The title complex, [BaNi(C3H2O4)2(H2O)3]n, is polymeric, with two non-equivalent malonate dianions bridging one Ni atom and five different Ba atoms. The Ni atoms have a distorted octahedral (NiO6) environment, and are coordinated by four malonate O atoms in a planar arrangement and two water molecules in axial positions. The Ba atom may be described as a BaO9 polyhedron in a monocapped square-antiprismatic environment, which involves two water molecules and seven O atoms from different malonate ligands. The three-dimensional structure is further maintained and stabilized by hydrogen bonds.
Supporting information
CCDC reference: 677090
The title complex was prepared under continuous stirring with successive
addition of malonic acid (0.31 g, 3 mmol), NiCl2·6H2O (0.47 g, 2 mmol),and Ba(OH)2·8H2O (0.63 g, 2 mmol) to distilled water (20 ml) at
room temperature. After filtration, slow evaporation over a period of 3 d at
room temperature provided green needle crystals of (I).
All difference peaks larger than 1.0 e Å-3 are around atom Ba1. The highest
difference peak lies 0.85 Å from atom Ba1. All H atoms attached to O atoms
were found in difference Fourier maps. During refinement, the H atoms were
fixed at O—H distances of 0.85 Å and their Uiso(H) values were
set at 1.2Ueq(O). H atoms of CH2 groups were treated as riding
[C—H = 0.97 Å and Uiso(H) = 1.2Ueq(C)].
Data collection: CrystalClear (Rigaku/MSC, 2005); cell refinement: CrystalClear (Rigaku/MSC, 2005); data reduction: CrystalClear (Rigaku/MSC, 2005); program(s) used to solve structure: SHELXTL (Bruker, 2001); program(s) used to refine structure: SHELXTL (Bruker, 2001); molecular graphics: SHELXTL (Bruker, 2001); software used to prepare material for publication: SHELXTL (Bruker, 2001).
Poly[µ-aqua-diaqua-µ
4-malonato-µ
3-malonato-barium(II)nickel(II)]
top
Crystal data top
[BaNi(C3H2O4)2(H2O)3] | F(000) = 872 |
Mr = 454.19 | Dx = 2.504 Mg m−3 |
Monoclinic, Cc | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: C -2yc | Cell parameters from 2018 reflections |
a = 12.177 (2) Å | θ = 2.9–27.9° |
b = 13.842 (3) Å | µ = 4.86 mm−1 |
c = 7.1502 (14) Å | T = 294 K |
β = 91.17 (3)° | Needle, green |
V = 1204.9 (4) Å3 | 0.12 × 0.10 × 0.06 mm |
Z = 4 | |
Data collection top
Rigaku Saturn diffractometer | 1432 independent reflections |
Radiation source: fine-focus sealed tube | 1424 reflections with I > 2σ(I) |
Confocal monochromator | Rint = 0.026 |
Detector resolution: 28.676 pixels mm-1 | θmax = 25.0°, θmin = 2.9° |
ω scans | h = −12→14 |
Absorption correction: multi-scan (Jacobson, 1998) | k = −16→16 |
Tmin = 0.558, Tmax = 0.738 | l = −7→8 |
3369 measured reflections | |
Refinement top
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)] = 0.042 | H-atom parameters constrained |
wR(F2) = 0.099 | w = 1/[σ2(Fo2) + (0.0834P)2] where P = (Fo2 + 2Fc2)/3 |
S = 1.09 | (Δ/σ)max < 0.001 |
1432 reflections | Δρmax = 1.23 e Å−3 |
173 parameters | Δρmin = −0.65 e Å−3 |
2 restraints | Absolute structure: Flack (1983), 365 Friedel pairs |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: 0.18 (6) |
Crystal data top
[BaNi(C3H2O4)2(H2O)3] | V = 1204.9 (4) Å3 |
Mr = 454.19 | Z = 4 |
Monoclinic, Cc | Mo Kα radiation |
a = 12.177 (2) Å | µ = 4.86 mm−1 |
b = 13.842 (3) Å | T = 294 K |
c = 7.1502 (14) Å | 0.12 × 0.10 × 0.06 mm |
β = 91.17 (3)° | |
Data collection top
Rigaku Saturn diffractometer | 1432 independent reflections |
Absorption correction: multi-scan (Jacobson, 1998) | 1424 reflections with I > 2σ(I) |
Tmin = 0.558, Tmax = 0.738 | Rint = 0.026 |
3369 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.042 | H-atom parameters constrained |
wR(F2) = 0.099 | Δρmax = 1.23 e Å−3 |
S = 1.09 | Δρmin = −0.65 e Å−3 |
1432 reflections | Absolute structure: Flack (1983), 365 Friedel pairs |
173 parameters | Absolute structure parameter: 0.18 (6) |
2 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 | x | y | z | Uiso*/Ueq | |
Ba1 | 1.09630 (6) | 0.58864 (3) | 0.08472 (7) | 0.0509 (2) | |
Ni1 | 0.85771 (10) | 0.75456 (8) | −0.04657 (15) | 0.0512 (3) | |
O1 | 0.9631 (6) | 0.7449 (5) | 0.1789 (11) | 0.0559 (16) | |
O2 | 0.9781 (7) | 0.7695 (6) | 0.4821 (11) | 0.0636 (18) | |
O3 | 0.7784 (6) | 0.8606 (5) | 0.0811 (9) | 0.0552 (15) | |
O4 | 0.7371 (6) | 0.9655 (5) | 0.3024 (10) | 0.0556 (14) | |
O5 | 0.9218 (6) | 0.6344 (5) | −0.1662 (10) | 0.0544 (14) | |
O6 | 0.8982 (5) | 0.4912 (5) | −0.2985 (10) | 0.0557 (14) | |
O7 | 0.7548 (6) | 0.7731 (5) | −0.2746 (11) | 0.0547 (15) | |
O8 | 0.6865 (6) | 0.7295 (5) | −0.5471 (11) | 0.0574 (16) | |
O9 | 0.9735 (6) | 0.8426 (5) | −0.1723 (11) | 0.0559 (14) | |
H9A | 0.9638 | 0.8268 | −0.2864 | 0.067* | |
H9B | 1.0392 | 0.8419 | −0.1299 | 0.067* | |
O10 | 0.7560 (6) | 0.6563 (5) | 0.0964 (10) | 0.0553 (15) | |
H10A | 0.7326 | 0.6906 | 0.1855 | 0.066* | |
H10B | 0.7977 | 0.6092 | 0.1251 | 0.066* | |
O11 | 1.0786 (7) | 0.5978 (4) | 0.4634 (13) | 0.0568 (16) | |
H11A | 1.1443 | 0.6011 | 0.5063 | 0.068* | |
H11B | 1.0375 | 0.6461 | 0.4850 | 0.068* | |
C1 | 0.9578 (8) | 0.7975 (7) | 0.3218 (16) | 0.054 (2) | |
C2 | 0.9203 (12) | 0.9001 (8) | 0.295 (2) | 0.065 (3) | |
H2A | 0.9267 | 0.9336 | 0.4143 | 0.078* | |
H2B | 0.9687 | 0.9319 | 0.2087 | 0.078* | |
C3 | 0.8056 (9) | 0.9090 (6) | 0.2238 (17) | 0.052 (2) | |
C4 | 0.8685 (9) | 0.5759 (7) | −0.2656 (16) | 0.052 (2) | |
C5 | 0.7550 (11) | 0.6044 (8) | −0.349 (2) | 0.065 (3) | |
H5A | 0.7437 | 0.5679 | −0.4633 | 0.078* | |
H5B | 0.6998 | 0.5830 | −0.2621 | 0.078* | |
C6 | 0.7321 (8) | 0.7106 (8) | −0.3936 (15) | 0.055 (2) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Ba1 | 0.0510 (3) | 0.0496 (3) | 0.0522 (3) | −0.0004 (2) | 0.00175 (19) | 0.0002 (2) |
Ni1 | 0.0525 (6) | 0.0502 (5) | 0.0509 (7) | 0.0025 (4) | 0.0007 (5) | −0.0013 (5) |
O1 | 0.059 (4) | 0.059 (4) | 0.050 (4) | 0.008 (3) | −0.003 (3) | −0.001 (3) |
O2 | 0.060 (4) | 0.076 (4) | 0.054 (4) | 0.015 (3) | 0.000 (3) | −0.002 (3) |
O3 | 0.058 (3) | 0.052 (3) | 0.055 (4) | 0.010 (3) | 0.003 (3) | −0.002 (3) |
O4 | 0.060 (3) | 0.056 (3) | 0.052 (3) | 0.006 (3) | 0.004 (3) | 0.005 (3) |
O5 | 0.058 (3) | 0.049 (3) | 0.055 (4) | 0.002 (3) | −0.004 (3) | 0.001 (3) |
O6 | 0.051 (3) | 0.054 (3) | 0.062 (4) | 0.004 (3) | 0.002 (3) | −0.001 (3) |
O7 | 0.056 (4) | 0.050 (3) | 0.058 (4) | 0.007 (3) | −0.001 (3) | 0.001 (3) |
O8 | 0.052 (4) | 0.060 (4) | 0.060 (4) | 0.008 (3) | −0.005 (3) | −0.007 (3) |
O9 | 0.058 (4) | 0.057 (3) | 0.053 (3) | −0.001 (3) | 0.004 (3) | −0.001 (3) |
O10 | 0.060 (4) | 0.052 (3) | 0.054 (4) | 0.003 (3) | 0.005 (3) | −0.002 (3) |
O11 | 0.054 (4) | 0.050 (3) | 0.067 (4) | 0.003 (2) | −0.002 (3) | 0.002 (3) |
C1 | 0.051 (5) | 0.057 (5) | 0.054 (5) | 0.006 (4) | 0.000 (4) | −0.005 (4) |
C2 | 0.070 (7) | 0.059 (6) | 0.066 (7) | 0.000 (4) | 0.002 (6) | −0.010 (5) |
C3 | 0.052 (6) | 0.049 (5) | 0.056 (6) | 0.000 (3) | 0.007 (5) | 0.003 (3) |
C4 | 0.049 (5) | 0.053 (4) | 0.053 (6) | 0.001 (3) | 0.001 (4) | 0.001 (4) |
C5 | 0.061 (6) | 0.060 (5) | 0.075 (7) | 0.006 (5) | −0.009 (5) | −0.001 (5) |
C6 | 0.047 (4) | 0.064 (5) | 0.055 (5) | −0.001 (4) | 0.001 (4) | −0.003 (5) |
Geometric parameters (Å, º) top
Ba1—O11 | 2.724 (10) | O4—C3 | 1.281 (12) |
Ba1—O11i | 2.729 (6) | O5—C4 | 1.251 (13) |
Ba1—O4ii | 2.778 (7) | O6—C4 | 1.250 (12) |
Ba1—O1 | 2.794 (7) | O7—C6 | 1.241 (13) |
Ba1—O6iii | 2.796 (6) | O8—C6 | 1.247 (13) |
Ba1—O5 | 2.825 (7) | O9—H9A | 0.8505 |
Ba1—O4iv | 2.857 (7) | O9—H9B | 0.8495 |
Ba1—O7v | 2.885 (7) | O10—H10A | 0.8486 |
Ba1—O8v | 2.911 (7) | O10—H10B | 0.8495 |
Ba1—Ni1 | 3.8059 (14) | O11—H11A | 0.8518 |
Ba1—Ba1i | 4.3362 (8) | O11—H11B | 0.8524 |
Ni1—O3 | 1.989 (6) | C1—C2 | 1.503 (15) |
Ni1—O5 | 2.033 (7) | C2—C3 | 1.482 (19) |
Ni1—O1 | 2.045 (8) | C2—H2A | 0.9700 |
Ni1—O7 | 2.052 (8) | C2—H2B | 0.9700 |
Ni1—O9 | 2.082 (7) | C4—C5 | 1.545 (17) |
Ni1—O10 | 2.117 (7) | C5—C6 | 1.528 (16) |
O1—C1 | 1.257 (14) | C5—H5A | 0.9700 |
O2—C1 | 1.230 (14) | C5—H5B | 0.9700 |
O3—C3 | 1.259 (14) | | |
| | | |
O11—Ba1—O11i | 110.6 (2) | O1—Ni1—O10 | 86.7 (3) |
O11—Ba1—O4ii | 142.9 (2) | O7—Ni1—O10 | 96.3 (3) |
O11i—Ba1—O4ii | 63.9 (2) | O9—Ni1—O10 | 173.2 (3) |
O11—Ba1—O1 | 70.5 (2) | C1—O1—Ni1 | 124.1 (6) |
O11i—Ba1—O1 | 140.0 (3) | C1—O1—Ba1 | 133.1 (6) |
O4ii—Ba1—O1 | 138.9 (2) | Ni1—O1—Ba1 | 102.6 (3) |
O11—Ba1—O6iii | 68.6 (2) | C3—O3—Ni1 | 129.9 (7) |
O11i—Ba1—O6iii | 70.0 (2) | C3—O4—Ba1vi | 124.8 (6) |
O4ii—Ba1—O6iii | 131.3 (2) | C3—O4—Ba1vii | 120.9 (7) |
O1—Ba1—O6iii | 74.1 (2) | Ba1vi—O4—Ba1vii | 100.6 (2) |
O11—Ba1—O5 | 123.2 (2) | C4—O5—Ni1 | 124.7 (7) |
O11i—Ba1—O5 | 87.5 (2) | C4—O5—Ba1 | 126.2 (6) |
O4ii—Ba1—O5 | 93.8 (2) | Ni1—O5—Ba1 | 101.9 (3) |
O1—Ba1—O5 | 63.0 (2) | C4—O6—Ba1i | 133.0 (6) |
O6iii—Ba1—O5 | 68.7 (2) | C6—O7—Ni1 | 125.6 (7) |
O11—Ba1—O4iv | 62.9 (2) | C6—O7—Ba1viii | 94.9 (6) |
O11i—Ba1—O4iv | 69.6 (2) | Ni1—O7—Ba1viii | 138.9 (3) |
O4ii—Ba1—O4iv | 82.09 (17) | C6—O8—Ba1viii | 93.5 (6) |
O1—Ba1—O4iv | 132.5 (2) | Ni1—O9—H9A | 100.4 |
O6iii—Ba1—O4iv | 96.5 (2) | Ni1—O9—H9B | 118.7 |
O5—Ba1—O4iv | 156.2 (2) | H9A—O9—H9B | 116.8 |
O11—Ba1—O7v | 71.8 (2) | Ni1—O10—H10A | 102.2 |
O11i—Ba1—O7v | 141.8 (2) | Ni1—O10—H10B | 104.9 |
O4ii—Ba1—O7v | 90.8 (2) | H10A—O10—H10B | 117.2 |
O1—Ba1—O7v | 77.9 (2) | Ba1—O11—Ba1iii | 105.4 (2) |
O6iii—Ba1—O7v | 137.2 (2) | Ba1—O11—H11A | 105.6 |
O5—Ba1—O7v | 124.2 (2) | Ba1iii—O11—H11A | 82.5 |
O4iv—Ba1—O7v | 79.4 (2) | Ba1—O11—H11B | 106.0 |
O11—Ba1—O8v | 108.6 (2) | Ba1iii—O11—H11B | 136.7 |
O11i—Ba1—O8v | 137.9 (2) | H11A—O11—H11B | 116.3 |
O4ii—Ba1—O8v | 75.8 (2) | O2—C1—O1 | 124.2 (10) |
O1—Ba1—O8v | 68.5 (2) | O2—C1—C2 | 118.0 (10) |
O6iii—Ba1—O8v | 140.5 (2) | O1—C1—C2 | 117.7 (10) |
O5—Ba1—O8v | 83.3 (2) | C3—C2—C1 | 113.8 (9) |
O4iv—Ba1—O8v | 117.8 (2) | C3—C2—H2A | 108.8 |
O7v—Ba1—O8v | 44.3 (2) | C1—C2—H2A | 108.8 |
O11—Ba1—C6v | 87.9 (2) | C3—C2—H2B | 108.8 |
O11i—Ba1—C6v | 149.8 (3) | C1—C2—H2B | 108.8 |
O4ii—Ba1—C6v | 86.8 (2) | H2A—C2—H2B | 107.7 |
O1—Ba1—C6v | 67.8 (2) | O3—C3—O4 | 121.1 (11) |
O6iii—Ba1—C6v | 140.2 (2) | O3—C3—C2 | 117.8 (9) |
O5—Ba1—C6v | 102.4 (2) | O4—C3—C2 | 121.1 (11) |
O4iv—Ba1—C6v | 100.7 (2) | O6—C4—O5 | 124.4 (10) |
O7v—Ba1—C6v | 22.5 (2) | O6—C4—C5 | 115.3 (9) |
O8v—Ba1—C6v | 22.6 (2) | O5—C4—C5 | 120.2 (9) |
O3—Ni1—O5 | 172.2 (3) | C6—C5—C4 | 118.9 (10) |
O3—Ni1—O1 | 89.4 (3) | C6—C5—H5A | 107.6 |
O5—Ni1—O1 | 92.2 (3) | C4—C5—H5A | 107.6 |
O3—Ni1—O7 | 88.7 (3) | C6—C5—H5B | 107.6 |
O5—Ni1—O7 | 90.1 (3) | C4—C5—H5B | 107.6 |
O1—Ni1—O7 | 176.4 (3) | H5A—C5—H5B | 107.0 |
O3—Ni1—O9 | 96.1 (3) | O7—C6—O8 | 123.1 (10) |
O5—Ni1—O9 | 91.6 (3) | O7—C6—C5 | 119.3 (10) |
O1—Ni1—O9 | 87.6 (3) | O8—C6—C5 | 117.5 (10) |
O7—Ni1—O9 | 89.5 (3) | O7—C6—Ba1viii | 62.6 (5) |
O3—Ni1—O10 | 87.6 (3) | O8—C6—Ba1viii | 63.9 (5) |
O5—Ni1—O10 | 84.9 (3) | C5—C6—Ba1viii | 157.9 (7) |
Symmetry codes: (i) x, −y+1, z−1/2; (ii) x+1/2, −y+3/2, z−1/2; (iii) x, −y+1, z+1/2; (iv) x+1/2, y−1/2, z; (v) x+1/2, −y+3/2, z+1/2; (vi) x−1/2, −y+3/2, z+1/2; (vii) x−1/2, y+1/2, z; (viii) x−1/2, −y+3/2, z−1/2. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O9—H9A···O2ix | 0.85 | 1.85 | 2.672 (11) | 163 |
O11—H11A···O3v | 0.85 | 1.79 | 2.622 (11) | 166 |
O11—H11B···O2 | 0.85 | 1.85 | 2.677 (10) | 162 |
O9—H9B···O8v | 0.85 | 2.12 | 2.903 (10) | 153 |
O10—H10A···O8x | 0.85 | 2.07 | 2.886 (10) | 160 |
O10—H10B···O6iii | 0.85 | 1.92 | 2.772 (10) | 176 |
Symmetry codes: (iii) x, −y+1, z+1/2; (v) x+1/2, −y+3/2, z+1/2; (ix) x, y, z−1; (x) x, y, z+1. |
Experimental details
Crystal data |
Chemical formula | [BaNi(C3H2O4)2(H2O)3] |
Mr | 454.19 |
Crystal system, space group | Monoclinic, Cc |
Temperature (K) | 294 |
a, b, c (Å) | 12.177 (2), 13.842 (3), 7.1502 (14) |
β (°) | 91.17 (3) |
V (Å3) | 1204.9 (4) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 4.86 |
Crystal size (mm) | 0.12 × 0.10 × 0.06 |
|
Data collection |
Diffractometer | Rigaku Saturn diffractometer |
Absorption correction | Multi-scan (Jacobson, 1998) |
Tmin, Tmax | 0.558, 0.738 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3369, 1432, 1424 |
Rint | 0.026 |
(sin θ/λ)max (Å−1) | 0.595 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.042, 0.099, 1.09 |
No. of reflections | 1432 |
No. of parameters | 173 |
No. of restraints | 2 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 1.23, −0.65 |
Absolute structure | Flack (1983), 365 Friedel pairs |
Absolute structure parameter | 0.18 (6) |
Selected geometric parameters (Å, º) topBa1—O11 | 2.724 (10) | Ba1—O8v | 2.911 (7) |
Ba1—O11i | 2.729 (6) | Ba1—Ni1 | 3.8059 (14) |
Ba1—O4ii | 2.778 (7) | Ni1—O3 | 1.989 (6) |
Ba1—O1 | 2.794 (7) | Ni1—O5 | 2.033 (7) |
Ba1—O6iii | 2.796 (6) | Ni1—O1 | 2.045 (8) |
Ba1—O5 | 2.825 (7) | Ni1—O7 | 2.052 (8) |
Ba1—O4iv | 2.857 (7) | Ni1—O9 | 2.082 (7) |
Ba1—O7v | 2.885 (7) | Ni1—O10 | 2.117 (7) |
| | | |
O2—C1—O1 | 124.2 (10) | O6—C4—O5 | 124.4 (10) |
O3—C3—O4 | 121.1 (11) | O7—C6—O8 | 123.1 (10) |
Symmetry codes: (i) x, −y+1, z−1/2; (ii) x+1/2, −y+3/2, z−1/2; (iii) x, −y+1, z+1/2; (iv) x+1/2, y−1/2, z; (v) x+1/2, −y+3/2, z+1/2. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O9—H9A···O2vi | 0.85 | 1.85 | 2.672 (11) | 163.0 |
O11—H11A···O3v | 0.85 | 1.79 | 2.622 (11) | 165.7 |
O11—H11B···O2 | 0.85 | 1.85 | 2.677 (10) | 162.2 |
O9—H9B···O8v | 0.85 | 2.12 | 2.903 (10) | 152.8 |
O10—H10A···O8vii | 0.85 | 2.07 | 2.886 (10) | 159.8 |
O10—H10B···O6iii | 0.85 | 1.92 | 2.772 (10) | 175.9 |
Symmetry codes: (iii) x, −y+1, z+1/2; (v) x+1/2, −y+3/2, z+1/2; (vi) x, y, z−1; (vii) x, y, z+1. |
Heterobimetallic malonate complexes involving transition and alkaline-earth metals have attracted much attention recently in the area of topology design and for their potential applications in molecular-based magnetism, catalysis, supramolecular chemistry and materials science (Gil de Muro et al., 1998, 2004; Fu et al., 2006). The use of dicarboxylate ligands as small building blocks to generate metal-organic frameworks of different dimensionalities may lead to interesting network architectures (Rodriguez-Martin et al., 2002). From a coordination standpoint, the malonate ligand, with two neighboring carboxylate groups, is a very flexible ligand. Its basic coordination mode is as a chelate via two distal carboxylate O atoms to form a six-membered ring and the coordinating ability of the nonchelating O atoms makes the formation of polymeric networks possible (Djeghri et al., 2005, 2006). In the course of our study of heterobimetallic malonate complexes involving transition and alkaline-earth metals, we have recently reported the crystal structures of poly[tetraaqua-di-µ4-malonato-barium(II)zinc(II)] (Guo & Guo, 2006) and poly[tetra-µ-aqua-hexaaquadi-µ3-malonato-dinitratodibarium(II)nickel(II)] (Guo & Cao, 2006). Interestingly, when nickel chloride was used in an attempt to obtain a product similar or isotypic to that of the zinc compound, a completly different crystal structure was obtained. We report here the structure of the bimetallic malonate complex (I).
The asymmetric unit of (I) comprises one Ni atom, one Ba atom, two complete malonate dianions (C1–C3/O1–O4 and C4–C6/O5–O8) and three non-equivalent water molecules (O9–O11), and is shown in Fig. 1 in a symmetry-expanded view that displays the full coordination of the Ba and Ni atoms. Selected geometric parameters are given in Table 1.
The Ba atom is surrounded by an O9 donor set in an approximate monocapped square antiprismatic environment (Fig. 1). The four coordination sites of the basal plane are occupied by atoms O6iii from a malonate dianion, O4iv from a second malonate ligand and two coordinated water molecules (O11 and O11i). The opposite plane contains two O atoms (O1 and O5) from two malonate ligands, a bridging O atom (O4ii) from a third malonate ligand and a chelating carboxylate O atom (O7v) from a fourth malonate ligand (see Fig. 1 for symmetry codes). Finally, the capping site is occupied by the chelating atom O8v. Of the Ba—O distances (Table 1), Ba—O7v and Ba—O8v are the longest, probably as a result of strain in the four-membered chelate. The Ba—O(water) bonds are slightly shorter than those in [Ba2Ni(C3H2O4)2(NO3)2(H2O)10] (Guo & Cao, 2006), while the Ba—O(malonate) bond distances correspond well with the sum of the ionic radii [1.21 + 1.66 = 2.87 Å for 10-coordinate Ba2+ ions; Bauer et al., 2005] and are comparable to the values reported for barium oxydiacetates (Baggio et al. 2004). The BaO9 polyhedra share edges to form zigzag chains propagated in the c direction via pairs of water bridges (O11 and O11i) or bridging malonate O4ii and O4iv atoms. This results in Ba1···Ba1i separations of 4.3362 (8) Å.
The Ni atom has octahedral coordination, with atoms O1, O3, O5 and O7 of two non-equivalent malonate dianions in a planar arrangement, and atoms O9 and O10 from two water molecules in a trans conformation. The Ni—O(water) bonds are slightly longer while the Ni—O(malonate) bonds are somewhat shorter than those in [CaNi(mal)2(H2O)4]·2H2O (Gil de Muro et al., 2000). Thus, the coordination octahedra of the Ni atoms can be visualized as having a slightly elongated axial distortion.
Also evident in Fig. 1 is the variability of the coordination modes of the malonate ligand. Monodentate, bidentate chelating, chelated six-membered and bridging coordination modes are all present. In the case of the C1–C3/O1–O4 malonate dianion, atom O1 adopts both a monodentate mode bonding to Ni and a bridging bonding mode to Ni and Ba. Atom O4 adopts a bridging mode to connect two Ba atoms. Furthermore, two carboxyl groups (atoms O1 and O3) adopt a six-membered chelating mode, forming a ring around Ni with an envelope conformation, with arom C2 displaced by 0.65 Å from the plane defined by the other atoms in the ring. For the C4–C6/O5–O8 malonate dianion, the coordination modes of atom O5 are the same as for atom O1; atom O6 adopts a monodentate mode, coordinating another Ba atom. Atoms O7 and O8 from the same carboxyl function chelate the Ba atom at (x - 1/2, -y + 3/2, z - 1/2) to form a four-membered ring. Atoms O7 and O5 from different carboxyl groups form a six-membered chelate (Ni1/O5/C4–C6/O7) with a boat conformation; atoms Ni1 and C5 lie 0.52 and 0.42 Å, respectively, out of the O5/C4/C6/O7 plane. The Ni1···Ba1 separation of 3.8059 (14) Å, mediated by the O1,O5 double bridge, is much less than the sum of their van der Waals radii (2.30 + 2.14 = 4.44 Å). This suggests some degree of interaction between the Ni and Ba atoms.
The structure as a whole consists of two distinct types of layer (Fig. 2), both perpendicular to [100] and stacked alternately in the a direction. The first of these (Fig. 3) is composed entirely of Ni atoms, malonate dianions and water molecules (O9, O10). Hydrogen bonding plays an important role in the stabilization of the extended layers. The noncoordinated O2 atom is involved in forming strong hydrogen bonds (O9—H9A···O2vi; symmetry codes as in Table 2) (Brown, 1976). Within this layer, and along the c direction, O9—H9A···O2vi and O10—H10A···O8vii hydrogen bonds are responsible for the formation of a 12-membered hydrogen-bonded R22(12) ring (Bernstein et al., 1995). In the b direction, the neighbouring Ni coordination octahedra are linked together via O10—H10B···O6iii hydrogen bonds and 14-membered hydrogen-bonded R22(14) rings. In this way, a complete two-dimensional connectivity is achieved parallel to the bc plane.
The other type of layer, type 2, consists of Ba atoms and water molecules (Fig. 2). In the crystallographic a direction, the connectivity of two layers is achieved by means of O1, O5 and O7 bridging atoms and O6—C4—O5, O4—C3—O3 and O8—C6—O7 bridges between Ni1 coordination octahedra and neighbouring BaO9 polyhedra. At the same time, the zigzag BaO9 polyhedral chains in the c direction are linked into layers and complete the three-dimensional connectivity of the structure. The interlayer connectivity is further enhanced by hydrogen bonds of the form O11—H11A···O3v and O11—H11B···O2 (Table 2).