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Acta Cryst. (2008). E64, m257    [ doi:10.1107/S1600536807067293 ]

The inorganic-organic hybrid material triethylenetetrammonium hexachloridorhodate(III) chloride

T. Hahn and W. Frank

Abstract top

Single crystals of the new title compound [systematic name: 1,4,7,10-tetrazoniadecane hexachloridorhodate(III) chloride], [H3N(CH2)2NH2(CH2)2NH2(CH2)2NH3][RhCl6]Cl, were obtained from the corresponding amine and rhodium trichloride in hydrochloric acid solution by slow crystallization under diffusion-controlled conditions at room temperature. Its solid-state structure is defined by a three-dimensional framework of numerous electrostatic-supported N-H...Cl hydrogen bonds between the ionic components of the compound. Within this framework, layered arrangements of the complex ions on one hand and of the protonated amines and chloride ions on the other hand, can be recognized. The octahedral hexachloridorhodate(III) anion resides on a \overline{1} symmetry site, while the triethylenetetrammonium cation and the chloride ion both reside on twofold axes.

Comment top

As part of our research on inorganic-organic hybrid materials various alkylammonium hexahalogenidorhodates(III) have been synthesized and structurally characterized with focus on the principles of organization of the organic and inorganic components on the one hand and the hydrogen bonding networks on the other (Frank & Rei\&s, 1996; Frank & Rei\&s, 1997; Frank & Bujak, 2002; Frank & Graf, 2004). The aim of the work described in this report was to examine the structural properties of a compound extending the series of known hexachloridorhodates(III) with cations of the general formula H3N(CH2)2(NH2(CH2)2)nNH3(n+2)+ [n = 0 (Gillard et al., 1996; Rei\&s, 1996), n = 1 (Frank et al., 1996)].

A light red microcrystalline unresolvable substance is obtained in a fast precipitation reaction by mixing hydrochloric acid solutions of triethylene tetrammonium chloride (n = 2 according to the prementioned formula) and rhodium trichloride. A diffusion controlled crystallization procedure yielded single crystals of sufficient size for single-crystal structure analysis. The results of elemental analyses and spectroscopic investigations agreed with the formula [H3N(CH2)2(NH2(CH2)2)2NH3][RhCl6]Cl. The structure determination shows [H3N(CH2)2(NH2(CH2)2)2NH3]4+, [RhCl6]3- and Cl- to be present in the crystal in a ratio of 1:1:1 (Fig. 1). The [RhCl6]3- ion has a crystallographically imposed 1 symmetry. As expected, the rhodium atom at the centre is coordinated in a nearly ideal octahedral geometry by the six chlorido ligands (Table 1). The complex ion is surrounded by four NH3 groups and two NH2 groups of altogether six triethylene tetrammonium cations. All the N–H—Cl hydrogen bonds between these cations and the chlorido ligands of the complex anion have to be considered as weak interactions (Fig. 1 and Table 2). This is indicated by N – Cl distances varying between 3.165 (2) Å and 3.267 (2) Å (with H – Cl distances from 2.28 Å to 2.45 Å) (Table 2), as well as by the IR frequencies of the N – H stretching modes. The triethylene tetrammonium cation resides on a twofold axis. Its conformation deviates substantially from the ideal all-trans (zigzag chain-like) arrangement. The deviation is primarily described by a torsion of 54.3 (3)° around the bond between C2 and N2, so that the cation's conformation resembles to a stretched 's'. Apart from that the bond lengths and angles are as expected. The cation has ten weak hydrogen bonds to its environment, so its hydrogen bond donor functions are completely saturated (Fig. 1). The NH3 group (N1) is connected to two [RhCl6]3- octahedra by two hydrogen bonds, while the NH2 group (N2) is connected to a third [RhCl6]3- octahedron, i. e. taking into account the site symmetry each cation contacts six octahedra. The single Cl- ion (Cl4) resides on a twofold axis and is fixed by hydrogen bonds to two NH3 and two NH2 groups, which are positioned in a distorted tetrahedral arrangement (Fig. 1) and belong to four triethylene tetrammonium cations.

In total the arrangement of the ionic components defines a dense inorganic-organic three-dimensional network through extensive electrostatically supported hydrogen bonding. In principle the arrangement of the complex anions agrees well with the one described for diethylene triammonium hexachloridorhodate(III) (Frank et al., 1996). The conformational flexibility of the organic cation seems to play a crucial role for the formation of a dense solid. It facilitates the organization of the cations and the single chloride anions into layers that are free of cavities. These cation/chloride layers and layers of the complex anions are stacked alternately along the crystallographic a axis (Fig. 2). From another point of view the arrangement of the [RhCl6]3- ions can be regarded as a distorted face centered cubic packing, if these anions are considered to be pseudo spherical species. A structural fragment, consisting of a central chloride ion and four quarters of surrounding protonated amines, may be considered as a triply positive charged 'pseudo cation' situated in the center of the octahedral holes within the close packing of complex ions (Fig. 3).

Related literature top

For related literature, see: Frank & Bujak (2002); Frank & Graf (2004); Frank & Rei\&s (1996, 1997); Frank, Rei\&s & Kleinwächter (1996); Gillard et al. (1996); Rei\&s (1996).

Experimental top

Mixing hydrochloric acid solutions of triethylene tetrammonium chloride and rhodium trichloride yields a unresolvable microcrystalline powder. To obtain suitable single crystals it is necessary to slow down this precipitation reaction so that controlled growth can be accomplished. For this purpose a three chamber vessel with two lateral chambers and one central chamber, which is separated from the lateral ones by two microporous membranes was used, a setup that guarantees a slow diffusion of the components of the precipitation reaction into the central chamber. The lateral chambers were filled with 5 ml of 20% hydrochloric acid solution of rhodium trichloride and 5 ml of a saturated solution of triethylene tetrammonium in concentrated hydrochloric acid, respectively, while the central chamber contained pure concentrated hydrochloric acid. Within some days dark red brick-shaped crystals were obtained in the central chamber, that were suitable for X-ray structure analysis and single-crystal ATR-IR and Raman spectroscopy. IR data (ν, cm-1): 3545 (w, br), 3113 (s), 3083 (s, sh), 2993 (s) 2911 (s), 2845 (s), 2800 (s), 2760 (s), 2718 (s, sh), 2610 (m, sh), 2539 (m, sh), 2438 (w), 2390 (w), 2343 (w), 1879 (w), 1585 (m), 1566 (m), 1483 (m), 1457 (m), 1440 (m), 1361 (w), 1245 (w), 1295 (w), 1246 (w), 1158 (w), 1135 (w), 1072 (w), 1026 (w), 983 (w, sh), 973, (w), 892 (vw), 871 (w), 794 (vw, sh), 775 (m); Raman data (ν, cm-1): 3121 (w, sh), 2987 (w, sh), 2956 (m), 2882 (vw), 2824 (vw), 1566 (w), 1492 (w), 1454 (w), 1434 (w), 1401 (vw), 1336 (w), 1292 (w), 1203 (vw), 1173 (vw), 1092 (vw, sh), 1072 (w), 1013 (w), 952 (w), 824 (w), 768 (w), 513 (w), 304 (s), 284 (s), 171 (m), 121 (w, sh); C, H, N-analysis (501.34): C 14.46 (calc. 14.37); H 4.59 (calc. 4.42); N 10.93 (calc. 11.18) %.

Refinement top

The atomic coordinates of hydrogen atoms in idealized positions were included in the refinement in riding model approximation. C–H and N–H distances for the CH2, NH2 and NH3 groups were allowed to refine, the same shifts being applied along the C–H and N–H bonds of a group, respectively, and in additon the torsion angle of the NH3 group was allowed to refine freely. Uiso(H) was set to 1.2 Ueq(carrier atom) for the CH2 groups. A common Uiso value was refined for the hydrogen atoms of the NH2 and the NH3 group, respectively. Only one significant electron-density maximum (1.33 e Å-3 at 0.87 Å from Rh1) was found in the final difference Fourier map.

Computing details top

Data collection: IPDS (Stoe & Cie (2000); cell refinement: IPDS (Stoe & Cie (2000); data reduction: IPDS (Stoe & Cie (2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 2006); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997) and enCIFer (Allen et al., 2004).

Figures top
[Figure 1] Fig. 1. : The ionic components of triethylene tetrammonium hexachloridorhodate(III) chloride with their hydrogen bond environment. Hydrogen atoms are drawn with an arbitrary radius and displacement ellipsoids are drawn at the 50% probability level. Dashed lines indicate further hydrogen bonds establishing a three dimensional network. Hydrogen atom labels are omitted for clarity. [Symmetry codes: (i) -x + 1, -y + 2, -z + 1; (ii) -x + 1/2, y + 1/2, -z + 1/2; (iii) -x + 1/2, y + 3/2, -z + 1; (iv) -x + 1, -y + 1, -z + 1; (v) -x + 1/2, -y + 1/2, -z + 1.]
[Figure 2] Fig. 2. : Packing diagram, view along [001]. The [RhCl6]3- ions are arranged in layers which are separated by layers of the organic components.
[Figure 3] Fig. 3. : Part of the distorted face centered cubic packing of [RhCl6]3- ions with triply charged virtual cations in the octahedral holes; note the relationship to the simple sodium chloride structure if the anions would be treated as pseudo spheres.
Triethylenetetrammonium hexachloridorhodate(III) chloride top
Crystal data top
(C6H22N4)[RhCl6]ClF000 = 1000
Mr = 501.34Dx = 1.934 Mg m−3
Monoclinic, C2/cMo Kα radiation
λ = 0.71073 Å
a = 16.8062 (13) ÅCell parameters from 7998 reflections
b = 8.7803 (8) Åθ = 5.1–51.8º
c = 12.3114 (11) ŵ = 2.07 mm−1
β = 108.602 (9)ºT = 123 (2) K
V = 1721.8 (3) Å3Brick shaped, dark red
Z = 40.6 × 0.4 × 0.2 mm
Data collection top
Stoe IPDS-1
diffractometer		1670 independent reflections
Radiation source: fine-focus sealed tube1518 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.100
Detector resolution: 0 pixels mm-1θmax = 26.0º
T = 123(2) Kθmin = 2.7º
φ scansh = −20→20
Absorption correction: analytical
(Sheldrick, 1997)		k = −10→10
Tmin = 0.022, Tmax = 0.050l = −15→15
11939 measured reflections
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)] = 0.027H-atom parameters constrained
wR(F2) = 0.079  w = 1/[σ2(Fo2) + (0.0533P)2 + 0.1116P]
where P = (Fo2 + 2Fc2)/3
S = 1.04(Δ/σ)max < 0.001
1670 reflectionsΔρmax = 1.33 e Å−3
96 parametersΔρmin = −0.48 e Å−3
Primary atom site location: structure-invariant direct methodsExtinction correction: none
Crystal data top
(C6H22N4)[RhCl6]ClV = 1721.8 (3) Å3
Mr = 501.34Z = 4
Monoclinic, C2/cMo Kα
a = 16.8062 (13) ŵ = 2.07 mm−1
b = 8.7803 (8) ÅT = 123 (2) K
c = 12.3114 (11) Å0.6 × 0.4 × 0.2 mm
β = 108.602 (9)º
Data collection top
Stoe IPDS-1
diffractometer		1670 independent reflections
Absorption correction: analytical
(Sheldrick, 1997)		1518 reflections with I > 2σ(I)
Tmin = 0.022, Tmax = 0.050Rint = 0.100
11939 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.02796 parameters
wR(F2) = 0.079H-atom parameters constrained
S = 1.04Δρmax = 1.33 e Å−3
1670 reflectionsΔρmin = −0.48 e Å−3
Special details top

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 (Å2) top
xyzUiso*/Ueq
Rh10.25000.25000.50000.01442 (13)
Cl10.30357 (4)0.15203 (6)0.36024 (4)0.01911 (16)
Cl20.18197 (4)0.44496 (6)0.37375 (5)0.02252 (17)
Cl30.37037 (4)0.40149 (6)0.56865 (4)0.02213 (16)
Cl40.50000.28717 (11)0.25000.0277 (2)
N10.36274 (14)0.5023 (2)0.31408 (16)0.0223 (4)
H110.39430.43720.28920.036*
H120.31970.53470.25440.036*
H130.34280.45490.36460.036*
N20.41689 (14)0.8552 (2)0.49770 (18)0.0229 (4)
H210.38320.92740.51710.040*
H220.44460.80060.56370.040*
C10.41463 (17)0.6344 (3)0.3702 (2)0.0228 (5)
H310.43610.68030.32040.027*
H320.45760.60220.43040.027*
C20.3615 (2)0.7477 (2)0.4109 (3)0.0238 (6)
H410.32730.80350.34780.029*
H420.32620.69470.44400.029*
C30.48081 (16)0.9362 (3)0.4577 (2)0.0229 (5)
H510.45480.97760.38280.027*
H520.52360.86650.45390.027*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Rh10.0143 (2)0.01504 (18)0.01519 (18)0.00114 (8)0.00653 (13)0.00025 (8)
Cl10.0210 (3)0.0198 (3)0.0190 (3)0.0017 (2)0.0099 (2)−0.00171 (19)
Cl20.0247 (4)0.0230 (3)0.0223 (3)0.0078 (2)0.0109 (2)0.0065 (2)
Cl30.0205 (3)0.0269 (3)0.0200 (3)−0.0064 (2)0.0079 (2)−0.0027 (2)
Cl40.0256 (5)0.0257 (4)0.0321 (5)0.0000.0094 (4)0.000
N10.0258 (12)0.0213 (10)0.0208 (10)−0.0014 (9)0.0087 (8)0.0009 (8)
N20.0223 (12)0.0204 (10)0.0268 (10)0.0005 (9)0.0089 (9)−0.0026 (8)
C10.0220 (14)0.0225 (11)0.0243 (11)−0.0018 (10)0.0080 (10)−0.0009 (9)
C20.0236 (17)0.0210 (14)0.0273 (14)−0.0005 (9)0.0087 (12)−0.0009 (8)
C30.0200 (13)0.0207 (11)0.0294 (12)0.0021 (10)0.0100 (10)−0.0010 (10)
Geometric parameters (Å, °) top
Rh1—Cl12.3450 (5)N1—H130.8970
Rh1—Cl22.3494 (6)N2—H210.9301
Rh1—Cl32.3420 (6)N2—H220.9301
N1—C11.484 (3)C1—H310.9002
N2—C21.505 (3)C1—H320.9002
N2—C31.497 (3)C2—H410.9429
C1—C21.524 (4)C2—H420.9429
C3—C3i1.527 (5)C3—H510.9563
N1—H110.8970C3—H520.9563
N1—H120.8970
Cl1—Rh1—Cl290.089 (19)H21—N2—H22107.6
Cl1—Rh1—Cl389.06 (2)N1—C1—H31109.6
Cl2—Rh1—Cl390.40 (2)C2—C1—H31109.6
N1—C1—C2110.2 (2)N1—C1—H32109.6
C1—C2—N2110.3 (2)C2—C1—H32109.6
C2—N2—C3114.2 (2)H31—C1—H32108.1
N2—C3—C3i108.4 (2)N2—C2—H41109.6
C1—N1—H11109.5C1—C2—H41109.6
C1—N1—H12109.5N2—C2—H42109.6
H11—N1—H12109.5C1—C2—H42109.6
C1—N1—H13109.5H41—C2—H42108.1
H11—N1—H13109.5N2—C3—H51110.0
H12—N1—H13109.5C3i—C3—H51110.0
C3—N2—H21108.7N2—C3—H52110.0
C2—N2—H21108.7C3i—C3—H52110.0
C3—N2—H22108.7H51—C3—H52108.4
C2—N2—H22108.7
N1—C1—C2—N2162.70 (19)C2—N2—C3—C3i168.2 (2)
C3—N2—C2—C154.3 (3)
Symmetry codes: (i) −x+1, −y+2, −z+1.
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
N1—H12···Cl1ii0.902.343.213 (2)164
N1—H13···Cl30.902.453.2195 (19)144
N1—H11···Cl40.902.383.267 (2)169
N2—H21···Cl2iii0.932.283.165 (2)159
N2—H22···Cl4iv0.932.323.224 (2)166
Symmetry codes: (ii) −x+1/2, y+1/2, −z+1/2; (iii) −x+1/2, −y+3/2, −z+1; (iv) −x+1, −y+1, −z+1.
Table 1
Selected geometric parameters (Å, °) top
Rh1—Cl12.3450 (5)N2—C21.505 (3)
Rh1—Cl22.3494 (6)N2—C31.497 (3)
Rh1—Cl32.3420 (6)C1—C21.524 (4)
N1—C11.484 (3)C3—C3i1.527 (5)
Cl1—Rh1—Cl290.089 (19)C1—C2—N2110.3 (2)
Cl1—Rh1—Cl389.06 (2)C2—N2—C3114.2 (2)
Cl2—Rh1—Cl390.40 (2)N2—C3—C3i108.4 (2)
N1—C1—C2110.2 (2)
N1—C1—C2—N2162.70 (19)C2—N2—C3—C3i168.2 (2)
C3—N2—C2—C154.3 (3)
Symmetry codes: (i) −x+1, −y+2, −z+1.
Table 2
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
N1—H12···Cl1ii0.902.343.213 (2)164
N1—H13···Cl30.902.453.2195 (19)144
N1—H11···Cl40.902.383.267 (2)169
N2—H21···Cl2iii0.932.283.165 (2)159
N2—H22···Cl4iv0.932.323.224 (2)166
Symmetry codes: (ii) −x+1/2, y+1/2, −z+1/2; (iii) −x+1/2, −y+3/2, −z+1; (iv) −x+1, −y+1, −z+1.
Acknowledgements top

We thank Ms E. Hammes for technical support.

references
References top

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