Di­aqua­bis­[μ-(R,R)-tartrato-κ⁴O¹,O²:O³,O⁴]­dinickel(II) trihydrate

In the crystal structure of the title compound, [Ni₂(C₄H₄O₆)₂(H₂O)₂]·3H₂O, two nickel cations, two tartrate anions and two water mol­ecules form the dimeric complex. Each nickel cation is in a distorted octahedral environment composed of four O atoms of two crystallographically independent tartrate anions, one water mol­ecule and one O atom of a symmetry-equivalent tartrate anion. The asymmetric unit contains three additional water mol­ecules which are connected via hydrogen bonding.

S1. Comment

In 1984, Bostelaar et al. (1984) reported the crystal structure of diaquabis[(R,R)-tartrato-O¹,O²:O³,O⁴]dinickel(II) trihydrate. The orthorhombic unit cell was a = 7.805 (3) Å, b = 11.068 (4) Å and c = 8.974 (8) Å, with Z = 2. From the systematic extinctions, the chiral space group P2₁2₁2 was selected. In the crystal structure, some disordering of the incorporated water molecules was observed and very short intermolecular O···O distances occurred. In addition, some atoms of the tartrate anions showed unusual anisotropic displacement parameters.

During our investigations on the synthesis of new nickel thioantimonates under solvothermal conditions, we obtained crystals of the same composition as Bostelaar et al. (1984). In contrast to the previously reported structure, we found an orthorhombic unit cell with a doubled c axis. The systematic extinctions are in accordance with the chiral space group P2₁2₁2₁. Without the doubled c axis, the systematic extinctions lead to space group P2₁2₁2. We note that the doubled c axis is observed at 295 and 150 K, thus excluding the possibility that the doubling is caused by a low-temperature phase transition.

The asymmetric unit of the title compound, (I), contains two crystallographically independent nickel cations and tartrate anions, as well as five crystallographically independent molecules of water, all being located in general positions. Each Ni²⁺ cation is connected to two halves of two different tartate dianions through chelation by the alcohol and the carboxylate group, forming dimeric [(R,R)-tartrato-O¹,O²:O³,O⁴]dinickel(II) complexes. The remaining two coordination sites of the Ni²⁺ cation are occupied by one water molecule and one O atom of a non-chelating carboxylate group from a symmetry equivalent dimeric complex. As expected, the Ni—O distances to the chelating carboxylate O atoms [2.007 (2)–2.013 (2) Å] are significantly shorter than those to the hydroxyl O atoms [2.066 (2)–2.100 (2) Å]. The Ni—O distances to O atoms of the water molecules range from 2.031 (2) to 2.033 (2) Å and the distances to the non-chelating carboxylate O atom are between 2.043 (2) and 2.046 (2) Å. The coordination polyhedron around the two crystallographically independent Ni²⁺ cations can be described as a distorted octahedron. The dimers are additionally connected by O—H···O hydrogen bonding between the H atoms of the water molecules, which are coordinated to the Ni²⁺ cations, and the carboxylate O atoms of symmetry equivalent dimers, which act as the acceptors. For these contacts, the shortest intermolecular O···H distances are 1.82 [O···O 2.638 (2) Å] and 1.82 Å [O···O 2.590 (2) Å], and the corresponding O—H···O angles amount to 178 and 157°. The three additional crystallographically independent water molecules connect the dimers via O—H···O hydrogen bonding. These water molecules act as acceptors for the H atoms of the tartrate hydroxyl groups and as donors for hydrogen bonds to the carboxylate O atoms and to other water molecules. Distances and angles indicate strong hydrogen bonds.

Concerning the geometry of the tartrate anions in space group P2₁2₁2, the dimeric complexes are located around a twofold axis and therefore the tartrate dianions must be equivalent for symmetry reasons. A detailed analysis of the conformation of both crystallographically independent tartrate molecules in the title compound shows small but significant differences of their geometry.

S2. Experimental

The title compound was prepared by the reaction of powdered nickel (1 mmol) with 1,3-phenylenediamine (1 mmol) in a colloidal solution of Sb₂S₃ (1%, 10 ml) which was stabilized with potassium antimony tartrate. The mixture was heated in a Teflon-lined steel autocalve at 413 K for 6 d. After cooling, the product as green crystals was filtered off and washed with water.

S3. Refinement

The H atoms of O—H groups were located from difference map, but were refined as rigid groups with idealized O—H bond lengths of 0.82 Å. H atoms on C atoms were positioned with idealized geometry and refined using a riding model. All H atoms were refined using fixed isotropic displacement parameters [U_iso(H) = 1.2U_eq(C) for methylene H atoms, or 1.5U_eqO(OH)]. The absolute structure was determined using the Flack x parameter and is in agreement with the selected setting. In addition, inversion of the structure leads to significant poorer reliability factors [R1 for all reflections with F_o > 4σ(F_o) = 0.0454; wR2 for all reflections = 0.1213]. The structure contains an additional pseudosymmetry element which is a translation in the direction of the c axis by 0.5.

Computing details

Data collection: IPDS Program Package (Stoe & Cie, 1998); cell refinement: IPDS Program Package; data reduction: IPDS Program Package; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP in SHELXTL (Bruker, 1998); software used to prepare material for publication: CIFTAB in SHELXTL.

Figures

Fig. 1. The crystal structure of (I) with labeling and displacement ellipsoids drawn at the 50% probability level. [Symmetry codes: (i) 1 - x, 0.5 + y, 0.5 - z; (ii) 2 - x, -0.5 + y, 0.5 - z.]

Diaquabis ((R,R)-tartrato-O¹,O²:O³,O⁴)dinickel(II) Trihydrate

Crystal data

[Ni2(C4H4O6)2(H2O)2]·3H2O	Dx = 2.159 Mg m^−3
Mr = 503.64	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, P212121	Cell parameters from 8000 reflections
a = 7.8072 (5) Å	θ = 3–28°
b = 11.0636 (8) Å	µ = 2.53 mm^−1
c = 17.9361 (9) Å	T = 150 K
V = 1549.24 (17) Å^3	Block, green
Z = 4	0.3 × 0.2 × 0.2 mm
F(000) = 1032

Data collection

Stoe Imaging Plate Diffraction System diffractometer	3665 independent reflections
Radiation source: fine-focus sealed tube	3602 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.041
ϕ scans	θmax = 28.1°, θmin = 2.9°
Absorption correction: numerical (X-SHAPE; Stoe & Cie, 1998)	h = −10→10
Tmin = 0.605, Tmax = 0.735	k = −14→14
22323 measured reflections	l = −22→22

Refinement

Refinement on F^2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	Constrained
R[F^2 > 2σ(F^2)] = 0.024	w = 1/[σ^2(Fo^2) + (0.0446P)^2 + 0.7939P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.063	(Δ/σ)max = 0.001
S = 1.06	Δρmax = 0.38 e Å^−3
3665 reflections	Δρmin = −0.80 e Å^−3
245 parameters	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.0083 (7)
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack (1983)
Secondary atom site location: difference Fourier map	Absolute structure parameter: 0.002 (9)

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	0.89538 (3)	0.28198 (2)	0.362625 (14)	0.00377 (8)
Ni2	0.62521 (3)	0.71153 (2)	0.348885 (14)	0.00382 (8)
O1	0.72642 (18)	0.23801 (13)	0.28237 (9)	0.0069 (3)
O2	0.57950 (19)	0.31173 (13)	0.18598 (9)	0.0089 (3)
C1	0.6965 (2)	0.31615 (18)	0.23284 (12)	0.0047 (4)
C2	0.8130 (3)	0.42718 (18)	0.22766 (12)	0.0043 (4)
H2	0.8804	0.4216	0.1804	0.005*
O3	0.93045 (18)	0.42737 (13)	0.28896 (9)	0.0057 (3)
H3A	1.0214	0.4574	0.2756	0.009*
C3	0.7053 (2)	0.54235 (17)	0.22494 (12)	0.0045 (4)
H3	0.6316	0.5385	0.1794	0.007*
O4	0.59490 (18)	0.55118 (13)	0.28856 (8)	0.0058 (3)
H4A	0.4990	0.5297	0.2755	0.009*
C4	0.8147 (2)	0.65682 (17)	0.21970 (12)	0.0049 (4)
O5	0.78517 (19)	0.74233 (13)	0.26340 (9)	0.0092 (3)
O6	0.9237 (2)	0.65827 (13)	0.16872 (9)	0.0094 (3)
O11	1.03870 (18)	0.35422 (14)	0.44429 (9)	0.0079 (3)
O12	1.0195 (2)	0.43875 (15)	0.55646 (9)	0.0097 (3)
C11	0.9571 (3)	0.40782 (18)	0.49540 (12)	0.0050 (4)
C12	0.7696 (3)	0.43927 (19)	0.48366 (12)	0.0059 (4)
H12	0.7008	0.4060	0.5260	0.007*
O13	0.71333 (18)	0.38595 (14)	0.41619 (9)	0.0075 (3)
H13A	0.6109	0.3698	0.4175	0.011*
C13	0.7492 (3)	0.57826 (19)	0.48167 (12)	0.0057 (4)
H13	0.8163	0.6139	0.5238	0.007*
O14	0.80952 (18)	0.62819 (14)	0.41388 (9)	0.0074 (3)
H14A	0.9130	0.6410	0.4142	0.011*
C14	0.5617 (3)	0.61165 (18)	0.49162 (12)	0.0057 (4)
O15	0.48718 (18)	0.66914 (14)	0.44002 (9)	0.0074 (3)
O16	0.4952 (2)	0.58046 (15)	0.55139 (9)	0.0105 (3)
O21	0.83427 (19)	0.14688 (13)	0.43469 (9)	0.0082 (3)
H21A	0.8930	0.0859	0.4303	0.012*
H21B	0.7356	0.1217	0.4369	0.012*
O22	0.69955 (18)	0.87481 (13)	0.38925 (9)	0.0080 (3)
H22A	0.6262	0.9073	0.4151	0.012*
H22B	0.7813	0.8787	0.4179	0.012*
O23	1.26101 (19)	0.49717 (12)	0.24702 (10)	0.0108 (3)
H23A	1.2606	0.4642	0.2061	0.016*
H23B	1.2509	0.5679	0.2340	0.016*
O24	0.3784 (2)	0.3714 (2)	0.39201 (11)	0.0274 (4)
H24A	0.3119	0.3504	0.4250	0.041*
H24B	0.3531	0.3550	0.3488	0.041*
O25	1.1467 (2)	0.61999 (18)	0.40338 (13)	0.0280 (5)
H25A	1.2263	0.6544	0.4244	0.042*
H25B	1.1632	0.5493	0.3917	0.042*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ni1	0.00354 (12)	0.00453 (12)	0.00325 (14)	−0.00001 (9)	−0.00015 (9)	−0.00052 (9)
Ni2	0.00366 (12)	0.00432 (12)	0.00347 (13)	0.00035 (9)	0.00034 (8)	0.00002 (9)
O1	0.0083 (6)	0.0073 (6)	0.0053 (7)	−0.0029 (5)	−0.0032 (5)	0.0004 (5)
O2	0.0077 (6)	0.0084 (7)	0.0104 (8)	−0.0037 (5)	−0.0064 (6)	0.0005 (5)
C1	0.0034 (8)	0.0060 (9)	0.0048 (10)	−0.0015 (6)	0.0010 (7)	−0.0013 (7)
C2	0.0047 (8)	0.0063 (8)	0.0020 (10)	−0.0021 (7)	−0.0014 (7)	−0.0005 (7)
O3	0.0032 (6)	0.0087 (6)	0.0052 (7)	−0.0020 (5)	−0.0018 (5)	0.0028 (5)
C3	0.0038 (8)	0.0065 (9)	0.0033 (10)	−0.0009 (7)	0.0017 (7)	−0.0002 (7)
O4	0.0038 (6)	0.0073 (6)	0.0061 (7)	−0.0007 (5)	0.0025 (5)	−0.0023 (5)
C4	0.0044 (8)	0.0058 (9)	0.0045 (10)	−0.0003 (7)	−0.0001 (7)	0.0016 (7)
O5	0.0121 (7)	0.0067 (7)	0.0088 (8)	−0.0018 (5)	0.0054 (6)	−0.0017 (5)
O6	0.0096 (7)	0.0084 (7)	0.0103 (8)	−0.0031 (5)	0.0061 (5)	−0.0009 (5)
O11	0.0048 (6)	0.0118 (7)	0.0071 (8)	0.0008 (5)	−0.0018 (5)	−0.0034 (6)
O12	0.0088 (7)	0.0116 (7)	0.0087 (8)	0.0029 (6)	−0.0049 (6)	−0.0039 (6)
C11	0.0053 (8)	0.0046 (9)	0.0053 (10)	−0.0013 (6)	−0.0005 (7)	0.0018 (7)
C12	0.0045 (8)	0.0083 (9)	0.0048 (10)	0.0013 (7)	−0.0018 (7)	−0.0013 (7)
O13	0.0038 (6)	0.0106 (7)	0.0081 (8)	0.0006 (5)	−0.0017 (5)	−0.0054 (5)
C13	0.0036 (8)	0.0082 (9)	0.0053 (10)	0.0023 (7)	0.0017 (7)	0.0005 (7)
O14	0.0031 (6)	0.0117 (7)	0.0074 (8)	0.0009 (5)	0.0015 (5)	0.0056 (5)
C14	0.0047 (8)	0.0054 (9)	0.0072 (10)	0.0005 (7)	0.0009 (7)	−0.0019 (7)
O15	0.0036 (6)	0.0124 (7)	0.0063 (8)	0.0022 (5)	0.0014 (5)	0.0026 (5)
O16	0.0083 (7)	0.0144 (8)	0.0087 (8)	0.0036 (6)	0.0050 (6)	0.0041 (6)
O21	0.0065 (6)	0.0072 (6)	0.0109 (8)	−0.0002 (5)	0.0030 (5)	0.0041 (6)
O22	0.0048 (6)	0.0089 (7)	0.0104 (8)	0.0010 (5)	−0.0029 (5)	−0.0054 (6)
O23	0.0140 (8)	0.0066 (7)	0.0117 (9)	0.0016 (6)	−0.0005 (6)	−0.0011 (5)
O24	0.0090 (8)	0.0572 (13)	0.0161 (10)	−0.0087 (8)	0.0007 (8)	0.0001 (9)
O25	0.0081 (7)	0.0255 (10)	0.0504 (14)	−0.0013 (7)	0.0014 (8)	−0.0115 (9)

Geometric parameters (Å, º)

Ni1—O11	2.0091 (15)	C4—O5	1.250 (2)
Ni1—O1	2.0121 (15)	O6—Ni1^iv	2.0456 (15)
Ni1—O21	2.0328 (15)	O11—C11	1.264 (3)
Ni1—O6^i	2.0456 (15)	O12—C11	1.246 (3)
Ni1—O13	2.0655 (15)	C11—C12	1.520 (3)
Ni1—O3	2.0995 (15)	C12—O13	1.416 (2)
Ni2—O5	2.0066 (16)	C12—C13	1.546 (3)
Ni2—O15	2.0132 (15)	C12—H12	1.0000
Ni2—O22	2.0308 (15)	O13—H13A	0.8200
Ni2—O2^ii	2.0430 (15)	C13—O14	1.416 (2)
Ni2—O14	2.0688 (15)	C13—C14	1.520 (3)
Ni2—O4	2.0914 (14)	C13—H13	1.0000
O1—C1	1.261 (3)	O14—H14A	0.8200
O2—C1	1.242 (2)	C14—O16	1.240 (3)
O2—Ni2^iii	2.0430 (15)	C14—O15	1.265 (3)
C1—C2	1.531 (3)	O21—H21A	0.8200
C2—O3	1.432 (2)	O21—H21B	0.8201
C2—C3	1.527 (3)	O22—H22A	0.8200
C2—H2	1.0000	O22—H22B	0.8201
O3—H3A	0.8199	O23—H23A	0.8199
C3—O4	1.433 (2)	O23—H23B	0.8200
C3—C4	1.530 (3)	O24—H24A	0.8200
C3—H3	1.0001	O24—H24B	0.8199
O4—H4A	0.8199	O25—H25A	0.8200
C4—O6	1.249 (3)	O25—H25B	0.8200
O11—Ni1—O1	169.38 (6)	O4—C3—H3	107.9
O11—Ni1—O21	87.68 (6)	C2—C3—H3	107.9
O1—Ni1—O21	97.08 (6)	C4—C3—H3	107.8
O11—Ni1—O6^i	94.70 (6)	C3—O4—Ni2	113.68 (11)
O1—Ni1—O6^i	95.41 (6)	C3—O4—H4A	107.6
O21—Ni1—O6^i	81.08 (6)	Ni2—O4—H4A	119.8
O11—Ni1—O13	79.78 (6)	O6—C4—O5	125.07 (18)
O1—Ni1—O13	90.93 (6)	O6—C4—C3	115.84 (17)
O21—Ni1—O13	87.26 (6)	O5—C4—C3	119.02 (18)
O6^i—Ni1—O13	167.32 (7)	C4—O5—Ni2	117.72 (13)
O11—Ni1—O3	94.67 (6)	C4—O6—Ni1^iv	132.86 (14)
O1—Ni1—O3	79.66 (6)	C11—O11—Ni1	115.77 (13)
O21—Ni1—O3	173.76 (6)	O12—C11—O11	124.68 (19)
O6^i—Ni1—O3	104.45 (6)	O12—C11—C12	115.82 (19)
O13—Ni1—O3	87.47 (6)	O11—C11—C12	119.50 (19)
O5—Ni2—O15	173.25 (6)	O13—C12—C11	108.78 (17)
O5—Ni2—O22	86.76 (6)	O13—C12—C13	111.25 (17)
O15—Ni2—O22	94.06 (7)	C11—C12—C13	109.28 (18)
O5—Ni2—O2^ii	99.26 (7)	O13—C12—H12	109.2
O15—Ni2—O2^ii	87.49 (6)	C11—C12—H12	109.2
O22—Ni2—O2^ii	81.38 (6)	C13—C12—H12	109.2
O5—Ni2—O14	94.21 (6)	C12—O13—Ni1	114.58 (12)
O15—Ni2—O14	79.10 (6)	C12—O13—H13A	111.7
O22—Ni2—O14	89.82 (6)	Ni1—O13—H13A	124.3
O2^ii—Ni2—O14	163.42 (6)	O14—C13—C14	109.05 (17)
O5—Ni2—O4	79.58 (6)	O14—C13—C12	111.93 (17)
O15—Ni2—O4	99.32 (6)	C14—C13—C12	109.77 (18)
O22—Ni2—O4	166.24 (6)	O14—C13—H13	108.7
O2^ii—Ni2—O4	102.32 (6)	C14—C13—H13	108.7
O14—Ni2—O4	89.55 (6)	C12—C13—H13	108.7
C1—O1—Ni1	117.36 (13)	C13—O14—Ni2	115.23 (12)
C1—O2—Ni2^iii	143.48 (14)	C13—O14—H14A	113.0
O2—C1—O1	125.85 (18)	Ni2—O14—H14A	127.7
O2—C1—C2	115.30 (18)	O16—C14—O15	125.47 (18)
O1—C1—C2	118.84 (17)	O16—C14—C13	115.90 (19)
O3—C2—C3	112.08 (16)	O15—C14—C13	118.63 (18)
O3—C2—C1	109.58 (16)	C14—O15—Ni2	117.72 (13)
C3—C2—C1	110.13 (16)	Ni1—O21—H21A	114.4
O3—C2—H2	108.3	Ni1—O21—H21B	120.1
C3—C2—H2	108.3	H21A—O21—H21B	104.5
C1—C2—H2	108.3	Ni2—O22—H22A	113.1
C2—O3—Ni1	113.49 (11)	Ni2—O22—H22B	119.5
C2—O3—H3A	109.3	H22A—O22—H22B	99.5
Ni1—O3—H3A	127.4	H23A—O23—H23B	99.7
O4—C3—C2	111.26 (16)	H24A—O24—H24B	117.8
O4—C3—C4	109.15 (16)	H25A—O25—H25B	116.1
C2—C3—C4	112.66 (16)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3A···O23	0.82	1.99	2.797 (2)	168
O4—H4A···O23^v	0.82	1.96	2.776 (2)	173
O13—H13A···O24	0.82	1.87	2.655 (2)	160
O14—H14A···O25	0.82	1.85	2.640 (2)	162
O21—H21A···O16^vi	0.82	2.03	2.823 (2)	162
O21—H21B···O12^vii	0.82	1.82	2.638 (2)	178
O22—H22A···O12^viii	0.82	1.96	2.679 (2)	145
O22—H22B···O16^ix	0.82	1.82	2.590 (2)	157
O23—H23A···O22^i	0.82	2.00	2.811 (2)	170
O23—H23B···O1^iv	0.82	1.91	2.718 (2)	167
O24—H24A···O11^v	0.82	2.16	2.820 (2)	137
O24—H24B···O5^iii	0.82	2.60	3.382 (3)	160
O25—H25A···O15^x	0.82	2.06	2.792 (2)	148
O25—H25B···O24^x	0.82	2.59	3.299 (3)	146

Symmetry codes: (i) −x+2, y−1/2, −z+1/2; (iii) −x+1, y−1/2, −z+1/2; (iv) −x+2, y+1/2, −z+1/2; (v) x−1, y, z; (vi) x+1/2, −y+1/2, −z+1; (vii) x−1/2, −y+1/2, −z+1; (viii) x−1/2, −y+3/2, −z+1; (ix) x+1/2, −y+3/2, −z+1; (x) x+1, y, z.