PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of actaeInternational Union of Crystallographysearchopen accessarticle submissionjournal home pagethis article
 
Acta Crystallogr Sect E Struct Rep Online. 2010 January 1; 66(Pt 1): m71.
Published online 2009 December 16. doi:  10.1107/S1600536809052933
PMCID: PMC2980076

{μ-trans-N,N′-Bis[2-(2-hydroxy­ethyl­amino)eth­yl]oxamidato(2−)}bis­[picrato­nickel(II)]

Abstract

The title complex, [Ni2(C6H2N3O7)2(C10H20N4O4)], contains a centrosymmetric binuclear unit in which the oxamide ligand (located on a centre of symmetry) acts in a bis-­tetra­dentate fashion and the picrate anion binds to nickel(II) in a bidentate mode. The NiII atom displays a distorted octa­hedral coordination with axial elongation. The binuclear mol­ecules are linked by inter­molecular N—H(...)O, O—H(...)O and C—H(...)O hydrogen bonds into a two-dimensonal supra­molecular network extending parallel to (100).

Related literature

For background to oxamido compounds and their complexes, see: Ruiz et al. (1999 [triangle]); Ojima & Nonoyama (1988 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-66-00m71-scheme1.jpg

Experimental

Crystal data

  • [Ni2(C6H2N3O7)2(C10H20N4O4)]
  • M r = 833.93
  • Triclinic, An external file that holds a picture, illustration, etc.
Object name is e-66-00m71-efi1.jpg
  • a = 7.7893 (16) Å
  • b = 8.1405 (16) Å
  • c = 12.417 (3) Å
  • α = 98.00 (3)°
  • β = 99.00 (3)°
  • γ = 94.36 (3)°
  • V = 766.2 (3) Å3
  • Z = 1
  • Mo Kα radiation
  • μ = 1.33 mm−1
  • T = 298 K
  • 0.19 × 0.14 × 0.10 mm

Data collection

  • Bruker SMART CCD diffractometer
  • Absorption correction: multi-scan (SADABS; Sheldrick, 1996 [triangle]) T min = 0.786, T max = 0.879
  • 4040 measured reflections
  • 2703 independent reflections
  • 2233 reflections with I > 2σ(I)
  • R int = 0.015

Refinement

  • R[F 2 > 2σ(F 2)] = 0.035
  • wR(F 2) = 0.087
  • S = 1.23
  • 2703 reflections
  • 235 parameters
  • 1 restraint
  • H-atom parameters constrained
  • Δρmax = 0.39 e Å−3
  • Δρmin = −0.30 e Å−3

Data collection: SMART (Bruker, 1998 [triangle]); cell refinement: SAINT (Bruker, 1998 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: SHELXTL (Sheldrick, 2008 [triangle]); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009 [triangle]).

Table 1
Selected bond lengths (Å)
Table 2
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809052933/si2223sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809052933/si2223Isup2.hkl

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

Acknowledgments

We acknowledge the financial support of the Science Foundation of Shandong.

supplementary crystallographic information

Comment

Oxamido compounds and their complexes have been investigated extensively (Ruiz et al., 1999) by virtue of their bioactivities and the versatile bridging function (Ojima & Nonoyama, 1988). We selected N,N'-bis(3-aminopropyl)oxamide as a bridging ligand and picrate as a terminal group to synthesize a new binuclear nickel(II) compound, (I).

The title compound, (I) (Fig. 1), is a binuclear nickel(II) complex containing a total of 52 non-H atoms. Two terminal picrate ligands and a µ3-trans-oxamidato bridge with an inversion centre at the mid-point of the C—C bond of the oxamide group. The geometry of each nickel(II) atom is distorted octahedral. For the Ni1, atoms O2 and O4 are in axial positions. The equatorial plane is composed of three atoms from the oxamide bridge (N1, N2, and O1) and the phenolic oxygen atom (O3) from the picrate ligand. The maximum displacement of the four atoms from the equatorial plane is 0.1117 (15) Å at N1, and the nickel(II) atom lies 0.0524 (8) Å out of the plane. The Ni—N bond lenghts (Table 1) are 1.903 (3) and 2.032 (3)Å, whereas the bond lengths of Ni1—O2 and Ni1—O4 are relatively long and can be considered as a (4+1+1) coordination. As a terminal group, the picrate anion assumes a bidentate mode, forming a six-membered chelate ring on the nickel(II) ion. The dihedral angle between the benzyl ring of the picrate ion and the equatorial plane is 88.28 (3)°.

The crystal structure is stabilized by hydrogen bonding. As shown in Fig. 2, a two-dimensional infinite network is formed via the N—H···O and O—H···O intermolecular hydrogen bonds. The adjacent layers are further connected by non-classical C—H···O hydrogen bonding contacts (Table 2) to form a two-dimensional supramolecular architecture in a zig-zag fashion parallel to the b,c plane (Fig. 2).

Experimental

To a stirred methanol solution (10 ml) containing Ni(pic)2.6H2O (0.1255 g, 0.2 mmol) was added dropwise a ethanol solution (10 ml) of N,N'-bis(N-hydroxyethylaminoethyl)oxamide (0.0262 g, 0.1 mmol) and piperidine (0.0170 g, 0.2 mmol) at room temperature. The mixture was stirred quickly at 323 K for 8 h. The resulting solution was filtered and the filtrate was kept at room temperature. Green crystals suitable for X-ray analysis were obtained from the filtrate by slow evaporation for about two weeks.Yield, 46%, analysis, calculated for C22H24N10O18Ni2: C 31.69, H, 2.90; N 16.80%; found: C 31.75, H 2.91, N, 16.82%.

Refinement

H atoms were positioned geometrically [0.93 (CH), 0.97 (CH2), 0.85 (OH) and 0.90 (NH)Å] and constrained to ride on their parent atoms with Uiso(H) =1.2Ueq(C/N).

Figures

Fig. 1.
The binuclear complex of (I) with 30% displacement ellipsoids. [Symmetry code: A = -x, -y + 1, -z + 1]
Fig. 2.
A view of the three-dimensional hydrogen-bonding structure of (I). The H-bonds are shown as dotted lines. [Symmetry codes: i = -x, -y, -z + 2; ii = -x, -y, -z + 1; iii = x, y - 1, z]

Crystal data

[Ni2(C6H2N3O7)2(C10H20N4O4)]Z = 1
Mr = 833.93F(000) = 426
Triclinic, P1Dx = 1.807 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 7.7893 (16) ÅCell parameters from 1927 reflections
b = 8.1405 (16) Åθ = 2.5–26.3°
c = 12.417 (3) ŵ = 1.33 mm1
α = 98.00 (3)°T = 298 K
β = 99.00 (3)°Block, green
γ = 94.36 (3)°0.19 × 0.14 × 0.10 mm
V = 766.2 (3) Å3

Data collection

Bruker SMART CCD diffractometer2703 independent reflections
Radiation source: fine-focus sealed tube2233 reflections with I > 2σ(I)
graphiteRint = 0.015
[var phi] and ω scansθmax = 25.2°, θmin = 1.7°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)h = −9→9
Tmin = 0.786, Tmax = 0.879k = −9→7
4040 measured reflectionsl = −14→13

Refinement

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) = 0.087H-atom parameters constrained
S = 1.23w = 1/[σ2(Fo2) + (0.0205P)2 + 0.7682P] where P = (Fo2 + 2Fc2)/3
2703 reflections(Δ/σ)max = 0.001
235 parametersΔρmax = 0.39 e Å3
1 restraintΔρmin = −0.30 e Å3

Special details

Experimental. a DELU restraint was applied for Ni1 O2 with s.u. 0.002.
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 > 2sigma(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)

xyzUiso*/Ueq
C10.0883 (4)0.5501 (4)0.5131 (3)0.0339 (8)
C20.3717 (5)0.5619 (5)0.6319 (3)0.0446 (9)
H2A0.37640.68240.64850.054*
H2B0.45160.53390.58110.054*
C30.4200 (5)0.4875 (5)0.7369 (3)0.0471 (10)
H3A0.54600.49880.75860.057*
H3B0.37040.54700.79600.057*
C40.4620 (5)0.2008 (5)0.6579 (4)0.0553 (11)
H4A0.56910.19010.70690.066*
H4B0.49300.25240.59680.066*
C50.3688 (6)0.0319 (5)0.6149 (4)0.0609 (12)
H5A0.4466−0.04100.58310.073*
H5B0.3266−0.01700.67400.073*
C6−0.0763 (4)0.1046 (4)0.7864 (3)0.0334 (8)
C7−0.1144 (5)0.2293 (4)0.8705 (3)0.0375 (8)
C8−0.1927 (5)0.1921 (5)0.9576 (3)0.0418 (9)
H8−0.21580.27731.00980.050*
C9−0.2359 (5)0.0297 (5)0.9669 (3)0.0412 (9)
C10−0.2086 (5)−0.0995 (5)0.8879 (3)0.0415 (9)
H10−0.2417−0.20980.89350.050*
C11−0.1322 (5)−0.0607 (4)0.8020 (3)0.0361 (8)
N10.1953 (4)0.4904 (4)0.5843 (2)0.0369 (7)
N20.3526 (4)0.3088 (4)0.7183 (2)0.0415 (7)
H2C0.34900.27540.78490.050*
N3−0.0728 (5)0.4047 (4)0.8665 (3)0.0477 (8)
N4−0.3140 (4)−0.0112 (6)1.0595 (3)0.0551 (9)
N5−0.1030 (5)−0.1992 (4)0.7211 (3)0.0502 (8)
O1−0.1140 (3)0.3225 (3)0.5345 (2)0.0428 (6)
O20.2266 (4)0.0540 (4)0.5331 (2)0.0666 (8)
H20.1526−0.03380.52050.080*
O3−0.0095 (3)0.1265 (3)0.70232 (19)0.0436 (6)
O40.0475 (5)0.4475 (4)0.8204 (3)0.0690 (9)
O5−0.1590 (4)0.5052 (4)0.9118 (3)0.0659 (9)
O6−0.3605 (5)0.1016 (5)1.1207 (3)0.0776 (10)
O7−0.3329 (4)−0.1582 (5)1.0716 (3)0.0751 (10)
O8−0.2239 (5)−0.3026 (4)0.6812 (3)0.0860 (11)
O90.0423 (5)−0.2056 (4)0.6993 (3)0.0839 (11)
Ni10.10416 (6)0.29778 (6)0.63579 (4)0.03242 (15)

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
C10.042 (2)0.0292 (18)0.0307 (18)0.0014 (15)0.0064 (15)0.0059 (14)
C20.044 (2)0.040 (2)0.049 (2)−0.0028 (18)0.0027 (18)0.0139 (18)
C30.050 (2)0.042 (2)0.044 (2)−0.0062 (18)−0.0010 (18)0.0075 (18)
C40.047 (2)0.053 (3)0.066 (3)0.008 (2)0.007 (2)0.013 (2)
C50.075 (3)0.045 (3)0.069 (3)0.011 (2)0.025 (3)0.014 (2)
C60.0320 (18)0.0347 (19)0.0329 (19)0.0005 (15)0.0000 (15)0.0111 (15)
C70.042 (2)0.033 (2)0.0366 (19)0.0030 (16)0.0029 (16)0.0090 (16)
C80.039 (2)0.051 (2)0.034 (2)0.0085 (18)0.0046 (16)0.0037 (17)
C90.037 (2)0.057 (3)0.0332 (19)0.0033 (18)0.0075 (16)0.0150 (18)
C100.039 (2)0.043 (2)0.043 (2)−0.0024 (17)0.0038 (17)0.0175 (18)
C110.038 (2)0.037 (2)0.0332 (19)0.0017 (16)0.0066 (15)0.0068 (15)
N10.0415 (17)0.0315 (16)0.0375 (16)−0.0006 (13)0.0038 (14)0.0102 (13)
N20.0489 (19)0.0416 (18)0.0341 (16)0.0012 (15)0.0034 (14)0.0122 (14)
N30.063 (2)0.0400 (19)0.0382 (18)0.0034 (17)0.0061 (17)0.0048 (15)
N40.047 (2)0.083 (3)0.0378 (19)−0.001 (2)0.0070 (16)0.020 (2)
N50.065 (2)0.0384 (19)0.050 (2)−0.0060 (18)0.0203 (18)0.0107 (16)
O10.0475 (15)0.0405 (15)0.0396 (14)−0.0067 (12)0.0017 (12)0.0162 (11)
O20.075 (2)0.0558 (18)0.064 (2)−0.0065 (15)0.0163 (17)−0.0078 (15)
O30.0592 (17)0.0378 (15)0.0348 (14)−0.0045 (12)0.0134 (12)0.0086 (11)
O40.101 (3)0.0412 (17)0.067 (2)−0.0132 (17)0.0391 (19)0.0013 (15)
O50.081 (2)0.0470 (18)0.071 (2)0.0230 (17)0.0149 (18)0.0048 (15)
O60.080 (2)0.108 (3)0.0499 (19)0.004 (2)0.0307 (18)0.0088 (19)
O70.083 (2)0.091 (3)0.063 (2)0.001 (2)0.0255 (18)0.0423 (19)
O80.097 (3)0.068 (2)0.079 (2)−0.030 (2)0.018 (2)−0.0194 (19)
O90.085 (3)0.054 (2)0.122 (3)0.0086 (18)0.060 (2)−0.0012 (19)
Ni10.0384 (3)0.0306 (2)0.0281 (2)−0.00288 (18)0.00314 (18)0.01040 (17)

Geometric parameters (Å, °)

C1—O1i1.282 (4)C8—C91.364 (5)
C1—N11.289 (4)C8—H80.9300
C1—C1i1.510 (7)C9—C101.387 (5)
C2—N11.451 (5)C9—N41.449 (5)
C2—C31.520 (5)C10—C111.363 (5)
C2—H2A0.9700C10—H100.9300
C2—H2B0.9700C11—N51.458 (5)
C3—N21.482 (5)N1—Ni11.903 (3)
C3—H3A0.9700N2—Ni12.032 (3)
C3—H3B0.9700N2—H2C0.9100
C4—N21.479 (5)N3—O41.225 (4)
C4—C51.492 (6)N3—O51.229 (4)
C4—H4A0.9700N4—O61.223 (5)
C4—H4B0.9700N4—O71.227 (5)
C5—O21.421 (5)N5—O91.208 (4)
C5—H5A0.9700N5—O81.208 (4)
C5—H5B0.9700O1—C1i1.282 (4)
C6—O31.266 (4)O1—Ni11.991 (3)
C6—C111.431 (5)O2—Ni12.537 (3)
C6—C71.433 (5)O2—H20.8634
C7—C81.380 (5)O3—Ni11.942 (2)
C7—N31.450 (5)O4—Ni12.561 (3)
O1i—C1—N1128.9 (3)C10—C11—C6125.0 (3)
O1i—C1—C1i119.2 (4)C10—C11—N5117.1 (3)
N1—C1—C1i111.9 (4)C6—C11—N5117.9 (3)
N1—C2—C3106.0 (3)C1—N1—C2126.0 (3)
N1—C2—H2A110.5C1—N1—Ni1115.6 (2)
C3—C2—H2A110.5C2—N1—Ni1118.3 (2)
N1—C2—H2B110.5C4—N2—C3112.9 (3)
C3—C2—H2B110.5C4—N2—Ni1112.5 (2)
H2A—C2—H2B108.7C3—N2—Ni1105.4 (2)
N2—C3—C2109.9 (3)C4—N2—H2C108.6
N2—C3—H3A109.7C3—N2—H2C108.6
C2—C3—H3A109.7Ni1—N2—H2C108.6
N2—C3—H3B109.7O4—N3—O5122.6 (4)
C2—C3—H3B109.7O4—N3—C7119.3 (3)
H3A—C3—H3B108.2O5—N3—C7118.0 (3)
N2—C4—C5111.5 (3)O6—N4—O7123.2 (4)
N2—C4—H4A109.3O6—N4—C9118.6 (4)
C5—C4—H4A109.3O7—N4—C9118.2 (4)
N2—C4—H4B109.3O9—N5—O8123.6 (4)
C5—C4—H4B109.3O9—N5—C11117.9 (3)
H4A—C4—H4B108.0O8—N5—C11118.5 (4)
O2—C5—C4106.6 (4)C1i—O1—Ni1108.8 (2)
O2—C5—H5A110.4C5—O2—Ni199.8 (2)
C4—C5—H5A110.4C5—O2—H2109.0
O2—C5—H5B110.4Ni1—O2—H2110.6
C4—C5—H5B110.4C6—O3—Ni1142.1 (2)
H5A—C5—H5B108.6N3—O4—Ni1124.3 (2)
O3—C6—C11119.7 (3)N1—Ni1—O3170.56 (12)
O3—C6—C7127.8 (3)N1—Ni1—O184.45 (11)
C11—C6—C7112.5 (3)O3—Ni1—O193.01 (11)
C8—C7—C6123.2 (3)N1—Ni1—N282.75 (12)
C8—C7—N3116.3 (3)O3—Ni1—N2100.22 (12)
C6—C7—N3120.5 (3)O1—Ni1—N2166.66 (11)
C9—C8—C7119.7 (4)N1—Ni1—O2105.46 (11)
C9—C8—H8120.1O3—Ni1—O283.96 (11)
C7—C8—H8120.1O1—Ni1—O2103.16 (11)
C8—C9—C10121.2 (3)N2—Ni1—O276.77 (12)
C8—C9—N4120.3 (4)N1—Ni1—O496.75 (11)
C10—C9—N4118.5 (4)O3—Ni1—O474.84 (10)
C11—C10—C9118.3 (3)O1—Ni1—O4101.91 (12)
C11—C10—H10120.8N2—Ni1—O483.37 (12)
C9—C10—H10120.8O2—Ni1—O4147.80 (11)
N1—C2—C3—N239.7 (4)O5—N3—O4—Ni1−138.5 (3)
N2—C4—C5—O266.6 (4)C7—N3—O4—Ni142.8 (5)
O3—C6—C7—C8178.0 (3)C1—N1—Ni1—O3−74.6 (8)
C11—C6—C7—C81.4 (5)C2—N1—Ni1—O3102.0 (7)
O3—C6—C7—N3−1.3 (6)C1—N1—Ni1—O10.2 (3)
C11—C6—C7—N3−177.9 (3)C2—N1—Ni1—O1176.8 (3)
C6—C7—C8—C90.6 (5)C1—N1—Ni1—N2176.4 (3)
N3—C7—C8—C9179.9 (3)C2—N1—Ni1—N2−7.0 (3)
C7—C8—C9—C10−2.4 (5)C1—N1—Ni1—O2102.3 (3)
C7—C8—C9—N4178.4 (3)C2—N1—Ni1—O2−81.1 (3)
C8—C9—C10—C112.0 (5)C1—N1—Ni1—O4−101.2 (3)
N4—C9—C10—C11−178.8 (3)C2—N1—Ni1—O475.4 (3)
C9—C10—C11—C60.2 (6)C6—O3—Ni1—N1−25.6 (10)
C9—C10—C11—N5179.2 (3)C6—O3—Ni1—O1−99.7 (4)
O3—C6—C11—C10−178.8 (3)C6—O3—Ni1—N282.1 (4)
C7—C6—C11—C10−1.8 (5)C6—O3—Ni1—O2157.4 (4)
O3—C6—C11—N52.3 (5)C6—O3—Ni1—O41.9 (4)
C7—C6—C11—N5179.2 (3)C1i—O1—Ni1—N1−0.3 (2)
O1i—C1—N1—C23.4 (6)C1i—O1—Ni1—O3170.6 (2)
C1i—C1—N1—C2−176.4 (3)C1i—O1—Ni1—N2−16.7 (6)
O1i—C1—N1—Ni1179.7 (3)C1i—O1—Ni1—O2−104.9 (2)
C1i—C1—N1—Ni1−0.1 (5)C1i—O1—Ni1—O495.5 (2)
C3—C2—N1—C1160.4 (3)C4—N2—Ni1—N1−95.1 (3)
C3—C2—N1—Ni1−15.9 (4)C3—N2—Ni1—N128.3 (2)
C5—C4—N2—C3−165.1 (3)C4—N2—Ni1—O393.9 (3)
C5—C4—N2—Ni1−46.0 (4)C3—N2—Ni1—O3−142.6 (2)
C2—C3—N2—C478.4 (4)C4—N2—Ni1—O1−78.6 (6)
C2—C3—N2—Ni1−44.8 (4)C3—N2—Ni1—O144.8 (6)
C8—C7—N3—O4153.4 (4)C4—N2—Ni1—O212.7 (2)
C6—C7—N3—O4−27.3 (5)C3—N2—Ni1—O2136.1 (2)
C8—C7—N3—O5−25.4 (5)C4—N2—Ni1—O4167.2 (3)
C6—C7—N3—O5154.0 (3)C3—N2—Ni1—O4−69.4 (2)
C8—C9—N4—O69.2 (5)C5—O2—Ni1—N198.6 (2)
C10—C9—N4—O6−170.0 (4)C5—O2—Ni1—O3−81.9 (2)
C8—C9—N4—O7−172.0 (4)C5—O2—Ni1—O1−173.6 (2)
C10—C9—N4—O78.8 (5)C5—O2—Ni1—N220.1 (2)
C10—C11—N5—O9−127.5 (4)C5—O2—Ni1—O4−33.3 (3)
C6—C11—N5—O951.5 (5)N3—O4—Ni1—N1147.0 (3)
C10—C11—N5—O851.1 (5)N3—O4—Ni1—O3−28.6 (3)
C6—C11—N5—O8−129.9 (4)N3—O4—Ni1—O161.3 (3)
C4—C5—O2—Ni1−47.1 (3)N3—O4—Ni1—N2−131.1 (3)
C11—C6—O3—Ni1−173.9 (3)N3—O4—Ni1—O2−79.2 (4)
C7—C6—O3—Ni19.7 (6)

Symmetry codes: (i) −x, −y+1, −z+1.

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N2—H2C···O7ii0.912.153.054 (4)171
O2—H2···O1iii0.862.343.084 (4)145
C10—H10···O5iv0.932.493.319 (5)149

Symmetry codes: (ii) −x, −y, −z+2; (iii) −x, −y, −z+1; (iv) x, y−1, z.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: SI2223).

References

  • Bruker, (1998). SMART and SAINT Bruker AXS Inc., Madison, Wisconsin, USA.
  • Ojima, H. & Nonoyama, K. (1988). Coord. Chem. Rev.92, 85–111.
  • Ruiz, R., Faus, J., Lloret, F., Julve, M. & Journaurx, Y. (1999). Coord. Chem. Rev.193–195, 1069–1117.
  • Sheldrick, G. M. (1996). SADABS University of Göttingen, Germany.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Spek, A. L. (2009). Acta Cryst. D65, 148–155. [PMC free article] [PubMed]

Articles from Acta Crystallographica Section E: Structure Reports Online are provided here courtesy of International Union of Crystallography