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

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890

A monoclinic polymorph of di­chloro­bis­(cyano­guanidine)zinc(II)

CROSSMARK_Color_square_no_text.svg

aDepartment of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, Scotland
*Correspondence e-mail: w.harrison@abdn.ac.uk

(Received 9 September 2005; accepted 13 September 2005; online 17 September 2005)

The mol­ecular title compound, β-[ZnCl2(C2H4N4)2], crytallizes as a monoclinic polymorph of the known triclinic structure of this material. A complex network of N—H⋯N and N—H⋯Cl hydrogen bonds help to establish the crystal packing.

Comment

The title compound, (I)[link] (Fig. 1[link]), crystallizes as a monoclinic polymorph (space group P21/c) of the known triclinic structure (hereafter known as the α polymorph) of this material (Pickardt & Kuhn, 1995[Pickardt, J. & Kuhn, B. (1995). Z. Kristallogr. 210, 901-901,.]). Polymorph (I)[link] contains isolated [ZnCl2(C2H4N4)2] mol­ecules, with the Zn2+ cations coordinated by two chloride ions and two cyanide N atoms of the cyano­guanidine ligands. The geometries of the zinc ions in (I)[link] (Table 1[link]) and in the α polymorph [Zn—N = 1.975 (6) and 1.977 (5)Å; Zn—Cl = 2.236 (2) and 2.2565 (17)Å] are very similar. There are no significant differences in the geometries of the organic groups in the two structures. Slight differences arise in terms of the orientation of the guanidine `arms' of the ligands. In (I)[link], the dihedral angle between the mean planes of the C2/N2/N3/N3 and C4/N6/N7/N8 groupings is 27.7 (2)°. The equivalent value of 42.7 (5)° for the α polymorph shows that these two groupings are significantly more twisted in the triclinic polymorph (data calculated with PLATON; Spek, 2003[Spek, A. L. (2003). J. Appl. Cryst. 36, 7-13.]).

[Scheme 1]

As well as van der Waals forces, the mol­ecules of (I)[link] inter­act by way of N—H⋯N and N—H⋯Cl hydrogen bonds (Table 2[link]) of varied lengths and strengths. The N—H⋯N bonds link the mol­ecules into [100] stacks of dimers and the N—H⋯Cl bonds crosslink the [100] columns into a three-dimensional network (Fig. 2[link]). Unfortunately, some of the H-atom positions in the α polymorph appear to be incorrect, so a detailed comparison of the hydrogen bonding in the two structures is not possible.

Other compounds with the stoichiometry [M(C2H4N4)2X2] (M = divalent metal cation and X = halide) include [Cd(C2H4N4)2I2] (Chiesi Villa et al., 1974[Chiesi Villa, A., Coghi, L., Manfredotti, A. G. & Guastini, C. (1974). Cryst. Struct. Commun. 3, 739-742.]) and [Cd(C2H4N4)2Br2] (Pickardt & Kuhn, 1996[Pickardt, J. & Kuhn, B. (1996). Z. Naturforsch. Teil B, 51, 1701-1706.]). Neither of these shares a structure with the zinc compounds discussed here. The iodide is mol­ecular (space group Pbcn), whereas the bromide is polymeric, via Cd—(Br,Br)—Cd bridges.

[Figure 1]
Figure 1
The mol­ecular structure of (I)[link], showing 50% displacement ellipsoids (H atoms are drawn as spheres of arbitrary radius).
[Figure 2]
Figure 2
[100] projection of the packing in (I)[link], with the ZnN2Cl2 groupings represented by polyhedra. Colour key: C black, H white, N blue, and Cl green. The H⋯N and H⋯Cl portions of the hydrogen bonds are highlighted in yellow and green, respectively.

Experimental

The following solutions were mixed at 293 K in a Petri dish, resulting in a colourless mixture: 10 ml of 0.1 M cyano­guanidine, 1 ml of 1 M ZnCl2 and 1 ml of dilute HCl. Colourless rods and bars of (I)[link] grew over the course of a few days as the water evaporated at 293 K.

Crystal data
  • [CnCl2(C4H8N8)]

  • Mr = 304.45

  • Monoclinic, P 21 /c

  • a = 4.9315 (3) Å

  • b = 14.6161 (10) Å

  • c = 15.5026 (11) Å

  • β = 93.928 (2)°

  • V = 1114.79 (13) Å3

  • Z = 4

  • Dx = 1.814 Mg m−3

  • Mo Kα radiation

  • Cell parameters from 2094 reflections

  • θ = 2.6–26.8°

  • μ = 2.66 mm−1

  • T = 293 (2) K

  • Bar, colourless

  • 0.31 × 0.08 × 0.02 mm

Data collection
  • Bruker SMART1000 CCD diffractometer

  • ω scans

  • Absorption correction: multi-scan(SADABS; Bruker, 1999[Bruker (1999). SMART (Version 5.624), SAINT-Plus (Version 6.02A) and SADABS (Version 2.03). Bruker AXS Inc., Madison, Wisconsin, USA.])Tmin = 0.495, Tmax = 0.950

  • 7331 measured reflections

  • 2444 independent reflections

  • 1610 reflections with I > 2σ(I)

  • Rint = 0.051

  • θmax = 27.0°

  • h = −6 → 6

  • k = −18 → 13

  • l = −19 → 19

Refinement
  • Refinement on F2

  • R[F2 > 2σ(F2)] = 0.035

  • wR(F2) = 0.077

  • S = 0.91

  • 2444 reflections

  • 136 parameters

  • H-atom parameters constrained

  • w = 1/[σ2(Fo2) + (0.0345P)2] where P = (Fo2 + 2Fc2)/3

  • (Δ/σ)max = 0.001

  • Δρmax = 0.38 e Å−3

  • Δρmin = −0.34 e Å−3

Table 1
Selected geometric parameters (Å, °)[link]

Zn1—N1 1.974 (3)
Zn1—N5 1.984 (3)
Zn1—Cl2 2.2302 (10)
Zn1—Cl1 2.2664 (10)
C1—N1—Zn1 166.5 (3)
C3—N5—Zn1 174.2 (3)

Table 2
Hydrogen-bond geometry (Å, °)[link]

D—H⋯A D—H H⋯A DA D—H⋯A
N4—H3⋯N6i 0.86 2.46 3.082 (4) 130
N4—H4⋯N2ii 0.86 2.31 3.156 (4) 168
N3—H1⋯Cl1iii 0.86 2.57 3.365 (3) 155
N4—H3⋯Cl1iii 0.86 2.77 3.520 (3) 147
N7—H5⋯Cl2iv 0.86 2.47 3.282 (3) 158
N7—H6⋯Cl1v 0.86 2.56 3.368 (3) 156
N8—H7⋯Cl2iv 0.86 2.63 3.402 (3) 151
N8—H8⋯Cl1vi 0.86 2.50 3.322 (3) 160
Symmetry codes: (i) -x+2, -y, -z+1; (ii) -x+3, -y, -z+1; (iii) [x+1, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]; (iv) [x-1, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]; (v) x-1, y, z; (vi) [-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}].

The H atoms were placed in idealized positions (N—H = 0.86Å) and refined as riding with the constraint Uiso(H) = 1.2Ueq(N) applied.

Data collection: SMART (Bruker, 1999[Bruker (1999). SMART (Version 5.624), SAINT-Plus (Version 6.02A) and SADABS (Version 2.03). Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT-Plus (Bruker, 1999[Bruker (1999). SMART (Version 5.624), SAINT-Plus (Version 6.02A) and SADABS (Version 2.03). Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.]); molecular graphics: ORTEP3 (Farrugia, 1997[Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.]); software used to prepare material for publication: SHELXL97.

Supporting information


Comment top

The title compound, (I) (Fig. 1), crystallizes as a monoclinic polymorph (space group P21/c) of the known triclinic structure (hereafter known as the α polymorph) of this material (Pickardt & Kuhn, 1995). Polymorph (I) contains isolated [ZnCl2(C2H4N4)2] molecules, with the Zn2+ cations coordinated by two chloride ions and two cyanide N atoms of the cyanoguanidine ligands. The geometries of the zinc ions in (I) (Table 1) and in the α polymorph [Zn—N = 1.975 (6) and 1.977 (5) Å; Zn—Cl = 2.236 (2) and 2.2565 (17) Å] are very similar. There are no significant differences in the geometries of the organic groups in the two structures. Slight differences arise in terms of the orientation of the guanidine `arms' of the ligands. In (I), the dihedral angle between the mean planes of the C2/N2/N3/N3 and C4/N6/N7/N8 groupings is 27.7 (2)°. The equivalent value of 42.7 (5)° for the α polymorph shows that these two groupings are significantly more twisted in the triclinic polymorph (data calculated with PLATON; Spek, 2003).

As well as van der Waals forces, the molecules of (I) interact by way of N—H···N and N—H···Cl hydrogen bonds (Table 2) of varied lengths and strengths. The N—H···N bonds link the molecules into [100] stacks of dimers and the N—H···Cl bonds crosslink the [100] columns into a three-dimensional network (Fig. 2). Unfortunately, some of the H-atom positions in the α polymorph appear to be incorrect, so a detailed comparison of the hydrogen bonding in the two structures is not possible.

Other compounds with the stoichiometry M(C2H4N4)2X2 (M = divalent metal cation and X = halide) include Cd(C2H4N4)2I2 (Chiesi Villa et al., 1974) and Cd(C2H4N4)2Br2 (Pickardt & Kuhn, 1996). Neither of these shares a structure with the zinc compounds discussed here. The iodide is molecular (space group Pbcn), whereas the bromide is polymeric, via Cd—(Br,Br)—Cd bridges.

Experimental top

The following solutions were mixed at 293 K in a Petri dish, resulting in a colourless mixture: 10 ml of 0.1 M cyanoguanidine, 1 ml of 1 M ZnCl2 and 1 ml of dilute HCl. Colourless rods and bars of (I) grew over the course of a few days as the water evaporated at 293 K.

Refinement top

The H atoms were placed in idealized positions (N—H = 0.86 Å) and refined as riding with the constraint Uiso(H) = 1.2Ueq(N) applied.

Computing details top

Data collection: SMART (Bruker, 1999); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), showing 50% displacement ellipsoids (H atoms are drawn as spheres of arbitrary radius).
[Figure 2] Fig. 2. [100] projection of the packing in (I), with the ZnN2Cl2 groupings represented by polyhedra. Colour key: C black, H white, N blue, and Cl green. The H···N and H···Cl portions of the hydrogen bonds are highlighted in yellow and green, respectively.
dichlorobis(cyanoguanidine)zinc(II) top
Crystal data top
[CnCl2(C4H8N8)]F(000) = 608
Mr = 304.45Dx = 1.814 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 2094 reflections
a = 4.9315 (3) Åθ = 2.6–26.8°
b = 14.6161 (10) ŵ = 2.66 mm1
c = 15.5026 (11) ÅT = 293 K
β = 93.928 (2)°Bar, colourless
V = 1114.79 (13) Å30.31 × 0.08 × 0.02 mm
Z = 4
Data collection top
Bruker SMART1000 CCD
diffractometer
2444 independent reflections
Radiation source: fine-focus sealed tube1610 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.051
ω scansθmax = 27.0°, θmin = 1.9°
Absorption correction: multi-scan
(SADABS; Bruker, 1999)
h = 66
Tmin = 0.495, Tmax = 0.950k = 1813
7331 measured reflectionsl = 1919
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)] = 0.035Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.077H-atom parameters constrained
S = 0.91 w = 1/[σ2(Fo2) + (0.0345P)2]
where P = (Fo2 + 2Fc2)/3
2444 reflections(Δ/σ)max = 0.001
136 parametersΔρmax = 0.38 e Å3
0 restraintsΔρmin = 0.34 e Å3
Crystal data top
[CnCl2(C4H8N8)]V = 1114.79 (13) Å3
Mr = 304.45Z = 4
Monoclinic, P21/cMo Kα radiation
a = 4.9315 (3) ŵ = 2.66 mm1
b = 14.6161 (10) ÅT = 293 K
c = 15.5026 (11) Å0.31 × 0.08 × 0.02 mm
β = 93.928 (2)°
Data collection top
Bruker SMART1000 CCD
diffractometer
2444 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 1999)
1610 reflections with I > 2σ(I)
Tmin = 0.495, Tmax = 0.950Rint = 0.051
7331 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0350 restraints
wR(F2) = 0.077H-atom parameters constrained
S = 0.91Δρmax = 0.38 e Å3
2444 reflectionsΔρmin = 0.34 e Å3
136 parameters
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
Zn10.57190 (7)0.26684 (3)0.41448 (2)0.03114 (12)
Cl10.77571 (18)0.35115 (6)0.31465 (5)0.0421 (2)
Cl20.35476 (17)0.35081 (7)0.50813 (6)0.0427 (2)
N10.8270 (5)0.1795 (2)0.47356 (17)0.0377 (7)
C11.0125 (7)0.1372 (2)0.4988 (2)0.0305 (7)
N21.2201 (5)0.0859 (2)0.52099 (17)0.0358 (7)
C21.3399 (7)0.0944 (2)0.6013 (2)0.0324 (8)
N31.2696 (6)0.1547 (2)0.65774 (19)0.0515 (9)
H11.35420.15690.70810.062*
H21.13870.19210.64460.062*
N41.5405 (6)0.0377 (2)0.62248 (18)0.0463 (8)
H31.62370.04050.67300.056*
H41.58850.00230.58580.056*
N50.3319 (6)0.1889 (2)0.33726 (18)0.0390 (7)
C30.2135 (7)0.1398 (2)0.2928 (2)0.0328 (8)
N60.1010 (6)0.0754 (2)0.2464 (2)0.0501 (9)
C40.0951 (7)0.0945 (3)0.1849 (2)0.0374 (8)
N70.2052 (6)0.1752 (2)0.17497 (18)0.0440 (8)
H50.32770.18470.13380.053*
H60.15550.21890.20970.053*
N80.1731 (7)0.0286 (2)0.1315 (2)0.0587 (10)
H70.29570.03880.09050.070*
H80.10160.02490.13750.070*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Zn10.0351 (2)0.0310 (2)0.02591 (19)0.00114 (19)0.00776 (14)0.00054 (18)
Cl10.0544 (5)0.0371 (6)0.0336 (5)0.0095 (4)0.0057 (4)0.0064 (4)
Cl20.0458 (5)0.0462 (6)0.0349 (5)0.0078 (4)0.0073 (4)0.0088 (4)
N10.0362 (15)0.0371 (19)0.0380 (16)0.0058 (14)0.0092 (13)0.0066 (14)
C10.0336 (17)0.033 (2)0.0238 (16)0.0042 (15)0.0018 (14)0.0007 (14)
N20.0376 (15)0.0360 (18)0.0323 (15)0.0105 (13)0.0083 (12)0.0020 (13)
C20.0345 (16)0.033 (2)0.0289 (17)0.0001 (15)0.0026 (14)0.0023 (15)
N30.0550 (18)0.063 (3)0.0347 (17)0.0247 (17)0.0107 (15)0.0110 (16)
N40.0561 (18)0.044 (2)0.0356 (17)0.0196 (16)0.0203 (14)0.0042 (14)
N50.0400 (15)0.040 (2)0.0350 (16)0.0022 (14)0.0094 (13)0.0020 (14)
C30.0372 (17)0.031 (2)0.0291 (17)0.0031 (15)0.0086 (15)0.0076 (15)
N60.065 (2)0.0292 (19)0.0513 (19)0.0025 (15)0.0324 (17)0.0066 (15)
C40.0428 (19)0.034 (2)0.0335 (18)0.0035 (16)0.0102 (16)0.0018 (16)
N70.0536 (17)0.038 (2)0.0375 (17)0.0079 (15)0.0196 (14)0.0067 (14)
N80.072 (2)0.037 (2)0.061 (2)0.0068 (17)0.0378 (19)0.0153 (17)
Geometric parameters (Å, º) top
Zn1—N11.974 (3)N4—H30.860
Zn1—N51.984 (3)N4—H40.860
Zn1—Cl22.2302 (10)N5—C31.130 (4)
Zn1—Cl12.2664 (10)C3—N61.287 (4)
N1—C11.150 (4)N6—C41.340 (4)
C1—N21.296 (4)C4—N71.303 (5)
N2—C21.347 (4)C4—N81.310 (4)
C2—N31.305 (4)N7—H50.860
C2—N41.315 (4)N7—H60.860
N3—H10.860N8—H70.860
N3—H20.860N8—H80.860
N1—Zn1—N5104.10 (13)C2—N4—H3120.0
N1—Zn1—Cl2111.92 (9)C2—N4—H4120.0
N5—Zn1—Cl2114.55 (9)H3—N4—H4120.0
N1—Zn1—Cl1111.74 (9)C3—N5—Zn1174.2 (3)
N5—Zn1—Cl1100.03 (9)N5—C3—N6172.2 (4)
Cl2—Zn1—Cl1113.61 (4)C3—N6—C4120.5 (3)
C1—N1—Zn1166.5 (3)N7—C4—N8119.3 (3)
N1—C1—N2175.1 (4)N7—C4—N6123.1 (3)
C1—N2—C2118.7 (3)N8—C4—N6117.5 (3)
N3—C2—N4119.2 (3)C4—N7—H5120.0
N3—C2—N2124.2 (3)C4—N7—H6120.0
N4—C2—N2116.5 (3)H5—N7—H6120.0
C2—N3—H1120.0C4—N8—H7120.0
C2—N3—H2120.0C4—N8—H8120.0
H1—N3—H2120.0H7—N8—H8120.0
N5—Zn1—N1—C1112.9 (12)C1—N2—C2—N33.6 (5)
Cl2—Zn1—N1—C1122.8 (12)C1—N2—C2—N4176.5 (3)
Cl1—Zn1—N1—C15.9 (13)C3—N6—C4—N8170.1 (4)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N4—H3···N6i0.862.463.082 (4)130
N4—H4···N2ii0.862.313.156 (4)168
N3—H1···Cl1iii0.862.573.365 (3)155
N4—H3···Cl1iii0.862.773.520 (3)147
N7—H5···Cl2iv0.862.473.282 (3)158
N7—H6···Cl1v0.862.563.368 (3)156
N8—H7···Cl2iv0.862.633.402 (3)151
N8—H8···Cl1vi0.862.503.322 (3)160
Symmetry codes: (i) x+2, y, z+1; (ii) x+3, y, z+1; (iii) x+1, y+1/2, z+1/2; (iv) x1, y+1/2, z1/2; (v) x1, y, z; (vi) x+1, y1/2, z+1/2.

Experimental details

Crystal data
Chemical formula[CnCl2(C4H8N8)]
Mr304.45
Crystal system, space groupMonoclinic, P21/c
Temperature (K)293
a, b, c (Å)4.9315 (3), 14.6161 (10), 15.5026 (11)
β (°) 93.928 (2)
V3)1114.79 (13)
Z4
Radiation typeMo Kα
µ (mm1)2.66
Crystal size (mm)0.31 × 0.08 × 0.02
Data collection
DiffractometerBruker SMART1000 CCD
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 1999)
Tmin, Tmax0.495, 0.950
No. of measured, independent and
observed [I > 2σ(I)] reflections
7331, 2444, 1610
Rint0.051
(sin θ/λ)max1)0.639
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.035, 0.077, 0.91
No. of reflections2444
No. of parameters136
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.38, 0.34

Computer programs: SMART (Bruker, 1999), SAINT (Bruker, 1999), SAINT, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-3 (Farrugia, 1997), SHELXL97.

Selected geometric parameters (Å, º) top
Zn1—N11.974 (3)Zn1—Cl22.2302 (10)
Zn1—N51.984 (3)Zn1—Cl12.2664 (10)
C1—N1—Zn1166.5 (3)C3—N5—Zn1174.2 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N4—H3···N6i0.862.463.082 (4)130
N4—H4···N2ii0.862.313.156 (4)168
N3—H1···Cl1iii0.862.573.365 (3)155
N4—H3···Cl1iii0.862.773.520 (3)147
N7—H5···Cl2iv0.862.473.282 (3)158
N7—H6···Cl1v0.862.563.368 (3)156
N8—H7···Cl2iv0.862.633.402 (3)151
N8—H8···Cl1vi0.862.503.322 (3)160
Symmetry codes: (i) x+2, y, z+1; (ii) x+3, y, z+1; (iii) x+1, y+1/2, z+1/2; (iv) x1, y+1/2, z1/2; (v) x1, y, z; (vi) x+1, y1/2, z+1/2.
 

References

First citationBruker (1999). SMART (Version 5.624), SAINT-Plus (Version 6.02A) and SADABS (Version 2.03). Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationChiesi Villa, A., Coghi, L., Manfredotti, A. G. & Guastini, C. (1974). Cryst. Struct. Commun. 3, 739–742.  CAS Google Scholar
First citationFarrugia, L. J. (1997). J. Appl. Cryst. 30, 565.  CrossRef IUCr Journals Google Scholar
First citationPickardt, J. & Kuhn, B. (1995). Z. Kristallogr. 210, 901–901,.  CrossRef CAS Web of Science Google Scholar
First citationPickardt, J. & Kuhn, B. (1996). Z. Naturforsch. Teil B, 51, 1701–1706.  CAS Google Scholar
First citationSheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.  Google Scholar
First citationSpek, A. L. (2003). J. Appl. Cryst. 36, 7–13.  Web of Science CrossRef CAS IUCr Journals Google Scholar

© International Union of Crystallography. Prior permission is not required to reproduce short quotations, tables and figures from this article, provided the original authors and source are cited. For more information, click here.

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