rac-catena-Poly[nickel(II)-di-μ-tryptophanato]

The title complex, [Ni(C₁₁H₁₁N₂O₂)₂]_n or [Ni(D-trp)(L-trp)]_n [D-trp = (R)-2-amino-3-(3-indol­yl)propionate and L-trp = (S)-2-amino-3-(3-indol­yl)propionate], was formed by a hydro­thermal method from hexa­aqua­nickel(II) perchlorate and L-tryptophan. The Ni^II atom is located on an inversion center and has an octa­hedral coordination geometry formed by four O atoms and two N atoms from D– and L-tryptophan ligands. Each D– and L-tryptophan ligand bridges the Ni^II atoms through the carboxylate group, leading to a two-dimensional structure parallel to the bc plane.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.009 Å
• R factor = 0.053
• wR factor = 0.145
• Data-to-parameter ratio = 12.3

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density ....       3.05
PLAT341_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...          9
PLAT420_ALERT_2_C D-H Without Acceptor       N1     -   H1A    ...          ?
PLAT420_ALERT_2_C D-H Without Acceptor       N2     -   H2     ...          ?

Alert level G
PLAT793_ALERT_1_G Check the Absolute Configuration of C2     = ...          R
PLAT794_ALERT_5_G Check Predicted Bond Valency for Ni1         (2)       2.00

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   4 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   3 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

Metal-organic coordination polymers have particular and special structural characteristics with some cave-holes and channels. It can be applied in selected catalysis-molecular recognition-reversible exchange of host–guest molecules(ions)-superpurity separation-biological conductor etc. In recent years, such polymers have been widely investigated. However, a single-crystal structure of a coordination polymer formed with nickel(II) and trp has not been reported. For this reason we prepared and characterized the title compound, [Ni(D-trp)(L-trp)]_n.

The Ni^II atom is coordinated by two N atoms and two O atoms from a L-trp ligand and a D-trp ligand, and two O atoms from another two carboxyl groups of adjacent L-trp and D-trp (Fig. 1). The angles at the Ni^II atom (Table 1) show the Ni^II atom exists in a distorted octahedral geometry. The Ni—N bond distances is 2.096 (4) Å and the Ni—O bond distances are 2.037 (3) and 2.096 (4) Å. Furthermore, from Fig. 2, it can be seen that the complex shows a two-dimensional network structure assembled by double chains of ···-O—C—O—Ni—O—C—O—Ni.

Related literature

For related literature, see: Cai et al. (2000); Cheng et al. (2005); Henrick et al. (1978); Kumita et al. (2001); Rodríguez et al. (1990); Wu et al. (2004); Zhang et al. (2005); Zhou et al. (2005).

S2. Experimental

To an aqueous solution (5 ml) of L-trp (1.00 mmol), KOH (1.0 mmol) was added and stirred for 0.5 h at room temperature. Then an aqueous solution of nickel perchlorate (0.5 mmol) was dropped. The reaction mixture was airproofed with autoclave and keeped at 423 K for 72 h. The Cambridge blue rhomboidal column crystals were obtained after cooling to room temperature.

S3. Refinement

H atoms were located in a difference map and refined as riding, with C—H = 0.93 - 0.98 and N—H = 0.86 - 0.90 Å, and with U_iso(H) = 1.2U_eq(N,C). The highest peak in a difference Fourier map is located 1.17 Å from atom H2A.

Computing details

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT (Siemens, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997a); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997a); molecular graphics: SHELXTL (Sheldrick, 1997b); software used to prepare material for publication: SHELXTL (Sheldrick, 1997b).

Figures

	Fig. 1. A part of the polymeric structure of the title complex. Displacement ellipsoids are drawn at the 30% probability level. H atoms have been omitted.
	Fig. 2. A packing diagram of the title complex, viewed along the b axis. H atoms have been omitted.

rac-catena-Poly[nickel(II)-µ-[(R)-2-amino-3-(3-indolyl)propionato]- µ-[(S)-2-amino-3-(3-indolyl)propionato]]

Crystal data

[Ni(C11H11N2O2)2]	F(000) = 484
Mr = 465.15	Dx = 1.557 Mg m^−3
Monoclinic, P21/c	Melting point > 573 K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 19.724 (3) Å	Cell parameters from 1329 reflections
b = 5.6139 (11) Å	θ = 3.1–25.3°
c = 9.0372 (18) Å	µ = 1.02 mm^−1
β = 97.616 (2)°	T = 298 K
V = 991.9 (3) Å^3	Column, blue
Z = 2	0.23 × 0.15 × 0.12 mm

Data collection

Bruker SMART 1000 CCD area-detector diffractometer	1743 independent reflections
Radiation source: fine-focus sealed tube	1268 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.056
φ and ω scans	θmax = 25.0°, θmin = 2.1°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −23→23
Tmin = 0.800, Tmax = 0.888	k = −6→4
4673 measured reflections	l = −10→10

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.053	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.145	H-atom parameters not refined
S = 1.05	w = 1/[σ^2(Fo^2) + (0.068P)^2 + 1.7837P] where P = (Fo^2 + 2Fc^2)/3
1743 reflections	(Δ/σ)max < 0.001
142 parameters	Δρmax = 1.12 e Å^−3
0 restraints	Δρmin = −0.37 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Ni1	0.0000	0.5000	0.5000	0.0247 (3)
N1	0.08527 (18)	0.3482 (8)	0.4204 (4)	0.0319 (9)
H1A	0.1170	0.3089	0.4975	0.038*
H1B	0.0728	0.2150	0.3683	0.038*
N2	0.3207 (2)	0.2013 (10)	0.3808 (5)	0.0553 (13)
H2	0.3397	0.0766	0.3494	0.066*
O1	0.01149 (15)	0.7461 (6)	0.3396 (3)	0.0326 (8)
O2	0.07096 (15)	0.8160 (7)	0.1518 (3)	0.0419 (9)
C1	0.0607 (2)	0.7074 (9)	0.2681 (5)	0.0311 (11)
C2	0.1135 (2)	0.5215 (11)	0.3245 (5)	0.0402 (13)
H2A	0.1249	0.4346	0.2370	0.048*
C3	0.1768 (3)	0.6344 (12)	0.3952 (6)	0.0511 (15)
H3A	0.1694	0.6884	0.4938	0.061*
H3B	0.1853	0.7743	0.3375	0.061*
C4	0.2533 (3)	0.2782 (14)	0.3365 (6)	0.0578 (18)
H4	0.2220	0.2016	0.2663	0.069*
C5	0.2400 (3)	0.4820 (11)	0.4112 (7)	0.0469 (13)
C6	0.3012 (2)	0.5362 (11)	0.5021 (6)	0.0449 (14)
C7	0.3498 (2)	0.3595 (11)	0.4816 (6)	0.0426 (13)
C8	0.4167 (3)	0.3702 (15)	0.5587 (7)	0.0641 (18)
H8	0.4483	0.2513	0.5463	0.077*
C9	0.4342 (3)	0.5554 (14)	0.6507 (8)	0.070 (2)
H9	0.4789	0.5669	0.6982	0.084*
C10	0.3882 (3)	0.7258 (15)	0.6757 (8)	0.073 (2)
H10	0.4018	0.8477	0.7428	0.087*
C11	0.3217 (3)	0.7233 (12)	0.6041 (8)	0.0614 (17)
H11	0.2909	0.8419	0.6225	0.074*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ni1	0.0225 (4)	0.0370 (5)	0.0160 (4)	0.0001 (4)	0.0077 (3)	−0.0006 (4)
N1	0.0244 (19)	0.046 (3)	0.0254 (19)	0.0039 (19)	0.0044 (15)	0.0032 (18)
N2	0.046 (3)	0.061 (3)	0.059 (3)	0.011 (3)	0.008 (2)	−0.005 (3)
O1	0.0296 (16)	0.046 (2)	0.0250 (16)	0.0046 (15)	0.0126 (13)	0.0082 (15)
O2	0.0276 (16)	0.066 (3)	0.0341 (18)	0.0095 (18)	0.0122 (14)	0.0230 (17)
C1	0.024 (2)	0.049 (3)	0.021 (2)	0.002 (2)	0.0064 (18)	0.006 (2)
C2	0.027 (2)	0.055 (4)	0.041 (3)	0.008 (3)	0.016 (2)	0.023 (3)
C3	0.044 (3)	0.059 (4)	0.050 (3)	0.003 (3)	0.005 (3)	−0.003 (3)
C4	0.038 (3)	0.088 (5)	0.045 (3)	−0.018 (3)	−0.006 (2)	0.014 (3)
C5	0.036 (3)	0.049 (3)	0.058 (3)	0.003 (3)	0.012 (2)	0.015 (3)
C6	0.028 (3)	0.054 (4)	0.054 (3)	0.004 (3)	0.014 (2)	0.012 (3)
C7	0.033 (3)	0.050 (4)	0.046 (3)	0.006 (3)	0.005 (2)	0.004 (3)
C8	0.039 (3)	0.083 (5)	0.069 (4)	0.016 (4)	0.000 (3)	0.013 (4)
C9	0.049 (4)	0.086 (6)	0.071 (5)	−0.003 (4)	−0.007 (3)	0.005 (4)
C10	0.062 (4)	0.085 (6)	0.070 (4)	−0.022 (4)	0.002 (3)	−0.005 (4)
C11	0.068 (4)	0.047 (4)	0.077 (4)	0.010 (3)	0.038 (3)	0.007 (3)

Geometric parameters (Å, º)

Ni1—O1^i	2.037 (3)	C2—H2A	0.9800
Ni1—O1	2.037 (3)	C3—C5	1.504 (8)
Ni1—N1	2.096 (4)	C3—H3A	0.9700
Ni1—N1^i	2.096 (4)	C3—H3B	0.9700
Ni1—O2^ii	2.098 (3)	C4—C5	1.371 (9)
Ni1—O2^iii	2.098 (3)	C4—H4	0.9300
N1—C2	1.462 (6)	C5—C6	1.400 (8)
N1—H1A	0.9000	C6—C7	1.408 (8)
N1—H1B	0.9000	C6—C11	1.420 (9)
N2—C7	1.346 (7)	C7—C8	1.410 (7)
N2—C4	1.405 (7)	C8—C9	1.347 (10)
N2—H2	0.8600	C8—H8	0.9300
O1—C1	1.254 (5)	C9—C10	1.358 (10)
O2—C1	1.254 (5)	C9—H9	0.9300
O2—Ni1^iv	2.098 (3)	C10—C11	1.384 (9)
C1—C2	1.514 (7)	C10—H10	0.9300
C2—C3	1.468 (7)	C11—H11	0.9300
O1^i—Ni1—O1	180.0	C3—C2—H2A	107.0
O1^i—Ni1—N1	97.96 (14)	C1—C2—H2A	107.0
O1—Ni1—N1	82.04 (14)	C2—C3—C5	116.3 (5)
O1^i—Ni1—N1^i	82.04 (14)	C2—C3—H3A	108.2
O1—Ni1—N1^i	97.96 (14)	C5—C3—H3A	108.2
N1—Ni1—N1^i	180.00 (10)	C2—C3—H3B	108.2
O1^i—Ni1—O2^ii	89.77 (14)	C5—C3—H3B	108.2
O1—Ni1—O2^ii	90.23 (14)	H3A—C3—H3B	107.4
N1—Ni1—O2^ii	85.90 (14)	C5—C4—N2	110.6 (5)
N1^i—Ni1—O2^ii	94.10 (14)	C5—C4—H4	124.7
O1^i—Ni1—O2^iii	90.23 (14)	N2—C4—H4	124.7
O1—Ni1—O2^iii	89.77 (14)	C4—C5—C6	105.3 (5)
N1—Ni1—O2^iii	94.10 (14)	C4—C5—C3	129.6 (5)
N1^i—Ni1—O2^iii	85.90 (14)	C6—C5—C3	124.9 (6)
O2^ii—Ni1—O2^iii	180.0	C5—C6—C7	108.6 (5)
C2—N1—Ni1	108.6 (3)	C5—C6—C11	133.6 (6)
C2—N1—H1A	110.0	C7—C6—C11	117.8 (5)
Ni1—N1—H1A	110.0	N2—C7—C6	108.5 (5)
C2—N1—H1B	110.0	N2—C7—C8	130.5 (6)
Ni1—N1—H1B	110.0	C6—C7—C8	120.9 (6)
H1A—N1—H1B	108.4	C9—C8—C7	118.9 (6)
C7—N2—C4	107.0 (5)	C9—C8—H8	120.6
C7—N2—H2	126.5	C7—C8—H8	120.6
C4—N2—H2	126.5	C8—C9—C10	121.7 (6)
C1—O1—Ni1	114.6 (3)	C8—C9—H9	119.2
C1—O2—Ni1^iv	128.3 (3)	C10—C9—H9	119.2
O2—C1—O1	124.7 (4)	C9—C10—C11	121.9 (7)
O2—C1—C2	115.9 (4)	C9—C10—H10	119.1
O1—C1—C2	119.4 (4)	C11—C10—H10	119.1
N1—C2—C3	113.4 (4)	C10—C11—C6	118.8 (6)
N1—C2—C1	111.0 (3)	C10—C11—H11	120.6
C3—C2—C1	110.9 (5)	C6—C11—H11	120.6
N1—C2—H2A	107.0
O1^i—Ni1—N1—C2	−167.6 (3)	N2—C4—C5—C6	1.3 (6)
O1—Ni1—N1—C2	12.4 (3)	N2—C4—C5—C3	176.6 (6)
O2^ii—Ni1—N1—C2	−78.4 (3)	C2—C3—C5—C4	19.8 (9)
O2^iii—Ni1—N1—C2	101.6 (3)	C2—C3—C5—C6	−165.7 (5)
N1—Ni1—O1—C1	−0.5 (3)	C4—C5—C6—C7	−1.1 (6)
N1^i—Ni1—O1—C1	179.5 (3)	C3—C5—C6—C7	−176.7 (5)
O2^ii—Ni1—O1—C1	85.3 (3)	C4—C5—C6—C11	179.1 (6)
O2^iii—Ni1—O1—C1	−94.7 (3)	C3—C5—C6—C11	3.5 (10)
Ni1^iv—O2—C1—O1	−22.6 (8)	C4—N2—C7—C6	0.2 (6)
Ni1^iv—O2—C1—C2	158.9 (3)	C4—N2—C7—C8	−178.5 (6)
Ni1—O1—C1—O2	169.3 (4)	C5—C6—C7—N2	0.6 (6)
Ni1—O1—C1—C2	−12.1 (6)	C11—C6—C7—N2	−179.6 (5)
Ni1—N1—C2—C3	104.8 (4)	C5—C6—C7—C8	179.4 (5)
Ni1—N1—C2—C1	−20.8 (5)	C11—C6—C7—C8	−0.8 (8)
O2—C1—C2—N1	−158.3 (4)	N2—C7—C8—C9	177.2 (6)
O1—C1—C2—N1	23.0 (7)	C6—C7—C8—C9	−1.3 (9)
O2—C1—C2—C3	74.6 (6)	C7—C8—C9—C10	2.9 (11)
O1—C1—C2—C3	−104.0 (5)	C8—C9—C10—C11	−2.4 (11)
N1—C2—C3—C5	73.4 (6)	C9—C10—C11—C6	0.2 (10)
C1—C2—C3—C5	−160.9 (5)	C5—C6—C11—C10	−178.9 (6)
C7—N2—C4—C5	−0.9 (7)	C7—C6—C11—C10	1.3 (8)

Symmetry codes: (i) −x, −y+1, −z+1; (ii) x, −y+3/2, z+1/2; (iii) −x, y−1/2, −z+1/2; (iv) −x, y+1/2, −z+1/2.