The 4,4′-bipyridine molecules in the title compound, C
10H
8N
2·2H
2O, are stacked in the direction of the crystallographic
b axis. These stacks are connected
via O—H
N and O—H
O hydrogen bonds to form sheets which lie parallel to (100). Chains of O—H
O hydrogen-bonded water molecules are located between the bipyridine stacks. Altogether, four crystallographically independent water molecules and two crystallographically independent bipyridine molecules are involved.
Supporting information
CCDC reference: 158276
Compound (I) was obtained as a by-product in the reaction of PbCl2,
4,4'-bipyridine (ACROS) and squaric acid (ACROS) in the ratio 1:4:1 in water
under hydrothermal conditions using Teflon-lined steel autoclaves. The
reaction mixture was heated at 423 K for 1 d and cooled to room temperature at
1 K min-1. The precipitate was filtered off and the residue consisted of
colourless needles of (I) as the major phase and only a few colourless blocks
of a second phase which it has not been possible to identify up to now.
Compound (I) decomposes in air within a few hours, leading to a white powder
of 4,4'-bipyridine which is amorphous under X-ray powder diffraction.
H atoms bound to C were positioned with idealized geometry and refined with
fixed isotropic displacement parameters using a riding model with C—H 0.95 Å. The water H atoms were initially located in a difference map; however,
this resulted in some excessively large O—H distances. Free refinement of
the water H atoms or with restrained O—H bond lengths always yielded a poor
O—H geometry. Therefore, the coordinates of the H atoms from the difference
map were recalculated to give O—H distances of 0.90 Å and refined with
fixed isotropic displacement parameters using a riding model. The origin was
fixed by floating-origin restraints (Flack & Schwarzenbach, 1988). Because no
heavy atom was present, the absolute structure could not be determined.
Therefore, all Friedel equivalents measured were merged. The observed
reflection conditions are in agreement with the centrosymmetric space group
P21/n, but the structure cannot be solved in this space group.
In addition, the structures of both independent molecules are very similar.
However, a detailed analysis of the crystal structure shows that the correct
space group is P21 and that the structure is pseudo-centrosymmetric.
Data collection: IPDS (Stoe & Cie, 1998); cell refinement: IPDS; data reduction: IPDS; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP in SHELXTL/PC (Siemens, 1990); software used to prepare material for publication: SHELXL97.
Crystal data top
C10H8N2·2H2O | F(000) = 408 |
Mr = 192.22 | Dx = 1.302 Mg m−3 |
Monoclinic, P21 | Mo Kα radiation, λ = 0.71073 Å |
a = 9.1333 (7) Å | Cell parameters from 5270 reflections |
b = 7.4310 (4) Å | θ = 3–26° |
c = 14.7171 (12) Å | µ = 0.09 mm−1 |
β = 101.052 (9)° | T = 130 K |
V = 980.32 (12) Å3 | Needle, colourless |
Z = 4 | 0.50 × 0.06 × 0.05 mm |
Data collection top
Stoe IPDS diffractometer | 1278 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.043 |
Graphite monochromator | θmax = 26.0°, θmin = 2.4° |
ϕ scans | h = −11→10 |
7618 measured reflections | k = −9→8 |
2044 independent reflections | l = −18→18 |
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)] = 0.041 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.126 | H-atom parameters constrained |
S = 1.02 | w = 1/[σ2(Fo2) + (0.0803P)2] where P = (Fo2 + 2Fc2)/3 |
2044 reflections | (Δ/σ)max < 0.001 |
253 parameters | Δρmax = 0.19 e Å−3 |
1 restraint | Δρmin = −0.21 e Å−3 |
Crystal data top
C10H8N2·2H2O | V = 980.32 (12) Å3 |
Mr = 192.22 | Z = 4 |
Monoclinic, P21 | Mo Kα radiation |
a = 9.1333 (7) Å | µ = 0.09 mm−1 |
b = 7.4310 (4) Å | T = 130 K |
c = 14.7171 (12) Å | 0.50 × 0.06 × 0.05 mm |
β = 101.052 (9)° | |
Data collection top
Stoe IPDS diffractometer | 1278 reflections with I > 2σ(I) |
7618 measured reflections | Rint = 0.043 |
2044 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.041 | 1 restraint |
wR(F2) = 0.126 | H-atom parameters constrained |
S = 1.02 | Δρmax = 0.19 e Å−3 |
2044 reflections | Δρmin = −0.21 e Å−3 |
253 parameters | |
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 | |
N1 | 0.5589 (4) | 0.5588 (6) | −0.2292 (2) | 0.0208 (9) | |
N2 | 0.4503 (4) | 0.5629 (7) | 0.2362 (2) | 0.0212 (9) | |
N3 | 1.0492 (4) | 0.8127 (6) | 0.2680 (2) | 0.0204 (8) | |
N4 | 0.9438 (4) | 0.8117 (7) | 0.7329 (3) | 0.0219 (9) | |
C1 | 0.5186 (4) | 0.5674 (7) | −0.0443 (3) | 0.0164 (8) | |
C2 | 0.4061 (4) | 0.6219 (7) | −0.1172 (3) | 0.0176 (8) | |
H2 | 0.3129 | 0.6619 | −0.1050 | 0.021* | |
C3 | 0.4298 (4) | 0.6179 (7) | −0.2057 (3) | 0.0191 (8) | |
H3 | 0.3521 | 0.6586 | −0.2537 | 0.023* | |
C4 | 0.6675 (4) | 0.5084 (7) | −0.1594 (3) | 0.0201 (9) | |
H4 | 0.7591 | 0.4686 | −0.1740 | 0.024* | |
C5 | 0.6543 (4) | 0.5107 (7) | −0.0663 (3) | 0.0187 (9) | |
H5 | 0.7352 | 0.4747 | −0.0191 | 0.022* | |
C6 | 0.4958 (4) | 0.5684 (7) | 0.0523 (3) | 0.0162 (8) | |
C7 | 0.3608 (4) | 0.5105 (7) | 0.0736 (3) | 0.0196 (9) | |
H7 | 0.2818 | 0.4716 | 0.0259 | 0.024* | |
C8 | 0.3431 (4) | 0.5106 (8) | 0.1657 (3) | 0.0205 (9) | |
H8 | 0.2505 | 0.4716 | 0.1790 | 0.025* | |
C9 | 0.5794 (4) | 0.6223 (7) | 0.2137 (3) | 0.0198 (8) | |
H9 | 0.6556 | 0.6645 | 0.2622 | 0.024* | |
C10 | 0.6066 (4) | 0.6252 (7) | 0.1256 (3) | 0.0191 (8) | |
H10 | 0.7002 | 0.6656 | 0.1144 | 0.023* | |
C11 | 1.0061 (4) | 0.8170 (7) | 0.4517 (3) | 0.0169 (9) | |
C12 | 0.8945 (4) | 0.8764 (7) | 0.3796 (3) | 0.0176 (8) | |
H12 | 0.8019 | 0.9190 | 0.3913 | 0.021* | |
C13 | 0.9230 (4) | 0.8714 (7) | 0.2895 (3) | 0.0201 (9) | |
H13 | 0.8470 | 0.9127 | 0.2406 | 0.024* | |
C14 | 1.1555 (5) | 0.7566 (8) | 0.3388 (3) | 0.0216 (9) | |
H14 | 1.2467 | 0.7137 | 0.3249 | 0.026* | |
C15 | 1.1401 (4) | 0.7577 (7) | 0.4293 (3) | 0.0183 (9) | |
H15 | 1.2197 | 0.7185 | 0.4766 | 0.022* | |
C16 | 0.9830 (4) | 0.8163 (8) | 0.5484 (3) | 0.0172 (9) | |
C17 | 0.8488 (4) | 0.7628 (7) | 0.5719 (3) | 0.0192 (9) | |
H17 | 0.7671 | 0.7281 | 0.5249 | 0.023* | |
C18 | 0.8352 (5) | 0.7604 (8) | 0.6632 (3) | 0.0223 (9) | |
H18 | 0.7437 | 0.7202 | 0.6777 | 0.027* | |
C19 | 1.0706 (4) | 0.8647 (7) | 0.7109 (3) | 0.0211 (9) | |
H19 | 1.1486 | 0.9016 | 0.7597 | 0.025* | |
C20 | 1.0980 (4) | 0.8703 (7) | 0.6206 (3) | 0.0180 (8) | |
H20 | 1.1915 | 0.9095 | 0.6086 | 0.022* | |
O1 | 0.4437 (3) | 0.5899 (6) | 0.57807 (17) | 0.0294 (11) | |
H1O1 | 0.5031 | 0.5704 | 0.6335 | 0.044* | |
H2O1 | 0.4769 | 0.5434 | 0.5293 | 0.044* | |
O2 | 0.5446 (3) | 0.4639 (6) | 0.42664 (18) | 0.0288 (11) | |
H1O2 | 0.4984 | 0.4994 | 0.3699 | 0.043* | |
H2O2 | 0.5475 | 0.3430 | 0.4237 | 0.043* | |
O3 | 0.9399 (3) | 0.8450 (6) | 0.07543 (18) | 0.0287 (10) | |
H1O3 | 1.0012 | 0.8307 | 0.1306 | 0.043* | |
H2O3 | 0.9744 | 0.7962 | 0.0276 | 0.043* | |
O4 | 1.0446 (3) | 0.7191 (7) | 0.92429 (18) | 0.0293 (11) | |
H1O4 | 0.9930 | 0.7494 | 0.8680 | 0.044* | |
H2O4 | 1.0344 | 0.5986 | 0.9255 | 0.044* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
N1 | 0.0232 (16) | 0.024 (2) | 0.0171 (15) | 0.0009 (15) | 0.0080 (12) | 0.0007 (14) |
N2 | 0.0219 (15) | 0.026 (2) | 0.0170 (15) | −0.0007 (16) | 0.0080 (12) | 0.0022 (14) |
N3 | 0.0182 (14) | 0.022 (2) | 0.0204 (16) | −0.0010 (15) | 0.0025 (12) | 0.0006 (15) |
N4 | 0.0204 (15) | 0.022 (2) | 0.0232 (17) | 0.0019 (16) | 0.0053 (13) | 0.0015 (15) |
C1 | 0.0157 (15) | 0.015 (2) | 0.0179 (17) | −0.0016 (14) | 0.0029 (13) | 0.0025 (15) |
C2 | 0.0135 (15) | 0.014 (2) | 0.0246 (17) | −0.0002 (15) | 0.0021 (13) | 0.0003 (16) |
C3 | 0.0171 (15) | 0.020 (2) | 0.0198 (16) | 0.0005 (15) | 0.0035 (12) | 0.0003 (16) |
C4 | 0.0135 (15) | 0.023 (3) | 0.0240 (19) | 0.0021 (16) | 0.0049 (13) | −0.0006 (17) |
C5 | 0.0171 (16) | 0.021 (3) | 0.0178 (18) | 0.0032 (15) | 0.0035 (13) | 0.0012 (16) |
C6 | 0.0156 (15) | 0.014 (2) | 0.0191 (17) | 0.0008 (15) | 0.0028 (12) | −0.0007 (16) |
C7 | 0.0186 (16) | 0.021 (3) | 0.0200 (18) | −0.0032 (16) | 0.0049 (13) | 0.0011 (17) |
C8 | 0.0159 (15) | 0.025 (3) | 0.0213 (18) | −0.0021 (16) | 0.0047 (13) | 0.0029 (17) |
C9 | 0.0179 (15) | 0.021 (2) | 0.0198 (15) | −0.0024 (15) | 0.0020 (12) | −0.0011 (16) |
C10 | 0.0164 (15) | 0.016 (2) | 0.0242 (17) | 0.0009 (15) | 0.0031 (14) | 0.0004 (16) |
C11 | 0.0171 (16) | 0.015 (2) | 0.0199 (18) | −0.0030 (15) | 0.0061 (13) | −0.0020 (16) |
C12 | 0.0158 (15) | 0.021 (2) | 0.0175 (16) | 0.0003 (15) | 0.0061 (13) | −0.0014 (15) |
C13 | 0.0210 (16) | 0.022 (3) | 0.0170 (16) | −0.0003 (16) | 0.0028 (12) | 0.0020 (16) |
C14 | 0.0193 (16) | 0.023 (3) | 0.024 (2) | 0.0008 (17) | 0.0080 (14) | 0.0000 (17) |
C15 | 0.0126 (15) | 0.019 (2) | 0.0225 (19) | −0.0003 (15) | 0.0020 (12) | −0.0007 (16) |
C16 | 0.0168 (16) | 0.014 (2) | 0.0210 (18) | 0.0016 (15) | 0.0046 (13) | 0.0019 (16) |
C17 | 0.0141 (15) | 0.019 (3) | 0.0239 (19) | 0.0011 (15) | 0.0033 (13) | 0.0003 (17) |
C18 | 0.0193 (16) | 0.026 (3) | 0.0228 (19) | 0.0003 (17) | 0.0072 (13) | 0.0014 (18) |
C19 | 0.0202 (16) | 0.025 (3) | 0.0182 (16) | 0.0019 (16) | 0.0026 (13) | 0.0007 (17) |
C20 | 0.0159 (16) | 0.022 (2) | 0.0171 (16) | 0.0003 (16) | 0.0051 (13) | −0.0008 (15) |
O1 | 0.0279 (14) | 0.041 (3) | 0.0185 (13) | 0.0043 (12) | 0.0021 (11) | −0.0022 (13) |
O2 | 0.0293 (14) | 0.039 (3) | 0.0173 (13) | 0.0029 (11) | 0.0027 (11) | 0.0022 (11) |
O3 | 0.0269 (14) | 0.039 (3) | 0.0199 (14) | 0.0077 (11) | 0.0030 (11) | −0.0021 (11) |
O4 | 0.0298 (15) | 0.038 (3) | 0.0196 (14) | 0.0044 (12) | 0.0035 (11) | 0.0000 (12) |
Geometric parameters (Å, º) top
N1—C4 | 1.337 (6) | C6—C10 | 1.396 (6) |
N1—C3 | 1.363 (5) | C6—C7 | 1.397 (6) |
N2—C8 | 1.341 (6) | C7—C8 | 1.395 (6) |
N2—C9 | 1.359 (5) | C9—C10 | 1.365 (5) |
N3—C13 | 1.326 (5) | C11—C12 | 1.394 (6) |
N3—C14 | 1.347 (6) | C11—C15 | 1.399 (6) |
N4—C19 | 1.321 (5) | C11—C16 | 1.478 (6) |
N4—C18 | 1.339 (6) | C12—C13 | 1.400 (5) |
C1—C2 | 1.396 (5) | C14—C15 | 1.366 (6) |
C1—C5 | 1.404 (6) | C16—C17 | 1.395 (6) |
C1—C6 | 1.476 (6) | C16—C20 | 1.401 (6) |
C2—C3 | 1.361 (5) | C17—C18 | 1.373 (6) |
C4—C5 | 1.399 (6) | C19—C20 | 1.399 (5) |
| | | |
C4—N1—C3 | 116.5 (4) | N2—C9—C10 | 124.2 (4) |
C8—N2—C9 | 116.3 (4) | C9—C10—C6 | 119.5 (4) |
C13—N3—C14 | 116.6 (4) | C12—C11—C15 | 117.7 (4) |
C19—N4—C18 | 116.9 (4) | C12—C11—C16 | 121.1 (4) |
C2—C1—C5 | 117.5 (4) | C15—C11—C16 | 121.2 (4) |
C2—C1—C6 | 121.3 (4) | C11—C12—C13 | 118.1 (4) |
C5—C1—C6 | 121.1 (4) | N3—C13—C12 | 124.2 (4) |
C3—C2—C1 | 120.0 (4) | N3—C14—C15 | 124.0 (4) |
C2—C3—N1 | 123.6 (4) | C14—C15—C11 | 119.3 (4) |
N1—C4—C5 | 123.9 (4) | C17—C16—C20 | 117.4 (4) |
C4—C5—C1 | 118.3 (4) | C17—C16—C11 | 122.2 (4) |
C10—C6—C7 | 117.4 (4) | C20—C16—C11 | 120.3 (4) |
C10—C6—C1 | 122.1 (4) | C18—C17—C16 | 119.6 (4) |
C7—C6—C1 | 120.5 (4) | N4—C18—C17 | 123.7 (4) |
C8—C7—C6 | 119.3 (4) | N4—C19—C20 | 124.5 (4) |
N2—C8—C7 | 123.3 (4) | C19—C20—C16 | 117.8 (4) |
| | | |
C5—C1—C2—C3 | 0.4 (7) | C15—C11—C12—C13 | 0.6 (7) |
C6—C1—C2—C3 | −179.4 (4) | C16—C11—C12—C13 | −179.2 (4) |
C1—C2—C3—N1 | 1.5 (8) | C14—N3—C13—C12 | −0.6 (7) |
C4—N1—C3—C2 | −2.2 (7) | C11—C12—C13—N3 | 0.4 (8) |
C3—N1—C4—C5 | 1.1 (8) | C13—N3—C14—C15 | −0.2 (8) |
N1—C4—C5—C1 | 0.7 (9) | N3—C14—C15—C11 | 1.2 (9) |
C2—C1—C5—C4 | −1.4 (8) | C12—C11—C15—C14 | −1.3 (8) |
C6—C1—C5—C4 | 178.3 (4) | C16—C11—C15—C14 | 178.5 (4) |
C2—C1—C6—C10 | −139.2 (6) | C12—C11—C16—C17 | 41.1 (6) |
C5—C1—C6—C10 | 41.1 (6) | C15—C11—C16—C17 | −138.6 (7) |
C2—C1—C6—C7 | 41.2 (6) | C12—C11—C16—C20 | −139.0 (7) |
C5—C1—C6—C7 | −138.6 (7) | C15—C11—C16—C20 | 41.2 (6) |
C10—C6—C7—C8 | −0.5 (8) | C20—C16—C17—C18 | −1.6 (8) |
C1—C6—C7—C8 | 179.1 (4) | C11—C16—C17—C18 | 178.3 (4) |
C9—N2—C8—C7 | 1.8 (8) | C19—N4—C18—C17 | −0.9 (8) |
C6—C7—C8—N2 | −0.4 (9) | C16—C17—C18—N4 | 1.8 (9) |
C8—N2—C9—C10 | −2.4 (7) | C18—N4—C19—C20 | −0.1 (7) |
N2—C9—C10—C6 | 1.6 (8) | N4—C19—C20—C16 | 0.1 (8) |
C7—C6—C10—C9 | 0.0 (7) | C17—C16—C20—C19 | 0.7 (7) |
C1—C6—C10—C9 | −179.7 (4) | C11—C16—C20—C19 | −179.2 (4) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H11O···N1i | 0.90 | 1.99 | 2.839 (4) | 157 |
O1—H21O···O2 | 0.90 | 1.84 | 2.735 (4) | 176 |
O2—H12O···N2 | 0.90 | 1.99 | 2.866 (4) | 164 |
O2—H22O···O1ii | 0.90 | 1.88 | 2.783 (6) | 178 |
O3—H13O···N3 | 0.90 | 1.99 | 2.829 (4) | 155 |
O3—H23O···O4iii | 0.90 | 1.85 | 2.748 (4) | 174 |
O4—H14O···N4 | 0.90 | 2.01 | 2.874 (5) | 162 |
O4—H24O···O3iv | 0.90 | 1.90 | 2.784 (7) | 167 |
Symmetry codes: (i) x, y, z+1; (ii) −x+1, y−1/2, −z+1; (iii) x, y, z−1; (iv) −x+2, y−1/2, −z+1. |
Experimental details
Crystal data |
Chemical formula | C10H8N2·2H2O |
Mr | 192.22 |
Crystal system, space group | Monoclinic, P21 |
Temperature (K) | 130 |
a, b, c (Å) | 9.1333 (7), 7.4310 (4), 14.7171 (12) |
β (°) | 101.052 (9) |
V (Å3) | 980.32 (12) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.50 × 0.06 × 0.05 |
|
Data collection |
Diffractometer | Stoe IPDS diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 7618, 2044, 1278 |
Rint | 0.043 |
(sin θ/λ)max (Å−1) | 0.616 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.041, 0.126, 1.02 |
No. of reflections | 2044 |
No. of parameters | 253 |
No. of restraints | 1 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.19, −0.21 |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H11O···N1i | 0.90 | 1.99 | 2.839 (4) | 157 |
O1—H21O···O2 | 0.90 | 1.84 | 2.735 (4) | 176 |
O2—H12O···N2 | 0.90 | 1.99 | 2.866 (4) | 164 |
O2—H22O···O1ii | 0.90 | 1.88 | 2.783 (6) | 178 |
O3—H13O···N3 | 0.90 | 1.99 | 2.829 (4) | 155 |
O3—H23O···O4iii | 0.90 | 1.85 | 2.748 (4) | 174 |
O4—H14O···N4 | 0.90 | 2.01 | 2.874 (5) | 162 |
O4—H24O···O3iv | 0.90 | 1.90 | 2.784 (7) | 167 |
Symmetry codes: (i) x, y, z+1; (ii) −x+1, y−1/2, −z+1; (iii) x, y, z−1; (iv) −x+2, y−1/2, −z+1. |
The title compound, (I), was obtained as a by-product in a synthesis for the preparation of new coordination polymers under hydrothermal conditions. Whereas the crystal structure of anhydrous 4,4'-bipyridine is known (Boag et al., 1999), no structure of a hydrated form has been reported so far. \sch
In the crystal structure of (I), the 4,4'-bipyridine molecules are stacked in the direction of the crystallographic b axis (Fig. 1a). There are two different stacks, each built up of one of the two crystallographically independent 4,4'-bipyridine molecules. Within the stacks, each of the two six-membered rings of neighbouring molecules are stacked perfectly onto each other and are always parallel. The distances between the centres of neighbouring rings are 3.70 (1) and 3.74 (1) Å in one stack (C1—C10), and 3.71 (1) and 3.72 (1) Å in the other stack (C11—C20). Between the stacks are channels in which the water molecules are located. The water molecules are connected via O—H···O hydrogen bonds to form two crystallographically independent chains parallel to the b axis, each built up of two crystallographically independent water molecules (Fig. 1 b). Within the chains, the O atom of each water molecule acts as an acceptor for a hydrogen bond from a neighbouring water molecule, and as a donor through one H atom to a 4,4'-bipyridine molecule and through the other H atom to the next neighbouring water molecule. The ranges of the O···H distances (1.84–1.90 Å) and the O···O distances [2.736 (7)–2.785 (7) Å] indicate strong hydrogen bonding. The O—H···O angles are between 167 and 178°. The H···N distances range from 1.99 to 2.01 Å and the O···N distances range from 2.829 (4) to 2.874 (4) Å. The O—H···N angles are between 155 and 164°. The interactions between the water and the 4,4'-bipyridine molecules lead to 4,4'-bipyridine···H2O···H2O···4,4'-bipyridine chains, which proceed in the direction of the c axis. The combination of all these hydrogen-bonding interactions results in the formation of sheets which lie parallel to (100).
The two crystallographically independent 4,4'-bipyridine molecules in the asymmetric unit have similar geometrical parameters. The six-membered rings are twisted by 41.6 (1)° in both molecules. This value is similar to that of 37.2° determined for 4,4'-bipyridine in the gas phase (Almenningen & Bastiansen, 1958) and corresponds closely with the value of 48.6° obtained from theoretical calculations (Ould-Moussa et al., 1996). In contrast, in the structure of anhydrous 4,4'-bipyridine, which also exhibits two crystallographically independent molecules in the asymmetric unit, these angles amount to 18.5 (1) and 34.9 (1)° (Boag et al., 1999). All other geometrical parameters are similar to those in the anhydrous structure of 4,4'-bipyridine (Boag et al., 1999).