metal-organic compounds
Bis(hydrogen L-glutamato)palladium(II)
aInstitut für Chemie, Naturwissenschaftliche Fakultät II, Martin-Luther-Universität Halle-Wittenberg, Kurt-Mothes-Str. 2, 06120 Halle, Germany
*Correspondence e-mail: kurt.merzweiler@chemie.uni-halle.de
In the title compound, [Pd(C5H8NO4)2], the Pd(II) atom is coordinated by two O atoms and two N atoms of two N,O-chelating hydrogen L-glutatmate ligands in a square–planar geometry with the N and O atoms in a mutually trans arrangement. The complex units are embedded in a network of N—H⋯O and O—H⋯O hydrogen-bonding interactions that stabilize the three-dimensional The strongest hydrogen bonds are formed between the γ-COOH untis of adjacent glutamate ligands, leading to dimers of the type R22(8) with O⋯O separations of 2.640 (6) Å.
Related literature
For the synthesis of the title compound, see: Spacu & Scherzer (1962). For the structures of related palladium complexes with amino acid ligands, see: Vagg (1979); Jarzab et al. (1973); Sabat et al. (1979); Pletnev et al. (1992); Hao et al. (2007); Gao et al. (2008).
Experimental
Crystal data
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Data collection: X-AREA (Stoe & Cie, 2009); cell X-AREA; data reduction: X-RED (Stoe & Cie, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2009); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009).
Supporting information
https://doi.org/10.1107/S1600536811035860/wm2526sup1.cif
contains datablocks I, publication_text. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536811035860/wm2526Isup2.hkl
The title compound was prepared from K2PdCl4 and sodium hydrogen glutamate according to a procedure described by Spacu & Scherzer (1962). For the growth of single crystals, the reaction mixture was stored at 278 K for several weeks.
C-bound H atoms of the hydrogen glutamate units were positioned geometrically and refinded using a riding model with Uiso(H) = 1.2 Ueq(C) [d(C—H) = 0.99 (for C–H) and 1.00 Å (for CH2)]. H atoms attached to N and O were located from difference fourier maps and refined with N—H distances fixed at 0.85 (2) Å (Uiso(H) = 1.2 Ueq(N)) and O—H distances fixed at 0.85 (2) and 0.86 (2) Å (Uiso(H) = 1.2 Ueq(O)).
The title compound, [Pd(C5H8NO4)2] (I), consists of a palladium(II) atom which is coordinated by two N and two O atoms of two chelating hydrogen glutamate ligands. The metal atom adopts a distorted square–planar coordination with the two N atoms and the two O atoms in mutual trans arrangements. The maximum deviation from the least squares plane through the atoms Pd, N1, N2, O1 and O5 is 0.026 Å for N2. The distances Pd—O (1.976 (8), 2.024 (7) Å) and Pd—N (2.005 (11), 2.072 (9) Å) are in agreement with the values observed for other Pd(II) amino acid derivatives, like cis-bis(L-tyrosinato)-palladium(II) hemihydrate (Jarzab et al., 1973), bis(L-tyrosinato)-palladium(II) (Sabat et al., 1979), bis(L-valinato)-palladium(II) monohydrate (Pletnev et al., 1992); Hao et al., 2007), cis-bis(L-aspartato-N,O)-palladium(II) (Gao et al., 2008) or bis(L-serinato)-palladium(II) (Vagg, 1979). For both the hydrogen glutatmate ligands, the five membered PdNC2O chelate rings adopt envelope conformations with a nearly coplanar arrangement of the Pd, O, C and N atoms at the flap positions.
The main conformational difference between both chelate rings arises from the orientation of the carboxyethyl groups. In the case of C2 the carboxyethyl group is in an axial position and for C7 an equatorially arrangend carboxyethyl group is observed (Fig. 1).
The packing of the complex units is supported by different types of hydrogen bonding interactions. The strongest hydrogen bridges are formed between the γ-carboxyl groups of neighbouring molecules. Consequently, R22(8) motifs are observed and the complex units are arranged in chains. Additionally, there are N—H···O hydrogen bridges of the type C11(4) and C11(5) which are formed between amino groups and oxygen atoms of adjacent α-carboxylate groups (Fig. 2)
For the synthesis, see: Spacu & Scherzer (1962). For the structures of related palladium complexes with amino acid ligands, see: Vagg (1979); Jarzab et al. (1973); Sabat et al. (1979); Pletnev et al. (1992); Hao et al. (2007); Gao et al. (2008).
Data collection: X-AREA (Stoe & Cie, 2009); cell
X-AREA (Stoe & Cie, 2009); data reduction: X-RED (Stoe & Cie, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).Fig. 1. Molecular structure of (I). Displacement ellipsoids are drawn at the 50% probabiltiy level. | |
Fig. 2. Arrangement of the hydrogen bonds around the complex unit. [Symmetry operators: (i) x + 1, y + 1, z; (ii) x, y + 1, z; (iii) x - 1, y + 1, z + 1; (iv) x + 1, y - 1, z - 1; (v) x - 1, y - 1, z; (vi) x, y - 1, z; (vii) x + 1, y, z; (viii) x - 1, y, z.] |
[Pd(C5H8NO4)2] | Z = 1 |
Mr = 398.66 | F(000) = 201 |
Triclinic, P1 | Dx = 2.070 Mg m−3 |
Hall symbol: P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 4.8858 (3) Å | Cell parameters from 7673 reflections |
b = 5.1605 (4) Å | θ = 3.1–29.3° |
c = 13.3651 (9) Å | µ = 1.49 mm−1 |
α = 93.725 (6)° | T = 200 K |
β = 99.734 (6)° | Prism, yellow |
γ = 104.245 (6)° | 0.17 × 0.06 × 0.04 mm |
V = 319.90 (4) Å3 |
Stoe IPDS 2T diffractometer | 2406 independent reflections |
Radiation source: sealed X-ray tube, 12 x 0.4 mm long-fine focus | 2389 reflections with I > 2σ(I) |
Plane graphite monochromator | Rint = 0.044 |
Detector resolution: 6.67 pixels mm-1 | θmax = 26.0°, θmin = 3.1° |
ω–scans | h = −6→6 |
Absorption correction: integration (X-RED; Stoe & Cie, 2009) | k = −6→6 |
Tmin = 0.806, Tmax = 0.973 | l = −16→16 |
4724 measured reflections |
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)] = 0.029 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.066 | w = 1/[σ2(Fo2) + (0.0356P)2 + 0.1842P] where P = (Fo2 + 2Fc2)/3 |
S = 1.04 | (Δ/σ)max < 0.001 |
2406 reflections | Δρmax = 0.37 e Å−3 |
208 parameters | Δρmin = −0.74 e Å−3 |
9 restraints | Absolute structure: Flack (1983), 1146 Friedel pairs |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: −0.02 (4) |
[Pd(C5H8NO4)2] | γ = 104.245 (6)° |
Mr = 398.66 | V = 319.90 (4) Å3 |
Triclinic, P1 | Z = 1 |
a = 4.8858 (3) Å | Mo Kα radiation |
b = 5.1605 (4) Å | µ = 1.49 mm−1 |
c = 13.3651 (9) Å | T = 200 K |
α = 93.725 (6)° | 0.17 × 0.06 × 0.04 mm |
β = 99.734 (6)° |
Stoe IPDS 2T diffractometer | 2406 independent reflections |
Absorption correction: integration (X-RED; Stoe & Cie, 2009) | 2389 reflections with I > 2σ(I) |
Tmin = 0.806, Tmax = 0.973 | Rint = 0.044 |
4724 measured reflections |
R[F2 > 2σ(F2)] = 0.029 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.066 | Δρmax = 0.37 e Å−3 |
S = 1.04 | Δρmin = −0.74 e Å−3 |
2406 reflections | Absolute structure: Flack (1983), 1146 Friedel pairs |
208 parameters | Absolute structure parameter: −0.02 (4) |
9 restraints |
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 | ||
C1 | 0.649 (3) | 0.240 (2) | 0.7428 (9) | 0.020 (3) | |
C2 | 0.478 (2) | −0.043 (2) | 0.7031 (8) | 0.015 (2) | |
H3 | 0.6076 | −0.1464 | 0.6791 | 0.017* | |
C3 | 0.2260 (11) | −0.0501 (11) | 0.6139 (4) | 0.0219 (11) | |
H4 | 0.1138 | −0.2395 | 0.5939 | 0.026* | |
H5 | 0.0971 | 0.0487 | 0.6394 | 0.026* | |
C4 | 0.3130 (13) | 0.0694 (11) | 0.5184 (4) | 0.0234 (11) | |
H6 | 0.1410 | 0.1014 | 0.4755 | 0.028* | |
H7 | 0.4546 | 0.2460 | 0.5398 | 0.028* | |
C5 | 0.4388 (11) | −0.1010 (11) | 0.4554 (4) | 0.0224 (11) | |
C6 | −0.125 (2) | 0.009 (2) | 1.0111 (8) | 0.018 (2) | |
C7 | 0.098 (2) | 0.272 (2) | 1.0603 (9) | 0.019 (2) | |
H11 | 0.2662 | 0.2244 | 1.1017 | 0.023* | |
C8 | −0.0210 (12) | 0.4448 (10) | 1.1299 (4) | 0.0213 (11) | |
H12 | −0.2096 | 0.4604 | 1.0938 | 0.026* | |
H13 | 0.1110 | 0.6279 | 1.1447 | 0.026* | |
C9 | −0.0580 (13) | 0.3289 (13) | 1.2308 (4) | 0.0249 (12) | |
H14 | −0.1794 | 0.1414 | 1.2162 | 0.030* | |
H15 | 0.1325 | 0.3254 | 1.2694 | 0.030* | |
C10 | −0.1944 (12) | 0.4914 (11) | 1.2950 (4) | 0.0210 (11) | |
N1 | 0.345 (2) | −0.179 (2) | 0.7842 (7) | 0.018 (2) | |
H2 | 0.464 (16) | −0.25 (2) | 0.820 (7) | 0.022* | |
H1 | 0.196 (12) | −0.311 (12) | 0.767 (7) | 0.022* | |
N2 | 0.194 (2) | 0.405 (2) | 0.9716 (8) | 0.020 (2) | |
H10 | 0.054 (15) | 0.46 (2) | 0.944 (8) | 0.024* | |
H9 | 0.346 (13) | 0.526 (13) | 0.999 (7) | 0.024* | |
O1 | 0.5808 (17) | 0.3460 (16) | 0.8246 (6) | 0.023 (2) | |
O2 | 0.8325 (17) | 0.3614 (16) | 0.6976 (6) | 0.0259 (16) | |
O3 | 0.3977 (9) | −0.0697 (8) | 0.3575 (3) | 0.0278 (8) | |
H8 | 0.503 (13) | −0.150 (12) | 0.328 (5) | 0.033* | |
O4 | 0.5723 (10) | −0.2598 (10) | 0.4909 (3) | 0.0289 (9) | |
O5 | −0.0695 (16) | −0.1097 (14) | 0.9320 (6) | 0.0206 (18) | |
O6 | −0.3437 (17) | −0.0908 (16) | 1.0453 (6) | 0.0237 (15) | |
O7 | −0.1369 (9) | 0.4718 (8) | 1.3941 (3) | 0.0267 (8) | |
H16 | −0.220 (15) | 0.553 (12) | 1.432 (5) | 0.032* | |
O8 | −0.3538 (9) | 0.6250 (9) | 1.2573 (3) | 0.0319 (9) | |
Pd | 0.26234 (18) | 0.11739 (15) | 0.87796 (9) | 0.01627 (10) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.021 (6) | 0.011 (5) | 0.029 (6) | 0.004 (4) | 0.005 (5) | −0.001 (4) |
C2 | 0.007 (4) | 0.025 (4) | 0.014 (4) | 0.007 (3) | 0.004 (3) | 0.003 (3) |
C3 | 0.017 (2) | 0.026 (3) | 0.023 (3) | 0.007 (2) | 0.003 (2) | 0.000 (2) |
C4 | 0.027 (3) | 0.024 (3) | 0.021 (3) | 0.011 (2) | 0.005 (2) | 0.002 (2) |
C5 | 0.017 (3) | 0.025 (3) | 0.022 (3) | −0.001 (2) | 0.004 (2) | 0.001 (2) |
C6 | 0.014 (5) | 0.024 (6) | 0.015 (5) | 0.009 (5) | −0.001 (4) | 0.001 (4) |
C7 | 0.012 (4) | 0.016 (4) | 0.027 (4) | 0.000 (3) | 0.002 (3) | −0.003 (3) |
C8 | 0.028 (3) | 0.017 (2) | 0.020 (3) | 0.004 (2) | 0.010 (2) | −0.001 (2) |
C9 | 0.027 (3) | 0.027 (3) | 0.023 (3) | 0.009 (3) | 0.008 (3) | 0.001 (2) |
C10 | 0.021 (3) | 0.026 (3) | 0.019 (3) | 0.007 (2) | 0.008 (2) | 0.003 (2) |
N1 | 0.020 (5) | 0.016 (5) | 0.018 (4) | 0.004 (4) | 0.006 (4) | −0.009 (3) |
N2 | 0.015 (5) | 0.022 (5) | 0.027 (5) | 0.005 (4) | 0.006 (4) | 0.013 (4) |
O1 | 0.028 (4) | 0.023 (5) | 0.019 (4) | 0.010 (4) | 0.003 (3) | −0.006 (4) |
O2 | 0.024 (3) | 0.023 (3) | 0.029 (3) | −0.001 (2) | 0.011 (2) | −0.001 (2) |
O3 | 0.037 (2) | 0.033 (2) | 0.0169 (18) | 0.0129 (18) | 0.0092 (16) | 0.0034 (16) |
O4 | 0.035 (3) | 0.038 (3) | 0.021 (2) | 0.022 (2) | 0.0092 (19) | 0.003 (2) |
O5 | 0.018 (4) | 0.013 (4) | 0.031 (4) | 0.000 (3) | 0.010 (3) | 0.002 (3) |
O6 | 0.021 (3) | 0.024 (3) | 0.026 (3) | 0.003 (2) | 0.007 (2) | 0.004 (2) |
O7 | 0.031 (2) | 0.035 (2) | 0.0165 (18) | 0.0136 (18) | 0.0065 (16) | −0.0001 (16) |
O8 | 0.035 (2) | 0.048 (3) | 0.020 (2) | 0.023 (2) | 0.0071 (17) | 0.0018 (18) |
Pd | 0.01683 (17) | 0.01537 (15) | 0.01715 (16) | 0.00487 (11) | 0.00451 (11) | −0.00026 (10) |
C1—O2 | 1.231 (14) | C7—H11 | 1.0000 |
C1—O1 | 1.318 (14) | C8—C9 | 1.530 (7) |
C1—C2 | 1.508 (17) | C8—H12 | 0.9900 |
C2—N1 | 1.483 (16) | C8—H13 | 0.9900 |
C2—C3 | 1.553 (11) | C9—C10 | 1.503 (8) |
C2—H3 | 1.0000 | C9—H14 | 0.9900 |
C3—C4 | 1.532 (7) | C9—H15 | 0.9900 |
C3—H4 | 0.9900 | C10—O8 | 1.230 (7) |
C3—H5 | 0.9900 | C10—O7 | 1.323 (7) |
C4—C5 | 1.485 (7) | Pd—N1 | 2.072 (9) |
C4—H6 | 0.9900 | N1—H2 | 0.85 (2) |
C4—H7 | 0.9900 | N1—H1 | 0.85 (2) |
C5—O4 | 1.238 (7) | Pd—N2 | 2.005 (11) |
C5—O3 | 1.316 (7) | N2—H10 | 0.85 (2) |
C6—O6 | 1.243 (14) | N2—H9 | 0.85 (2) |
C6—O5 | 1.289 (14) | Pd—O1 | 1.976 (8) |
C6—C7 | 1.538 (16) | O3—H8 | 0.86 (2) |
C7—N2 | 1.493 (16) | O5—Pd | 2.024 (7) |
C7—C8 | 1.529 (12) | O7—H16 | 0.85 (2) |
O2—C1—O1 | 124.1 (11) | C9—C8—H12 | 109.1 |
O2—C1—C2 | 120.1 (10) | C7—C8—H13 | 109.1 |
O1—C1—C2 | 115.7 (11) | C9—C8—H13 | 109.1 |
N1—C2—C1 | 110.6 (9) | H12—C8—H13 | 107.8 |
N1—C2—C3 | 106.2 (8) | C10—C9—C8 | 111.8 (5) |
C1—C2—C3 | 111.7 (9) | C10—C9—H14 | 109.3 |
N1—C2—H3 | 109.4 | C8—C9—H14 | 109.3 |
C1—C2—H3 | 109.4 | C10—C9—H15 | 109.3 |
C3—C2—H3 | 109.4 | C8—C9—H15 | 109.3 |
C4—C3—C2 | 115.7 (5) | H14—C9—H15 | 107.9 |
C4—C3—H4 | 108.4 | O8—C10—O7 | 123.0 (5) |
C2—C3—H4 | 108.4 | O8—C10—C9 | 122.2 (5) |
C4—C3—H5 | 108.4 | O7—C10—C9 | 114.8 (5) |
C2—C3—H5 | 108.4 | C2—N1—Pd | 106.8 (8) |
H4—C3—H5 | 107.4 | C2—N1—H2 | 110 (6) |
C5—C4—C3 | 114.6 (4) | Pd—N1—H2 | 108 (8) |
C5—C4—H6 | 108.6 | C2—N1—H1 | 119 (7) |
C3—C4—H6 | 108.6 | Pd—N1—H1 | 110 (7) |
C5—C4—H7 | 108.6 | H2—N1—H1 | 102 (9) |
C3—C4—H7 | 108.6 | C7—N2—Pd | 106.3 (7) |
H6—C4—H7 | 107.6 | C7—N2—H10 | 105 (7) |
O4—C5—O3 | 122.1 (5) | Pd—N2—H10 | 111 (9) |
O4—C5—C4 | 123.5 (5) | C7—N2—H9 | 103 (7) |
O3—C5—C4 | 114.5 (5) | Pd—N2—H9 | 114 (8) |
O6—C6—O5 | 120.4 (11) | H10—N2—H9 | 115 (10) |
O6—C6—C7 | 123.5 (10) | C1—O1—Pd | 116.3 (8) |
O5—C6—C7 | 116.1 (10) | C5—O3—H8 | 109 (5) |
N2—C7—C8 | 114.0 (9) | C6—O5—Pd | 113.1 (8) |
N2—C7—C6 | 104.2 (10) | C10—O7—H16 | 117 (5) |
C8—C7—C6 | 112.8 (8) | O1—Pd—N2 | 97.7 (4) |
N2—C7—H11 | 108.6 | O1—Pd—O5 | 178.6 (4) |
C8—C7—H11 | 108.6 | N2—Pd—O5 | 81.3 (4) |
C6—C7—H11 | 108.6 | O1—Pd—N1 | 81.7 (4) |
C7—C8—C9 | 112.6 (6) | N2—Pd—N1 | 178.3 (6) |
C7—C8—H12 | 109.1 | O5—Pd—N1 | 99.3 (4) |
O2—C1—C2—N1 | 161.2 (10) | C8—C9—C10—O7 | −155.6 (5) |
O1—C1—C2—N1 | −20.8 (13) | C1—C2—N1—Pd | 30.8 (10) |
O2—C1—C2—C3 | −80.7 (12) | C3—C2—N1—Pd | −90.6 (8) |
O1—C1—C2—C3 | 97.3 (11) | C8—C7—N2—Pd | −168.6 (6) |
N1—C2—C3—C4 | −177.5 (6) | C6—C7—N2—Pd | −45.3 (9) |
C1—C2—C3—C4 | 61.8 (10) | O2—C1—O1—Pd | 176.4 (9) |
C2—C3—C4—C5 | 74.0 (8) | C2—C1—O1—Pd | −1.5 (12) |
C3—C4—C5—O4 | −28.6 (8) | O6—C6—O5—Pd | 171.2 (8) |
C3—C4—C5—O3 | 151.5 (5) | C7—C6—O5—Pd | −10.6 (11) |
O6—C6—C7—N2 | −144.1 (10) | C1—O1—Pd—N2 | −166.0 (8) |
O5—C6—C7—N2 | 37.8 (12) | C1—O1—Pd—N1 | 15.7 (8) |
O6—C6—C7—C8 | −20.0 (15) | C7—N2—Pd—O1 | −147.4 (7) |
O5—C6—C7—C8 | 161.8 (8) | C7—N2—Pd—O5 | 33.7 (7) |
N2—C7—C8—C9 | −168.1 (8) | C6—O5—Pd—N2 | −13.5 (7) |
C6—C7—C8—C9 | 73.4 (10) | C6—O5—Pd—N1 | 164.8 (7) |
C7—C8—C9—C10 | −176.1 (6) | C2—N1—Pd—O1 | −25.3 (7) |
C8—C9—C10—O8 | 26.5 (8) | C2—N1—Pd—O5 | 153.7 (7) |
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H9···O6i | 0.85 (2) | 2.15 (4) | 2.979 (15) | 162 (8) |
N2—H10···O5ii | 0.85 (2) | 2.43 (8) | 3.121 (13) | 138 (10) |
O7—H16···O4iii | 0.85 (2) | 1.80 (2) | 2.639 (6) | 169 (7) |
O3—H8···O8iv | 0.86 (2) | 1.79 (3) | 2.640 (6) | 167 (7) |
N1—H1···O2v | 0.85 (2) | 2.15 (3) | 2.996 (15) | 170 (9) |
N1—H2···O1vi | 0.85 (2) | 2.30 (8) | 2.998 (13) | 139 (10) |
N1—H2···O5vii | 0.85 (2) | 2.42 (7) | 3.117 (13) | 140 (10) |
Symmetry codes: (i) x+1, y+1, z; (ii) x, y+1, z; (iii) x−1, y+1, z+1; (iv) x+1, y−1, z−1; (v) x−1, y−1, z; (vi) x, y−1, z; (vii) x+1, y, z. |
Experimental details
Crystal data | |
Chemical formula | [Pd(C5H8NO4)2] |
Mr | 398.66 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 200 |
a, b, c (Å) | 4.8858 (3), 5.1605 (4), 13.3651 (9) |
α, β, γ (°) | 93.725 (6), 99.734 (6), 104.245 (6) |
V (Å3) | 319.90 (4) |
Z | 1 |
Radiation type | Mo Kα |
µ (mm−1) | 1.49 |
Crystal size (mm) | 0.17 × 0.06 × 0.04 |
Data collection | |
Diffractometer | Stoe IPDS 2T |
Absorption correction | Integration (X-RED; Stoe & Cie, 2009) |
Tmin, Tmax | 0.806, 0.973 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4724, 2406, 2389 |
Rint | 0.044 |
(sin θ/λ)max (Å−1) | 0.617 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.029, 0.066, 1.04 |
No. of reflections | 2406 |
No. of parameters | 208 |
No. of restraints | 9 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.37, −0.74 |
Absolute structure | Flack (1983), 1146 Friedel pairs |
Absolute structure parameter | −0.02 (4) |
Computer programs: X-AREA (Stoe & Cie, 2009), X-RED (Stoe & Cie, 2009), SHELXS97 (Sheldrick, 2008), DIAMOND (Brandenburg, 2009), SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H9···O6i | 0.85 (2) | 2.15 (4) | 2.979 (15) | 162 (8) |
N2—H10···O5ii | 0.85 (2) | 2.43 (8) | 3.121 (13) | 138 (10) |
O7—H16···O4iii | 0.85 (2) | 1.80 (2) | 2.639 (6) | 169 (7) |
O3—H8···O8iv | 0.86 (2) | 1.79 (3) | 2.640 (6) | 167 (7) |
N1—H1···O2v | 0.85 (2) | 2.15 (3) | 2.996 (15) | 170 (9) |
N1—H2···O1vi | 0.85 (2) | 2.30 (8) | 2.998 (13) | 139 (10) |
N1—H2···O5vii | 0.85 (2) | 2.42 (7) | 3.117 (13) | 140 (10) |
Symmetry codes: (i) x+1, y+1, z; (ii) x, y+1, z; (iii) x−1, y+1, z+1; (iv) x+1, y−1, z−1; (v) x−1, y−1, z; (vi) x, y−1, z; (vii) x+1, y, z. |
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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.
The title compound, [Pd(C5H8NO4)2] (I), consists of a palladium(II) atom which is coordinated by two N and two O atoms of two chelating hydrogen glutamate ligands. The metal atom adopts a distorted square–planar coordination with the two N atoms and the two O atoms in mutual trans arrangements. The maximum deviation from the least squares plane through the atoms Pd, N1, N2, O1 and O5 is 0.026 Å for N2. The distances Pd—O (1.976 (8), 2.024 (7) Å) and Pd—N (2.005 (11), 2.072 (9) Å) are in agreement with the values observed for other Pd(II) amino acid derivatives, like cis-bis(L-tyrosinato)-palladium(II) hemihydrate (Jarzab et al., 1973), bis(L-tyrosinato)-palladium(II) (Sabat et al., 1979), bis(L-valinato)-palladium(II) monohydrate (Pletnev et al., 1992); Hao et al., 2007), cis-bis(L-aspartato-N,O)-palladium(II) (Gao et al., 2008) or bis(L-serinato)-palladium(II) (Vagg, 1979). For both the hydrogen glutatmate ligands, the five membered PdNC2O chelate rings adopt envelope conformations with a nearly coplanar arrangement of the Pd, O, C and N atoms at the flap positions.
The main conformational difference between both chelate rings arises from the orientation of the carboxyethyl groups. In the case of C2 the carboxyethyl group is in an axial position and for C7 an equatorially arrangend carboxyethyl group is observed (Fig. 1).
The packing of the complex units is supported by different types of hydrogen bonding interactions. The strongest hydrogen bridges are formed between the γ-carboxyl groups of neighbouring molecules. Consequently, R22(8) motifs are observed and the complex units are arranged in chains. Additionally, there are N—H···O hydrogen bridges of the type C11(4) and C11(5) which are formed between amino groups and oxygen atoms of adjacent α-carboxylate groups (Fig. 2)