metal-organic compounds
The inorganic–organic hybrid material triethylenetetrammonium hexachloridorhodate(III) chloride
aInstitut für Anorganische Chemie und Strukturchemie, Lehrstuhl II, Heinrich-Heine-Universität Düsseldorf, Universitätsstrasse 1, 40225 Düsseldorf, Germany
*Correspondence e-mail: wfrank@uni-duesseldorf.de
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 and chloride ions on the other hand, can be recognized. The octahedral hexachloridorhodate(III) anion resides on a symmetry site, while the triethylenetetrammonium cation and the chloride ion both reside on twofold axes.
Related literature
For related literature, see: Frank & Bujak (2002); Frank & Graf (2004); Frank & Reiss (1996, 1997); Frank, Reiss & Kleinwächter (1996); Gillard et al. (1996); Reiss (1996).
Experimental
Crystal data
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Refinement
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Data collection: IPDS (Stoe & Cie (2000); cell IPDS; data reduction: IPDS; 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 and enCIFer (Allen et al., 2004).
Supporting information
https://doi.org/10.1107/S1600536807067293/gk2126sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536807067293/gk2126Isup2.hkl
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 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) %.
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 (The atomic coordinates of hydrogen atoms in idealized positions were included in the
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.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 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 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.
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 imposedIn 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
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).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).
Data collection: IPDS (Stoe & Cie (2000); cell
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).(C6H22N4)[RhCl6]Cl | F(000) = 1000 |
Mr = 501.34 | Dx = 1.934 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
a = 16.8062 (13) Å | Cell parameters from 7998 reflections |
b = 8.7803 (8) Å | θ = 5.1–51.8° |
c = 12.3114 (11) Å | µ = 2.07 mm−1 |
β = 108.602 (9)° | T = 123 K |
V = 1721.8 (3) Å3 | Brick shaped, dark red |
Z = 4 | 0.6 × 0.4 × 0.2 mm |
Stoe IPDS-1 diffractometer | 1670 independent reflections |
Radiation source: fine-focus sealed tube | 1518 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.100 |
Detector resolution: 0 pixels mm-1 | θmax = 26.0°, θmin = 2.7° |
φ scans | h = −20→20 |
Absorption correction: analytical (Sheldrick, 1997) | k = −10→10 |
Tmin = 0.022, Tmax = 0.050 | l = −15→15 |
11939 measured reflections |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.027 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.079 | H-atom parameters constrained |
S = 1.04 | w = 1/[σ2(Fo2) + (0.0533P)2 + 0.1116P] where P = (Fo2 + 2Fc2)/3 |
1670 reflections | (Δ/σ)max < 0.001 |
96 parameters | Δρmax = 1.33 e Å−3 |
0 restraints | Δρmin = −0.48 e Å−3 |
(C6H22N4)[RhCl6]Cl | V = 1721.8 (3) Å3 |
Mr = 501.34 | Z = 4 |
Monoclinic, C2/c | Mo Kα radiation |
a = 16.8062 (13) Å | µ = 2.07 mm−1 |
b = 8.7803 (8) Å | T = 123 K |
c = 12.3114 (11) Å | 0.6 × 0.4 × 0.2 mm |
β = 108.602 (9)° |
Stoe IPDS-1 diffractometer | 1670 independent reflections |
Absorption correction: analytical (Sheldrick, 1997) | 1518 reflections with I > 2σ(I) |
Tmin = 0.022, Tmax = 0.050 | Rint = 0.100 |
11939 measured reflections |
R[F2 > 2σ(F2)] = 0.027 | 0 restraints |
wR(F2) = 0.079 | H-atom parameters constrained |
S = 1.04 | Δρmax = 1.33 e Å−3 |
1670 reflections | Δρmin = −0.48 e Å−3 |
96 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
Rh1 | 0.2500 | 0.2500 | 0.5000 | 0.01442 (13) | |
Cl1 | 0.30357 (4) | 0.15203 (6) | 0.36024 (4) | 0.01911 (16) | |
Cl2 | 0.18197 (4) | 0.44496 (6) | 0.37375 (5) | 0.02252 (17) | |
Cl3 | 0.37037 (4) | 0.40149 (6) | 0.56865 (4) | 0.02213 (16) | |
Cl4 | 0.5000 | 0.28717 (11) | 0.2500 | 0.0277 (2) | |
N1 | 0.36274 (14) | 0.5023 (2) | 0.31408 (16) | 0.0223 (4) | |
H11 | 0.3943 | 0.4372 | 0.2892 | 0.036* | |
H12 | 0.3197 | 0.5347 | 0.2544 | 0.036* | |
H13 | 0.3428 | 0.4549 | 0.3646 | 0.036* | |
N2 | 0.41689 (14) | 0.8552 (2) | 0.49770 (18) | 0.0229 (4) | |
H21 | 0.3832 | 0.9274 | 0.5171 | 0.040* | |
H22 | 0.4446 | 0.8006 | 0.5637 | 0.040* | |
C1 | 0.41463 (17) | 0.6344 (3) | 0.3702 (2) | 0.0228 (5) | |
H31 | 0.4361 | 0.6803 | 0.3204 | 0.027* | |
H32 | 0.4576 | 0.6022 | 0.4304 | 0.027* | |
C2 | 0.3615 (2) | 0.7477 (2) | 0.4109 (3) | 0.0238 (6) | |
H41 | 0.3273 | 0.8035 | 0.3478 | 0.029* | |
H42 | 0.3262 | 0.6947 | 0.4440 | 0.029* | |
C3 | 0.48081 (16) | 0.9362 (3) | 0.4577 (2) | 0.0229 (5) | |
H51 | 0.4548 | 0.9776 | 0.3828 | 0.027* | |
H52 | 0.5236 | 0.8665 | 0.4539 | 0.027* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Rh1 | 0.0143 (2) | 0.01504 (18) | 0.01519 (18) | 0.00114 (8) | 0.00653 (13) | 0.00025 (8) |
Cl1 | 0.0210 (3) | 0.0198 (3) | 0.0190 (3) | 0.0017 (2) | 0.0099 (2) | −0.00171 (19) |
Cl2 | 0.0247 (4) | 0.0230 (3) | 0.0223 (3) | 0.0078 (2) | 0.0109 (2) | 0.0065 (2) |
Cl3 | 0.0205 (3) | 0.0269 (3) | 0.0200 (3) | −0.0064 (2) | 0.0079 (2) | −0.0027 (2) |
Cl4 | 0.0256 (5) | 0.0257 (4) | 0.0321 (5) | 0.000 | 0.0094 (4) | 0.000 |
N1 | 0.0258 (12) | 0.0213 (10) | 0.0208 (10) | −0.0014 (9) | 0.0087 (8) | 0.0009 (8) |
N2 | 0.0223 (12) | 0.0204 (10) | 0.0268 (10) | 0.0005 (9) | 0.0089 (9) | −0.0026 (8) |
C1 | 0.0220 (14) | 0.0225 (11) | 0.0243 (11) | −0.0018 (10) | 0.0080 (10) | −0.0009 (9) |
C2 | 0.0236 (17) | 0.0210 (14) | 0.0273 (14) | −0.0005 (9) | 0.0087 (12) | −0.0009 (8) |
C3 | 0.0200 (13) | 0.0207 (11) | 0.0294 (12) | 0.0021 (10) | 0.0100 (10) | −0.0010 (10) |
Rh1—Cl1 | 2.3450 (5) | N1—H13 | 0.8970 |
Rh1—Cl2 | 2.3494 (6) | N2—H21 | 0.9301 |
Rh1—Cl3 | 2.3420 (6) | N2—H22 | 0.9301 |
N1—C1 | 1.484 (3) | C1—H31 | 0.9002 |
N2—C2 | 1.505 (3) | C1—H32 | 0.9002 |
N2—C3 | 1.497 (3) | C2—H41 | 0.9429 |
C1—C2 | 1.524 (4) | C2—H42 | 0.9429 |
C3—C3i | 1.527 (5) | C3—H51 | 0.9563 |
N1—H11 | 0.8970 | C3—H52 | 0.9563 |
N1—H12 | 0.8970 | ||
Cl1—Rh1—Cl2 | 90.089 (19) | H21—N2—H22 | 107.6 |
Cl1—Rh1—Cl3 | 89.06 (2) | N1—C1—H31 | 109.6 |
Cl2—Rh1—Cl3 | 90.40 (2) | C2—C1—H31 | 109.6 |
N1—C1—C2 | 110.2 (2) | N1—C1—H32 | 109.6 |
C1—C2—N2 | 110.3 (2) | C2—C1—H32 | 109.6 |
C2—N2—C3 | 114.2 (2) | H31—C1—H32 | 108.1 |
N2—C3—C3i | 108.4 (2) | N2—C2—H41 | 109.6 |
C1—N1—H11 | 109.5 | C1—C2—H41 | 109.6 |
C1—N1—H12 | 109.5 | N2—C2—H42 | 109.6 |
H11—N1—H12 | 109.5 | C1—C2—H42 | 109.6 |
C1—N1—H13 | 109.5 | H41—C2—H42 | 108.1 |
H11—N1—H13 | 109.5 | N2—C3—H51 | 110.0 |
H12—N1—H13 | 109.5 | C3i—C3—H51 | 110.0 |
C3—N2—H21 | 108.7 | N2—C3—H52 | 110.0 |
C2—N2—H21 | 108.7 | C3i—C3—H52 | 110.0 |
C3—N2—H22 | 108.7 | H51—C3—H52 | 108.4 |
C2—N2—H22 | 108.7 | ||
N1—C1—C2—N2 | 162.70 (19) | C2—N2—C3—C3i | 168.2 (2) |
C3—N2—C2—C1 | 54.3 (3) |
Symmetry code: (i) −x+1, −y+2, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H12···Cl1ii | 0.90 | 2.34 | 3.213 (2) | 164 |
N1—H13···Cl3 | 0.90 | 2.45 | 3.2195 (19) | 144 |
N1—H11···Cl4 | 0.90 | 2.38 | 3.267 (2) | 169 |
N2—H21···Cl2iii | 0.93 | 2.28 | 3.165 (2) | 159 |
N2—H22···Cl4iv | 0.93 | 2.32 | 3.224 (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. |
Experimental details
Crystal data | |
Chemical formula | (C6H22N4)[RhCl6]Cl |
Mr | 501.34 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 123 |
a, b, c (Å) | 16.8062 (13), 8.7803 (8), 12.3114 (11) |
β (°) | 108.602 (9) |
V (Å3) | 1721.8 (3) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 2.07 |
Crystal size (mm) | 0.6 × 0.4 × 0.2 |
Data collection | |
Diffractometer | Stoe IPDS1 |
Absorption correction | Analytical (Sheldrick, 1997) |
Tmin, Tmax | 0.022, 0.050 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 11939, 1670, 1518 |
Rint | 0.100 |
(sin θ/λ)max (Å−1) | 0.616 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.027, 0.079, 1.04 |
No. of reflections | 1670 |
No. of parameters | 96 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 1.33, −0.48 |
Computer programs: IPDS (Stoe & Cie (2000), SHELXS97 (Sheldrick, 1997), DIAMOND (Brandenburg, 2006), SHELXL97 (Sheldrick, 1997) and enCIFer (Allen et al., 2004).
Rh1—Cl1 | 2.3450 (5) | N2—C2 | 1.505 (3) |
Rh1—Cl2 | 2.3494 (6) | N2—C3 | 1.497 (3) |
Rh1—Cl3 | 2.3420 (6) | C1—C2 | 1.524 (4) |
N1—C1 | 1.484 (3) | C3—C3i | 1.527 (5) |
Cl1—Rh1—Cl2 | 90.089 (19) | C1—C2—N2 | 110.3 (2) |
Cl1—Rh1—Cl3 | 89.06 (2) | C2—N2—C3 | 114.2 (2) |
Cl2—Rh1—Cl3 | 90.40 (2) | N2—C3—C3i | 108.4 (2) |
N1—C1—C2 | 110.2 (2) | ||
N1—C1—C2—N2 | 162.70 (19) | C2—N2—C3—C3i | 168.2 (2) |
C3—N2—C2—C1 | 54.3 (3) |
Symmetry code: (i) −x+1, −y+2, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H12···Cl1ii | 0.90 | 2.34 | 3.213 (2) | 164 |
N1—H13···Cl3 | 0.90 | 2.45 | 3.2195 (19) | 144 |
N1—H11···Cl4 | 0.90 | 2.38 | 3.267 (2) | 169 |
N2—H21···Cl2iii | 0.93 | 2.28 | 3.165 (2) | 159 |
N2—H22···Cl4iv | 0.93 | 2.32 | 3.224 (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
We thank Ms E. Hammes for technical support.
References
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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).