Download citation
Download citation
link to html
The title complex, (C4H12N2)[Ni2(C6H5O7)2(H2O)4], was synthesized under solvothermal conditions. Both cation and anion possess crystallographically imposed inversion symmetry. The citrate ion acts as a quadridentate ligand, coordinating through the hydroxyl and two carboxylate O atoms to one nickel atom, and bridging the second metal centre through the remaining carboxylate group. The coordination around each NiII atom is completed to distorted octa­hedral by the O atoms of two water mol­ecules. The crystal structure is stabilized by intra- and inter­molecular O—H...O and N—H...O hydrogen-bonding inter­actions.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807020569/rz2135sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536807020569/rz2135Isup2.hkl
Contains datablock I

CCDC reference: 650509

Key indicators

  • Single-crystal X-ray study
  • T = 298 K
  • Mean [sigma](C-C) = 0.003 Å
  • R factor = 0.029
  • wR factor = 0.073
  • Data-to-parameter ratio = 15.6

checkCIF/PLATON results

No syntax errors found



Alert level C PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ .... ? PLAT232_ALERT_2_C Hirshfeld Test Diff (M-X) Ni1 - O1W .. 5.34 su PLAT720_ALERT_4_C Number of Unusual/Non-Standard Label(s) ........ 4
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 3 ALERT level C = Check and explain 0 ALERT level G = General alerts; check 1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 1 ALERT type 2 Indicator that the structure model may be wrong or deficient 0 ALERT type 3 Indicator that the structure quality may be low 1 ALERT type 4 Improvement, methodology, query or suggestion 0 ALERT type 5 Informative message, check

Comment top

Up to now, hundreds of metal citrate complexes with diverse architectures have been synthesized and well documented in the literature (Kaliva et al., 2004; Kefalas et al., 2005; Wang et al., 2005; Xiang et al., 2005; Zhang et al., 2006). Some complexes contain centrosymmetric dimers with 1-D polymeric chain or 2-D layer structure (Zhou et al., 2005; Baggio & Perec, 2004), some are similar to the title complex (Baker et al., 1983; Kotsakis et al., 2003), most of them have monovalent counter ions. In this paper, the complex we report has a divalent organic piperazinium cation. Its structure is shown in Fig. 1. Each citrate ligand is triply deprotonated, and chelates to the Ni atom through the α-hydroxyl, α-carboxyl and one β-carboxyl oxygen atom. The other β-carboxyl oxygen atom spans over to the second Ni atom of the dimer. The distorted octahedral coordination sphere of each nickel atom is completed by the oxygen atoms of two water molecules. Selected geometric parameters of the complex are given in Table 1. The piperazinium cations occupy the space between the nickel-citrate dimers. The anions and the cations are connected by strong N—H···O hydrogen bonds. There are intramolecular hydrogen bonds between the hydroxyl groups and the carboxyl groups. Hydrogen bonding interactions are also observed between the coordinated water molecules and the carboxyl groups of neighbouring anions, forming a three-dimensional network (Table 2, Fig. 2).

Related literature top

For related literature, see: Baggio & Perec (2004); Baker et al. (1983); Kaliva et al. (2004); Kefalas et al. (2005); Kotsakis et al. (2003); Wang et al. (2005); Xiang et al. (2005); Zhang et al. (2006); Zhou et al. (2005).

Experimental top

Nickel chloride hexahydrate (0.072 g, 0.3 mmol) and citric acid monohydrate (0.061 g, 0.3 mmol) were dissolved in water/ethanol (1:1 v/v) solution (5 ml). Piperazine hexahydrate (0.096 g, 0.5 mmol) was then added and the solution stirred for 30 min. The resulting solution was transferred into Teflon-lined autoclave and heated at 130 °C under autogenous pressure for 5 days. Green block crystals suitable for X-ray analysis were collected from the reaction mixture.

Refinement top

The structure was solved by Patterson method. All hydrogen atoms were included in the riding model approximation, with C–H = 0.97 Å, N–H = 0.90 Å, O–H = 0.85 Å, and with Uiso(H) = 1.2 Ueq(C, N, O).

Structure description top

Up to now, hundreds of metal citrate complexes with diverse architectures have been synthesized and well documented in the literature (Kaliva et al., 2004; Kefalas et al., 2005; Wang et al., 2005; Xiang et al., 2005; Zhang et al., 2006). Some complexes contain centrosymmetric dimers with 1-D polymeric chain or 2-D layer structure (Zhou et al., 2005; Baggio & Perec, 2004), some are similar to the title complex (Baker et al., 1983; Kotsakis et al., 2003), most of them have monovalent counter ions. In this paper, the complex we report has a divalent organic piperazinium cation. Its structure is shown in Fig. 1. Each citrate ligand is triply deprotonated, and chelates to the Ni atom through the α-hydroxyl, α-carboxyl and one β-carboxyl oxygen atom. The other β-carboxyl oxygen atom spans over to the second Ni atom of the dimer. The distorted octahedral coordination sphere of each nickel atom is completed by the oxygen atoms of two water molecules. Selected geometric parameters of the complex are given in Table 1. The piperazinium cations occupy the space between the nickel-citrate dimers. The anions and the cations are connected by strong N—H···O hydrogen bonds. There are intramolecular hydrogen bonds between the hydroxyl groups and the carboxyl groups. Hydrogen bonding interactions are also observed between the coordinated water molecules and the carboxyl groups of neighbouring anions, forming a three-dimensional network (Table 2, Fig. 2).

For related literature, see: Baggio & Perec (2004); Baker et al. (1983); Kaliva et al. (2004); Kefalas et al. (2005); Kotsakis et al. (2003); Wang et al. (2005); Xiang et al. (2005); Zhang et al. (2006); Zhou et al. (2005).

Computing details top

Data collection: RAPID-AUTO (Rigaku, 1998); cell refinement: RAPID-AUTO; data reduction: RAPID-AUTO; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL/PC (Sheldrick, 1993); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. The crystal structure of the title compound with ellipsoids drawn at the 50% probability level. Symmetry codes: (i) 1 - x, -y, -z; (ii) -x, 1 - y, -z.
[Figure 2] Fig. 2. Packing diagram of the title compound viewed along the b axis. Hydrogen bonds are represented by dotted lines.
Piperazinium tetraaquabis(µ2-citrato)dinickelate(II) top
Crystal data top
(C4H12N2)[Ni2(C6H5O7)2(H2O)4]F(000) = 680
Mr = 655.80Dx = 1.869 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 9899 reflections
a = 13.342 (3) Åθ = 3.0–27.6°
b = 6.7054 (13) ŵ = 1.71 mm1
c = 13.613 (3) ÅT = 298 K
β = 106.93 (3)°Block, green
V = 1165.1 (5) Å30.20 × 0.18 × 0.15 mm
Z = 2
Data collection top
Rigaku R-AXIS RAPID
diffractometer
2462 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.046
Graphite monochromatorθmax = 27.5°, θmin = 3.1°
Oscillation scansh = 1717
10894 measured reflectionsk = 88
2677 independent reflectionsl = 1717
Refinement top
Refinement on F2Primary atom site location: patt
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.029Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.073H-atom parameters constrained
S = 1.08 w = 1/[σ2(Fo2) + (0.033P)2 + 0.5209P]
where P = (Fo2 + 2Fc2)/3
2677 reflections(Δ/σ)max < 0.001
172 parametersΔρmax = 0.36 e Å3
0 restraintsΔρmin = 0.58 e Å3
Crystal data top
(C4H12N2)[Ni2(C6H5O7)2(H2O)4]V = 1165.1 (5) Å3
Mr = 655.80Z = 2
Monoclinic, P21/nMo Kα radiation
a = 13.342 (3) ŵ = 1.71 mm1
b = 6.7054 (13) ÅT = 298 K
c = 13.613 (3) Å0.20 × 0.18 × 0.15 mm
β = 106.93 (3)°
Data collection top
Rigaku R-AXIS RAPID
diffractometer
2462 reflections with I > 2σ(I)
10894 measured reflectionsRint = 0.046
2677 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0290 restraints
wR(F2) = 0.073H-atom parameters constrained
S = 1.08Δρmax = 0.36 e Å3
2677 reflectionsΔρmin = 0.58 e Å3
172 parameters
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
Ni10.356449 (16)0.10184 (3)0.089492 (15)0.01502 (9)
O10.46895 (9)0.27879 (17)0.05413 (8)0.0168 (2)
H10.49790.21210.01670.020*
O1W0.21588 (10)0.1791 (2)0.01518 (10)0.0267 (3)
H1WA0.20100.09650.06470.032*
H1WB0.22070.29450.03920.032*
O20.48547 (10)0.00460 (18)0.19579 (9)0.0210 (3)
O2W0.26483 (10)0.07943 (18)0.14890 (10)0.0215 (3)
H2WB0.22690.00910.17600.026*
H2WA0.30340.15420.19510.026*
O30.62422 (12)0.1371 (2)0.30710 (10)0.0308 (3)
O40.34262 (10)0.33467 (19)0.18366 (10)0.0225 (3)
O50.38093 (11)0.60449 (18)0.27900 (11)0.0247 (3)
O60.62307 (10)0.11233 (19)0.00955 (10)0.0239 (3)
O70.78853 (11)0.1785 (2)0.09831 (11)0.0329 (3)
N10.00054 (13)0.3898 (2)0.09153 (11)0.0207 (3)
H1A0.02780.29360.13770.025*
H1B0.05230.44810.10950.025*
C10.54617 (13)0.3207 (2)0.15133 (12)0.0155 (3)
C20.55405 (13)0.1389 (2)0.22351 (12)0.0165 (3)
C30.50727 (14)0.5019 (2)0.19770 (13)0.0191 (3)
H3A0.56010.53720.26100.023*
H3B0.50080.61320.15070.023*
C40.40335 (14)0.4756 (2)0.22078 (13)0.0172 (3)
C50.65218 (14)0.3690 (3)0.13446 (14)0.0200 (3)
H5A0.64570.49220.09580.024*
H5B0.70320.39100.20070.024*
C60.69299 (14)0.2077 (3)0.07807 (12)0.0193 (3)
C70.08284 (14)0.5411 (3)0.09266 (13)0.0226 (4)
H7A0.14240.47600.07920.027*
H7B0.10650.60240.16000.027*
C80.04050 (15)0.7003 (3)0.01229 (13)0.0227 (4)
H8A0.01520.77300.02910.027*
H8B0.09590.79410.01230.027*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ni10.01363 (13)0.01736 (13)0.01496 (13)0.00038 (8)0.00552 (9)0.00189 (8)
O10.0153 (5)0.0214 (6)0.0144 (5)0.0000 (5)0.0054 (4)0.0003 (5)
O1W0.0247 (7)0.0296 (7)0.0237 (6)0.0077 (6)0.0039 (5)0.0015 (6)
O20.0214 (6)0.0190 (6)0.0206 (6)0.0021 (5)0.0029 (5)0.0026 (5)
O2W0.0207 (6)0.0231 (6)0.0238 (6)0.0001 (5)0.0112 (5)0.0014 (5)
O30.0296 (7)0.0320 (7)0.0225 (6)0.0021 (6)0.0056 (6)0.0017 (6)
O40.0202 (6)0.0222 (6)0.0286 (6)0.0044 (5)0.0123 (5)0.0088 (6)
O50.0268 (7)0.0219 (6)0.0306 (7)0.0042 (5)0.0168 (6)0.0100 (5)
O60.0162 (6)0.0321 (7)0.0240 (6)0.0009 (5)0.0067 (5)0.0123 (5)
O70.0160 (6)0.0441 (8)0.0376 (7)0.0008 (6)0.0062 (6)0.0163 (7)
N10.0228 (8)0.0223 (7)0.0181 (7)0.0029 (6)0.0078 (6)0.0051 (6)
C10.0142 (7)0.0168 (7)0.0163 (7)0.0022 (6)0.0056 (6)0.0041 (6)
C20.0158 (8)0.0181 (7)0.0158 (7)0.0020 (7)0.0051 (6)0.0027 (6)
C30.0194 (8)0.0158 (7)0.0244 (8)0.0016 (7)0.0101 (7)0.0048 (7)
C40.0188 (8)0.0158 (7)0.0183 (7)0.0021 (7)0.0075 (6)0.0011 (6)
C50.0181 (8)0.0207 (8)0.0232 (8)0.0043 (7)0.0092 (7)0.0058 (7)
C60.0175 (8)0.0237 (8)0.0185 (7)0.0018 (7)0.0080 (7)0.0019 (7)
C70.0211 (8)0.0272 (9)0.0181 (8)0.0022 (8)0.0032 (7)0.0014 (7)
C80.0258 (9)0.0197 (8)0.0235 (8)0.0034 (7)0.0085 (7)0.0018 (7)
Geometric parameters (Å, º) top
Ni1—O22.0078 (14)N1—C8ii1.487 (2)
Ni1—O6i2.0419 (13)N1—C71.492 (2)
Ni1—O2W2.0498 (13)N1—H1A0.9000
Ni1—O42.0622 (12)N1—H1B0.9000
Ni1—O1W2.0638 (15)C1—C31.528 (2)
Ni1—O12.0769 (12)C1—C51.532 (2)
O1—C11.448 (2)C1—C21.550 (2)
O1—H10.8499C3—C41.519 (2)
O1W—H1WA0.8501C3—H3A0.9700
O1W—H1WB0.8500C3—H3B0.9700
O2—C21.261 (2)C5—C61.516 (2)
O2W—H2WB0.8501C5—H5A0.9700
O2W—H2WA0.8499C5—H5B0.9700
O3—C21.245 (2)C7—C81.515 (3)
O4—C41.252 (2)C7—H7A0.9700
O5—C41.266 (2)C7—H7B0.9700
O6—C61.281 (2)C8—N1ii1.487 (2)
O6—Ni1i2.0419 (12)C8—H8A0.9700
O7—C61.239 (2)C8—H8B0.9700
O2—Ni1—O6i89.77 (6)O1—C1—C2108.98 (13)
O2—Ni1—O2W90.44 (5)C3—C1—C2109.40 (13)
O6i—Ni1—O2W93.06 (6)C5—C1—C2111.48 (14)
O2—Ni1—O490.63 (5)O3—C2—O2123.64 (16)
O6i—Ni1—O4175.09 (5)O3—C2—C1118.72 (15)
O2W—Ni1—O491.84 (5)O2—C2—C1117.56 (14)
O2—Ni1—O1W174.29 (5)C4—C3—C1115.69 (14)
O6i—Ni1—O1W89.43 (6)C4—C3—H3A108.4
O2W—Ni1—O1W83.96 (6)C1—C3—H3A108.4
O4—Ni1—O1W90.65 (6)C4—C3—H3B108.4
O2—Ni1—O180.03 (5)C1—C3—H3B108.4
O6i—Ni1—O190.23 (5)H3A—C3—H3B107.4
O2W—Ni1—O1169.91 (5)O4—C4—O5121.66 (16)
O4—Ni1—O185.02 (5)O4—C4—C3121.80 (15)
O1W—Ni1—O1105.63 (5)O5—C4—C3116.54 (15)
C1—O1—Ni1105.60 (9)C6—C5—C1114.11 (14)
C1—O1—H1108.9C6—C5—H5A108.7
Ni1—O1—H1108.8C1—C5—H5A108.7
Ni1—O1W—H1WA109.8C6—C5—H5B108.7
Ni1—O1W—H1WB109.8C1—C5—H5B108.7
H1WA—O1W—H1WB108.3H5A—C5—H5B107.6
C2—O2—Ni1112.28 (11)O7—C6—O6124.52 (16)
Ni1—O2W—H2WB109.9O7—C6—C5119.87 (16)
Ni1—O2W—H2WA109.8O6—C6—C5115.59 (15)
H2WB—O2W—H2WA108.4N1—C7—C8110.69 (15)
C4—O4—Ni1131.14 (11)N1—C7—H7A109.5
C6—O6—Ni1i128.50 (12)C8—C7—H7A109.5
C8ii—N1—C7110.63 (14)N1—C7—H7B109.5
C8ii—N1—H1A109.5C8—C7—H7B109.5
C7—N1—H1A109.5H7A—C7—H7B108.1
C8ii—N1—H1B109.5N1ii—C8—C7110.87 (14)
C7—N1—H1B109.5N1ii—C8—H8A109.5
H1A—N1—H1B108.1C7—C8—H8A109.5
O1—C1—C3107.15 (13)N1ii—C8—H8B109.5
O1—C1—C5110.25 (13)C7—C8—H8B109.5
C3—C1—C5109.47 (14)H8A—C8—H8B108.1
Symmetry codes: (i) x+1, y, z; (ii) x, y+1, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1···O60.851.832.5632 (18)144
O1W—H1WA···O7i0.851.912.645 (2)143
O2W—H2WB···O5iii0.851.882.7163 (19)167
O2W—H2WA···O5iv0.852.082.903 (2)165
N1—H1A···O5iii0.901.892.765 (2)163
N1—H1B···O3v0.902.112.960 (2)157
Symmetry codes: (i) x+1, y, z; (iii) x+1/2, y1/2, z+1/2; (iv) x, y1, z; (v) x+1/2, y+1/2, z+1/2.

Experimental details

Crystal data
Chemical formula(C4H12N2)[Ni2(C6H5O7)2(H2O)4]
Mr655.80
Crystal system, space groupMonoclinic, P21/n
Temperature (K)298
a, b, c (Å)13.342 (3), 6.7054 (13), 13.613 (3)
β (°) 106.93 (3)
V3)1165.1 (5)
Z2
Radiation typeMo Kα
µ (mm1)1.71
Crystal size (mm)0.20 × 0.18 × 0.15
Data collection
DiffractometerRigaku R-AXIS RAPID
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
10894, 2677, 2462
Rint0.046
(sin θ/λ)max1)0.649
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.029, 0.073, 1.08
No. of reflections2677
No. of parameters172
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.36, 0.58

Computer programs: RAPID-AUTO (Rigaku, 1998), RAPID-AUTO, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL/PC (Sheldrick, 1993), SHELXL97.

Selected geometric parameters (Å, º) top
Ni1—O22.0078 (14)Ni1—O42.0622 (12)
Ni1—O6i2.0419 (13)Ni1—O1W2.0638 (15)
Ni1—O2W2.0498 (13)Ni1—O12.0769 (12)
O2—Ni1—O6i89.77 (6)O2W—Ni1—O1W83.96 (6)
O2—Ni1—O2W90.44 (5)O4—Ni1—O1W90.65 (6)
O6i—Ni1—O2W93.06 (6)O2—Ni1—O180.03 (5)
O2—Ni1—O490.63 (5)O6i—Ni1—O190.23 (5)
O6i—Ni1—O4175.09 (5)O2W—Ni1—O1169.91 (5)
O2W—Ni1—O491.84 (5)O4—Ni1—O185.02 (5)
O2—Ni1—O1W174.29 (5)O1W—Ni1—O1105.63 (5)
O6i—Ni1—O1W89.43 (6)
Symmetry code: (i) x+1, y, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1···O60.851.832.5632 (18)143.7
O1W—H1WA···O7i0.851.912.645 (2)143.2
O2W—H2WB···O5ii0.851.882.7163 (19)166.9
O2W—H2WA···O5iii0.852.082.903 (2)164.6
N1—H1A···O5ii0.901.892.765 (2)163.4
N1—H1B···O3iv0.902.112.960 (2)157.3
Symmetry codes: (i) x+1, y, z; (ii) x+1/2, y1/2, z+1/2; (iii) x, y1, z; (iv) x+1/2, y+1/2, z+1/2.
 

Follow Acta Cryst. E
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds