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The mononuclear title complex, [Co(C6H6NO6)(C2H8N2)]·3H2O, contains an octahedrally coordinated CoIII atom. The N-(carboxy­methyl)­aspartate moiety is coordinated as a tetradentate ligand, providing an OONO-donor set and forming two trans five-membered chelate rings and one six-membered chelate ring. A seven-membered chelate ring is also formed, which consists of part of the six-membered chelate ring and part of one of the five-membered chelate rings. The crystal structure of the complex is stabilized by hydrogen bonds with three water mol­ecules.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270103006449/sk1619sup1.cif
Contains datablocks fp_01_03, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270103006449/sk1619Isup2.hkl
Contains datablock I

CCDC reference: 214145

Comment top

The heteroligand complexes of cobalt(III) with polyaminocarboxyacids are extensively studied and are of interest not only for their stereochemistry (McLachlan et al., 1995) but also for their application in the bioinorganic field, as they provide simple structural models of metalloprotein active sites (Igi et al., 1981). The tetradentate branched ligands of the type aminopolycarboxylate are used because they form stable complexes in solution (Bernauer, 1976). Recently, we have prepared a novel OONO-type tetradentate ligand, N-carboxymethylaspartic acid (H3cma, C6H9NO6, Maderova et al., 2002). The formation of a complex between CoIII and cma3− and glycine has been studied previously (Colomb & Bernauer, 1977), but the structure of the complex was not resolved. Depending on the relative position of the carboxylate groups forming the five-membered chelate rings, the tetradentate ligand can adopt two different geometries in the coordination octahedron of the cobalt atom (Figure I). Therefore we report here the crystal structure of the title compound, rac-[Co(cma)(en)]·3H2O (where en is ethylenediamine), (I).

The crystal structure of (I) contains discrete molecules, which have a slightly distorted octahedral coordination geometry around the Co atom, with cma3− bonded as a tetradentate trans OONO ligand. The coordination about the Co atom can be considered to be meridional, with the three carboxylic O atoms (O2, O4 and O6) in one plane and the three N atoms (N5, N11 and N14) in another plane. The aspartic acid portion of the cma3− ligand is coordinated to the Co atom through the α-amino N5, α-carboxylate O2 and β-carboxylate O4 atoms. This coordination mode is similar to that found for various bis(L-aspartato)cobalt(III) complexes previously reported in the literature (Oonishi et al., 1973, 1975). The H atom attached to N5 is on the same (syn) side of the O2/N5/N14 plane as? the coordinated β-carboxylate O4 atom. The glycinate group (N5–C6–C7–O6) is attached to the Co atom through the carboxylate O6 atom, and occupies a position trans to the β-carboxylate O4 atom. The bidentate ethylenediamine ligands occupies the two remaining coordination sites about the Co atom.

Ethylenediamine atom N11 is coordinated to the Co atom in a position trans to the α-amino N5 atom of cma3−, and atom N14 is attached trans to the α-carboxylate O2 atom of the cma3− ligand.

The bond distances observed within the cma3− and ethylenediamine ligands are comparable to average values found in structures of other complexes containing aspartic acid (Oonishi et al., 1973, 1975). The bond lengths and angles within the ethylenediamine ligands are normal (Templeton et al., 1979). The bond distances Co—N and Co—O are similar to the cobalt secondary amino N atom (Halloran et al., 1975; Voss et al., 1978), the cobalt primary amino N atom (Herak et al., 1974; Thorup, 1975, 1977), and the cobalt carboxylate O atom distances found in other cobalt(III) complexes containing polyamines, amino acids and amino polycarboxylates.

The O2—Co—N14 angle is closed slightly, to 178.61 (8)°, and the C1—N5—C6 angle is opened to 114.16 (17)°, which is evidence of some strain in the arrangement of the chelate rings. The O6—C7—C6 angle of 116.8 (2)° is larger than the ideal tetrahedral value of 109°, a feature also found in complexes (Hammershoi et al., 1984) and free aspartates (Oonishi et al., 1973; Sekizaki, 1978). The average Co–O (carboxylate) bond length is 1.896 Å and the average Co—N bond length is 1.937 Å.

The bond angles around the Co atom deviate from an ideal octahedral geometry by 0.11–7.07°. The greatest deviation from 90° occurs for the angles contained in the two five-membered chelate rings [N5—Co—O2 = 84.09 (10)°, N5—Co—O6 = 87.76 (11)°, and O4—Co—N11 = 86.99 (11)°; N14—Co—N5 = 97.29 (11)°, O4–Co–N5 = 94.67 (11)° and O2–Co–N11 = 92.40 (10)°]. The smallest angular deviation from the ideal geometry is for the O6—Co—O2 angle [90.10 (9)°].

The ethylenediamine ligand does not appear to interact sterically with any part of the cma3− ligand. There are virtually no differences in bond lengths and bond angles within the Co—O2—C2—C1—N5 and Co—O6—C7—C6—N5 chelate rings.

In the crystal, the CoIII complex and three water molecules are stabilized by an infinite three-dimensional framework of strong O—H···O and N—H···O hydrogen bonds.

Experimental top

rac-N-Carboxymethylaspartic acid, H3cmaa, was prepared according to the method of Maderova et al. (2002) and (I) was prepared according to Shibata (1983). All chemicals were analytical grade. A mixture of H3cmaa (5 mmol) in water (5 ml) and freshly prepared K3[Co(CO3)3]·3H2O was placed in water (50 ml) and heated with stirring at 323 K for 20 min. The colour of the solution changed from green to wine-red. After addition of ethylenediamine (5 mmol), the mixture was heated with stirring at 333 K for 3 h. After cooling to room temperature, the reaction mixture was filtered. Crystals of (I) were grown by slow evaporation of an aqueous solution at room temperature. After three days red crystals were obtained. Compound purity was tested by FTIR spectra, by 1H NMR spectra and by elemental analysis (Elemental Analyzer Carlo Erba 1106), Analysis; calculated for (I): C 26.6%, H 5.5%, N 11.6%; found: C 26.3%, H 5.3%, N 11.5%.

Refinement top

H atoms were fixed in their theoretical geometrical positions with Ueq values derived from the? corresponding C or N atoms. The H atoms attached to atoms O11, O12 and O13 were refined freely, except for one? O–H distance that was restrained to 0.9 Å, and a common free variable was used to describe simultaneously the Ueq values of all six water H atoms.

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2002); cell refinement: CrysAlis RED; data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Johnson & Burnett, 1996); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997), PARST (Nardelli, 1995).

Figures top
[Figure 1]
Fig.1: The two different geometries, viz. cis (a) and trans (b), adopted in the coordination octahedron of the Co atom.

Fig.2: ORTEPIII plot of (I). Displacement ellipsoids are drawn at the 50% probability level.
[N-(Carboxylatomethyl)aspartato(3-)](ethylenediamine)cobalt(III) trihydrate top
Crystal data top
[Co(C6H6NO6)(C2H8N2)]·3H2OF(000) = 752
Mr = 361.20Dx = 1.672 Mg m3
Monoclinic, CcMo Kα radiation, λ = 0.71073 Å
Hall symbol: C -2ycCell parameters from 1591 reflections
a = 11.6265 (13) Åθ = 3.7–26.5°
b = 14.5467 (9) ŵ = 1.25 mm1
c = 10.0565 (11) ÅT = 120 K
β = 122.475 (15)°Prism, dark red
V = 1434.9 (3) Å30.50 × 0.20 × 0.20 mm
Z = 4
Data collection top
Kuma KM4 + CCD
diffractometer
1746 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.035
Enhance (Oxford Diffraction) monochromatorθmax = 26.0°, θmin = 3.7°
Detector resolution: 16.3 pixels mm-1h = 814
rotation method, ω–scank = 1717
3217 measured reflectionsl = 1210
1763 independent reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.022H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.057 w = 1/[σ2(Fo2) + (0.045P)2 + 0.35P]
where P = (Fo2 + 2Fc2)/3
S = 1.04(Δ/σ)max = 0.001
1763 reflectionsΔρmax = 0.48 e Å3
209 parametersΔρmin = 0.43 e Å3
8 restraintsAbsolute structure: Flack (1983)
Primary atom site location: structure-invariant direct methodsAbsolute structure parameter: 0.010 (12)
Crystal data top
[Co(C6H6NO6)(C2H8N2)]·3H2OV = 1434.9 (3) Å3
Mr = 361.20Z = 4
Monoclinic, CcMo Kα radiation
a = 11.6265 (13) ŵ = 1.25 mm1
b = 14.5467 (9) ÅT = 120 K
c = 10.0565 (11) Å0.50 × 0.20 × 0.20 mm
β = 122.475 (15)°
Data collection top
Kuma KM4 + CCD
diffractometer
1746 reflections with I > 2σ(I)
3217 measured reflectionsRint = 0.035
1763 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.022H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.057Δρmax = 0.48 e Å3
S = 1.04Δρmin = 0.43 e Å3
1763 reflectionsAbsolute structure: Flack (1983)
209 parametersAbsolute structure parameter: 0.010 (12)
8 restraints
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
Co0.35015 (2)0.223668 (17)0.27710 (3)0.00876 (10)
O10.2203 (2)0.02814 (12)0.1602 (2)0.0176 (4)
O20.24978 (18)0.12213 (12)0.14300 (19)0.0125 (3)
O30.6680 (2)0.05597 (12)0.4237 (2)0.0210 (4)
O40.51695 (18)0.16634 (12)0.3381 (2)0.0126 (4)
O50.0152 (2)0.29141 (14)0.2504 (2)0.0183 (4)
O60.18561 (19)0.28534 (11)0.2126 (2)0.0120 (4)
C10.3398 (3)0.06075 (16)0.4001 (3)0.0115 (5)
H10.29930.02100.44570.014*
C20.2615 (2)0.04812 (17)0.2200 (3)0.0123 (5)
C30.4897 (3)0.03569 (16)0.4718 (3)0.0138 (5)
H3A0.53940.04660.58690.017*
H3B0.49540.03090.45570.017*
C40.5618 (3)0.08775 (16)0.4064 (3)0.0131 (5)
N50.3287 (2)0.15934 (13)0.4315 (2)0.0105 (4)
H50.39900.17500.53290.013*
C60.1955 (3)0.18501 (18)0.4074 (3)0.0138 (5)
H6A0.20940.20710.50820.017*
H6B0.13590.13010.37400.017*
C70.1257 (3)0.26004 (18)0.2828 (3)0.0122 (5)
O110.1627 (2)0.31925 (13)0.3471 (2)0.0192 (4)
O120.3430 (2)0.40775 (14)0.5720 (3)0.0270 (5)
O130.2025 (4)0.3404 (2)0.6962 (4)0.0512 (8)
N110.3615 (2)0.28368 (13)0.1123 (3)0.0120 (4)
H11A0.38410.24130.06200.014*
H11B0.27840.30880.03910.014*
C120.4667 (3)0.35695 (17)0.1830 (3)0.0164 (5)
H12A0.45240.40210.10180.020*
H12B0.55910.33030.23110.020*
C130.4503 (3)0.40221 (17)0.3071 (3)0.0176 (5)
H13A0.52620.44560.37080.021*
H13B0.36330.43660.25710.021*
N140.4513 (2)0.32730 (14)0.4080 (2)0.0121 (4)
H14A0.41240.34760.46170.014*
H14B0.53970.31000.48060.014*
H11V0.208 (4)0.367 (2)0.288 (4)0.039 (4)*
H11W0.089 (3)0.312 (3)0.343 (5)0.039 (4)*
H12V0.294 (4)0.4564 (19)0.526 (4)0.039 (4)*
H12W0.309 (4)0.384 (3)0.624 (4)0.039 (4)*
H13V0.212 (4)0.382 (2)0.767 (4)0.039 (4)*
H13W0.233 (5)0.2862 (17)0.745 (5)0.039 (4)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Co0.00737 (15)0.00998 (15)0.00771 (15)0.00041 (12)0.00324 (11)0.00068 (12)
O10.0179 (10)0.0148 (9)0.0152 (8)0.0031 (7)0.0057 (7)0.0035 (7)
O20.0116 (8)0.0143 (8)0.0096 (7)0.0016 (7)0.0043 (6)0.0010 (6)
O30.0151 (10)0.0170 (9)0.0315 (10)0.0066 (7)0.0129 (8)0.0066 (8)
O40.0104 (9)0.0129 (8)0.0137 (8)0.0002 (7)0.0060 (7)0.0010 (7)
O50.0121 (10)0.0307 (10)0.0125 (9)0.0053 (8)0.0068 (7)0.0040 (7)
O60.0104 (9)0.0154 (9)0.0096 (8)0.0016 (7)0.0050 (7)0.0025 (6)
C10.0125 (12)0.0098 (10)0.0094 (11)0.0017 (9)0.0041 (9)0.0011 (8)
C20.0076 (12)0.0166 (11)0.0107 (11)0.0013 (9)0.0035 (9)0.0013 (9)
C30.0124 (13)0.0109 (11)0.0129 (11)0.0005 (9)0.0034 (10)0.0005 (8)
C40.0087 (11)0.0138 (12)0.0107 (11)0.0003 (9)0.0012 (9)0.0013 (8)
N50.0100 (10)0.0113 (9)0.0090 (9)0.0004 (8)0.0044 (8)0.0008 (7)
C60.0132 (13)0.0172 (13)0.0141 (12)0.0016 (10)0.0094 (10)0.0040 (9)
C70.0096 (12)0.0170 (11)0.0073 (10)0.0016 (10)0.0028 (9)0.0013 (9)
O110.0217 (10)0.0179 (10)0.0240 (9)0.0035 (8)0.0163 (8)0.0050 (7)
O120.0368 (13)0.0218 (10)0.0307 (11)0.0134 (9)0.0235 (10)0.0080 (8)
O130.081 (2)0.0487 (16)0.0557 (17)0.0371 (15)0.0581 (17)0.0288 (13)
N110.0128 (11)0.0124 (10)0.0116 (10)0.0015 (8)0.0072 (9)0.0017 (7)
C120.0159 (13)0.0163 (12)0.0180 (12)0.0020 (10)0.0098 (11)0.0040 (10)
C130.0168 (13)0.0128 (11)0.0168 (12)0.0023 (10)0.0048 (11)0.0010 (9)
N140.0085 (11)0.0133 (9)0.0096 (9)0.0005 (8)0.0016 (9)0.0000 (7)
Geometric parameters (Å, º) top
Co—O41.8849 (17)C6—C71.522 (3)
Co—O61.8860 (17)C6—H6A0.9900
Co—O21.9172 (16)C6—H6B0.9900
Co—N141.9300 (19)O11—H11V0.881 (19)
Co—N111.939 (2)O11—H11W0.89 (4)
Co—N51.9407 (19)O12—H12V0.870 (19)
O1—C21.230 (3)O12—H12W0.88 (5)
O2—C21.291 (3)O13—H13V0.900 (19)
O3—C41.240 (3)O13—H13W0.895 (19)
O4—C41.292 (3)N11—C121.482 (3)
O5—C71.234 (3)N11—H11A0.9200
O6—C71.283 (3)N11—H11B0.9200
C1—N51.488 (3)C12—C131.510 (4)
C1—C31.530 (3)C12—H12A0.9900
C1—C21.539 (3)C12—H12B0.9900
C1—H11.0000C13—N141.487 (3)
C3—C41.517 (3)C13—H13A0.9900
C3—H3A0.9900C13—H13B0.9900
C3—H3B0.9900N14—H14A0.9200
N5—C61.483 (3)N14—H14B0.9200
N5—H50.9300
O4—Co—O6177.43 (7)C6—N5—H5110.2
O4—Co—O291.15 (7)C1—N5—H5110.2
O6—Co—O290.11 (7)Co—N5—H5110.2
O4—Co—N1488.82 (8)N5—C6—C7111.23 (18)
O6—Co—N1489.87 (8)N5—C6—H6A109.4
O2—Co—N14178.61 (8)C7—C6—H6A109.4
O4—Co—N1186.94 (8)N5—C6—H6B109.4
O6—Co—N1190.78 (8)C7—C6—H6B109.4
O2—Co—N1192.28 (8)H6A—C6—H6B108.0
N14—Co—N1186.33 (8)O5—C7—O6123.1 (2)
O4—Co—N594.50 (8)O5—C7—C6120.1 (2)
O6—Co—N587.86 (8)O6—C7—C6116.8 (2)
O2—Co—N584.31 (7)H11V—O11—H11W108 (4)
N14—Co—N597.07 (8)H12V—O12—H12W105 (4)
N11—Co—N5176.33 (8)H13V—O13—H13W108 (4)
C2—O2—Co112.99 (13)C12—N11—Co109.26 (15)
C4—O4—Co128.07 (16)C12—N11—H11A109.8
C7—O6—Co115.12 (16)Co—N11—H11A109.8
N5—C1—C3109.58 (17)C12—N11—H11B109.8
N5—C1—C2107.63 (17)Co—N11—H11B109.8
C3—C1—C2109.29 (19)H11A—N11—H11B108.3
N5—C1—H1110.1N11—C12—C13105.9 (2)
C3—C1—H1110.1N11—C12—H12A110.6
C2—C1—H1110.1C13—C12—H12A110.6
O1—C2—O2124.73 (19)N11—C12—H12B110.6
O1—C2—C1120.87 (19)C13—C12—H12B110.6
O2—C2—C1114.33 (18)H12A—C12—H12B108.7
C4—C3—C1115.64 (17)N14—C13—C12106.55 (19)
C4—C3—H3A108.4N14—C13—H13A110.4
C1—C3—H3A108.4C12—C13—H13A110.4
C4—C3—H3B108.4N14—C13—H13B110.4
C1—C3—H3B108.4C12—C13—H13B110.4
H3A—C3—H3B107.4H13A—C13—H13B108.6
O3—C4—O4119.6 (2)C13—N14—Co109.14 (13)
O3—C4—C3119.6 (2)C13—N14—H14A109.9
O4—C4—C3120.7 (2)Co—N14—H14A109.9
C6—N5—C1114.16 (17)C13—N14—H14B109.9
C6—N5—Co108.60 (13)Co—N14—H14B109.9
C1—N5—Co103.33 (13)H14A—N14—H14B108.3
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N5—H5···O5i0.931.922.832 (3)168
N11—H11A···O11ii0.922.122.937 (3)148
N11—H11B···O3iii0.922.293.086 (3)144
N14—H14A···O120.921.902.812 (3)171
N14—H14B···O2i0.922.313.057 (2)139
N14—H14B···O6i0.922.453.243 (3)145
O11—H11W···O50.89 (7)1.90 (2)2.747 (3)157 (4)
O11—H11V···O1iv0.88 (2)1.88 (2)2.752 (3)171 (4)
O12—H12W···O130.88 (5)1.85 (5)2.719 (3)168 (4)
O12—H12V···O3iv0.87 (2)1.92 (2)2.783 (3)172 (4)
O13—H13V···O3v0.90 (2)2.09 (3)2.941 (3)156 (4)
O13—H13W···O11i0.89 (2)1.88 (2)2.757 (3)166 (5)
Symmetry codes: (i) x+1/2, y+1/2, z+1/2; (ii) x+1/2, y+1/2, z1/2; (iii) x1/2, y+1/2, z1/2; (iv) x1/2, y+1/2, z; (v) x1/2, y+1/2, z+1/2.

Experimental details

Crystal data
Chemical formula[Co(C6H6NO6)(C2H8N2)]·3H2O
Mr361.20
Crystal system, space groupMonoclinic, Cc
Temperature (K)120
a, b, c (Å)11.6265 (13), 14.5467 (9), 10.0565 (11)
β (°) 122.475 (15)
V3)1434.9 (3)
Z4
Radiation typeMo Kα
µ (mm1)1.25
Crystal size (mm)0.50 × 0.20 × 0.20
Data collection
DiffractometerKuma KM4 + CCD
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
3217, 1763, 1746
Rint0.035
(sin θ/λ)max1)0.617
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.022, 0.057, 1.04
No. of reflections1763
No. of parameters209
No. of restraints8
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.48, 0.43
Absolute structureFlack (1983)
Absolute structure parameter0.010 (12)

Computer programs: CrysAlis CCD (Oxford Diffraction, 2002), CrysAlis RED, SHELXS97 (Sheldrick, 1990), ORTEPIII (Johnson & Burnett, 1996), SHELXL97 (Sheldrick, 1997), PARST (Nardelli, 1995).

Selected geometric parameters (Å, º) top
Co—O41.8849 (17)Co—N141.9300 (19)
Co—O61.8860 (17)Co—N111.939 (2)
Co—O21.9172 (16)Co—N51.9407 (19)
O4—Co—O6177.43 (7)O6—Co—N587.86 (8)
O4—Co—O291.15 (7)O2—Co—N584.31 (7)
O6—Co—O290.11 (7)N14—Co—N597.07 (8)
O4—Co—N1488.82 (8)N11—Co—N5176.33 (8)
O6—Co—N1489.87 (8)C2—O2—Co112.99 (13)
O2—Co—N14178.61 (8)C4—O4—Co128.07 (16)
O4—Co—N1186.94 (8)C7—O6—Co115.12 (16)
O6—Co—N1190.78 (8)C6—N5—Co108.60 (13)
O2—Co—N1192.28 (8)C1—N5—Co103.33 (13)
N14—Co—N1186.33 (8)C12—N11—Co109.26 (15)
O4—Co—N594.50 (8)C13—N14—Co109.14 (13)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N5—H5···O5i0.931.922.832 (3)168
N11—H11A···O11ii0.922.122.937 (3)148
N11—H11B···O3iii0.922.293.086 (3)144
N14—H14A···O120.921.902.812 (3)171
N14—H14B···O2i0.922.313.057 (2)139
N14—H14B···O6i0.922.453.243 (3)145
O11—H11W···O50.89 (7)1.90 (2)2.747 (3)157 (4)
O11—H11V···O1iv0.88 (2)1.88 (2)2.752 (3)171 (4)
O12—H12W···O130.88 (5)1.85 (5)2.719 (3)168 (4)
O12—H12V···O3iv0.87 (2)1.92 (2)2.783 (3)172 (4)
O13—H13V···O3v0.90 (2)2.09 (3)2.941 (3)156 (4)
O13—H13W···O11i0.89 (2)1.88 (2)2.757 (3)166 (5)
Symmetry codes: (i) x+1/2, y+1/2, z+1/2; (ii) x+1/2, y+1/2, z1/2; (iii) x1/2, y+1/2, z1/2; (iv) x1/2, y+1/2, z; (v) x1/2, y+1/2, z+1/2.
 

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