Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801010455/cf6087sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536801010455/cf6087Isup2.hkl |
CCDC reference: 170750
Microcrystalline Hg(py)2Cr2O7 was prepared according to the method of Spacu & Dick (1929). Single crystals were grown by cooling an aqueous solution of the microcrystalline material, with two drops of pyridine added, from 393 K down to room temperature with a cooling rate of 2 K h-1. The reaction was performed in a 5 ml Teflon-lined stainless steel container which was two-thirds filled. The orange crystals are light sensitive and blacken within a few days under normal daylight.
Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ATOMS for WINDOWS (Dowty, 1998); software used to prepare material for publication: SHELXL97.
[Hg(C5H5N)2][Cr2O7] | F(000) = 2144 |
Mr = 574.79 | Dx = 2.583 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
a = 15.4741 (5) Å | Cell parameters from 10078 reflections |
b = 15.0135 (5) Å | θ = 2.7–28.3° |
c = 14.0407 (5) Å | µ = 11.84 mm−1 |
β = 115.018 (1)° | T = 293 K |
V = 2955.89 (17) Å3 | Parallelepiped, orange |
Z = 8 | 0.10 × 0.07 × 0.04 mm |
Siemens SMART CCD area-detector diffractometer | 3683 independent reflections |
Radiation source: fine-focus sealed tube | 3186 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.030 |
ω scans | θmax = 28.3°, θmin = 2.0° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −20→20 |
Tmin = 0.366, Tmax = 0.612 | k = −20→20 |
19668 measured reflections | l = −18→18 |
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)] = 0.018 | H-atom parameters constrained |
wR(F2) = 0.046 | w = 1/[σ2(Fo2) + (0.0166P)2 + 2.3706P] where P = (Fo2 + 2Fc2)/3 |
S = 1.21 | (Δ/σ)max = 0.001 |
3683 reflections | Δρmax = 1.06 e Å−3 |
204 parameters | Δρmin = −0.58 e Å−3 |
0 restraints | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.000071 (11) |
[Hg(C5H5N)2][Cr2O7] | V = 2955.89 (17) Å3 |
Mr = 574.79 | Z = 8 |
Monoclinic, C2/c | Mo Kα radiation |
a = 15.4741 (5) Å | µ = 11.84 mm−1 |
b = 15.0135 (5) Å | T = 293 K |
c = 14.0407 (5) Å | 0.10 × 0.07 × 0.04 mm |
β = 115.018 (1)° |
Siemens SMART CCD area-detector diffractometer | 3683 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 3186 reflections with I > 2σ(I) |
Tmin = 0.366, Tmax = 0.612 | Rint = 0.030 |
19668 measured reflections |
R[F2 > 2σ(F2)] = 0.018 | 0 restraints |
wR(F2) = 0.046 | H-atom parameters constrained |
S = 1.21 | Δρmax = 1.06 e Å−3 |
3683 reflections | Δρmin = −0.58 e Å−3 |
204 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 | ||
Hg1 | 0.0000 | 0.774387 (11) | 0.2500 | 0.02787 (6) | |
Hg2 | 0.2500 | 0.7500 | 1.0000 | 0.03017 (6) | |
Cr1 | 0.01526 (4) | 0.73603 (3) | 0.53425 (4) | 0.02824 (12) | |
Cr2 | 0.23539 (4) | 0.73338 (3) | 0.72142 (4) | 0.02824 (12) | |
O1 | −0.0124 (2) | 0.79567 (19) | 0.4289 (2) | 0.0482 (7) | |
O2 | 0.0232 (2) | 0.63289 (18) | 0.5100 (2) | 0.0539 (7) | |
O3 | −0.06502 (18) | 0.74723 (17) | 0.5787 (2) | 0.0401 (6) | |
O4 | 0.12511 (18) | 0.77627 (19) | 0.6295 (2) | 0.0465 (7) | |
O5 | 0.31376 (18) | 0.73993 (17) | 0.6739 (2) | 0.0414 (6) | |
O6 | 0.22471 (19) | 0.63117 (18) | 0.7478 (2) | 0.0550 (8) | |
O7 | 0.2678 (2) | 0.79329 (19) | 0.8269 (2) | 0.0464 (6) | |
N1 | 0.0000 | 0.6354 (2) | 0.2500 | 0.0309 (9) | |
N2 | 0.0000 | 0.9137 (2) | 0.2500 | 0.0281 (8) | |
N3 | 0.25972 (19) | 0.61034 (18) | 0.9887 (2) | 0.0309 (6) | |
C1 | 0.0582 (3) | 0.5909 (2) | 0.2192 (3) | 0.0376 (8) | |
H1 | 0.1001 | 0.6230 | 0.1981 | 0.045* | |
C2 | 0.0589 (3) | 0.4998 (3) | 0.2175 (3) | 0.0551 (11) | |
H2 | 0.0999 | 0.4690 | 0.1940 | 0.066* | |
C3 | 0.0000 | 0.4534 (4) | 0.2500 | 0.0623 (19) | |
H3 | 0.0000 | 0.3901 | 0.2500 | 0.075* | |
C4 | 0.0726 (3) | 0.9588 (2) | 0.2457 (3) | 0.0386 (8) | |
H4 | 0.1242 | 0.9268 | 0.2424 | 0.046* | |
C5 | 0.0745 (3) | 1.0503 (3) | 0.2459 (3) | 0.0495 (10) | |
H5 | 0.1271 | 1.0811 | 0.2433 | 0.059* | |
C6 | 0.0000 | 1.0967 (3) | 0.2500 | 0.0491 (15) | |
H6 | 0.0000 | 1.1600 | 0.2500 | 0.059* | |
C7 | 0.3310 (3) | 0.5734 (2) | 0.9725 (3) | 0.0376 (8) | |
H7 | 0.3754 | 0.6110 | 0.9617 | 0.045* | |
C8 | 0.3418 (3) | 0.4825 (3) | 0.9712 (3) | 0.0465 (10) | |
H8 | 0.3933 | 0.4576 | 0.9602 | 0.056* | |
C9 | 0.2766 (3) | 0.4282 (3) | 0.9860 (3) | 0.0502 (10) | |
H9 | 0.2824 | 0.3652 | 0.9851 | 0.060* | |
C10 | 0.2036 (3) | 0.4664 (3) | 1.0021 (3) | 0.0507 (10) | |
H10 | 0.1583 | 0.4299 | 1.0128 | 0.061* | |
C11 | 0.1959 (3) | 0.5571 (3) | 1.0029 (3) | 0.0414 (9) | |
H11 | 0.1447 | 0.5831 | 1.0136 | 0.050* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Hg1 | 0.02884 (10) | 0.02207 (10) | 0.03451 (11) | 0.000 | 0.01514 (8) | 0.000 |
Hg2 | 0.02762 (11) | 0.02790 (11) | 0.03573 (11) | 0.00094 (6) | 0.01411 (8) | 0.00063 (6) |
Cr1 | 0.0192 (3) | 0.0356 (3) | 0.0280 (3) | 0.00306 (19) | 0.0081 (2) | −0.0006 (2) |
Cr2 | 0.0187 (3) | 0.0342 (3) | 0.0293 (3) | −0.00174 (19) | 0.0076 (2) | 0.0001 (2) |
O1 | 0.0507 (17) | 0.0625 (18) | 0.0335 (14) | 0.0083 (13) | 0.0197 (13) | 0.0086 (12) |
O2 | 0.0475 (17) | 0.0440 (16) | 0.0625 (19) | 0.0086 (12) | 0.0157 (15) | −0.0097 (13) |
O3 | 0.0266 (14) | 0.0554 (17) | 0.0408 (15) | −0.0004 (10) | 0.0169 (12) | −0.0007 (11) |
O4 | 0.0212 (12) | 0.0487 (17) | 0.0555 (17) | 0.0010 (10) | 0.0026 (12) | −0.0003 (11) |
O5 | 0.0270 (14) | 0.0551 (17) | 0.0468 (16) | 0.0006 (10) | 0.0201 (13) | −0.0036 (11) |
O6 | 0.0456 (17) | 0.0435 (16) | 0.0665 (19) | −0.0089 (12) | 0.0146 (15) | 0.0128 (13) |
O7 | 0.0446 (16) | 0.0588 (17) | 0.0339 (14) | −0.0033 (13) | 0.0148 (13) | −0.0081 (12) |
N1 | 0.028 (2) | 0.025 (2) | 0.036 (2) | 0.000 | 0.0095 (18) | 0.000 |
N2 | 0.028 (2) | 0.025 (2) | 0.031 (2) | 0.000 | 0.0126 (17) | 0.000 |
N3 | 0.0282 (16) | 0.0295 (15) | 0.0356 (16) | −0.0006 (11) | 0.0141 (13) | −0.0008 (11) |
C1 | 0.031 (2) | 0.042 (2) | 0.038 (2) | 0.0061 (14) | 0.0129 (16) | −0.0011 (15) |
C2 | 0.061 (3) | 0.042 (2) | 0.052 (3) | 0.017 (2) | 0.014 (2) | −0.0065 (18) |
C3 | 0.078 (5) | 0.026 (3) | 0.065 (4) | 0.000 | 0.013 (4) | 0.000 |
C4 | 0.042 (2) | 0.035 (2) | 0.041 (2) | −0.0045 (15) | 0.0191 (18) | 0.0008 (15) |
C5 | 0.066 (3) | 0.038 (2) | 0.043 (2) | −0.0169 (19) | 0.022 (2) | 0.0019 (16) |
C6 | 0.082 (5) | 0.024 (3) | 0.035 (3) | 0.000 | 0.019 (3) | 0.000 |
C7 | 0.034 (2) | 0.040 (2) | 0.042 (2) | −0.0027 (15) | 0.0195 (17) | −0.0033 (15) |
C8 | 0.051 (3) | 0.042 (2) | 0.049 (2) | 0.0104 (17) | 0.024 (2) | −0.0046 (17) |
C9 | 0.066 (3) | 0.033 (2) | 0.048 (2) | −0.0005 (18) | 0.022 (2) | −0.0017 (16) |
C10 | 0.054 (3) | 0.041 (2) | 0.059 (3) | −0.0163 (18) | 0.026 (2) | 0.0006 (18) |
C11 | 0.034 (2) | 0.046 (2) | 0.048 (2) | −0.0064 (16) | 0.0210 (18) | −0.0022 (16) |
Hg1—N1 | 2.087 (4) | N2—C4i | 1.334 (4) |
Hg1—N2 | 2.092 (4) | N2—C4 | 1.334 (4) |
Hg1—O1 | 2.618 (3) | N3—C7 | 1.337 (4) |
Hg1—O1i | 2.618 (3) | N3—C11 | 1.350 (4) |
Hg1—O5ii | 2.625 (3) | C1—C2 | 1.367 (5) |
Hg1—O5iii | 2.625 (3) | C1—H1 | 0.950 |
Hg2—N3iv | 2.113 (3) | C2—C3 | 1.369 (5) |
Hg2—N3 | 2.113 (3) | C2—H2 | 0.950 |
Hg2—O3v | 2.596 (3) | C3—C2i | 1.369 (5) |
Hg2—O3vi | 2.596 (3) | C3—H3 | 0.950 |
Hg2—O7iv | 2.640 (3) | C4—C5 | 1.375 (5) |
Hg2—O7 | 2.640 (3) | C4—H4 | 0.950 |
Cr1—O2 | 1.601 (3) | C5—C6 | 1.370 (5) |
Cr1—O3 | 1.617 (3) | C5—H5 | 0.950 |
Cr1—O1 | 1.624 (3) | C6—C5i | 1.370 (5) |
Cr1—O4 | 1.766 (3) | C6—H6 | 0.950 |
Cr1—Cr2 | 3.3075 (7) | C7—C8 | 1.376 (5) |
Cr2—O6 | 1.604 (3) | C7—H7 | 0.950 |
Cr2—O5 | 1.615 (3) | C8—C9 | 1.379 (6) |
Cr2—O7 | 1.621 (3) | C8—H8 | 0.950 |
Cr2—O4 | 1.769 (3) | C9—C10 | 1.369 (6) |
O3—Hg2v | 2.596 (3) | C9—H9 | 0.950 |
O5—Hg1iii | 2.625 (3) | C10—C11 | 1.368 (5) |
N1—C1i | 1.332 (4) | C10—H10 | 0.950 |
N1—C1 | 1.332 (4) | C11—H11 | 0.950 |
N1—Hg1—N2 | 180.000 (1) | Cr2—O5—Hg1iii | 135.56 (15) |
N1—Hg1—O1 | 97.01 (6) | Cr2—O7—Hg2 | 126.34 (15) |
N2—Hg1—O1 | 82.99 (6) | C1i—N1—C1 | 119.8 (4) |
N1—Hg1—O1i | 97.01 (6) | C1i—N1—Hg1 | 120.1 (2) |
N2—Hg1—O1i | 82.99 (6) | C1—N1—Hg1 | 120.1 (2) |
O1—Hg1—O1i | 165.98 (13) | C4i—N2—C4 | 119.1 (4) |
N1—Hg1—O5ii | 85.30 (6) | C4i—N2—Hg1 | 120.5 (2) |
N2—Hg1—O5ii | 94.70 (6) | C4—N2—Hg1 | 120.5 (2) |
O1—Hg1—O5ii | 83.52 (9) | C7—N3—C11 | 119.2 (3) |
O1i—Hg1—O5ii | 97.64 (9) | C7—N3—Hg2 | 121.0 (2) |
N1—Hg1—O5iii | 85.30 (6) | C11—N3—Hg2 | 119.8 (2) |
N2—Hg1—O5iii | 94.70 (6) | N1—C1—C2 | 121.2 (4) |
O1—Hg1—O5iii | 97.64 (9) | N1—C1—H1 | 119.4 |
O1i—Hg1—O5iii | 83.52 (9) | C2—C1—H1 | 119.4 |
O5ii—Hg1—O5iii | 170.61 (11) | C1—C2—C3 | 119.5 (4) |
N3iv—Hg2—N3 | 180.000 (1) | C1—C2—H2 | 120.3 |
N3iv—Hg2—O3v | 86.97 (9) | C3—C2—H2 | 120.3 |
N3—Hg2—O3v | 93.03 (9) | C2i—C3—C2 | 118.8 (5) |
N3iv—Hg2—O3vi | 93.03 (9) | C2i—C3—H3 | 120.6 |
N3—Hg2—O3vi | 86.97 (9) | C2—C3—H3 | 120.6 |
O3v—Hg2—O3vi | 180.0 | N2—C4—C5 | 121.7 (4) |
N3iv—Hg2—O7iv | 97.87 (10) | N2—C4—H4 | 119.2 |
N3—Hg2—O7iv | 82.13 (10) | C5—C4—H4 | 119.2 |
O3v—Hg2—O7iv | 82.10 (8) | C6—C5—C4 | 119.4 (4) |
O3vi—Hg2—O7iv | 97.90 (8) | C6—C5—H5 | 120.3 |
N3iv—Hg2—O7 | 82.13 (10) | C4—C5—H5 | 120.3 |
N3—Hg2—O7 | 97.87 (10) | C5i—C6—C5 | 118.8 (5) |
O3v—Hg2—O7 | 97.90 (8) | C5i—C6—H6 | 120.6 |
O3vi—Hg2—O7 | 82.10 (8) | C5—C6—H6 | 120.6 |
O7iv—Hg2—O7 | 180.000 (1) | N3—C7—C8 | 121.8 (3) |
O2—Cr1—O3 | 108.87 (15) | N3—C7—H7 | 119.1 |
O2—Cr1—O1 | 110.71 (15) | C8—C7—H7 | 119.1 |
O3—Cr1—O1 | 110.16 (14) | C7—C8—C9 | 118.9 (4) |
O2—Cr1—O4 | 110.83 (13) | C7—C8—H8 | 120.6 |
O3—Cr1—O4 | 108.83 (14) | C9—C8—H8 | 120.6 |
O1—Cr1—O4 | 107.41 (14) | C10—C9—C8 | 119.0 (4) |
O6—Cr2—O5 | 108.81 (15) | C10—C9—H9 | 120.5 |
O6—Cr2—O7 | 110.00 (15) | C8—C9—H9 | 120.5 |
O5—Cr2—O7 | 110.35 (14) | C11—C10—C9 | 120.0 (4) |
O6—Cr2—O4 | 110.80 (13) | C11—C10—H10 | 120.0 |
O5—Cr2—O4 | 109.72 (14) | C9—C10—H10 | 120.0 |
O7—Cr2—O4 | 107.15 (14) | N3—C11—C10 | 121.1 (4) |
Cr1—O1—Hg1 | 135.12 (15) | N3—C11—H11 | 119.4 |
Cr1—O3—Hg2v | 136.54 (15) | C10—C11—H11 | 119.4 |
Cr1—O4—Cr2 | 138.62 (17) |
Symmetry codes: (i) −x, y, −z+1/2; (ii) x−1/2, −y+3/2, z−1/2; (iii) −x+1/2, −y+3/2, −z+1; (iv) −x+1/2, −y+3/2, −z+2; (v) −x, y, −z+3/2; (vi) x+1/2, −y+3/2, z+1/2. |
Experimental details
Crystal data | |
Chemical formula | [Hg(C5H5N)2][Cr2O7] |
Mr | 574.79 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 293 |
a, b, c (Å) | 15.4741 (5), 15.0135 (5), 14.0407 (5) |
β (°) | 115.018 (1) |
V (Å3) | 2955.89 (17) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 11.84 |
Crystal size (mm) | 0.10 × 0.07 × 0.04 |
Data collection | |
Diffractometer | Siemens SMART CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.366, 0.612 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 19668, 3683, 3186 |
Rint | 0.030 |
(sin θ/λ)max (Å−1) | 0.667 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.018, 0.046, 1.21 |
No. of reflections | 3683 |
No. of parameters | 204 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 1.06, −0.58 |
Computer programs: SMART (Siemens, 1996), SAINT (Siemens, 1996), SAINT, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ATOMS for WINDOWS (Dowty, 1998), SHELXL97.
Hg1—N1 | 2.087 (4) | Hg2—O7 | 2.640 (3) |
Hg1—N2 | 2.092 (4) | Cr1—O2 | 1.601 (3) |
Hg1—O1 | 2.618 (3) | Cr1—O3 | 1.617 (3) |
Hg1—O1i | 2.618 (3) | Cr1—O1 | 1.624 (3) |
Hg1—O5ii | 2.625 (3) | Cr1—O4 | 1.766 (3) |
Hg1—O5iii | 2.625 (3) | Cr1—Cr2 | 3.3075 (7) |
Hg2—N3iv | 2.113 (3) | Cr2—O6 | 1.604 (3) |
Hg2—N3 | 2.113 (3) | Cr2—O5 | 1.615 (3) |
Hg2—O3v | 2.596 (3) | Cr2—O7 | 1.621 (3) |
Hg2—O3vi | 2.596 (3) | Cr2—O4 | 1.769 (3) |
Hg2—O7iv | 2.640 (3) | ||
Cr1—O4—Cr2 | 138.62 (17) |
Symmetry codes: (i) −x, y, −z+1/2; (ii) x−1/2, −y+3/2, z−1/2; (iii) −x+1/2, −y+3/2, −z+1; (iv) −x+1/2, −y+3/2, −z+2; (v) −x, y, −z+3/2; (vi) x+1/2, −y+3/2, z+1/2. |
The preparation of metal dichromates(VI) with additional pyridine ligands (py) of general formula [M(py)n]mCr2O7 (n = 4, m = 1: MII = Cu, Ni, Co, Zn, Cd, Mn; n = 3, m = 2: MI = Ag; n = 2, m = 2: MI = Ag; n = 2, m = 1: MII = Hg) was described nearly 100 years ago (Briggs, 1908), but no crystallographic or structural data of these compounds have been reported in the meantime. Since the mercury compound is of considerable interest for application as a quick assay method to quantify mercury(II) ions in solution (Spacu & Dick, 1929), a structure analysis seemed desirable.
The two crystallographically independent mercury atoms are located at special positions with site symmetry 2 for Hg1 (Fig. 1) and 1 for Hg2 (Fig. 2), respectively. Both have a distorted octahedral coordination with two short axial bonds to N atoms of pyridine rings, ¯d(Hg—N) = 2.101 Å, and four longer equatorial bonds to terminal O atoms of the dichromate groups, ¯d(Hg—O) = 2.620 Å.
The Cr2O7 group (Fig. 3) displays a skew conformation with a dihedral angle of -31.58 (16)° for O2—Cr1···Cr2—O6 and a (Cr1—O4—Cr2) bridging angle of 138.62 (17)°. The two distinct [CrO4] tetrahedra show three short bonds ¯d(Cr—O)t = 1.614 Å to the terminal O atoms and a long bond ¯d(Cr—O)b = 1.768 Å to the bridging atom O4. The observed bond lengths and the bridging angle are in a range typical for other structures with dichromate groups and agree with those generally observed for [X2O7]2- anions (X = P, Cr, As, V) in inorganic compounds (Brown & Calvo, 1970; Clark & Morley, 1976; Nord & Kierkegaard, 1980).
Single building units of Hg(py)22+ and Cr2O72- groups form layers parallel to the ac plane and extend along [101] (Fig. 4). The two-dimensional connection within a layer is achieved via bonding of different mercury atoms to shared dichromate groups, whereas no covalent bonding between two adjacent layers is evident. The junction between two parallel layers is mainly accomplished by van der Waals interactions. A further weak interaction between terminal O atoms of one layer and pyridine H atoms of adjacent layers with distances d(O2—H10) and d(O6—H2) of ca 2.30 Å leads to additional stabilization. Except for O2 and O6, which are exclusively bonded to Cr atoms, all other O atoms show coordination number 2.