Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270104012648/fa1063sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270104012648/fa1063Isup2.hkl |
CCDC reference: 245860
A solution of pia (0.244 g, 2 mmol) in ethanol (30 ml) was added dropwise with stirring to a solution of nickel saccharinate (0.530 g, 1 mmol) in hot water (50 ml). The mixture was heated (to 353 K) in a temparature-controlled bath with stirring for 2 h. The resulting blue solution was evaporated at room temparature, yielding blue crystals suitable for X-ray diffraction analysis.
Atoms H3W and H4W, bonded to O2W, were found in a difference map and their parameters were refined with the O—H distance restrained to 0.82 (s.u.?) Å. The other H atoms were located in a difference Fourier map and their coordinates and Uiso parameters were freely refined [O—H = 0.80 (2)–0.89 (4) Å, N—H = 0.82 (3)–0.87 (3) Å and C—H = 0.88 (3)–1.00 (2) Å].
Data collection: X-AREA (Stoe & Cie, 2002); cell refinement: X-AREA; data reduction: X-RED32 (Stoe & Cie, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).
[Ni(C6H6N2O)2(H2O)2](C7H4NO3S)2·4H2O | Z = 1 |
Mr = 775.41 | F(000) = 402 |
Triclinic, P1 | Dx = 1.613 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 8.4478 (7) Å | Cell parameters from 13935 reflections |
b = 8.8751 (7) Å | θ = 2.6–29.0° |
c = 12.3854 (9) Å | µ = 0.82 mm−1 |
α = 81.560 (6)° | T = 293 K |
β = 72.655 (6)° | Plate, blue |
γ = 64.257 (6)° | 0.35 × 0.28 × 0.15 mm |
V = 798.24 (11) Å3 |
STOE IPDS-II diffractometer | 4243 independent reflections |
Radiation source: fine-focus sealed tube | 3267 reflections with I > 2σ(I) |
Plane graphite monochromator | Rint = 0.061 |
Detector resolution: 6.67 pixels mm-1 | θmax = 29.0°, θmin = 2.6° |
rotation method scans | h = −11→11 |
Absorption correction: integration (X-RED32; Stoe & Cie, 2002) | k = −12→12 |
Tmin = 0.661, Tmax = 0.828 | l = −16→16 |
18441 measured reflections |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.034 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.092 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.02 | w = 1/[σ2(Fo2) + (0.0539P)2] where P = (Fo2 + 2Fc2)/3 |
4207 reflections | (Δ/σ)max = 0.044 |
287 parameters | Δρmax = 0.31 e Å−3 |
2 restraints | Δρmin = −0.63 e Å−3 |
[Ni(C6H6N2O)2(H2O)2](C7H4NO3S)2·4H2O | γ = 64.257 (6)° |
Mr = 775.41 | V = 798.24 (11) Å3 |
Triclinic, P1 | Z = 1 |
a = 8.4478 (7) Å | Mo Kα radiation |
b = 8.8751 (7) Å | µ = 0.82 mm−1 |
c = 12.3854 (9) Å | T = 293 K |
α = 81.560 (6)° | 0.35 × 0.28 × 0.15 mm |
β = 72.655 (6)° |
STOE IPDS-II diffractometer | 4243 independent reflections |
Absorption correction: integration (X-RED32; Stoe & Cie, 2002) | 3267 reflections with I > 2σ(I) |
Tmin = 0.661, Tmax = 0.828 | Rint = 0.061 |
18441 measured reflections |
R[F2 > 2σ(F2)] = 0.034 | 2 restraints |
wR(F2) = 0.092 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.02 | Δρmax = 0.31 e Å−3 |
4207 reflections | Δρmin = −0.63 e Å−3 |
287 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
Ni1 | 0.0000 | 0.5000 | 0.5000 | 0.02811 (10) | |
S1 | 0.85099 (6) | 0.26341 (6) | 0.12654 (4) | 0.03816 (12) | |
O4 | 0.05234 (19) | 0.66522 (16) | 0.36526 (11) | 0.0365 (3) | |
O2 | 0.97326 (19) | 0.3085 (2) | 0.03402 (13) | 0.0560 (4) | |
O5 | −0.22722 (16) | 0.53655 (15) | 0.45586 (11) | 0.0344 (3) | |
O1 | 0.9384 (2) | 0.1083 (2) | 0.18296 (14) | 0.0572 (4) | |
O2W | 0.8759 (2) | 0.6675 (3) | 0.21039 (15) | 0.0527 (4) | |
O3 | 0.42664 (17) | 0.57728 (17) | 0.28724 (11) | 0.0411 (3) | |
O1W | 0.8804 (2) | 0.0217 (3) | 0.4258 (2) | 0.0674 (5) | |
N2 | −0.18510 (18) | 0.70195 (17) | 0.59537 (12) | 0.0289 (3) | |
N3 | 0.7291 (2) | 0.4123 (2) | 0.21548 (14) | 0.0407 (4) | |
N1 | −0.5228 (2) | 0.7034 (2) | 0.47645 (15) | 0.0383 (4) | |
C11 | 0.3527 (2) | 0.4176 (2) | 0.11839 (16) | 0.0349 (4) | |
C1 | −0.3671 (2) | 0.6593 (2) | 0.50040 (14) | 0.0298 (3) | |
C5 | −0.2857 (3) | 0.9224 (2) | 0.72110 (17) | 0.0415 (4) | |
C7 | 0.6738 (2) | 0.2615 (2) | 0.08123 (15) | 0.0323 (3) | |
C12 | 0.5148 (2) | 0.3849 (2) | 0.14016 (14) | 0.0294 (3) | |
C2 | −0.3541 (2) | 0.7604 (2) | 0.58212 (14) | 0.0289 (3) | |
C10 | 0.3537 (3) | 0.3240 (3) | 0.03788 (17) | 0.0408 (4) | |
C6 | −0.1514 (2) | 0.7804 (2) | 0.66366 (16) | 0.0357 (4) | |
C3 | −0.4943 (2) | 0.8993 (2) | 0.63798 (16) | 0.0367 (4) | |
C8 | 0.6795 (3) | 0.1659 (3) | 0.00131 (17) | 0.0419 (4) | |
C13 | 0.5516 (2) | 0.4680 (2) | 0.22064 (14) | 0.0320 (3) | |
C4 | −0.4592 (3) | 0.9816 (2) | 0.70833 (17) | 0.0420 (4) | |
C9 | 0.5145 (3) | 0.1999 (3) | −0.01923 (18) | 0.0446 (5) | |
H6 | −0.030 (3) | 0.731 (3) | 0.6726 (17) | 0.036 (5)* | |
H3 | −0.617 (3) | 0.938 (3) | 0.625 (2) | 0.050 (6)* | |
H10 | 0.244 (3) | 0.345 (3) | 0.021 (2) | 0.054 (7)* | |
H5 | −0.253 (3) | 0.974 (3) | 0.7670 (19) | 0.040 (6)* | |
H4 | −0.552 (3) | 1.082 (3) | 0.745 (2) | 0.055 (7)* | |
H8 | 0.003 (4) | 0.670 (4) | 0.310 (3) | 0.081 (10)* | |
H1 | −0.529 (3) | 0.644 (3) | 0.429 (2) | 0.052 (7)* | |
H11 | 0.508 (4) | 0.146 (4) | −0.071 (3) | 0.075 (9)* | |
H2 | −0.612 (4) | 0.784 (3) | 0.509 (2) | 0.058 (7)* | |
H9 | 0.246 (4) | 0.505 (3) | 0.157 (2) | 0.059 (7)* | |
H4W | 0.847 (5) | 0.591 (5) | 0.222 (3) | 0.103 (14)* | |
H7 | 0.169 (4) | 0.640 (4) | 0.337 (3) | 0.079 (9)* | |
H12 | 0.792 (4) | 0.078 (3) | −0.033 (2) | 0.063 (7)* | |
H3W | 0.925 (6) | 0.683 (5) | 0.143 (4) | 0.116 (14)* | |
H2W | 0.929 (8) | 0.068 (7) | 0.375 (4) | 0.21 (3)* | |
H1W | 0.921 (8) | −0.076 (3) | 0.414 (6) | 0.22 (3)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Ni1 | 0.02422 (14) | 0.02997 (16) | 0.02652 (16) | −0.00738 (11) | −0.00404 (11) | −0.00792 (11) |
S1 | 0.02472 (19) | 0.0527 (3) | 0.0339 (2) | −0.01097 (18) | −0.00741 (16) | −0.0086 (2) |
O4 | 0.0341 (6) | 0.0397 (7) | 0.0311 (7) | −0.0134 (5) | −0.0037 (5) | −0.0031 (5) |
O2 | 0.0326 (7) | 0.0910 (12) | 0.0450 (8) | −0.0300 (7) | 0.0003 (6) | −0.0107 (8) |
O5 | 0.0288 (6) | 0.0382 (6) | 0.0341 (6) | −0.0099 (5) | −0.0069 (5) | −0.0110 (5) |
O1 | 0.0429 (8) | 0.0610 (9) | 0.0526 (9) | −0.0010 (7) | −0.0216 (7) | −0.0052 (7) |
O2W | 0.0521 (9) | 0.0680 (11) | 0.0402 (9) | −0.0275 (8) | −0.0102 (7) | −0.0035 (8) |
O3 | 0.0353 (6) | 0.0480 (7) | 0.0362 (7) | −0.0125 (6) | −0.0036 (5) | −0.0173 (6) |
O1W | 0.0468 (9) | 0.0565 (10) | 0.0968 (15) | −0.0204 (8) | −0.0189 (9) | 0.0015 (10) |
N2 | 0.0288 (6) | 0.0312 (6) | 0.0245 (7) | −0.0101 (5) | −0.0045 (5) | −0.0062 (5) |
N3 | 0.0330 (7) | 0.0559 (9) | 0.0369 (8) | −0.0182 (7) | −0.0091 (6) | −0.0127 (7) |
N1 | 0.0318 (7) | 0.0395 (8) | 0.0440 (9) | −0.0097 (7) | −0.0144 (7) | −0.0087 (7) |
C11 | 0.0274 (8) | 0.0433 (9) | 0.0320 (9) | −0.0135 (7) | −0.0050 (6) | −0.0044 (7) |
C1 | 0.0304 (7) | 0.0314 (7) | 0.0272 (8) | −0.0126 (6) | −0.0073 (6) | −0.0001 (6) |
C5 | 0.0466 (10) | 0.0409 (9) | 0.0372 (10) | −0.0145 (8) | −0.0104 (8) | −0.0143 (8) |
C7 | 0.0272 (7) | 0.0371 (8) | 0.0295 (8) | −0.0104 (6) | −0.0055 (6) | −0.0051 (7) |
C12 | 0.0293 (7) | 0.0338 (8) | 0.0249 (8) | −0.0138 (6) | −0.0050 (6) | −0.0023 (6) |
C2 | 0.0273 (7) | 0.0287 (7) | 0.0261 (8) | −0.0080 (6) | −0.0057 (6) | −0.0019 (6) |
C10 | 0.0364 (9) | 0.0565 (11) | 0.0377 (10) | −0.0247 (8) | −0.0117 (8) | −0.0035 (8) |
C6 | 0.0346 (9) | 0.0391 (9) | 0.0326 (9) | −0.0122 (7) | −0.0082 (7) | −0.0093 (7) |
C3 | 0.0321 (8) | 0.0347 (8) | 0.0357 (9) | −0.0059 (7) | −0.0078 (7) | −0.0065 (7) |
C8 | 0.0389 (9) | 0.0433 (10) | 0.0390 (10) | −0.0115 (8) | −0.0065 (8) | −0.0137 (8) |
C13 | 0.0318 (8) | 0.0394 (8) | 0.0260 (8) | −0.0157 (7) | −0.0066 (6) | −0.0035 (7) |
C4 | 0.0413 (10) | 0.0356 (9) | 0.0380 (10) | −0.0041 (8) | −0.0077 (8) | −0.0122 (8) |
C9 | 0.0495 (11) | 0.0522 (11) | 0.0397 (11) | −0.0242 (9) | −0.0114 (9) | −0.0135 (9) |
Ni1—O5 | 2.0301 (12) | C11—C12 | 1.372 (2) |
Ni1—N2 | 2.0343 (13) | C11—C10 | 1.384 (3) |
Ni1—O4 | 2.1297 (13) | C11—H9 | 0.94 (3) |
S1—O2 | 1.4349 (16) | C1—C2 | 1.503 (2) |
S1—O1 | 1.4393 (17) | C5—C4 | 1.376 (3) |
S1—N3 | 1.6087 (16) | C5—C6 | 1.386 (2) |
S1—C7 | 1.7556 (18) | C5—H5 | 0.95 (2) |
O4—H8 | 0.89 (4) | C7—C8 | 1.372 (3) |
O4—H7 | 0.87 (3) | C7—C12 | 1.381 (2) |
O5—C1 | 1.248 (2) | C12—C13 | 1.495 (2) |
O2W—H4W | 0.80 (4) | C2—C3 | 1.376 (2) |
O2W—H3W | 0.83 (4) | C10—C9 | 1.384 (3) |
O3—C13 | 1.250 (2) | C10—H10 | 0.94 (2) |
O1W—H2W | 0.81 (6) | C6—H6 | 0.96 (2) |
O1W—H1W | 0.80 (2) | C3—C4 | 1.382 (3) |
N2—C6 | 1.331 (2) | C3—H3 | 1.00 (2) |
N2—C2 | 1.344 (2) | C8—C9 | 1.387 (3) |
N3—C13 | 1.343 (2) | C8—H12 | 0.95 (3) |
N1—C1 | 1.313 (2) | C4—H4 | 0.96 (2) |
N1—H1 | 0.87 (3) | C9—H11 | 0.88 (3) |
N1—H2 | 0.82 (3) | ||
O5i—Ni1—O5 | 180.0 | C4—C5—C6 | 118.86 (18) |
O5—Ni1—N2i | 99.95 (5) | C4—C5—H5 | 123.0 (13) |
O5—Ni1—N2 | 80.05 (5) | C6—C5—H5 | 118.1 (13) |
N2i—Ni1—N2 | 180.0 | C8—C7—C12 | 123.33 (17) |
O5—Ni1—O4 | 89.14 (6) | C8—C7—S1 | 130.16 (14) |
N2—Ni1—O4 | 89.17 (5) | C12—C7—S1 | 106.47 (13) |
O5—Ni1—O4i | 90.86 (6) | C11—C12—C7 | 119.63 (16) |
N2—Ni1—O4i | 90.83 (5) | C11—C12—C13 | 129.29 (15) |
O4—Ni1—O4i | 180.0 | C7—C12—C13 | 111.07 (15) |
O2—S1—O1 | 114.08 (10) | N2—C2—C3 | 121.70 (16) |
O2—S1—N3 | 111.60 (10) | N2—C2—C1 | 112.41 (13) |
O1—S1—N3 | 110.98 (9) | C3—C2—C1 | 125.89 (16) |
O2—S1—C7 | 110.19 (9) | C9—C10—C11 | 120.74 (18) |
O1—S1—C7 | 111.08 (10) | C9—C10—H10 | 119.6 (15) |
N3—S1—C7 | 97.77 (8) | C11—C10—H10 | 119.7 (15) |
Ni1—O4—H8 | 112 (2) | N2—C6—C5 | 121.79 (17) |
Ni1—O4—H7 | 113 (2) | N2—C6—H6 | 116.3 (13) |
H8—O4—H7 | 109 (3) | C5—C6—H6 | 121.9 (13) |
C1—O5—Ni1 | 114.74 (11) | C2—C3—C4 | 118.93 (17) |
H4W—O2W—H3W | 116 (4) | C2—C3—H3 | 118.6 (14) |
H2W—O1W—H1W | 111 (6) | C4—C3—H3 | 122.5 (14) |
C6—N2—C2 | 119.43 (14) | C7—C8—C9 | 116.32 (17) |
C6—N2—Ni1 | 126.23 (12) | C7—C8—H12 | 119.4 (17) |
C2—N2—Ni1 | 114.30 (11) | C9—C8—H12 | 124.2 (17) |
C13—N3—S1 | 110.76 (13) | O3—C13—N3 | 123.93 (17) |
C1—N1—H1 | 119.2 (16) | O3—C13—C12 | 122.20 (16) |
C1—N1—H2 | 118.4 (19) | N3—C13—C12 | 113.86 (15) |
H1—N1—H2 | 122 (2) | C5—C4—C3 | 119.28 (17) |
C12—C11—C10 | 118.56 (16) | C5—C4—H4 | 119.7 (15) |
C12—C11—H9 | 118.5 (16) | C3—C4—H4 | 120.9 (15) |
C10—C11—H9 | 122.9 (17) | C10—C9—C8 | 121.42 (19) |
O5—C1—N1 | 121.89 (17) | C10—C9—H11 | 117.0 (19) |
O5—C1—C2 | 118.47 (15) | C8—C9—H11 | 121.5 (19) |
N1—C1—C2 | 119.63 (15) |
Symmetry code: (i) −x, −y+1, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
O4—H8···O2Wii | 0.89 (4) | 1.87 (4) | 2.751 (2) | 171 (3) |
N1—H1···O3ii | 0.87 (3) | 2.11 (3) | 2.951 (2) | 161 (2) |
N1—H2···O1Wi | 0.82 (3) | 2.16 (3) | 2.971 (3) | 166 (3) |
O2W—H3W···O2iii | 0.83 (4) | 2.11 (4) | 2.929 (2) | 168 (4) |
O1W—H1W···O4iv | 0.80 (2) | 2.16 (2) | 2.956 (2) | 173 (7) |
O2W—H4W···N3 | 0.80 (4) | 2.22 (4) | 3.004 (3) | 164 (4) |
O4—H7···O3 | 0.87 (3) | 1.92 (3) | 2.7923 (19) | 175 (3) |
O1W—H2W···O1 | 0.81 (6) | 2.34 (5) | 2.940 (3) | 132 (6) |
Symmetry codes: (i) −x, −y+1, −z+1; (ii) x−1, y, z; (iii) −x+2, −y+1, −z; (iv) x+1, y−1, z. |
Experimental details
Crystal data | |
Chemical formula | [Ni(C6H6N2O)2(H2O)2](C7H4NO3S)2·4H2O |
Mr | 775.41 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 293 |
a, b, c (Å) | 8.4478 (7), 8.8751 (7), 12.3854 (9) |
α, β, γ (°) | 81.560 (6), 72.655 (6), 64.257 (6) |
V (Å3) | 798.24 (11) |
Z | 1 |
Radiation type | Mo Kα |
µ (mm−1) | 0.82 |
Crystal size (mm) | 0.35 × 0.28 × 0.15 |
Data collection | |
Diffractometer | STOE IPDS-II diffractometer |
Absorption correction | Integration (X-RED32; Stoe & Cie, 2002) |
Tmin, Tmax | 0.661, 0.828 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 18441, 4243, 3267 |
Rint | 0.061 |
(sin θ/λ)max (Å−1) | 0.681 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.034, 0.092, 1.02 |
No. of reflections | 4207 |
No. of parameters | 287 |
No. of restraints | 2 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.31, −0.63 |
Computer programs: X-AREA (Stoe & Cie, 2002), X-AREA, X-RED32 (Stoe & Cie, 2002), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).
Ni1—O5 | 2.0301 (12) | O5—C1 | 1.248 (2) |
Ni1—N2 | 2.0343 (13) | O3—C13 | 1.250 (2) |
Ni1—O4 | 2.1297 (13) | N2—C6 | 1.331 (2) |
S1—O2 | 1.4349 (16) | N2—C2 | 1.344 (2) |
S1—O1 | 1.4393 (17) | N1—C1 | 1.313 (2) |
O5—Ni1—N2 | 80.05 (5) | C6—N2—C2 | 119.43 (14) |
O5—Ni1—O4 | 89.14 (6) | C2—N2—Ni1 | 114.30 (11) |
N2—Ni1—O4 | 89.17 (5) | C13—N3—S1 | 110.76 (13) |
O2—S1—O1 | 114.08 (10) | O5—C1—N1 | 121.89 (17) |
C1—O5—Ni1 | 114.74 (11) | N2—C6—C5 | 121.79 (17) |
D—H···A | D—H | H···A | D···A | D—H···A |
O4—H8···O2Wi | 0.89 (4) | 1.87 (4) | 2.751 (2) | 171 (3) |
N1—H1···O3i | 0.87 (3) | 2.11 (3) | 2.951 (2) | 161 (2) |
N1—H2···O1Wii | 0.82 (3) | 2.16 (3) | 2.971 (3) | 166 (3) |
O2W—H3W···O2iii | 0.83 (4) | 2.11 (4) | 2.929 (2) | 168 (4) |
O1W—H1W···O4iv | 0.80 (2) | 2.16 (2) | 2.956 (2) | 173 (7) |
O2W—H4W···N3 | 0.80 (4) | 2.22 (4) | 3.004 (3) | 164 (4) |
O4—H7···O3 | 0.87 (3) | 1.92 (3) | 2.7923 (19) | 175 (3) |
O1W—H2W···O1 | 0.81 (6) | 2.34 (5) | 2.940 (3) | 132 (6) |
Symmetry codes: (i) x−1, y, z; (ii) −x, −y+1, −z+1; (iii) −x+2, −y+1, −z; (iv) x+1, y−1, z. |
The water soluble alkali and alkali-earth salts of saccharinate (sac) are widely used as non-caloric artificial sweeteners and food additives; neutral saccharin itself does not coordinate metal ions, but its deprotonated form (sac) interacts with trace elements in the human body and readily forms complexes with a large number of metal ions (Andaç et al., 2000; Zhang, 1994). The sac anion can bind metal centers through different donor atoms, for example, the endocyclic N and the exocyclic carbonyl or sulfonyl O atoms. A large number of crystal structures of sac compounds have revealed a variety of metal-bonding patterns for sac (Naumov et al., 2001; Icbudak et al., 2001), including (in order of observed frequency), monofunctional bonding to the deprotonated ring N atom, bifunctional amidate bridging through N and carbonyl O atoms, bifunctional chelation to N and carbonyl O atoms, monofunctional bonding to carbonyl O atoms, and trifunctional binding to N, carbonyl O and sulfonyl O atoms. Furthermore, sac molecules exist very often in a free ionic form, i.e. without metal bonding (Icbudak et al., 2001; Naumov et al., 2001; Çakır et al., 2003; Castellano et al., 2002) or quite rarely as a neutral form without metal bonding in a sac salt (Deng et al., 2001). Aqua complexes of sac with transition metals and inner transition metals have been reported (Haider et al., 1983; Kamenar & Jovanovski, 1982). The syntheses and structural and thermal charactrizations of mixed-ligand metal complexes of sac alongside mono- and bidentate N-donor ligands, such as pyridine (Magri et al., 1980; Quinzani et al., 1997; Javanovski et al., 1998; Quinzani et al., 1999), imidazole (Jianmin et al., 1992; Jianmin et al., 1997), phenanthroline (Deng et al., 2000; Baran et al., 2000) and monoethanolamine (Andaç et al., 2000), have been reported in the literature. A series of mixed-ligand sac complexes of CoII, NiII, CuII and ZnII with nicotinamide have also been reported (Çakır et al., 2003; Castellano et al., 2002).
Picolinamide (pia) ligands represent a promising class of bidentate complexing molecules that can be used to separate efficiently trivalent actinide and/or lanthanide cations from aqueous solutions of nuclear waste obtained by dissolution of spent fuel by nitric acid. These ligands possess such functionality because they combine a moderately hard amide O– and a softer pyridine N-binding site, which can cooperatively bind hard cations with possible discrimination as a function of size and hardness (Beaden et al., 2003). We describe here the coordination behaviour of pia – an isomer of nicotinamide – in a nickel complex that crystallized with saccharinate as counter-anion.
Fig. 1 shows an ORTEP-3 plot (Farrugia, 1997) of (I). The NiII ion is located on a center of symmetry, chelated by two pia molecules. Pia acts as a N,O-bidentate ligand and forms the equatorial plane of the coordination octahedron, while the water molecule occupies the axial position. The Ni—N distance is 2.0343 (13) Å, and the Ni—O distances are 2.0301 (12) and 2.1297 (13) Å (Table 1). These values are as expected and are comparable to those observed in the Ni–nicotinamide complex (Çakır et al., 2003). The unique sac anion in the asymmetric unit carries a single negative charge and acts as a counter-anion. The sac groups are essentially planar. The mean plane through the sac anion is almost parallel [dihedral angle 7.16 (2)°] to that through the pia moiety.
In the extended structure of (I), shown in Fig. 2, there are weak intermolecular π–π and π-ring interactions. The intermolecular π–π interaction occurs between the phenyl rings of the sac groups (hereafter A) of neighbouring molecules. Ring A is oriented in such a way that the perpendicular distance from A to Ai is 3.399 Å, with the closest distance being C7···C10i [3.692 (4) Å; symmetry code: (i) 1 − x,1 − y,-z]. The distance between the ring centroids is 3.6976 (12) Å. An inhomogeneous arrangement of π electron density through the phenyl ring is probably responsible for the mutual orientation of the phenyl rings and the parallel-displaced (PD) type of π–π interaction (Kamishima et al., 2001). Furthermore, ring A also makes an intermolecular π–π contact with the pyridine ring (B) of the picolinamide. Rings A and B are oriented in such a way that the perpendicular distance from A to B is 3.512 Å, with the closest distance being C2···C12 [3.574 (2) Å], and the dihedral angle between A and B is 6.75 (13)°. The distance between the ring centroids is 3.7147 (11) Å. Ring B is also involved in intermolecular O—H···π interactions with a free water molecule, with the following geometrical parameters: (i) the distance between atom H1W (bonded to O1W) and the centre of ring B is 3.25 (7) Å; (ii) the distance between atom H1W and the plane of ring B is 2.989 Å; (iii) the angle between the line connecting atom H1W to the centre of ring B, CgB, and the normal to the plane of B is 23.13°; (iv) the O1W—H1W···CgB angle is 95 (6)°. These interactions are shown with dashed lines in Fig. 2. The coordinated water molecules link the sac ion to the metal complex via O4—H7···O3 hydrogen bonds (Fig. 1). One unligated water molecule (O1W) is hydrogen bonded to the sac ion (O1W—H2W.·O1) and to the coordinated water molecule (O1W—H1W···O4iv). The other uncoordinated water molecule (O2W) is hydrogen bonded to sac (O2W—H4W···N3 and O2W–H3W.·O2i; symmetry codes as in Table 2). The other hydrogen bonds are listed in Table 2. This varied set of hydrogen-bonding, π–π and π–ring interactions employs most of the available topological features to stabilize the crystal structure.