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Chemists of the late 19th century, including Alfred Werner, prepared salts containing either green or violet cations of composition [CoCl2(en)2]+ (en is ethylenediamine, C2H8N2); we now refer to these as trans-dichloro and cis-dichloro species. We have discovered a third salt, purple in color, containing cations of the same elemental composition and whose asymmetric unit composition is [CoCl2(en)2]2Cl2·3H2O, in which the cobalt cations are a cis:trans dichloro pair. Such a discovery would undermine Werner's argument that if only two forms can be prepared, his octahedral theory was proven. Probably because his students never examined their crystals under a microscope, they failed to observe the `third' species, thereby ruining Werner's argument since he relied strictly on color to identify them. That was fortunate since our purple salt would have led him to abandon, or certainly delay, his momentous discovery. Our crystals consist of a 1:1 mixture of the cis and trans cations, thereby sharing the same elemental analysis and conductivity as the single salts, but not their crystal structure, inasmuch as X-ray diffraction had not even been discovered then. Serendipitously, our discovery would have been a great boon to his theoretical acumen, while his `two-color' argument may have doomed him.
Supporting information
CCDC reference: 1979857
Data collection: APEX2 (Bruker, 2008); cell refinement: APEX2 (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXT2014 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).
Crystal data top
[CoCl2(C2H8N2)2]2Cl2·3H2O | Z = 2 |
Mr = 625.02 | F(000) = 644 |
Triclinic, P1 | Dx = 1.696 Mg m−3 |
a = 8.7163 (3) Å | Cu Kα radiation, λ = 1.54178 Å |
b = 11.1146 (4) Å | Cell parameters from 9124 reflections |
c = 14.0703 (5) Å | θ = 3.3–70.0° |
α = 105.540 (2)° | µ = 16.88 mm−1 |
β = 94.630 (2)° | T = 100 K |
γ = 108.581 (2)° | Plate, purple |
V = 1224.06 (8) Å3 | 0.61 × 0.19 × 0.07 mm |
Data collection top
Bruker SMART CCD APEXII area-detector diffractometer | 4191 independent reflections |
Radiation source: fine-focus sealed tube | 3864 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.039 |
φ and ω scans | θmax = 70.1°, θmin = 3.3° |
Absorption correction: numerical (SADABS; Bruker, 2008) | h = −10→10 |
Tmin = 0.041, Tmax = 0.512 | k = −13→13 |
11708 measured reflections | l = −16→17 |
Refinement top
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)] = 0.038 | Hydrogen site location: mixed |
wR(F2) = 0.097 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.05 | w = 1/[σ2(Fo2) + (0.046P)2 + 2.482P] where P = (Fo2 + 2Fc2)/3 |
4191 reflections | (Δ/σ)max = 0.001 |
262 parameters | Δρmax = 0.63 e Å−3 |
6 restraints | Δρmin = −0.61 e Å−3 |
Special details top
Experimental. Crystal mounted on a Cryoloop using Paratone-N. |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes)
are estimated using the full covariance matrix. The cell esds are taken
into account individually in the estimation of esds in distances, angles
and torsion angles; correlations between esds in cell parameters are only
used when they are defined by crystal symmetry. An approximate (isotropic)
treatment of cell esds is used for estimating esds involving l.s. planes. |
Refinement. A suitable crystal was mounted on a Bruker-AXS SMART APEX II CCD
diffractometer at 100 (1)K. The cell dimensions and the intensities were all
collected with CuKα radiation (λ = 1.54178 Å). Data processing,
Lorentz-polarization, and face-indexed numerical absorption corrections were
performed using SAINT, APEX, and SADABS computer programs (see Table 1). The
structures were solved by direct methods and refined by full-matrix
least-squares methods on F2, using the SHELXTL V6.14 program package. All
non-hydrogen atoms were refined anisotropically. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
Co1 | 0.42187 (7) | 0.73638 (5) | 0.14491 (4) | 0.01168 (15) | |
Co2 | 0.79303 (6) | 0.68956 (5) | 0.51970 (4) | 0.00924 (14) | |
Cl1 | 0.32764 (11) | 0.57545 (8) | −0.00666 (6) | 0.01721 (19) | |
Cl2 | 0.51347 (10) | 0.89359 (8) | 0.29573 (6) | 0.01563 (19) | |
Cl3 | 0.63440 (10) | 0.58474 (8) | 0.36448 (6) | 0.01373 (18) | |
Cl4 | 0.78767 (10) | 0.49270 (8) | 0.54045 (6) | 0.01316 (18) | |
Cl5 | 0.76001 (12) | 0.71852 (9) | 0.82366 (6) | 0.0227 (2) | |
Cl6 | 0.01374 (10) | 0.10534 (8) | 0.68451 (6) | 0.01470 (18) | |
O1 | 0.1100 (4) | 0.7779 (4) | 0.9406 (3) | 0.0414 (8) | |
H17 | 0.148 (4) | 0.733 (4) | 0.897 (2) | 0.062* | |
H18 | 0.016 (2) | 0.770 (5) | 0.914 (4) | 0.062* | |
O2 | 0.7664 (5) | 0.3860 (4) | 0.2156 (2) | 0.0432 (8) | |
H19 | 0.747 (5) | 0.435 (4) | 0.266 (2) | 0.065* | |
H20 | 0.745 (7) | 0.410 (4) | 0.1658 (18) | 0.065* | |
O3 | 0.5023 (4) | 0.1432 (3) | 0.1398 (2) | 0.0305 (7) | |
H21 | 0.593 (3) | 0.206 (3) | 0.155 (4) | 0.046* | |
H22 | 0.426 (3) | 0.174 (3) | 0.144 (4) | 0.046* | |
N1 | 0.2064 (4) | 0.7574 (3) | 0.1388 (2) | 0.0159 (6) | |
H1 | 0.212914 | 0.833261 | 0.186719 | 0.019* | |
H2 | 0.173412 | 0.763287 | 0.077745 | 0.019* | |
N2 | 0.3316 (4) | 0.6019 (3) | 0.2111 (2) | 0.0144 (6) | |
H3 | 0.313452 | 0.518920 | 0.168638 | 0.017* | |
H4 | 0.404666 | 0.616195 | 0.266533 | 0.017* | |
N3 | 0.6337 (4) | 0.7098 (3) | 0.1477 (2) | 0.0142 (6) | |
H5 | 0.692505 | 0.745603 | 0.211330 | 0.017* | |
H6 | 0.616971 | 0.620975 | 0.126728 | 0.017* | |
N4 | 0.5159 (4) | 0.8733 (3) | 0.0821 (2) | 0.0160 (6) | |
H7 | 0.470585 | 0.843071 | 0.015773 | 0.019* | |
H8 | 0.493480 | 0.947905 | 0.111382 | 0.019* | |
N5 | 0.6062 (3) | 0.6816 (3) | 0.5887 (2) | 0.0120 (6) | |
H9 | 0.512396 | 0.619685 | 0.547593 | 0.014* | |
H10 | 0.622078 | 0.657047 | 0.644405 | 0.014* | |
N6 | 0.7769 (3) | 0.8544 (3) | 0.5035 (2) | 0.0109 (6) | |
H11 | 0.863005 | 0.925717 | 0.544269 | 0.013* | |
H12 | 0.781225 | 0.853698 | 0.438964 | 0.013* | |
N7 | 0.9474 (3) | 0.7845 (3) | 0.6464 (2) | 0.0125 (6) | |
H13 | 0.953437 | 0.871052 | 0.667513 | 0.015* | |
H14 | 0.912190 | 0.746168 | 0.694002 | 0.015* | |
N8 | 0.9891 (3) | 0.7074 (3) | 0.4581 (2) | 0.0126 (6) | |
H15 | 1.000030 | 0.626268 | 0.435687 | 0.015* | |
H16 | 0.978514 | 0.737298 | 0.404589 | 0.015* | |
C1 | 0.0869 (4) | 0.6391 (4) | 0.1558 (3) | 0.0170 (8) | |
H1A | 0.052416 | 0.561342 | 0.094154 | 0.020* | |
H1B | −0.011974 | 0.658018 | 0.174596 | 0.020* | |
C2 | 0.1742 (5) | 0.6107 (4) | 0.2403 (3) | 0.0173 (8) | |
H2B | 0.196065 | 0.683405 | 0.304030 | 0.021* | |
H2A | 0.105949 | 0.525646 | 0.249139 | 0.021* | |
C3 | 0.7253 (5) | 0.7758 (4) | 0.0804 (3) | 0.0188 (8) | |
H3B | 0.685320 | 0.718241 | 0.009783 | 0.023* | |
H3A | 0.844292 | 0.792811 | 0.097853 | 0.023* | |
C4 | 0.6966 (5) | 0.9058 (4) | 0.0943 (3) | 0.0203 (8) | |
H4A | 0.751559 | 0.968917 | 0.161818 | 0.024* | |
H4B | 0.740980 | 0.947287 | 0.043471 | 0.024* | |
C5 | 0.5898 (4) | 0.8145 (3) | 0.6176 (3) | 0.0132 (7) | |
H5A | 0.672188 | 0.875470 | 0.678075 | 0.016* | |
H5B | 0.478506 | 0.806985 | 0.632244 | 0.016* | |
C6 | 0.6185 (4) | 0.8662 (3) | 0.5296 (3) | 0.0131 (7) | |
H6A | 0.527159 | 0.812728 | 0.471989 | 0.016* | |
H6B | 0.625832 | 0.960587 | 0.547557 | 0.016* | |
C7 | 1.1125 (4) | 0.7791 (4) | 0.6318 (3) | 0.0149 (7) | |
H7B | 1.116821 | 0.690845 | 0.630727 | 0.018* | |
H7A | 1.198949 | 0.848989 | 0.686762 | 0.018* | |
C8 | 1.1372 (4) | 0.8025 (3) | 0.5325 (3) | 0.0149 (7) | |
H8A | 1.149399 | 0.895619 | 0.536881 | 0.018* | |
H8B | 1.237270 | 0.786491 | 0.513006 | 0.018* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Co1 | 0.0127 (3) | 0.0127 (3) | 0.0100 (3) | 0.0057 (2) | 0.0001 (2) | 0.0032 (2) |
Co2 | 0.0078 (3) | 0.0098 (3) | 0.0107 (3) | 0.0033 (2) | 0.0007 (2) | 0.0042 (2) |
Cl1 | 0.0178 (4) | 0.0176 (4) | 0.0134 (4) | 0.0068 (3) | −0.0008 (3) | 0.0010 (3) |
Cl2 | 0.0187 (4) | 0.0157 (4) | 0.0114 (4) | 0.0072 (3) | 0.0004 (3) | 0.0019 (3) |
Cl3 | 0.0126 (4) | 0.0139 (4) | 0.0128 (4) | 0.0035 (3) | −0.0008 (3) | 0.0035 (3) |
Cl4 | 0.0116 (4) | 0.0120 (4) | 0.0181 (4) | 0.0054 (3) | 0.0023 (3) | 0.0068 (3) |
Cl5 | 0.0304 (5) | 0.0235 (5) | 0.0175 (4) | 0.0105 (4) | 0.0080 (4) | 0.0095 (4) |
Cl6 | 0.0155 (4) | 0.0131 (4) | 0.0146 (4) | 0.0041 (3) | 0.0006 (3) | 0.0047 (3) |
O1 | 0.0399 (19) | 0.048 (2) | 0.0365 (18) | 0.0127 (17) | −0.0047 (16) | 0.0193 (16) |
O2 | 0.048 (2) | 0.052 (2) | 0.0345 (18) | 0.0232 (18) | 0.0060 (17) | 0.0148 (17) |
O3 | 0.0455 (19) | 0.0290 (16) | 0.0280 (15) | 0.0239 (15) | 0.0119 (16) | 0.0120 (14) |
N1 | 0.0162 (15) | 0.0182 (16) | 0.0144 (14) | 0.0088 (13) | 0.0005 (13) | 0.0043 (13) |
N2 | 0.0137 (15) | 0.0154 (15) | 0.0147 (14) | 0.0056 (12) | 0.0015 (13) | 0.0055 (12) |
N3 | 0.0122 (14) | 0.0183 (16) | 0.0131 (14) | 0.0070 (12) | 0.0010 (12) | 0.0049 (12) |
N4 | 0.0233 (17) | 0.0119 (15) | 0.0114 (14) | 0.0061 (13) | 0.0007 (13) | 0.0022 (12) |
N5 | 0.0105 (14) | 0.0166 (15) | 0.0129 (13) | 0.0066 (12) | 0.0043 (12) | 0.0080 (12) |
N6 | 0.0103 (14) | 0.0110 (14) | 0.0126 (13) | 0.0039 (12) | 0.0016 (12) | 0.0055 (12) |
N7 | 0.0128 (15) | 0.0109 (14) | 0.0129 (13) | 0.0031 (12) | 0.0002 (13) | 0.0043 (12) |
N8 | 0.0117 (14) | 0.0127 (14) | 0.0151 (14) | 0.0054 (12) | 0.0018 (13) | 0.0060 (12) |
C1 | 0.0124 (17) | 0.0208 (19) | 0.0172 (17) | 0.0067 (15) | 0.0026 (15) | 0.0039 (15) |
C2 | 0.0179 (19) | 0.0171 (18) | 0.0186 (17) | 0.0065 (15) | 0.0057 (16) | 0.0070 (15) |
C3 | 0.0180 (19) | 0.023 (2) | 0.0148 (17) | 0.0061 (16) | 0.0024 (16) | 0.0061 (16) |
C4 | 0.0199 (19) | 0.022 (2) | 0.0166 (17) | 0.0040 (16) | 0.0022 (16) | 0.0071 (16) |
C5 | 0.0110 (17) | 0.0144 (17) | 0.0158 (16) | 0.0067 (14) | 0.0046 (15) | 0.0041 (14) |
C6 | 0.0130 (17) | 0.0137 (17) | 0.0154 (16) | 0.0075 (14) | 0.0019 (15) | 0.0057 (14) |
C7 | 0.0112 (17) | 0.0143 (18) | 0.0183 (17) | 0.0054 (14) | −0.0020 (15) | 0.0041 (15) |
C8 | 0.0073 (16) | 0.0130 (17) | 0.0221 (18) | 0.0015 (14) | 0.0005 (15) | 0.0051 (15) |
Geometric parameters (Å, º) top
Co1—N4 | 1.952 (3) | N5—H9 | 0.9100 |
Co1—N2 | 1.958 (3) | N5—H10 | 0.9100 |
Co1—N3 | 1.960 (3) | N6—C6 | 1.494 (4) |
Co1—N1 | 1.963 (3) | N6—H11 | 0.9100 |
Co1—Cl2 | 2.2460 (9) | N6—H12 | 0.9100 |
Co1—Cl1 | 2.2713 (10) | N7—C7 | 1.487 (4) |
Co2—N7 | 1.950 (3) | N7—H13 | 0.9100 |
Co2—N6 | 1.952 (3) | N7—H14 | 0.9100 |
Co2—N5 | 1.953 (3) | N8—C8 | 1.483 (4) |
Co2—N8 | 1.956 (3) | N8—H15 | 0.9100 |
Co2—Cl4 | 2.2703 (9) | N8—H16 | 0.9100 |
Co2—Cl3 | 2.2719 (9) | C1—C2 | 1.517 (5) |
O1—H17 | 0.8400 (10) | C1—H1A | 0.9900 |
O1—H18 | 0.8401 (11) | C1—H1B | 0.9900 |
O2—H19 | 0.8401 (10) | C2—H2B | 0.9900 |
O2—H20 | 0.8402 (10) | C2—H2A | 0.9900 |
O3—H21 | 0.8400 (11) | C3—C4 | 1.509 (5) |
O3—H22 | 0.8400 (10) | C3—H3B | 0.9900 |
N1—C1 | 1.485 (5) | C3—H3A | 0.9900 |
N1—H1 | 0.9100 | C4—H4A | 0.9900 |
N1—H2 | 0.9100 | C4—H4B | 0.9900 |
N2—C2 | 1.489 (5) | C5—C6 | 1.506 (5) |
N2—H3 | 0.9100 | C5—H5A | 0.9900 |
N2—H4 | 0.9100 | C5—H5B | 0.9900 |
N3—C3 | 1.481 (5) | C6—H6A | 0.9900 |
N3—H5 | 0.9100 | C6—H6B | 0.9900 |
N3—H6 | 0.9100 | C7—C8 | 1.508 (5) |
N4—C4 | 1.484 (5) | C7—H7B | 0.9900 |
N4—H7 | 0.9100 | C7—H7A | 0.9900 |
N4—H8 | 0.9100 | C8—H8A | 0.9900 |
N5—C5 | 1.480 (4) | C8—H8B | 0.9900 |
| | | |
N4—Co1—N2 | 178.53 (13) | Co2—N6—H11 | 109.8 |
N4—Co1—N3 | 86.20 (13) | C6—N6—H12 | 109.8 |
N2—Co1—N3 | 93.22 (12) | Co2—N6—H12 | 109.8 |
N4—Co1—N1 | 94.44 (13) | H11—N6—H12 | 108.2 |
N2—Co1—N1 | 86.19 (12) | C7—N7—Co2 | 109.2 (2) |
N3—Co1—N1 | 178.15 (13) | C7—N7—H13 | 109.8 |
N4—Co1—Cl2 | 89.21 (9) | Co2—N7—H13 | 109.8 |
N2—Co1—Cl2 | 89.45 (9) | C7—N7—H14 | 109.8 |
N3—Co1—Cl2 | 91.06 (9) | Co2—N7—H14 | 109.8 |
N1—Co1—Cl2 | 90.69 (9) | H13—N7—H14 | 108.3 |
N4—Co1—Cl1 | 91.52 (9) | C8—N8—Co2 | 109.9 (2) |
N2—Co1—Cl1 | 89.82 (9) | C8—N8—H15 | 109.7 |
N3—Co1—Cl1 | 89.05 (9) | Co2—N8—H15 | 109.7 |
N1—Co1—Cl1 | 89.20 (9) | C8—N8—H16 | 109.7 |
Cl2—Co1—Cl1 | 179.27 (4) | Co2—N8—H16 | 109.7 |
N7—Co2—N6 | 92.48 (12) | H15—N8—H16 | 108.2 |
N7—Co2—N5 | 91.09 (12) | N1—C1—C2 | 106.6 (3) |
N6—Co2—N5 | 85.64 (12) | N1—C1—H1A | 110.4 |
N7—Co2—N8 | 85.45 (12) | C2—C1—H1A | 110.4 |
N6—Co2—N8 | 93.14 (12) | N1—C1—H1B | 110.4 |
N5—Co2—N8 | 176.28 (12) | C2—C1—H1B | 110.4 |
N7—Co2—Cl4 | 89.50 (9) | H1A—C1—H1B | 108.6 |
N6—Co2—Cl4 | 174.82 (9) | N2—C2—C1 | 106.4 (3) |
N5—Co2—Cl4 | 89.54 (9) | N2—C2—H2B | 110.4 |
N8—Co2—Cl4 | 91.79 (9) | C1—C2—H2B | 110.4 |
N7—Co2—Cl3 | 174.39 (9) | N2—C2—H2A | 110.4 |
N6—Co2—Cl3 | 86.60 (9) | C1—C2—H2A | 110.4 |
N5—Co2—Cl3 | 94.36 (9) | H2B—C2—H2A | 108.6 |
N8—Co2—Cl3 | 89.08 (9) | N3—C3—C4 | 107.3 (3) |
Cl4—Co2—Cl3 | 91.89 (3) | N3—C3—H3B | 110.3 |
H17—O1—H18 | 108 (5) | C4—C3—H3B | 110.3 |
H19—O2—H20 | 108 (4) | N3—C3—H3A | 110.3 |
H21—O3—H22 | 110 (4) | C4—C3—H3A | 110.3 |
C1—N1—Co1 | 108.1 (2) | H3B—C3—H3A | 108.5 |
C1—N1—H1 | 110.1 | N4—C4—C3 | 106.7 (3) |
Co1—N1—H1 | 110.1 | N4—C4—H4A | 110.4 |
C1—N1—H2 | 110.1 | C3—C4—H4A | 110.4 |
Co1—N1—H2 | 110.1 | N4—C4—H4B | 110.4 |
H1—N1—H2 | 108.4 | C3—C4—H4B | 110.4 |
C2—N2—Co1 | 109.1 (2) | H4A—C4—H4B | 108.6 |
C2—N2—H3 | 109.9 | N5—C5—C6 | 106.2 (3) |
Co1—N2—H3 | 109.9 | N5—C5—H5A | 110.5 |
C2—N2—H4 | 109.9 | C6—C5—H5A | 110.5 |
Co1—N2—H4 | 109.9 | N5—C5—H5B | 110.5 |
H3—N2—H4 | 108.3 | C6—C5—H5B | 110.5 |
C3—N3—Co1 | 108.5 (2) | H5A—C5—H5B | 108.7 |
C3—N3—H5 | 110.0 | N6—C6—C5 | 106.5 (3) |
Co1—N3—H5 | 110.0 | N6—C6—H6A | 110.4 |
C3—N3—H6 | 110.0 | C5—C6—H6A | 110.4 |
Co1—N3—H6 | 110.0 | N6—C6—H6B | 110.4 |
H5—N3—H6 | 108.4 | C5—C6—H6B | 110.4 |
C4—N4—Co1 | 109.1 (2) | H6A—C6—H6B | 108.6 |
C4—N4—H7 | 109.9 | N7—C7—C8 | 106.1 (3) |
Co1—N4—H7 | 109.9 | N7—C7—H7B | 110.5 |
C4—N4—H8 | 109.9 | C8—C7—H7B | 110.5 |
Co1—N4—H8 | 109.9 | N7—C7—H7A | 110.5 |
H7—N4—H8 | 108.3 | C8—C7—H7A | 110.5 |
C5—N5—Co2 | 109.2 (2) | H7B—C7—H7A | 108.7 |
C5—N5—H9 | 109.8 | N8—C8—C7 | 106.6 (3) |
Co2—N5—H9 | 109.8 | N8—C8—H8A | 110.4 |
C5—N5—H10 | 109.8 | C7—C8—H8A | 110.4 |
Co2—N5—H10 | 109.8 | N8—C8—H8B | 110.4 |
H9—N5—H10 | 108.3 | C7—C8—H8B | 110.4 |
C6—N6—Co2 | 109.4 (2) | H8A—C8—H8B | 108.6 |
C6—N6—H11 | 109.8 | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H18···Cl5i | 0.84 (3) | 2.29 (4) | 3.126 (4) | 171 (6) |
O3—H21···O2 | 0.84 (4) | 1.99 (4) | 2.797 (5) | 162 (3) |
O2—H19···Cl3 | 0.84 (3) | 2.38 (4) | 3.181 (4) | 160 (3) |
N2—H3···Cl5ii | 0.91 | 2.54 | 3.279 (3) | 138 |
N4—H7···O3iii | 0.91 | 2.26 | 3.066 (4) | 147 |
O1—H17···O2ii | 0.84 (3) | 2.12 (3) | 2.966 (5) | 178 (4) |
Symmetry codes: (i) x−1, y, z; (ii) −x+1, −y+1, −z+1; (iii) −x+1, −y+1, −z. |
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