metal-organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890

Poly[1,4-bis­­(ammonio­meth­yl)cyclo­hexane [di-μ-bromido-di­bromido­plumbate(II)]]

aMolecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Private Bag 3, PO Wits 2050, South Africa
*Correspondence e-mail: david.billing@wits.ac.za

(Received 27 April 2010; accepted 7 May 2010; online 15 May 2010)

The title compound, {(C8H20N2)[PbBr4]}n, crystallizes as an inorganic–organic hybrid with alternating layers of diammonium cations and two-dimensional corner-sharing PbBr6 octa­hedra extending parallel to the bc plane, which are eclipsed relative to one another. Both PbBr6 octa­hedra and the organic cation exhibit [\overline{1}] symmetry. The cations inter­act via N—H⋯Br hydrogen bonding in the right-angled halogen sub-type of the terminal halide hydrogen-bonding motif.

Related literature

For hydrogen-bonding nomenclature for inorganic–organic hybrids, see: Mitzi (1999[Mitzi, D. B. (1999). Prog. Inorg. Chem. 48, 1-121.]). Hybrid structures containing diammonium cations have been synthesized by Dobrzycki & Woźniak (2008[Dobrzycki, L. & Woźniak, K. (2008). CrystEngComm, 10, 577-589.]) and Zhu et al. (2003[Zhu, X., Mercier, N., Frère, P., Blanchard, P., Roncali, J., Allain, M., Pasquier, C. & Riou, A. (2003). Inorg. Chem. 42, 5330-5339.]). The semiconducting properties of similar hybrids were demonstrated by Mitzi (2004[Mitzi, D. B. (2004). J. Mater. Chem. 14, 2355-2365.]). For the related chloridoplumbate(II), see: Rayner & Billing (2010a[Rayner, M. K. & Billing, D. G. (2010a). Acta Cryst. E66, m659.]) and for the isotypic iodidoplumbate(II), see: Rayner & Billing (2010b[Rayner, M. K. & Billing, D. G. (2010b). Acta Cryst. E66, m660.]).

[Scheme 1]

Experimental

Crystal data
  • (C8H20N2)[PbBr4]

  • Mr = 671.09

  • Monoclinic, P 21 /c

  • a = 12.1042 (6) Å

  • b = 8.1955 (4) Å

  • c = 8.2160 (4) Å

  • β = 95.693 (1)°

  • V = 811.01 (7) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 20.23 mm−1

  • T = 173 K

  • 0.20 × 0.14 × 0.02 mm

Data collection
  • Bruker APEXII CCD area-detector diffractometer

  • Absorption correction: integration (XPREP; Bruker, 2005[Bruker (2005). APEX2, SAINT and XPREP. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.091, Tmax = 0.656

  • 10495 measured reflections

  • 1966 independent reflections

  • 1742 reflections with I > 2σ(I)

  • Rint = 0.063

Refinement
  • R[F2 > 2σ(F2)] = 0.021

  • wR(F2) = 0.047

  • S = 0.81

  • 1966 reflections

  • 70 parameters

  • H-atom parameters constrained

  • Δρmax = 0.78 e Å−3

  • Δρmin = −2.31 e Å−3

Table 1
Selected bond lengths (Å)

Pb1—Br2i 2.9821 (3)
Pb1—Br2ii 2.9886 (3)
Pb1—Br1i 3.0054 (4)
Symmetry codes: (i) -x+1, -y, -z; (ii) [x, -y+{\script{1\over 2}}, z+{\script{1\over 2}}].

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
N1—H1C⋯Br2i 0.91 2.54 3.387 (3) 154
N1—H1D⋯Br1ii 0.91 2.57 3.378 (3) 148
N1—H1D⋯Br2iii 0.91 2.94 3.446 (3) 117
N1—H1E⋯Br1 0.91 2.60 3.357 (3) 141
Symmetry codes: (i) -x+1, -y, -z; (ii) [x, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]; (iii) x, y, z+1.

Data collection: APEX2 (Bruker, 2005[Bruker (2005). APEX2, SAINT and XPREP. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2005[Bruker (2005). APEX2, SAINT and XPREP. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997[Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.]) and DIAMOND (Brandenburg, 1999[Brandenburg, K. (1999). DIAMOND. Crystal Impact GbR, Bonn, Germany.]); software used to prepare material for publication: WinGX (Farrugia, 1999[Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837-838.]) and PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]).

Supporting information


Comment top

Inorganic-organic hybrid materials are of interest due to their electronic and fluorescent properties (Mitzi, 2004). The title structure (Fig. 1) is one of three 2-dimensional hybrid structures that we have synthesized encorporating this diammonium cation. The structures differ in terms of their halogen ligands, which include bromide (presented here), chloride (Rayner & Billing, 2010a) and iodide (Rayner & Billing, 2010b). The bromide and iodide hybrids crystallize in the monoclinic crystal system in space group P21/c while the chloride compound crystallizes in the orthorhombic Pnma system.

In the title structure the lead atoms in the PbBr6 octahedra occupy inversion centers, giving the octahedra 1 symmetry. The PbBr6 octahedra share corners to form layers extending parallel to the bc plane. Octahedra from alternate layers are eclipsed relative to one another (Fig. 2). In all three structures only the trans form of the cation has been observed giving the cation 1 symmetry (Fig. 3). Very few inorganic-organic hybrid structures encorporating diammonium cations have been reported (Dobrzycki & Woźniak, 2008; Zhu et al., 2003). The ammonium cations interact with the inorganic layer via N—H···X (X = Br, I and Cl) hydrogen bonding in the right-angled halogen subtype of the terminal halide hydrogen bonding motif (Mitzi, 1999).

Related literature top

For hydrogen-bonding nomenclature for inorganic–organic hybrids, see: Mitzi (1999). Hybrid structures containing diammonium cations have been synthesized by Dobrzycki & Woźniak (2008) and Zhu et al. (2003). The semiconducting properties of similar hybrids were demonstrated by Mitzi (2004). For the related chloridoplumbate(II), see: Rayner & Billing (2010a) and for the isotypic iodidoplumbate(II), see: Rayner & Billing (2010b).

Experimental top

A mixture of 0.050 g (0.14 mmol) PbBr2 and 0.021 g (0.15 mmol) 1,4-bis-(aminomethyl)-cyclohexane (mixture of isomers) was dissolved in 5 ml HBr at 383 K and slowly cooled at a rate of 0.069 K/min to yield colourless, plate-shaped single crystals suitable for X-ray analysis.

Refinement top

The H atoms on the diammonium cation were refined using a riding-model, with C—H = 0.99 Å, N—H = 0.91 Å and with Uiso(H)=1.2Ueq(C) or 1.5Ueq(N). The highest residual electron density peak (0.78 e Å-3) was 0.923Å from Pb1.

Structure description top

Inorganic-organic hybrid materials are of interest due to their electronic and fluorescent properties (Mitzi, 2004). The title structure (Fig. 1) is one of three 2-dimensional hybrid structures that we have synthesized encorporating this diammonium cation. The structures differ in terms of their halogen ligands, which include bromide (presented here), chloride (Rayner & Billing, 2010a) and iodide (Rayner & Billing, 2010b). The bromide and iodide hybrids crystallize in the monoclinic crystal system in space group P21/c while the chloride compound crystallizes in the orthorhombic Pnma system.

In the title structure the lead atoms in the PbBr6 octahedra occupy inversion centers, giving the octahedra 1 symmetry. The PbBr6 octahedra share corners to form layers extending parallel to the bc plane. Octahedra from alternate layers are eclipsed relative to one another (Fig. 2). In all three structures only the trans form of the cation has been observed giving the cation 1 symmetry (Fig. 3). Very few inorganic-organic hybrid structures encorporating diammonium cations have been reported (Dobrzycki & Woźniak, 2008; Zhu et al., 2003). The ammonium cations interact with the inorganic layer via N—H···X (X = Br, I and Cl) hydrogen bonding in the right-angled halogen subtype of the terminal halide hydrogen bonding motif (Mitzi, 1999).

For hydrogen-bonding nomenclature for inorganic–organic hybrids, see: Mitzi (1999). Hybrid structures containing diammonium cations have been synthesized by Dobrzycki & Woźniak (2008) and Zhu et al. (2003). The semiconducting properties of similar hybrids were demonstrated by Mitzi (2004). For the related chloridoplumbate(II), see: Rayner & Billing (2010a) and for the isotypic iodidoplumbate(II), see: Rayner & Billing (2010b).

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and DIAMOND (Brandenburg, 1999); software used to prepare material for publication: WinGX (Farrugia, 1999) and PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. The asymmetric unit of the title compound with atom labels. Displacement ellipsoids were drawn at the 50% probability level. Symmetry codes: (a) 1-x, 1/2+y, 1/2-z (b) 1-x, 1-y, 1-z (c) x, 1/2-y, 1/2+z (d) -x, 1-y, 2-z.
[Figure 2] Fig. 2. Packing diagram viewed along the a axis. Hydrogen bonds are drawn as dashed red lines.
[Figure 3] Fig. 3. Packing diagram viewed along the b axis. Hydrogen bonds are drawn as dashed red lines.
Poly[1,4-bis(ammoniomethyl)cyclohexane [di-µ-bromido-dibromidoplumbate(II)]] top
Crystal data top
(C8H20N2)[PbBr4]F(000) = 608
Mr = 671.09Dx = 2.748 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 5293 reflections
a = 12.1042 (6) Åθ = 3.0–28.2°
b = 8.1955 (4) ŵ = 20.23 mm1
c = 8.2160 (4) ÅT = 173 K
β = 95.693 (1)°Plate, colourless
V = 811.01 (7) Å30.20 × 0.14 × 0.02 mm
Z = 2
Data collection top
Bruker APEXII CCD area-detector
diffractometer
1966 independent reflections
Radiation source: fine-focus sealed tube1742 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.063
φ and ω scansθmax = 28.0°, θmin = 1.7°
Absorption correction: integration
(XPREP; Bruker, 2005)
h = 1515
Tmin = 0.091, Tmax = 0.656k = 1010
10495 measured reflectionsl = 1010
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)] = 0.021Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.047H-atom parameters constrained
S = 0.81 w = 1/[σ2(Fo2) + (0.0349P)2 + 0.0549P]
where P = (Fo2 + 2Fc2)/3
1966 reflections(Δ/σ)max = 0.011
70 parametersΔρmax = 0.78 e Å3
0 restraintsΔρmin = 2.31 e Å3
Crystal data top
(C8H20N2)[PbBr4]V = 811.01 (7) Å3
Mr = 671.09Z = 2
Monoclinic, P21/cMo Kα radiation
a = 12.1042 (6) ŵ = 20.23 mm1
b = 8.1955 (4) ÅT = 173 K
c = 8.2160 (4) Å0.20 × 0.14 × 0.02 mm
β = 95.693 (1)°
Data collection top
Bruker APEXII CCD area-detector
diffractometer
1966 independent reflections
Absorption correction: integration
(XPREP; Bruker, 2005)
1742 reflections with I > 2σ(I)
Tmin = 0.091, Tmax = 0.656Rint = 0.063
10495 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0210 restraints
wR(F2) = 0.047H-atom parameters constrained
S = 0.81Δρmax = 0.78 e Å3
1966 reflectionsΔρmin = 2.31 e Å3
70 parameters
Special details top

Experimental. Numerical intergration absorption corrections based on indexed crystal faces were applied using the XPREP routine (Bruker, 2005)

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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
C10.2360 (3)0.0472 (4)0.4803 (5)0.0262 (8)
H1A0.27980.07110.58580.031*
H1B0.22820.14980.41660.031*
C20.1224 (3)0.0131 (4)0.5124 (4)0.0216 (8)
H20.13250.10950.58710.026*
C30.0636 (3)0.1206 (4)0.6011 (4)0.0257 (8)
H3A0.05580.21920.53120.031*
H3B0.10930.14990.70350.031*
C40.0501 (3)0.0661 (5)0.3589 (4)0.0247 (7)
H4A0.08690.15690.30580.030*
H4B0.04190.02610.28070.030*
N10.2966 (2)0.0758 (4)0.3879 (4)0.0230 (6)
H1C0.36440.03560.37000.035*
H1D0.30540.16950.44730.035*
H1E0.25690.09720.29040.035*
Br10.25157 (3)0.02969 (4)0.01928 (4)0.02426 (9)
Br20.50023 (3)0.18890 (4)0.31018 (4)0.02370 (9)
Pb10.50000.00000.00000.01590 (6)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.024 (2)0.0232 (17)0.0322 (19)0.0000 (15)0.0076 (16)0.0042 (14)
C20.024 (2)0.0206 (17)0.0210 (17)0.0015 (13)0.0039 (15)0.0010 (12)
C30.0206 (19)0.0285 (18)0.0277 (18)0.0035 (15)0.0011 (15)0.0101 (14)
C40.0213 (19)0.0285 (18)0.0246 (17)0.0011 (15)0.0040 (14)0.0042 (14)
N10.0203 (16)0.0229 (15)0.0267 (15)0.0014 (12)0.0065 (12)0.0019 (12)
Br10.0241 (2)0.02380 (17)0.02478 (17)0.00282 (13)0.00175 (14)0.00035 (12)
Br20.0311 (2)0.02090 (17)0.01975 (16)0.00481 (13)0.00579 (13)0.00695 (12)
Pb10.02093 (10)0.01395 (9)0.01320 (9)0.00121 (6)0.00358 (6)0.00007 (5)
Geometric parameters (Å, º) top
C1—N11.497 (4)C4—H4B0.9900
C1—C21.509 (5)N1—H1C0.9100
C1—H1A0.9900N1—H1D0.9100
C1—H1B0.9900N1—H1E0.9100
C2—C31.531 (4)Br1—Pb13.0054 (4)
C2—C41.526 (5)Br2—Pb12.9821 (3)
C2—H21.0000Br2—Pb1ii2.9886 (3)
C3—C4i1.514 (5)Pb1—Br2iii2.9821 (3)
C3—H3A0.9900Pb1—Br2iv2.9886 (3)
C3—H3B0.9900Pb1—Br2v2.9886 (3)
C4—C3i1.514 (5)Pb1—Br1iii3.0054 (4)
C4—H4A0.9900
N1—C1—C2111.7 (3)H4A—C4—H4B108.0
N1—C1—H1A109.3C1—N1—H1C109.5
C2—C1—H1A109.3C1—N1—H1D109.5
N1—C1—H1B109.3H1C—N1—H1D109.5
C2—C1—H1B109.3C1—N1—H1E109.5
H1A—C1—H1B108.0H1C—N1—H1E109.5
C1—C2—C3108.9 (3)H1D—N1—H1E109.5
C1—C2—C4114.0 (3)Pb1—Br2—Pb1ii152.724 (12)
C3—C2—C4110.0 (3)Br2iii—Pb1—Br2180.000 (11)
C1—C2—H2107.9Br2iii—Pb1—Br2iv89.827 (4)
C3—C2—H2107.9Br2—Pb1—Br2iv90.173 (4)
C4—C2—H2107.9Br2iii—Pb1—Br2v90.173 (4)
C4i—C3—C2111.6 (3)Br2—Pb1—Br2v89.827 (4)
C4i—C3—H3A109.3Br2iv—Pb1—Br2v180.000 (15)
C2—C3—H3A109.3Br2iii—Pb1—Br190.075 (10)
C4i—C3—H3B109.3Br2—Pb1—Br189.925 (10)
C2—C3—H3B109.3Br2iv—Pb1—Br184.697 (10)
H3A—C3—H3B108.0Br2v—Pb1—Br195.303 (10)
C3i—C4—C2111.3 (3)Br2iii—Pb1—Br1iii89.925 (10)
C3i—C4—H4A109.4Br2—Pb1—Br1iii90.075 (10)
C2—C4—H4A109.4Br2iv—Pb1—Br1iii95.303 (10)
C3i—C4—H4B109.4Br2v—Pb1—Br1iii84.697 (10)
C2—C4—H4B109.4Br1—Pb1—Br1iii180.000 (13)
N1—C1—C2—C3177.9 (3)C3—C2—C4—C3i55.8 (4)
N1—C1—C2—C454.7 (4)Pb1ii—Br2—Pb1—Br2iv0.28 (4)
C1—C2—C3—C4i178.5 (3)Pb1ii—Br2—Pb1—Br2v179.72 (4)
C4—C2—C3—C4i56.0 (4)Pb1ii—Br2—Pb1—Br184.42 (3)
C1—C2—C4—C3i178.4 (3)Pb1ii—Br2—Pb1—Br1iii95.58 (3)
Symmetry codes: (i) x, y, z+1; (ii) x+1, y+1/2, z1/2; (iii) x+1, y, z; (iv) x, y+1/2, z+1/2; (v) x+1, y1/2, z1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1C···Br2iii0.912.543.387 (3)154
N1—H1D···Br1iv0.912.573.378 (3)148
N1—H1D···Br2vi0.912.943.446 (3)117
N1—H1E···Br10.912.603.357 (3)141
Symmetry codes: (iii) x+1, y, z; (iv) x, y+1/2, z+1/2; (vi) x, y, z+1.

Experimental details

Crystal data
Chemical formula(C8H20N2)[PbBr4]
Mr671.09
Crystal system, space groupMonoclinic, P21/c
Temperature (K)173
a, b, c (Å)12.1042 (6), 8.1955 (4), 8.2160 (4)
β (°) 95.693 (1)
V3)811.01 (7)
Z2
Radiation typeMo Kα
µ (mm1)20.23
Crystal size (mm)0.20 × 0.14 × 0.02
Data collection
DiffractometerBruker APEXII CCD area-detector
Absorption correctionIntegration
(XPREP; Bruker, 2005)
Tmin, Tmax0.091, 0.656
No. of measured, independent and
observed [I > 2σ(I)] reflections
10495, 1966, 1742
Rint0.063
(sin θ/λ)max1)0.660
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.021, 0.047, 0.81
No. of reflections1966
No. of parameters70
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.78, 2.31

Computer programs: APEX2 (Bruker, 2005), SAINT (Bruker, 2005), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997) and DIAMOND (Brandenburg, 1999), WinGX (Farrugia, 1999) and PLATON (Spek, 2009).

Selected bond lengths (Å) top
Pb1—Br2i2.9821 (3)Pb1—Br1i3.0054 (4)
Pb1—Br2ii2.9886 (3)
Symmetry codes: (i) x+1, y, z; (ii) x, y+1/2, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1C···Br2i0.912.543.387 (3)154.4
N1—H1D···Br1ii0.912.573.378 (3)148.0
N1—H1D···Br2iii0.912.943.446 (3)116.9
N1—H1E···Br10.912.603.357 (3)141.3
Symmetry codes: (i) x+1, y, z; (ii) x, y+1/2, z+1/2; (iii) x, y, z+1.
 

Acknowledgements

The University of the Witwatersrand and the National Research Fund (GUN: 2069064) are acknowledged for the funding and infrastructure required to perform the experiment.

References

First citationBrandenburg, K. (1999). DIAMOND. Crystal Impact GbR, Bonn, Germany.  Google Scholar
First citationBruker (2005). APEX2, SAINT and XPREP. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationDobrzycki, L. & Woźniak, K. (2008). CrystEngComm, 10, 577–589.  Web of Science CSD CrossRef CAS Google Scholar
First citationFarrugia, L. J. (1997). J. Appl. Cryst. 30, 565.  CrossRef IUCr Journals Google Scholar
First citationFarrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838.  CrossRef CAS IUCr Journals Google Scholar
First citationMitzi, D. B. (1999). Prog. Inorg. Chem. 48, 1–121.  Web of Science CrossRef CAS Google Scholar
First citationMitzi, D. B. (2004). J. Mater. Chem. 14, 2355–2365.  Web of Science CrossRef CAS Google Scholar
First citationRayner, M. K. & Billing, D. G. (2010a). Acta Cryst. E66, m659.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationRayner, M. K. & Billing, D. G. (2010b). Acta Cryst. E66, m660.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationSpek, A. L. (2009). Acta Cryst. D65, 148–155.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationZhu, X., Mercier, N., Frère, P., Blanchard, P., Roncali, J., Allain, M., Pasquier, C. & Riou, A. (2003). Inorg. Chem. 42, 5330–5339.  Web of Science CSD CrossRef PubMed CAS Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Follow Acta Cryst. E
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds