Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536802003148/ci6103sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536802003148/ci6103Isup2.hkl |
CCDC reference: 182591
Colourless single crystals of (I) were grown as transparent plates, by slow evaporation of the saturated water–acetone mixture containing DL-alanine and zinc chloride, in stoichiometric ratio. The density was determined by the flotation method using a liquid mixture of carbon tetrachloride and bromoform.
Data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software; data reduction: CAD-4 Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 1999); software used to prepare material for publication: SHELXL97.
Fig. 1. The molecular structure of (I), with the atom-numbering scheme. Displacement ellipsoids are shown at the 50% probability level. | |
Fig. 2. Packing diagram of (I), viewed down the b axis. |
C6H14Cl2N2O4Zn | F(000) = 640 |
Mr = 314.46 | Dx = 1.780 Mg m−3 Dm = 1.77 (2) Mg m−3 Dm measured by flotation method |
Monoclinic, P21/c | Cu Kα radiation, λ = 1.5418 Å |
Hall symbol: -P 2ybc | Cell parameters from 25 reflections |
a = 9.996 (5) Å | θ = 16–24° |
b = 13.622 (4) Å | µ = 7.12 mm−1 |
c = 8.616 (3) Å | T = 293 K |
β = 90.30 (1)° | Plates, colourless |
V = 1173.2 (8) Å3 | 0.20 × 0.14 × 0.10 mm |
Z = 4 |
Enraf-Nonius CAD-4 diffractometer | 2097 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.044 |
Graphite monochromator | θmax = 67.9°, θmin = 4.4° |
ω–2θ scans | h = −12→11 |
Absorption correction: ψ scans (North et al., 1968) | k = −16→0 |
Tmin = 0.35, Tmax = 0.49 | l = 0→10 |
2282 measured reflections | 2 standard reflections every 100 reflections |
2134 independent reflections | intensity decay: <1% |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.040 | H-atom parameters constrained |
wR(F2) = 0.114 | w = 1/[σ2(Fo2) + (0.0605P)2 + 2.8047P] where P = (Fo2 + 2Fc2)/3 |
S = 1.15 | (Δ/σ)max < 0.001 |
2134 reflections | Δρmax = 0.51 e Å−3 |
137 parameters | Δρmin = −0.96 e Å−3 |
0 restraints | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0030 (4) |
C6H14Cl2N2O4Zn | V = 1173.2 (8) Å3 |
Mr = 314.46 | Z = 4 |
Monoclinic, P21/c | Cu Kα radiation |
a = 9.996 (5) Å | µ = 7.12 mm−1 |
b = 13.622 (4) Å | T = 293 K |
c = 8.616 (3) Å | 0.20 × 0.14 × 0.10 mm |
β = 90.30 (1)° |
Enraf-Nonius CAD-4 diffractometer | 2097 reflections with I > 2σ(I) |
Absorption correction: ψ scans (North et al., 1968) | Rint = 0.044 |
Tmin = 0.35, Tmax = 0.49 | 2 standard reflections every 100 reflections |
2282 measured reflections | intensity decay: <1% |
2134 independent reflections |
R[F2 > 2σ(F2)] = 0.040 | 0 restraints |
wR(F2) = 0.114 | H-atom parameters constrained |
S = 1.15 | Δρmax = 0.51 e Å−3 |
2134 reflections | Δρmin = −0.96 e Å−3 |
137 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 | ||
Zn1 | 0.71059 (4) | −0.04277 (3) | 0.75589 (5) | 0.0200 (2) | |
Cl1 | 0.51376 (9) | −0.10007 (7) | 0.84660 (10) | 0.0291 (3) | |
Cl2 | 0.86984 (9) | −0.14992 (6) | 0.83302 (11) | 0.0300 (3) | |
O2A | 0.5833 (3) | 0.15896 (17) | 0.7783 (3) | 0.0256 (6) | |
O1A | 0.7617 (3) | 0.07791 (19) | 0.8666 (3) | 0.0338 (6) | |
N1A | 0.6195 (3) | 0.3120 (2) | 0.9625 (3) | 0.0248 (6) | |
H1A1 | 0.5419 | 0.2854 | 0.9898 | 0.037* | |
H1A2 | 0.6128 | 0.3361 | 0.8668 | 0.037* | |
H1A3 | 0.6403 | 0.3602 | 1.0281 | 0.037* | |
C1A | 0.6836 (3) | 0.1509 (2) | 0.8610 (4) | 0.0196 (7) | |
C2A | 0.7258 (4) | 0.2359 (2) | 0.9670 (4) | 0.0228 (7) | |
H2A | 0.7331 | 0.2110 | 1.0735 | 0.027* | |
C3A | 0.8595 (4) | 0.2787 (3) | 0.9212 (6) | 0.0405 (10) | |
H3A1 | 0.8822 | 0.3315 | 0.9903 | 0.061* | |
H3A2 | 0.8542 | 0.3031 | 0.8168 | 0.061* | |
H3A3 | 0.9270 | 0.2287 | 0.9274 | 0.061* | |
O2B | 0.6619 (3) | −0.16576 (18) | 0.4876 (3) | 0.0277 (6) | |
O1B | 0.7220 (3) | −0.01135 (18) | 0.5308 (3) | 0.0282 (6) | |
N1B | 0.7036 (3) | −0.1605 (2) | 0.1863 (3) | 0.0258 (7) | |
H1B1 | 0.7281 | −0.1539 | 0.0877 | 0.039* | |
H1B2 | 0.6150 | −0.1656 | 0.1914 | 0.039* | |
H1B3 | 0.7409 | −0.2144 | 0.2259 | 0.039* | |
C1B | 0.7058 (3) | −0.0861 (2) | 0.4441 (4) | 0.0188 (7) | |
C2B | 0.7484 (4) | −0.0733 (2) | 0.2764 (4) | 0.0226 (7) | |
H2B | 0.7048 | −0.0147 | 0.2338 | 0.027* | |
C3B | 0.8994 (5) | −0.0616 (4) | 0.2620 (5) | 0.0437 (11) | |
H3B1 | 0.9225 | −0.0538 | 0.1547 | 0.066* | |
H3B2 | 0.9430 | −0.1188 | 0.3030 | 0.066* | |
H3B3 | 0.9278 | −0.0048 | 0.3192 | 0.066* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Zn1 | 0.0300 (3) | 0.0110 (3) | 0.0190 (3) | −0.00029 (16) | 0.00362 (19) | −0.00056 (15) |
Cl1 | 0.0321 (5) | 0.0294 (5) | 0.0259 (4) | −0.0067 (3) | 0.0070 (3) | −0.0013 (3) |
Cl2 | 0.0323 (5) | 0.0193 (4) | 0.0384 (5) | 0.0049 (3) | 0.0009 (4) | 0.0013 (3) |
O2A | 0.0390 (15) | 0.0208 (12) | 0.0171 (11) | −0.0033 (11) | −0.0009 (10) | −0.0004 (9) |
O1A | 0.0322 (14) | 0.0180 (13) | 0.0511 (17) | 0.0045 (11) | −0.0027 (12) | −0.0166 (12) |
N1A | 0.0340 (16) | 0.0184 (14) | 0.0219 (14) | 0.0061 (12) | −0.0003 (12) | −0.0087 (11) |
C1A | 0.0258 (17) | 0.0144 (15) | 0.0188 (15) | −0.0036 (13) | 0.0077 (13) | −0.0020 (12) |
C2A | 0.0319 (19) | 0.0151 (16) | 0.0213 (16) | 0.0027 (14) | 0.0005 (13) | −0.0057 (13) |
C3A | 0.030 (2) | 0.027 (2) | 0.064 (3) | −0.0053 (16) | 0.0006 (19) | −0.0130 (19) |
O2B | 0.0398 (15) | 0.0196 (12) | 0.0240 (12) | −0.0075 (11) | 0.0076 (10) | 0.0002 (10) |
O1B | 0.0502 (16) | 0.0144 (12) | 0.0202 (12) | −0.0005 (11) | 0.0062 (11) | −0.0007 (9) |
N1B | 0.0336 (17) | 0.0252 (15) | 0.0187 (14) | 0.0002 (13) | 0.0022 (12) | −0.0048 (11) |
C1B | 0.0217 (16) | 0.0164 (15) | 0.0183 (15) | 0.0016 (13) | 0.0036 (12) | 0.0013 (12) |
C2B | 0.0362 (19) | 0.0131 (15) | 0.0188 (16) | 0.0012 (14) | 0.0055 (14) | 0.0017 (12) |
C3B | 0.043 (2) | 0.048 (3) | 0.040 (2) | −0.021 (2) | 0.0195 (19) | −0.013 (2) |
Zn1—O1A | 1.967 (3) | C3A—H3A2 | 0.96 |
Zn1—O1B | 1.990 (3) | C3A—H3A3 | 0.96 |
Zn1—Cl2 | 2.2572 (11) | O1B—C1B | 1.273 (4) |
Zn1—Cl1 | 2.2599 (13) | O2B—C1B | 1.230 (4) |
O2A—C1A | 1.232 (4) | N1B—C2B | 1.487 (4) |
O1A—C1A | 1.265 (4) | N1B—H1B1 | 0.89 |
N1A—C2A | 1.485 (4) | N1B—H1B2 | 0.89 |
N1A—H1A1 | 0.89 | N1B—H1B3 | 0.89 |
N1A—H1A2 | 0.89 | C1B—C2B | 1.518 (4) |
N1A—H1A3 | 0.89 | C2B—C3B | 1.523 (6) |
C1A—C2A | 1.531 (4) | C2B—H2B | 0.98 |
C2A—C3A | 1.513 (6) | C3B—H3B1 | 0.96 |
C2A—H2A | 0.98 | C3B—H3B2 | 0.96 |
C3A—H3A1 | 0.96 | C3B—H3B3 | 0.96 |
O1A—Zn1—O1B | 106.06 (12) | C2A—C3A—H3A3 | 109.5 |
O1A—Zn1—Cl2 | 102.53 (9) | H3A1—C3A—H3A3 | 109.5 |
O1B—Zn1—Cl2 | 112.45 (8) | H3A2—C3A—H3A3 | 109.5 |
O1A—Zn1—Cl1 | 110.20 (9) | C1B—O1B—Zn1 | 113.1 (2) |
O1B—Zn1—Cl1 | 117.77 (9) | C2B—N1B—H1B1 | 109.5 |
Cl2—Zn1—Cl1 | 106.78 (5) | C2B—N1B—H1B2 | 109.5 |
C1A—O1A—Zn1 | 118.7 (2) | H1B1—N1B—H1B2 | 109.5 |
C2A—N1A—H1A1 | 109.5 | C2B—N1B—H1B3 | 109.5 |
C2A—N1A—H1A2 | 109.5 | H1B1—N1B—H1B3 | 109.5 |
H1A1—N1A—H1A2 | 109.5 | H1B2—N1B—H1B3 | 109.5 |
C2A—N1A—H1A3 | 109.5 | O2B—C1B—O1B | 124.8 (3) |
H1A1—N1A—H1A3 | 109.5 | O2B—C1B—C2B | 119.6 (3) |
H1A2—N1A—H1A3 | 109.5 | O1B—C1B—C2B | 115.5 (3) |
O2A—C1A—O1A | 126.3 (3) | N1B—C2B—C1B | 108.6 (3) |
O2A—C1A—C2A | 119.9 (3) | N1B—C2B—C3B | 109.7 (3) |
O1A—C1A—C2A | 113.8 (3) | C1B—C2B—C3B | 111.9 (3) |
N1A—C2A—C3A | 110.9 (3) | N1B—C2B—H2B | 108.9 |
N1A—C2A—C1A | 108.5 (3) | C1B—C2B—H2B | 108.9 |
C3A—C2A—C1A | 112.1 (3) | C3B—C2B—H2B | 108.9 |
N1A—C2A—H2A | 108.4 | C2B—C3B—H3B1 | 109.5 |
C3A—C2A—H2A | 108.4 | C2B—C3B—H3B2 | 109.5 |
C1A—C2A—H2A | 108.4 | H3B1—C3B—H3B2 | 109.5 |
C2A—C3A—H3A1 | 109.5 | C2B—C3B—H3B3 | 109.5 |
C2A—C3A—H3A2 | 109.5 | H3B1—C3B—H3B3 | 109.5 |
H3A1—C3A—H3A2 | 109.5 | H3B2—C3B—H3B3 | 109.5 |
O1B—Zn1—O1A—C1A | 69.1 (3) | O1A—Zn1—O1B—C1B | 172.7 (2) |
Cl2—Zn1—O1A—C1A | −172.8 (3) | Cl2—Zn1—O1B—C1B | 61.4 (3) |
Cl1—Zn1—O1A—C1A | −59.4 (3) | Cl1—Zn1—O1B—C1B | −63.4 (3) |
Zn1—O1A—C1A—O2A | −8.6 (5) | Zn1—O1B—C1B—O2B | 13.6 (5) |
Zn1—O1A—C1A—C2A | 173.1 (2) | Zn1—O1B—C1B—C2B | −164.7 (2) |
O2A—C1A—C2A—N1A | 7.4 (4) | O2B—C1B—C2B—N1B | 10.3 (5) |
O1A—C1A—C2A—N1A | −174.2 (3) | O1B—C1B—C2B—N1B | −171.2 (3) |
O2A—C1A—C2A—C3A | −115.4 (4) | O2B—C1B—C2B—C3B | −110.9 (4) |
O1A—C1A—C2A—C3A | 63.0 (4) | O1B—C1B—C2B—C3B | 67.5 (4) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1A—H1A1···O2Bi | 0.89 | 2.15 | 2.864 (4) | 137 |
N1A—H1A2···Cl1i | 0.89 | 2.39 | 3.204 (3) | 152 |
N1A—H1A3···O1Bii | 0.89 | 2.22 | 2.960 (4) | 141 |
N1B—H1B1···Cl2iii | 0.89 | 2.62 | 3.478 (3) | 163 |
N1B—H1B2···O2Aiv | 0.89 | 2.00 | 2.886 (4) | 172 |
N1B—H1B3···Cl2v | 0.89 | 2.43 | 3.317 (3) | 173 |
C2B—H2B···Cl1iv | 0.98 | 2.77 | 3.680 (4) | 154 |
Symmetry codes: (i) −x+1, y+1/2, −z+3/2; (ii) x, −y+1/2, z+1/2; (iii) x, y, z−1; (iv) −x+1, −y, −z+1; (v) x, −y−1/2, z−1/2. |
Experimental details
Crystal data | |
Chemical formula | C6H14Cl2N2O4Zn |
Mr | 314.46 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 293 |
a, b, c (Å) | 9.996 (5), 13.622 (4), 8.616 (3) |
β (°) | 90.30 (1) |
V (Å3) | 1173.2 (8) |
Z | 4 |
Radiation type | Cu Kα |
µ (mm−1) | 7.12 |
Crystal size (mm) | 0.20 × 0.14 × 0.10 |
Data collection | |
Diffractometer | Enraf-Nonius CAD-4 diffractometer |
Absorption correction | ψ scans (North et al., 1968) |
Tmin, Tmax | 0.35, 0.49 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 2282, 2134, 2097 |
Rint | 0.044 |
(sin θ/λ)max (Å−1) | 0.601 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.040, 0.114, 1.15 |
No. of reflections | 2134 |
No. of parameters | 137 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.51, −0.96 |
Computer programs: CAD-4 Software (Enraf-Nonius, 1989), CAD-4 Software, SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), PLATON (Spek, 1999), SHELXL97.
Zn1—O1A | 1.967 (3) | C1A—C2A | 1.531 (4) |
Zn1—O1B | 1.990 (3) | C2A—C3A | 1.513 (6) |
Zn1—Cl2 | 2.2572 (11) | O1B—C1B | 1.273 (4) |
Zn1—Cl1 | 2.2599 (13) | O2B—C1B | 1.230 (4) |
O2A—C1A | 1.232 (4) | C1B—C2B | 1.518 (4) |
O1A—C1A | 1.265 (4) | C2B—C3B | 1.523 (6) |
O1A—Zn1—O1B | 106.06 (12) | O1A—Zn1—Cl1 | 110.20 (9) |
O1A—Zn1—Cl2 | 102.53 (9) | O1B—Zn1—Cl1 | 117.77 (9) |
O1B—Zn1—Cl2 | 112.45 (8) | Cl2—Zn1—Cl1 | 106.78 (5) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1A—H1A1···O2Bi | 0.89 | 2.15 | 2.864 (4) | 136.5 |
N1A—H1A2···Cl1i | 0.89 | 2.39 | 3.204 (3) | 152.2 |
N1A—H1A3···O1Bii | 0.89 | 2.22 | 2.960 (4) | 140.9 |
N1B—H1B1···Cl2iii | 0.89 | 2.62 | 3.478 (3) | 162.7 |
N1B—H1B2···O2Aiv | 0.89 | 2.00 | 2.886 (4) | 171.6 |
N1B—H1B3···Cl2v | 0.89 | 2.43 | 3.317 (3) | 172.7 |
C2B—H2B···Cl1iv | 0.98 | 2.77 | 3.680 (4) | 154.4 |
Symmetry codes: (i) −x+1, y+1/2, −z+3/2; (ii) x, −y+1/2, z+1/2; (iii) x, y, z−1; (iv) −x+1, −y, −z+1; (v) x, −y−1/2, z−1/2. |
Halogeno zinc–amino acid complexes are interesting as zinc is known to compete successfully with cadmium for protein binding sites. Zinc also plays an important biological role in the formation of a structural motif called `zinc fingers` which is characteristic of certain proteins that bind to DNA. The present study reports the crystal structure of a complex of DL-alanine with zinc chloride, namely dichlorobis(DL-alanine)zinc(II). Alanine, a non-essential amino acid commonly present in proteins, is hydrophobic and non-polar. A precise determination of the crystal strucure of DL-alanine itself was recently carried out in our laboratory (Subha Nandhini et al., 2001a). The crystal structure of a complex of sarcosine with zinc chloride, namely trichloro(sarcosinio)zinc(II) monohydrate (Krishnakumar et al., 2001), in which the amino acid exhibits an unusual cationic form, was also elucidated in our laboratory. A similar ionization state was observed in the case of L-histidine with zinc chloride (Foster et al., 1993). The crystal structures of dichlorobis(sarcosinato)zinc(II) (Subha Nandhini et al., 2001b) and dichlorobis(DL-valine)zinc(II) (Subha Nandhini et al., 2001c) have also been determined recently in our laboratory.
The molecular structure and atom-numbering scheme are shown in Fig.1. Both the alanine molecules in the asymmetric unit coordinating as ligands to Zn exist as zwitterions. However, the C1—O1 and C1—O2 bond lengths in molecule A [1.265 (4) and 1.232 (4) Å, respectively] and molecule B [1.273 (4) and 1.230 (4) Å, respectively] show significant deviations from those usually exhibited by zwitterions. These deviations may be due to the fact that the O1 atoms of both molecule A and B participate in the coordination environment around Zn. The torsion angles O1A—Zn1—O1B—C1B [172.7 (2)°] and O1B—Zn1—O1A—C1A [69.1 (3)°] describe the relative orientation of molecules A and B with respect to the metal. The coordination environment around Zn is remarkably similar to those observed in the structures of ZnCl2 with sarcosine (Subha Nandhini et al., 2001b), glycine (Hariharan et al., 1989) and L-proline (Yukawa et al., 1985). Fig.2 shows the packing of the molecules of (I), viewed down the b axis. The molecules aggregate into a layered arrangement parallel to the bc plane. These layers form hydrogen-bonded double layers involving inversion and glide-related molecules. The adjacent double layers have no hydrogen-bonded interactions between them and are held together by van der Waals interactions.