, θmin = 2.6°
non–profiled ω–2θ scans	h = −16→16
Absorption correction: ψ scan (North et al., 1968)	k = −16→16
Tmin = 0.423, Tmax = 0.502	l = −10→12
2016 measured reflections	3 standard reflections every 120 min
697 independent reflections	intensity decay: none

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.026	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.065	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0186P)^2] where P = (Fo^2 + 2Fc^2)/3
697 reflections	(Δ/σ)max < 0.001
42 parameters	Δρmax = 0.35 e Å^−3
0 restraints	Δρmin = −0.42 e Å^−3

Special details

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. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Sb1	0.0000	0.0000	0.0000	0.02973 (17)
Rb1	0.0000	0.0000	0.45233 (13)	0.0483 (4)	0.50
Cl1	0.15794 (7)	0.07923 (8)	0.13513 (9)	0.0523 (3)
O1	0.22441 (17)	0.16174 (17)	0.5233 (2)	0.0412 (6)
C1	0.2971 (3)	0.1260 (3)	0.4783 (4)	0.0438 (8)
H1A	0.3721	0.1783	0.5059	0.053*
H1B	0.2953	0.1216	0.3813	0.053*
C2	0.2621 (3)	0.0152 (3)	0.5368 (3)	0.0437 (8)
H2A	0.3183	−0.0049	0.5206	0.052*
H2B	0.2522	0.0167	0.6329	0.052*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Sb1	0.0274 (2)	0.0274 (2)	0.0344 (3)	0.01370 (10)	0.000	0.000
Rb1	0.0288 (3)	0.0288 (3)	0.0874 (10)	0.01439 (17)	0.000	0.000
Cl1	0.0416 (5)	0.0493 (5)	0.0630 (6)	0.0206 (4)	−0.0192 (4)	−0.0097 (4)
O1	0.0317 (11)	0.0344 (12)	0.0563 (14)	0.0156 (10)	0.0081 (10)	0.0068 (10)
C1	0.0249 (16)	0.0460 (19)	0.056 (2)	0.0143 (15)	0.0017 (14)	−0.0084 (17)
C2	0.0366 (18)	0.053 (2)	0.0489 (18)	0.0274 (17)	−0.0064 (15)	−0.0063 (16)

Geometric parameters (Å, º)

Sb1—Cl1^i	2.3617 (8)	Rb1—O1^v	2.917 (2)
Sb1—Cl1	2.3617 (8)	Rb1—Cl1^ii	3.7353 (16)
Sb1—Cl1^ii	2.3617 (8)	Rb1—Cl1	3.7353 (16)
Sb1—Cl1^iii	2.3617 (8)	Rb1—Cl1^v	3.7353 (16)
Sb1—Cl1^iv	2.3617 (8)	O1—C2^vii	1.422 (4)
Sb1—Cl1^v	2.3617 (8)	O1—C1	1.424 (4)
Rb1—O1^vi	2.839 (2)	C1—C2	1.504 (5)
Rb1—O1^vii	2.839 (2)	C1—H1A	0.9800
Rb1—O1^viii	2.839 (2)	C1—H1B	0.9800
Rb1—O1	2.917 (2)	C2—H2A	0.9800
Rb1—O1^ii	2.917 (2)	C2—H2B	0.9800
Cl1^i—Sb1—Cl1	180	O1^v—Rb1—Cl1^ii	110.28 (5)
Cl1^i—Sb1—Cl1^ii	89.97 (4)	O1^vi—Rb1—Cl1	124.94 (6)
Cl1—Sb1—Cl1^ii	90.03 (4)	O1^vii—Rb1—Cl1	86.21 (5)
Cl1^i—Sb1—Cl1^iii	90.03 (4)	O1^viii—Rb1—Cl1	73.47 (5)
Cl1—Sb1—Cl1^iii	89.97 (4)	O1—Rb1—Cl1	74.04 (5)
Cl1^ii—Sb1—Cl1^iii	89.97 (4)	O1^ii—Rb1—Cl1	110.28 (5)
Cl1^i—Sb1—Cl1^iv	90.03 (4)	O1^v—Rb1—Cl1	124.00 (5)
Cl1—Sb1—Cl1^iv	89.97 (4)	Cl1^ii—Rb1—Cl1	53.13 (3)
Cl1^ii—Sb1—Cl1^iv	180	O1^vi—Rb1—Cl1^v	86.21 (5)
Cl1^iii—Sb1—Cl1^iv	90.03 (4)	O1^vii—Rb1—Cl1^v	73.47 (5)
Cl1^i—Sb1—Cl1^v	89.97 (4)	O1^viii—Rb1—Cl1^v	124.94 (6)
Cl1—Sb1—Cl1^v	90.03 (4)	O1—Rb1—Cl1^v	110.28 (5)
Cl1^ii—Sb1—Cl1^v	90.03 (4)	O1^ii—Rb1—Cl1^v	124.00 (5)
Cl1^iii—Sb1—Cl1^v	180	O1^v—Rb1—Cl1^v	74.04 (5)
Cl1^iv—Sb1—Cl1^v	89.97 (4)	Cl1^ii—Rb1—Cl1^v	53.13 (3)
O1^vi—Rb1—O1^vii	119.261 (16)	Cl1—Rb1—Cl1^v	53.13 (3)
O1^vi—Rb1—O1^viii	119.261 (16)	Sb1—Cl1—Rb1	94.16 (3)
O1^vii—Rb1—O1^viii	119.261 (17)	C2^vii—O1—C1	112.0 (3)
O1^vi—Rb1—O1	160.83 (5)	C2^vii—O1—Rb1^vi	116.14 (19)
O1^vii—Rb1—O1	59.728 (14)	C1—O1—Rb1^vi	116.98 (18)
O1^viii—Rb1—O1	59.728 (14)	C2^vii—O1—Rb1	106.74 (18)
O1^vi—Rb1—O1^ii	59.728 (14)	C1—O1—Rb1	109.66 (18)
O1^vii—Rb1—O1^ii	160.83 (5)	O1—C1—C2	108.8 (3)
O1^viii—Rb1—O1^ii	59.728 (14)	O1—C1—H1A	109.9
O1—Rb1—O1^ii	114.18 (4)	C2—C1—H1A	109.9
O1^vi—Rb1—O1^v	59.728 (14)	O1—C1—H1B	109.9
O1^vii—Rb1—O1^v	59.728 (14)	C2—C1—H1B	109.9
O1^viii—Rb1—O1^v	160.83 (5)	H1A—C1—H1B	108.3
O1—Rb1—O1^v	114.18 (4)	O1^viii—C2—C1	108.5 (3)
O1^ii—Rb1—O1^v	114.18 (4)	O1^viii—C2—H2A	110.0
O1^vi—Rb1—Cl1^ii	73.47 (5)	C1—C2—H2A	110.0
O1^vii—Rb1—Cl1^ii	124.94 (6)	O1^viii—C2—H2B	110.0
O1^viii—Rb1—Cl1^ii	86.21 (5)	C1—C2—H2B	110.0
O1—Rb1—Cl1^ii	124.00 (5)	H2A—C2—H2B	108.4
O1^ii—Rb1—Cl1^ii	74.04 (5)
Cl1^ii—Sb1—Cl1—Rb1	−45.014 (18)	O1^v—Rb1—O1—C2^vii	−55.4 (2)
Cl1^iii—Sb1—Cl1—Rb1	−134.986 (18)	Cl1^ii—Rb1—O1—C2^vii	84.11 (19)
Cl1^iv—Sb1—Cl1—Rb1	134.986 (18)	Cl1—Rb1—O1—C2^vii	65.15 (18)
Cl1^v—Sb1—Cl1—Rb1	45.014 (18)	Cl1^v—Rb1—O1—C2^vii	25.6 (2)
O1^vi—Rb1—Cl1—Sb1	17.33 (7)	O1^vi—Rb1—O1—C1	116.1 (2)
O1^vii—Rb1—Cl1—Sb1	−106.12 (5)	O1^vii—Rb1—O1—C1	−151.4 (3)
O1^viii—Rb1—Cl1—Sb1	131.83 (6)	O1^viii—Rb1—O1—C1	23.52 (18)
O1—Rb1—Cl1—Sb1	−165.69 (5)	O1^ii—Rb1—O1—C1	49.1 (2)
O1^ii—Rb1—Cl1—Sb1	83.92 (6)	O1^v—Rb1—O1—C1	−176.96 (18)
O1^v—Rb1—Cl1—Sb1	−56.97 (6)	Cl1^ii—Rb1—O1—C1	−37.4 (2)
Cl1^ii—Rb1—Cl1—Sb1	33.987 (5)	Cl1—Rb1—O1—C1	−56.4 (2)
Cl1^v—Rb1—Cl1—Sb1	−33.987 (5)	Cl1^v—Rb1—O1—C1	−95.9 (2)
O1^vi—Rb1—O1—C2^vii	−122.41 (19)	C2^vii—O1—C1—C2	−175.1 (2)
O1^vii—Rb1—O1—C2^vii	−29.86 (17)	Rb1^vi—O1—C1—C2	−37.4 (3)
O1^viii—Rb1—O1—C2^vii	145.0 (2)	Rb1—O1—C1—C2	−56.8 (3)
O1^ii—Rb1—O1—C2^vii	170.62 (16)	O1—C1—C2—O1^viii	70.0 (4)

Symmetry codes: (i) −x, −y, −z; (ii) −x+y, −x, z; (iii) y, −x+y, −z; (iv) x−y, x, −z; (v) −y, x−y, z; (vi) −x, −y, −z+1; (vii) x−y, x, −z+1; (viii) y, −x+y, −z+1.

(2) (1,4,7,10,13,16-Hexaoxacyclooctadecane)caesium hexachloridoantimonate(V)

Crystal data

[Cs(C12H24O6)]·[SbCl6]	Dx = 1.999 Mg m^−3
Mr = 731.67	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3	Cell parameters from 3557 reflections
a = 14.0782 (10) Å	θ = 2.5–28.0°
c = 10.6230 (8) Å	µ = 3.29 mm^−1
V = 1823.4 (3) Å^3	T = 223 K
Z = 3	Prism, colourless
F(000) = 1056	0.20 × 0.17 × 0.16 mm

Data collection

Bruker APEX2 area-detector diffractometer	972 independent reflections
Radiation source: fine-focus sealed tube	867 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.038
ω scans	θmax = 28.0°, θmin = 2.5°
Absorption correction: numerical face-indexed (SADABS; Bruker, 2008)	h = −18→12
Tmin = 0.559, Tmax = 0.621	k = −18→18
3557 measured reflections	l = −13→13

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.031	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.079	H-atom parameters constrained
S = 1.09	w = 1/[σ^2(Fo^2) + (0.0332P)^2 + 4.4375P] where P = (Fo^2 + 2Fc^2)/3
972 reflections	(Δ/σ)max < 0.001
42 parameters	Δρmax = 1.49 e Å^−3
0 restraints	Δρmin = −0.53 e Å^−3

Special details

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. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Sb1	0.0000	0.0000	0.0000	0.04589 (17)
Cs1	0.0000	0.0000	0.41204 (7)	0.04685 (19)	0.50
Cl1	0.15971 (7)	0.08080 (8)	0.12770 (9)	0.0624 (2)
O1	0.22671 (17)	0.16479 (17)	0.5230 (2)	0.0509 (5)
C1	0.2980 (3)	0.1282 (3)	0.4785 (4)	0.0598 (9)
H1A	0.3736	0.1807	0.5030	0.072*
H1B	0.2947	0.1238	0.3864	0.072*
C2	0.2651 (3)	0.0180 (3)	0.5325 (3)	0.0573 (8)
H2A	0.3224	−0.0006	0.5159	0.069*
H2B	0.2561	0.0191	0.6238	0.069*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Sb1	0.03376 (18)	0.03376 (18)	0.0702 (3)	0.01688 (9)	0.000	0.000
Cs1	0.0368 (2)	0.0368 (2)	0.0669 (4)	0.01840 (11)	0.000	0.000
Cl1	0.0455 (4)	0.0536 (5)	0.0851 (6)	0.0226 (4)	−0.0127 (4)	−0.0058 (4)
O1	0.0400 (11)	0.0424 (11)	0.0690 (14)	0.0196 (9)	0.0055 (9)	0.0037 (10)
C1	0.0316 (14)	0.0510 (18)	0.090 (3)	0.0158 (13)	0.0052 (14)	−0.0048 (16)
C2	0.0401 (15)	0.060 (2)	0.077 (2)	0.0295 (15)	−0.0077 (15)	−0.0099 (17)

Geometric parameters (Å, º)

Sb1—Cl1^i	2.3732 (8)	Cs1—O1^iii	3.091 (2)
Sb1—Cl1	2.3732 (8)	Cs1—Cl1^iii	3.5938 (12)
Sb1—Cl1^ii	2.3731 (8)	Cs1—Cl1^ii	3.5938 (12)
Sb1—Cl1^iii	2.3732 (8)	Cs1—Cl1	3.5938 (12)
Sb1—Cl1^iv	2.3732 (8)	O1—C1	1.419 (4)
Sb1—Cl1^v	2.3732 (8)	O1—C2^vii	1.421 (4)
Cs1—O1^vi	2.939 (2)	C1—C2	1.494 (5)
Cs1—O1^vii	2.939 (2)	C1—H1A	0.9800
Cs1—O1^viii	2.939 (2)	C1—H1B	0.9800
Cs1—O1	3.091 (2)	C2—H2A	0.9800
Cs1—O1^ii	3.091 (2)	C2—H2B	0.9800
Cl1^i—Sb1—Cl1	180	O1^iii—Cs1—Cl1^iii	80.52 (4)
Cl1^i—Sb1—Cl1^ii	89.43 (3)	O1^vi—Cs1—Cl1^ii	93.13 (5)
Cl1—Sb1—Cl1^ii	90.57 (3)	O1^vii—Cs1—Cl1^ii	80.18 (5)
Cl1^i—Sb1—Cl1^iii	89.43 (3)	O1^viii—Cs1—Cl1^ii	135.04 (5)
Cl1—Sb1—Cl1^iii	90.57 (3)	O1—Cs1—Cl1^ii	117.14 (4)
Cl1^ii—Sb1—Cl1^iii	90.57 (3)	O1^ii—Cs1—Cl1^ii	80.52 (4)
Cl1^i—Sb1—Cl1^iv	90.57 (3)	O1^iii—Cs1—Cl1^ii	132.09 (5)
Cl1—Sb1—Cl1^iv	89.43 (3)	Cl1^iii—Cs1—Cl1^ii	55.97 (2)
Cl1^ii—Sb1—Cl1^iv	89.43 (3)	O1^vi—Cs1—Cl1	135.04 (5)
Cl1^iii—Sb1—Cl1^iv	180	O1^vii—Cs1—Cl1	93.13 (5)
Cl1^i—Sb1—Cl1^v	90.57 (3)	O1^viii—Cs1—Cl1	80.18 (5)
Cl1—Sb1—Cl1^v	89.43 (3)	O1—Cs1—Cl1	80.52 (4)
Cl1^ii—Sb1—Cl1^v	180	O1^ii—Cs1—Cl1	132.09 (4)
Cl1^iii—Sb1—Cl1^v	89.43 (3)	O1^iii—Cs1—Cl1	117.14 (4)
Cl1^iv—Sb1—Cl1^v	90.57 (3)	Cl1^iii—Cs1—Cl1	55.97 (2)
O1^vi—Cs1—O1^vii	114.67 (3)	Cl1^ii—Cs1—Cl1	55.97 (2)
O1^vi—Cs1—O1^viii	114.67 (3)	Sb1—Cl1—Cs1	92.05 (3)
O1^vii—Cs1—O1^viii	114.67 (3)	C1—O1—C2^vii	113.2 (3)
O1^vi—Cs1—O1	144.00 (4)	C1—O1—Cs1^vi	118.54 (17)
O1^vii—Cs1—O1	57.398 (13)	C2^vii—O1—Cs1^vi	118.79 (18)
O1^viii—Cs1—O1	57.398 (13)	C1—O1—Cs1	104.64 (18)
O1^vi—Cs1—O1^ii	57.398 (13)	C2^vii—O1—Cs1	101.95 (17)
O1^vii—Cs1—O1^ii	57.398 (13)	O1—C1—C2	109.9 (3)
O1^viii—Cs1—O1^ii	144.00 (4)	O1—C1—H1A	109.7
O1—Cs1—O1^ii	106.36 (5)	C2—C1—H1A	109.7
O1^vi—Cs1—O1^iii	57.398 (13)	O1—C1—H1B	109.7
O1^vii—Cs1—O1^iii	144.00 (4)	C2—C1—H1B	109.7
O1^viii—Cs1—O1^iii	57.398 (13)	H1A—C1—H1B	108.2
O1—Cs1—O1^iii	106.36 (5)	O1^viii—C2—C1	109.4 (3)
O1^ii—Cs1—O1^iii	106.36 (5)	O1^viii—C2—H2A	109.8
O1^vi—Cs1—Cl1^iii	80.18 (5)	C1—C2—H2A	109.8
O1^vii—Cs1—Cl1^iii	135.04 (5)	Cs1^vi—C2—H2A	163.2
O1^viii—Cs1—Cl1^iii	93.13 (5)	O1^viii—C2—H2B	109.8
O1—Cs1—Cl1^iii	132.09 (4)	C1—C2—H2B	109.8
O1^ii—Cs1—Cl1^iii	117.14 (4)	H2A—C2—H2B	108.2
Cl1^ii—Sb1—Cl1—Cs1	45.286 (18)	O1^iii—Cs1—O1—C1	62.2 (2)
Cl1^iii—Sb1—Cl1—Cs1	−45.286 (18)	Cl1^iii—Cs1—O1—C1	−29.8 (2)
Cl1^iv—Sb1—Cl1—Cs1	134.714 (18)	Cl1^ii—Cs1—O1—C1	−97.16 (19)
Cl1^v—Sb1—Cl1—Cs1	−134.714 (18)	Cl1—Cs1—O1—C1	−53.48 (19)
O1^vi—Cs1—Cl1—Sb1	19.85 (7)	O1^vi—Cs1—O1—C2^vii	−123.11 (19)
O1^vii—Cs1—Cl1—Sb1	−110.42 (5)	O1^vii—Cs1—O1—C2^vii	−35.26 (18)
O1^viii—Cs1—Cl1—Sb1	135.07 (5)	O1^viii—Cs1—O1—C2^vii	149.0 (2)
O1—Cs1—Cl1—Sb1	−166.63 (5)	O1^ii—Cs1—O1—C2^vii	−66.6 (2)
O1^ii—Cs1—Cl1—Sb1	−63.09 (6)	O1^iii—Cs1—O1—C2^vii	−179.66 (18)
O1^iii—Cs1—Cl1—Sb1	89.76 (5)	Cl1^iii—Cs1—O1—C2^vii	88.40 (19)
Cl1^iii—Cs1—Cl1—Sb1	34.486 (4)	Cl1^ii—Cs1—O1—C2^vii	21.0 (2)
Cl1^ii—Cs1—Cl1—Sb1	−34.486 (4)	Cl1—Cs1—O1—C2^vii	64.68 (19)
O1^vi—Cs1—O1—C1	118.73 (19)	C2^vii—O1—C1—C2	−175.0 (2)
O1^vii—Cs1—O1—C1	−153.4 (2)	Cs1^vi—O1—C1—C2	−28.9 (3)
O1^viii—Cs1—O1—C1	30.87 (18)	Cs1—O1—C1—C2	−64.8 (3)
O1^ii—Cs1—O1—C1	175.27 (18)	O1—C1—C2—O1^viii	70.9 (4)

Symmetry codes: (i) −x, −y, −z; (ii) −y, x−y, z; (iii) −x+y, −x, z; (iv) x−y, x, −z; (v) y, −x+y, −z; (vi) −x, −y, −z+1; (vii) x−y, x, −z+1; (viii) y, −x+y, −z+1.

(3) Ammonium hexachloridoantimonate(V)–1,4,7,10,13,16-hexaoxacyclooctadecane (1/1)

Crystal data

[(NH4)(C12H24O6)]·[SbCl6]	Dx = 1.750 Mg m^−3
Mr = 616.80	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3	Cell parameters from 24 reflections
a = 14.1069 (9) Å	θ = 12.6–17.2°
c = 10.1908 (8) Å	µ = 1.89 mm^−1
V = 1756.3 (2) Å^3	T = 223 K
Z = 3	Prism, colourless
F(000) = 924	0.25 × 0.23 × 0.18 mm

Data collection

Enraf–Nonius CAD4 diffractometer	673 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.037
Graphite monochromator	θmax = 25.3°, θmin = 2.6°
non–profiled ω–2θ scans	h = −16→16
Absorption correction: ψ scan (North et al., 1968)	k = −16→16
Tmin = 0.682, Tmax = 0.764	l = −11→12
2227 measured reflections	3 standard reflections every 120 min
708 independent reflections	intensity decay: none

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.022	Hydrogen site location: difference Fourier map
wR(F^2) = 0.056	H-atom parameters constrained
S = 1.14	w = 1/[σ^2(Fo^2) + (0.0283P)^2 + 1.1402P] where P = (Fo^2 + 2Fc^2)/3
708 reflections	(Δ/σ)max < 0.001
42 parameters	Δρmax = 0.36 e Å^−3
0 restraints	Δρmin = −0.44 e Å^−3

Special details

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. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Sb1	0.0000	0.0000	0.0000	0.03190 (15)
Cl1	0.15828 (5)	0.07881 (6)	0.13460 (7)	0.0534 (2)
O1	0.22474 (13)	0.06313 (13)	0.52237 (17)	0.0426 (4)
N1	0.0000	0.0000	0.4495 (8)	0.0469 (19)	0.50
H1	0.0000	0.0000	0.3611	0.070*	0.50
H2	0.0694	0.0323	0.4789	0.070*	0.50
C1	0.2472 (2)	−0.0156 (2)	0.4643 (3)	0.0461 (6)
H1A	0.3233	0.0045	0.4814	0.055*
H1B	0.2367	−0.0171	0.3691	0.055*
C2	0.1716 (2)	−0.1260 (2)	0.5210 (3)	0.0462 (6)
H2A	0.1942	−0.1782	0.4929	0.055*
H2B	0.1746	−0.1220	0.6171	0.055*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Sb1	0.03064 (17)	0.03064 (17)	0.0344 (2)	0.01532 (8)	0.000	0.000
Cl1	0.0455 (4)	0.0526 (4)	0.0598 (4)	0.0228 (3)	−0.0171 (3)	−0.0090 (3)
O1	0.0365 (9)	0.0382 (8)	0.0517 (10)	0.0178 (7)	0.0061 (7)	0.0003 (7)
N1	0.033 (2)	0.033 (2)	0.074 (5)	0.0167 (10)	0.000	0.000
C1	0.0356 (12)	0.0528 (15)	0.0536 (15)	0.0250 (11)	−0.0006 (10)	−0.0075 (12)
C2	0.0462 (14)	0.0483 (14)	0.0553 (15)	0.0320 (12)	−0.0090 (11)	−0.0060 (11)

Geometric parameters (Å, º)

Sb1—Cl1	2.3707 (6)	N1—H1	0.9000
Sb1—Cl1^i	2.3707 (6)	N1—H2	0.9000
Sb1—Cl1^ii	2.3707 (6)	C1—C2	1.495 (4)
Sb1—Cl1^iii	2.3707 (6)	C1—H1A	0.9800
Sb1—Cl1^iv	2.3707 (6)	C1—H1B	0.9800
Sb1—Cl1^v	2.3707 (6)	C2—H2A	0.9800
O1—C2^vi	1.422 (3)	C2—H2B	0.9800
O1—C1	1.426 (3)
Cl1—Sb1—Cl1^i	180	C2^vi—O1—C1	112.75 (18)
Cl1—Sb1—Cl1^ii	89.88 (3)	H1—N1—H2	109.5
Cl1^i—Sb1—Cl1^ii	90.12 (3)	O1—C1—C2	109.3 (2)
Cl1—Sb1—Cl1^iii	90.12 (3)	O1—C1—H1A	109.8
Cl1^i—Sb1—Cl1^iii	89.88 (3)	C2—C1—H1A	109.8
Cl1^ii—Sb1—Cl1^iii	90.12 (3)	O1—C1—H1B	109.8
Cl1—Sb1—Cl1^iv	90.12 (3)	C2—C1—H1B	109.8
Cl1^i—Sb1—Cl1^iv	89.88 (3)	H1A—C1—H1B	108.3
Cl1^ii—Sb1—Cl1^iv	180	O1^vii—C2—C1	109.2 (2)
Cl1^iii—Sb1—Cl1^iv	89.88 (3)	O1^vii—C2—H2A	109.8
Cl1—Sb1—Cl1^v	89.88 (3)	C1—C2—H2A	109.8
Cl1^i—Sb1—Cl1^v	90.12 (3)	O1^vii—C2—H2B	109.8
Cl1^ii—Sb1—Cl1^v	89.88 (3)	C1—C2—H2B	109.8
Cl1^iii—Sb1—Cl1^v	180	H2A—C2—H2B	108.3
Cl1^iv—Sb1—Cl1^v	90.12 (3)
C2^vi—O1—C1—C2	176.61 (17)	O1—C1—C2—O1^vii	68.8 (3)

Symmetry codes: (i) −x, −y, −z; (ii) −y, x−y, z; (iii) x−y, x, −z; (iv) y, −x+y, −z; (v) −x+y, −x, z; (vi) x−y, x, −z+1; (vii) y, −x+y, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H2···O1	0.90	2.06	2.928 (3)	162
N1—H1···Cl1	0.90	3.01	3.746 (7)	140
C2—H2A···Cl1^viii	0.98	3.09	3.798 (3)	130

Symmetry code: (viii) x−y+1/3, x−1/3, −z+2/3.