[Rb(18-crown-6)][Rb([2.2.2]-cryptand)]Rb2Sn9·5NH3

Stefanie Gaertner; Nikolaus Korber

doi:10.1107/S1600536811013997

. 2011 Apr 22;67(Pt 5):m613–m614. doi: 10.1107/S1600536811013997

[Rb(18-crown-6)][Rb([2.2.2]-cryptand)]Rb₂Sn₉·5NH₃

Stefanie Gaertner ^a, Nikolaus Korber ^a,^*

PMCID: PMC3089245 PMID: 21754329

Abstract

The crystal structure of the title compound, poly[[(4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane)rubidium] [[(1,4,7,10,13,16-hexaoxacyclooctadecane)rubidium]di-μ-rubidium-μ-nonastannide] pentaammonia], {[Rb(C₁₈H₃₆N₂O₆)][Rb₃Sn₉(C₁₂H₂₄O₆)C₁₂H₂₄O₆)]·5NH₃}_n represents the first ammoniate of a Zintl anion together with two different chelating substances, namely 18-crown-6 and [2.2.2]-cryptand. The involvement of these large molecules in the crystal structure of [Rb(18-crown-6)][Rb([2.2.2]-cryptand)]Rb₂Sn₉·5NH₃ leads to the formation of a new structural motif, namely one-dimensionally extended double strands running parallel to [100] and built by Sn₉ ⁴⁻ cages and Rb⁺ cations. The double strands are shielded by 18-crown-6 and [2.2.2]-cryptand. The cations are additionally coordinated by ammonia molecules. One of the four independent Rb⁺ cations is disordered over two sets of sites in a 0.74 (2):0.26 (2) ratio.

Related literature

For a recent review on nine-atom group 14 clusters in solution, see: Scharfe & Fässler (2010 ▶). For Zintl clusters in the solid state see: Fässler (2001 ▶); Hoch et al. (2003 ▶). The coordination of two cations by 18-crown-6 usually results in two-dimensional layers (Hauptmann & Fässler, 2002 ▶, 2003a ▶,b ▶), when three cations are coordinated by the latter, one-dimensional single strands are observed (Fässler & Hoffmann, 1999 ▶). The use of less [2.2.2]-cryptand gives two-dimensional double layers (Hauptmann et al., 2001 ▶), whereas larger amounts result in one-dimensional single strands (Burns & Corbett, 1985 ▶) or isolated nonastannide clusters without direct cation contacts (Corbett & Edwards, 1977 ▶).

Experimental

Crystal data

[Rb(C₁₂H₂₄O₆)][Rb₃Sn₉(C₁₈H₃₆N₂O₆)]·5NH₃
M _r = 2136.04
Monoclinic,
a = 10.790 (2) Å
b = 15.600 (3) Å
c = 36.960 (7) Å
β = 91.20 (3)°
V = 6220 (2) Å³
Z = 4
Mo Kα radiation
μ = 6.75 mm⁻¹
T = 123 K
0.25 × 0.2 × 0.15 mm

Data collection

Stoe IPDS diffractometer
Absorption correction: analytical (X-SHAPE; Stoe & Cie, 2002 ▶) T _min = 0.057, T _max = 0.119
36425 measured reflections
11435 independent reflections
7473 reflections with I > 2σ(I)
R _int = 0.099

Refinement

R[F ² > 2σ(F ²)] = 0.043
wR(F ²) = 0.112
S = 0.84
11435 reflections
608 parameters
H-atom parameters constrained
Δρ_max = 2.77 e Å⁻³
Δρ_min = −1.18 e Å⁻³

Data collection: X-AREA (Stoe & Cie, 2002 ▶); cell refinement: X-AREA; data reduction: X-RED (Stoe & Cie, 2002 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg, 2001 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811013997/hp2005sup1.cif

e-67-0m613-sup1.cif^{(48.7KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811013997/hp2005Isup2.hkl

e-67-0m613-Isup2.hkl^{(559.1KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

supplementary crystallographic information

Comment

Compounds which contain elements of group 14 elements in negative oxidation states can be obtained by reacting an electropositive metal with the favoured element in solid state reactions at high temperatures. Some of these Zintl phases contain molecular homoatomic clusters preformed in solid state (Hoch et al., 2003, Fassler, 2001). The dissolution of these cluster containing Zintl compounds in an appropriate solvent is a common route to obtain homoatomic building blocks in solution (Scharfe & Fassler, 2010). Dissolving the binary material Rb₁₂Sn₁₇, which contains four and nine atom clusters of tin, in liquid ammonia in presence of 18-crown-6 and [2.2.2]-cryptand yields a dark red solution, the colour of which is characteristic for polystannides in solution. After storage at 236 K for five months dark red, rod shaped crystals could be isolated, which only include the nine atom clusters Sn₉^4- and four Rb⁺, of which one Rb cation is coordinated by 18-crown-6 and one Rb⁺ is situated in the cavity of a [2.2.2]-cryptand molecule. The coordiantion of two cations by 18-crown-6 usually results in two-dimensional layers (Hauptmann & Fassler, 2003a,b; Hauptmann & Fassler, 2002), when three cations are coordinated by the latter, one-dimensional single strands are observed (Fassler & Hoffmann, 1999). The use of less [2.2.2]-cryptand gives two-dimensional double layers (Hauptmann et al., 2001), whereas larger amounts result in one-dimensional single strands (Burns & Corbett, 1985) or isolated nonastannide clusters without direct cation contacts (Corbett & Edwards, 1977). The presence of the two different chelating compounds offers the possibility of a new structral motif in nonastannide compounds. Here, one-dimensional double strands of nonastannide cages linked by Rb⁺ (Rb10, Rb12, Rb13) along the crystallographic a axis are observed. These double strands are shielded by 18-crown-6 molecules, which surround Rb10 (Fig.1). [2.2.2]-cryptand molecules around Rb11 isolate the double strands from each other. The coordination spheres of the Rb cations are saturated by ammonia molecules, additionally one ammonia molecule of crystallization is found (Fig. 2).

Experimental

0.36 g Rb₁₂Sn₁₇ (0.115 mmol), 0.06 g 18-crown-6 (0.25 mmol) and 0.09 g [2.2.2]-cryptand (0.25 mmol) were placed under Argon atmosphere in a baked out reaction vessel. Afterwards, 15 ml of dry liquid ammonia were condensed onto the reaction mixture, which yielded a dark red solution. After storage for five months at 236 K, dark red crystals could be obtained.