Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807049276/pk2052sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536807049276/pk2052Isup2.hkl |
CCDC reference: 653334
Key indicators
- Single-crystal X-ray study
- T = 173 K
- Mean (C-C) = 0.005 Å
- R factor = 0.064
- wR factor = 0.125
- Data-to-parameter ratio = 19.4
checkCIF/PLATON results
No syntax errors found
Alert level C RINTA01_ALERT_3_C The value of Rint is greater than 0.10 Rint given 0.116 PLAT020_ALERT_3_C The value of Rint is greater than 0.10 ......... 0.12 PLAT242_ALERT_2_C Check Low Ueq as Compared to Neighbors for C11 PLAT410_ALERT_2_C Short Intra H...H Contact H4 .. H4 .. 1.90 Ang. PLAT420_ALERT_2_C D-H Without Acceptor N4 - H4N ... ? PLAT480_ALERT_4_C Long H...A H-Bond Reported H4N .. S2 .. 2.94 Ang. PLAT480_ALERT_4_C Long H...A H-Bond Reported H4N .. S2 .. 2.94 Ang.
Alert level G PLAT794_ALERT_5_G Check Predicted Bond Valency for Co1 (2) 1.66 PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints ....... 2
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 7 ALERT level C = Check and explain 2 ALERT level G = General alerts; check 0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 3 ALERT type 2 Indicator that the structure model may be wrong or deficient 3 ALERT type 3 Indicator that the structure quality may be low 2 ALERT type 4 Improvement, methodology, query or suggestion 1 ALERT type 5 Informative message, check
For related literature, see: Knapp et al. (2007); Montney et al. (2007); Zapf et al. (1998).
Cobalt thiocyanate was obtained commercially. di-4-pyridylamine (dpa) was prepared via a published procedure (Zapf et al., 1998). Cobalt thiocyanate (58 mg, 0.33 mmol) and dpa (114 mg, 0.66 mmol) were added to 10 ml H2O in a 23 ml a Teflon-lined Parr acid digestion bomb. The mixture was then heated under autogenous pressure at 393 K for 48 h., whereupon it was cooled slowly to 293 K. Small dark blue crystals of the title compound were produced, entrained in a pink polycrystalline powder.
All H atoms bound to C atoms were placed in calculated positions, with C—H = 0.93 Å and refined in riding mode with Uiso = 1.2Ueq(C). Both of the H atoms bound to N within the dpa ligands were found via Fourier difference map, restrained with N—H = 0.88 (2) Å, and refined with Uiso =1.2Ueq(N).
In comparison to the wide variety of coordination polymers incorporating the rigid rod tethering ligand 4,4'-bipyridine, metal-organic materials based on di-4-pyridylamine (dpa) are much less common (Montney et al., 2007). The title compound was prepared during our continuing attempts to prepare metal pseudohalide/dpa coordination polymers (Knapp et al., 2007). The title compound possesses an asymmetric unit (Fig. 1) consisting of one cobalt atom, two N-bound isothiocyanate anions, and two halves of two crystallographically distinct dpa moieties. Both atoms of each dpa central N–H unit are situated on crystallographic 2-fold rotation axes.
Extension of the structure along the b crystal direction reveals an undulating 1-D chain coordination polymer of formulation [Co(NCS)2(dpa)]n, constructed via the linkage of [CoN4] coordination tetrahedra through the tethering, kinked dpa ligands. The Co–NNCS bond lengths are slightly shorter than the Co–Ndpa bond lengths, likely indicating a modicum of π-donation by the isothiocyanate ligands. The marked undulations in the 1-D chains are imparted by the varied amounts of torsional twisting within the dpa ligands as well as the tetrahedral coordination at cobalt. For one dpa ligand, the inter-ring torsion was measured as 19.6 (3)° via the through-bond/through-space torsion angle C4–C3–C3A–C4A, while the other exhibited a much more pronounced torsional twist of 39.4 (3)° (via the four-atom angle C7–C8–C8A–C7A). Within the 1-D chain motif, the Co–Co distances alternate between 11.464 (1) and 10.985 (1) Å.
As seen in Fig. 2, the 1-D [Co(NCS)2(dpa)]n chains aggregate into discrete pseudo 2-D layers through extensive cooperative π–π stacking interactions between the pyridyl rings of dpa units in neighboring chains (centroid-to-centroid distance = 3.693 (2) Å). Due to this arrangement, the through-space Co–Co distance between neighboring chain motifs within a pseudo 2-D layer is 5.767 (1) Å, over 5 Å closer than the through-ligand Co–Co distance within each chain. The central dpa N–H subunits and pendant sulfur atoms of the isothiocyanate ligands project into the interlamellar regions (Fig. 3), thereby permitting weak bifurcated N–H···S hydrogen bonding interactions between the layers, and propagating the full pseudo 3-D structure of the title compound. The closest Co–Co through-space distances between neighboring pseudo 2-D layers is 11.070 (1) Å.
For related literature, see: Knapp et al. (2007); Montney et al. (2007); Zapf et al. (1998).
Data collection: SMART (Bruker, 2001); cell refinement: SAINT-Plus (Bruker, 2003); data reduction: SAINT-Plus (Bruker, 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: CrystalMaker (CrystalMaker Software, 2005); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).
[Co(NCS)2(C10H9N3)] | F(000) = 1400 |
Mr = 346.31 | Dx = 1.593 Mg m−3 |
Orthorhombic, Pccn | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ab 2ac | Cell parameters from 33685 reflections |
a = 11.3975 (9) Å | θ = 2.3–28.3° |
b = 14.8905 (12) Å | µ = 1.47 mm−1 |
c = 17.0136 (14) Å | T = 173 K |
V = 2887.5 (4) Å3 | Block, blue |
Z = 8 | 0.22 × 0.10 × 0.06 mm |
Bruker SMART 1K diffractometer | 3576 independent reflections |
Radiation source: fine-focus sealed tube | 2384 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.117 |
ω scans | θmax = 28.3°, θmin = 2.3° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −15→15 |
Tmin = 0.764, Tmax = 0.915 | k = −19→19 |
33685 measured reflections | l = −22→22 |
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)] = 0.064 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.125 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.06 | w = 1/[σ2(Fo2) + (0.0414P)2 + 5.2183P] where P = (Fo2 + 2Fc2)/3 |
3576 reflections | (Δ/σ)max < 0.001 |
184 parameters | Δρmax = 0.35 e Å−3 |
2 restraints | Δρmin = −0.53 e Å−3 |
[Co(NCS)2(C10H9N3)] | V = 2887.5 (4) Å3 |
Mr = 346.31 | Z = 8 |
Orthorhombic, Pccn | Mo Kα radiation |
a = 11.3975 (9) Å | µ = 1.47 mm−1 |
b = 14.8905 (12) Å | T = 173 K |
c = 17.0136 (14) Å | 0.22 × 0.10 × 0.06 mm |
Bruker SMART 1K diffractometer | 3576 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 2384 reflections with I > 2σ(I) |
Tmin = 0.764, Tmax = 0.915 | Rint = 0.117 |
33685 measured reflections |
R[F2 > 2σ(F2)] = 0.064 | 2 restraints |
wR(F2) = 0.125 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.06 | Δρmax = 0.35 e Å−3 |
3576 reflections | Δρmin = −0.53 e Å−3 |
184 parameters |
Experimental. The small crystal size resulted in relatively weak diffraction and an Rint value in excess of 0.10 despite collection of 30 second frames. Nevertheless, refinement was satisfactory. |
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 > 2σ(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 | ||
Co1 | 0.11826 (4) | 0.01219 (3) | 0.27376 (3) | 0.02166 (15) | |
S1 | 0.38959 (13) | 0.14244 (13) | 0.44325 (9) | 0.0688 (5) | |
S2 | 0.32324 (12) | −0.12349 (10) | 0.06501 (8) | 0.0517 (4) | |
N1 | 0.0002 (3) | −0.0711 (2) | 0.32258 (19) | 0.0224 (7) | |
N2 | −0.2500 | −0.2500 | 0.4099 (3) | 0.0350 (13) | |
H2N | −0.2500 | −0.2500 | 0.4619 (12) | 0.042* | |
N3 | 0.0200 (3) | 0.1031 (2) | 0.21497 (18) | 0.0213 (7) | |
N4 | −0.2500 | 0.2500 | 0.1100 (3) | 0.0286 (11) | |
H4N | −0.2500 | 0.2500 | 0.0585 (12) | 0.034* | |
N5 | 0.2067 (3) | 0.0673 (2) | 0.3582 (2) | 0.0307 (8) | |
N6 | 0.2040 (3) | −0.0515 (2) | 0.1925 (2) | 0.0289 (8) | |
C1 | −0.0077 (4) | −0.0918 (3) | 0.3989 (2) | 0.0333 (10) | |
H1 | 0.0447 | −0.0653 | 0.4338 | 0.040* | |
C2 | −0.0899 (4) | −0.1506 (3) | 0.4279 (2) | 0.0370 (12) | |
H2 | −0.0923 | −0.1629 | 0.4815 | 0.044* | |
C3 | −0.1695 (3) | −0.1919 (3) | 0.3779 (2) | 0.0244 (9) | |
C4 | −0.1645 (4) | −0.1677 (3) | 0.3001 (2) | 0.0291 (10) | |
H4 | −0.2188 | −0.1907 | 0.2646 | 0.035* | |
C5 | −0.0789 (4) | −0.1094 (3) | 0.2748 (2) | 0.0298 (9) | |
H5 | −0.0758 | −0.0957 | 0.2215 | 0.036* | |
C6 | −0.0327 (3) | 0.1699 (3) | 0.2534 (2) | 0.0222 (8) | |
H6 | −0.0078 | 0.1827 | 0.3042 | 0.027* | |
C7 | −0.1216 (3) | 0.2210 (2) | 0.2220 (2) | 0.0250 (8) | |
H7 | −0.1558 | 0.2668 | 0.2513 | 0.030* | |
C8 | −0.1597 (3) | 0.2033 (2) | 0.1464 (2) | 0.0209 (8) | |
C9 | −0.1012 (3) | 0.1368 (3) | 0.1044 (2) | 0.0290 (9) | |
H9 | −0.1215 | 0.1250 | 0.0525 | 0.035* | |
C10 | −0.0133 (4) | 0.0888 (3) | 0.1400 (2) | 0.0276 (9) | |
H10 | 0.0248 | 0.0445 | 0.1112 | 0.033* | |
C11 | 0.2825 (4) | 0.0991 (3) | 0.3950 (2) | 0.0335 (10) | |
C12 | 0.2527 (4) | −0.0810 (3) | 0.1386 (2) | 0.0266 (9) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Co1 | 0.0196 (3) | 0.0225 (3) | 0.0229 (3) | 0.0014 (2) | −0.0008 (2) | 0.0028 (2) |
S1 | 0.0426 (8) | 0.1086 (13) | 0.0550 (9) | −0.0084 (9) | −0.0107 (7) | −0.0464 (9) |
S2 | 0.0493 (8) | 0.0760 (10) | 0.0300 (7) | 0.0062 (7) | 0.0046 (6) | −0.0156 (7) |
N1 | 0.0203 (16) | 0.0222 (17) | 0.0247 (18) | 0.0004 (13) | −0.0033 (14) | 0.0042 (14) |
N2 | 0.052 (3) | 0.036 (3) | 0.017 (2) | −0.023 (3) | 0.000 | 0.000 |
N3 | 0.0194 (16) | 0.0207 (16) | 0.0239 (18) | 0.0029 (13) | 0.0009 (13) | 0.0017 (14) |
N4 | 0.030 (3) | 0.039 (3) | 0.017 (2) | 0.015 (2) | 0.000 | 0.000 |
N5 | 0.0284 (19) | 0.039 (2) | 0.0252 (19) | −0.0045 (16) | 0.0029 (15) | 0.0024 (16) |
N6 | 0.0259 (19) | 0.0292 (19) | 0.032 (2) | 0.0061 (15) | 0.0004 (16) | 0.0018 (16) |
C1 | 0.041 (3) | 0.036 (3) | 0.023 (2) | −0.014 (2) | −0.0052 (19) | −0.0010 (19) |
C2 | 0.049 (3) | 0.045 (3) | 0.017 (2) | −0.021 (2) | −0.0003 (19) | 0.0030 (19) |
C3 | 0.029 (2) | 0.021 (2) | 0.024 (2) | −0.0043 (17) | −0.0012 (17) | −0.0015 (17) |
C4 | 0.026 (2) | 0.030 (2) | 0.031 (2) | −0.0062 (18) | −0.0109 (18) | 0.0061 (19) |
C5 | 0.032 (2) | 0.038 (2) | 0.019 (2) | −0.0061 (18) | −0.0036 (18) | 0.0115 (19) |
C6 | 0.0190 (19) | 0.029 (2) | 0.0185 (19) | −0.0017 (16) | −0.0017 (15) | −0.0005 (16) |
C7 | 0.0249 (19) | 0.0211 (18) | 0.029 (2) | 0.0047 (17) | 0.0031 (19) | −0.0037 (17) |
C8 | 0.0181 (18) | 0.022 (2) | 0.022 (2) | 0.0018 (15) | 0.0025 (15) | 0.0017 (16) |
C9 | 0.031 (2) | 0.039 (2) | 0.018 (2) | 0.0145 (19) | 0.0007 (17) | 0.0001 (17) |
C10 | 0.029 (2) | 0.029 (2) | 0.024 (2) | 0.0078 (18) | 0.0016 (17) | −0.0040 (18) |
C11 | 0.032 (2) | 0.045 (3) | 0.024 (2) | 0.000 (2) | 0.0040 (19) | −0.008 (2) |
C12 | 0.023 (2) | 0.028 (2) | 0.030 (2) | −0.0010 (18) | −0.0059 (18) | 0.0064 (18) |
Co1—N5 | 1.937 (4) | N6—C12 | 1.157 (5) |
Co1—N6 | 1.942 (4) | C1—C2 | 1.375 (6) |
Co1—N1 | 2.010 (3) | C1—H1 | 0.9300 |
Co1—N3 | 2.022 (3) | C2—C3 | 1.388 (5) |
S1—C11 | 1.606 (5) | C2—H2 | 0.9300 |
S2—C12 | 1.617 (4) | C3—C4 | 1.373 (6) |
N1—C1 | 1.337 (5) | C4—C5 | 1.375 (5) |
N1—C5 | 1.342 (5) | C4—H4 | 0.9300 |
N2—C3i | 1.374 (4) | C5—H5 | 0.9300 |
N2—C3 | 1.374 (4) | C6—C7 | 1.375 (5) |
N2—H2N | 0.88 (2) | C6—H6 | 0.9300 |
N3—C6 | 1.333 (5) | C7—C8 | 1.383 (5) |
N3—C10 | 1.348 (5) | C7—H7 | 0.9300 |
N4—C8 | 1.388 (4) | C8—C9 | 1.391 (5) |
N4—C8ii | 1.388 (4) | C9—C10 | 1.371 (5) |
N4—H4N | 0.876 (19) | C9—H9 | 0.9300 |
N5—C11 | 1.167 (5) | C10—H10 | 0.9300 |
N5—Co1—N6 | 118.24 (14) | C4—C3—N2 | 125.1 (4) |
N5—Co1—N1 | 107.65 (14) | C4—C3—C2 | 116.7 (4) |
N6—Co1—N1 | 109.26 (14) | N2—C3—C2 | 118.1 (4) |
N5—Co1—N3 | 111.84 (14) | C3—C4—C5 | 119.8 (4) |
N6—Co1—N3 | 104.70 (14) | C3—C4—H4 | 120.1 |
N1—Co1—N3 | 104.29 (13) | C5—C4—H4 | 120.1 |
C1—N1—C5 | 116.5 (3) | N1—C5—C4 | 123.7 (4) |
C1—N1—Co1 | 126.1 (3) | N1—C5—H5 | 118.1 |
C5—N1—Co1 | 117.5 (3) | C4—C5—H5 | 118.1 |
C3i—N2—C3 | 133.3 (5) | N3—C6—C7 | 123.7 (4) |
C3i—N2—H2N | 113.4 (2) | N3—C6—H6 | 118.2 |
C3—N2—H2N | 113.4 (2) | C7—C6—H6 | 118.2 |
C6—N3—C10 | 117.1 (3) | C6—C7—C8 | 119.1 (3) |
C6—N3—Co1 | 120.4 (3) | C6—C7—H7 | 120.4 |
C10—N3—Co1 | 121.2 (3) | C8—C7—H7 | 120.4 |
C8—N4—C8ii | 127.0 (5) | C7—C8—N4 | 123.5 (4) |
C8—N4—H4N | 116.5 (2) | C7—C8—C9 | 117.6 (3) |
C8ii—N4—H4N | 116.5 (2) | N4—C8—C9 | 118.9 (4) |
C11—N5—Co1 | 162.7 (3) | C10—C9—C8 | 119.6 (4) |
C12—N6—Co1 | 172.1 (3) | C10—C9—H9 | 120.2 |
N1—C1—C2 | 122.8 (4) | C8—C9—H9 | 120.2 |
N1—C1—H1 | 118.6 | N3—C10—C9 | 122.8 (4) |
C2—C1—H1 | 118.6 | N3—C10—H10 | 118.6 |
C1—C2—C3 | 120.4 (4) | C9—C10—H10 | 118.6 |
C1—C2—H2 | 119.8 | N5—C11—S1 | 178.2 (4) |
C3—C2—H2 | 119.8 | N6—C12—S2 | 178.3 (4) |
N5—Co1—N1—C1 | −6.3 (4) | C1—C2—C3—C4 | −2.8 (7) |
N6—Co1—N1—C1 | 123.3 (4) | C1—C2—C3—N2 | −179.9 (4) |
N3—Co1—N1—C1 | −125.2 (4) | N2—C3—C4—C5 | −179.4 (3) |
N5—Co1—N1—C5 | 173.2 (3) | C2—C3—C4—C5 | 3.8 (6) |
N6—Co1—N1—C5 | −57.3 (3) | C1—N1—C5—C4 | −0.6 (6) |
N3—Co1—N1—C5 | 54.2 (3) | Co1—N1—C5—C4 | 179.9 (3) |
N5—Co1—N3—C6 | −37.7 (3) | C3—C4—C5—N1 | −2.2 (7) |
N6—Co1—N3—C6 | −166.9 (3) | C10—N3—C6—C7 | 3.3 (5) |
N1—Co1—N3—C6 | 78.4 (3) | Co1—N3—C6—C7 | −164.0 (3) |
N5—Co1—N3—C10 | 155.5 (3) | N3—C6—C7—C8 | −0.2 (6) |
N6—Co1—N3—C10 | 26.3 (3) | C6—C7—C8—N4 | 178.9 (3) |
N1—Co1—N3—C10 | −88.4 (3) | C6—C7—C8—C9 | −3.0 (6) |
N6—Co1—N5—C11 | 21.6 (13) | C8ii—N4—C8—C7 | −23.5 (3) |
N1—Co1—N5—C11 | 145.9 (12) | C8ii—N4—C8—C9 | 158.4 (4) |
N3—Co1—N5—C11 | −100.1 (12) | C7—C8—C9—C10 | 3.2 (6) |
C5—N1—C1—C2 | 1.5 (6) | N4—C8—C9—C10 | −178.7 (3) |
Co1—N1—C1—C2 | −179.0 (3) | C6—N3—C10—C9 | −3.1 (6) |
N1—C1—C2—C3 | 0.2 (7) | Co1—N3—C10—C9 | 164.1 (3) |
C3i—N2—C3—C4 | 11.4 (3) | C8—C9—C10—N3 | −0.1 (6) |
C3i—N2—C3—C2 | −171.7 (4) |
Symmetry codes: (i) −x−1/2, −y−1/2, z; (ii) −x−1/2, −y+1/2, z. |
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2N···S1iii | 0.88 (2) | 2.78 (1) | 3.367 (4) | 126 (1) |
N2—H2N···S1iv | 0.88 (2) | 2.78 (1) | 3.367 (4) | 126 (1) |
N4—H4N···S2v | 0.88 (2) | 2.94 (2) | 3.621 (4) | 136 (1) |
N4—H4N···S2vi | 0.88 (2) | 2.94 (2) | 3.621 (4) | 136 (1) |
Symmetry codes: (iii) −x, −y, −z+1; (iv) x−1/2, y−1/2, −z+1; (v) −x, −y, −z; (vi) x−1/2, y+1/2, −z. |
Experimental details
Crystal data | |
Chemical formula | [Co(NCS)2(C10H9N3)] |
Mr | 346.31 |
Crystal system, space group | Orthorhombic, Pccn |
Temperature (K) | 173 |
a, b, c (Å) | 11.3975 (9), 14.8905 (12), 17.0136 (14) |
V (Å3) | 2887.5 (4) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 1.47 |
Crystal size (mm) | 0.22 × 0.10 × 0.06 |
Data collection | |
Diffractometer | Bruker SMART 1K |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.764, 0.915 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 33685, 3576, 2384 |
Rint | 0.117 |
(sin θ/λ)max (Å−1) | 0.667 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.064, 0.125, 1.06 |
No. of reflections | 3576 |
No. of parameters | 184 |
No. of restraints | 2 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.35, −0.53 |
Computer programs: SMART (Bruker, 2001), SAINT-Plus (Bruker, 2003), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), CrystalMaker (CrystalMaker Software, 2005).
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2N···S1i | 0.88 (2) | 2.775 (12) | 3.367 (4) | 125.6 (3) |
N2—H2N···S1ii | 0.88 (2) | 2.775 (12) | 3.367 (4) | 125.6 (3) |
N4—H4N···S2iii | 0.876 (19) | 2.943 (15) | 3.621 (4) | 135.6 (3) |
N4—H4N···S2iv | 0.876 (19) | 2.943 (15) | 3.621 (4) | 135.6 (3) |
Symmetry codes: (i) −x, −y, −z+1; (ii) x−1/2, y−1/2, −z+1; (iii) −x, −y, −z; (iv) x−1/2, y+1/2, −z. |
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In comparison to the wide variety of coordination polymers incorporating the rigid rod tethering ligand 4,4'-bipyridine, metal-organic materials based on di-4-pyridylamine (dpa) are much less common (Montney et al., 2007). The title compound was prepared during our continuing attempts to prepare metal pseudohalide/dpa coordination polymers (Knapp et al., 2007). The title compound possesses an asymmetric unit (Fig. 1) consisting of one cobalt atom, two N-bound isothiocyanate anions, and two halves of two crystallographically distinct dpa moieties. Both atoms of each dpa central N–H unit are situated on crystallographic 2-fold rotation axes.
Extension of the structure along the b crystal direction reveals an undulating 1-D chain coordination polymer of formulation [Co(NCS)2(dpa)]n, constructed via the linkage of [CoN4] coordination tetrahedra through the tethering, kinked dpa ligands. The Co–NNCS bond lengths are slightly shorter than the Co–Ndpa bond lengths, likely indicating a modicum of π-donation by the isothiocyanate ligands. The marked undulations in the 1-D chains are imparted by the varied amounts of torsional twisting within the dpa ligands as well as the tetrahedral coordination at cobalt. For one dpa ligand, the inter-ring torsion was measured as 19.6 (3)° via the through-bond/through-space torsion angle C4–C3–C3A–C4A, while the other exhibited a much more pronounced torsional twist of 39.4 (3)° (via the four-atom angle C7–C8–C8A–C7A). Within the 1-D chain motif, the Co–Co distances alternate between 11.464 (1) and 10.985 (1) Å.
As seen in Fig. 2, the 1-D [Co(NCS)2(dpa)]n chains aggregate into discrete pseudo 2-D layers through extensive cooperative π–π stacking interactions between the pyridyl rings of dpa units in neighboring chains (centroid-to-centroid distance = 3.693 (2) Å). Due to this arrangement, the through-space Co–Co distance between neighboring chain motifs within a pseudo 2-D layer is 5.767 (1) Å, over 5 Å closer than the through-ligand Co–Co distance within each chain. The central dpa N–H subunits and pendant sulfur atoms of the isothiocyanate ligands project into the interlamellar regions (Fig. 3), thereby permitting weak bifurcated N–H···S hydrogen bonding interactions between the layers, and propagating the full pseudo 3-D structure of the title compound. The closest Co–Co through-space distances between neighboring pseudo 2-D layers is 11.070 (1) Å.