Geometry and bond-length alternation in nonlinear optical materials. II. Effects of donor strength in two push–pull mol­ecules

The compounds N-[2-(4-cyano-5-dicyano­methyl­ene-2,2-dimethyl-2,5-dihydro­furan-3-yl)vin­yl]-N-phenyl­acetamide, C₂₀H₁₆N₄O₂,(I), and 2-{3-cyano-5,5-dimethyl-4-[2-(piperidin-1-yl)vin­yl]-2,5-dihydro­furan-2-yl­idene}malononitrile 0.376-hydrate, C₁₇H₁₈N₄O·0.376H₂O, (II), are novel push–pull mol­ecules. The significant bonding changes in the polyene chain compared with the parent mol­ecule 2-dicyano­methyl­ene-4,5,5-trimethyl-2,5-dihyrofuran-3-carbonitrile are consistent with the relative electron-donating properties of the acetanilido and piperidine groups. The packing of (I) utilizes one phen­yl–cyano C—H...N and two phenyl–carbonyl C—H...O hydrogen bonds. Compound (II) crystallizes with a partial water mol­ecule (0.376H₂O), consistent with cell packing that is dominated by attractive C—H...N(cyano) inter­actions. These com­pounds are precursors to novel nonlinear optical chromophores, studied to assess the impact of donor strength and the extent of conjugation on bond-length alternation, crystal packing and aggregation.

S1. Comment

Organic nonlinear optical materials continue to gain attention owing to their potential use in next generation photonic and optoelectronic devices. These devices will find applications in areas such as telecommunications and computing, and will be cheaper and easier to fabricate, have faster operating speeds, and lower drive voltages than current devices based on inorganic materials such as lithium niobate (Dalton, 2002). We have reported on the synthesis of a number of high figure of merit chromophores for nonlinear optics (Kay et al., 2004), as well as the X-ray crystallographic and structural properties of two of the crucial dye precursors used (Gainsford et al., 2007). We now report on the structural properties of two related derivatives, involving the acetanilido donor unit, (I), and the more powerful electron-donating nucleus piperidine, (II), in which the conjugated π-system between donor and acceptor has been shortened to just two C atoms.

The asymmetric unit contents of the title compounds (I) and (II) are shown in Figs. 1 and 2, with selected dimensions in Tables 1, 3 and 5. The structures have different configurations with regard to the C11═C12 bond (so atoms C7 and C12 are cis and trans with respect to the C4—C11 bond, as indicated by the C7—C4—C11═C12 torsion angles [or dihedral angles involving atoms C7, C4, C11 and C12?]). This alternative configurational arrangement has been observed before for closely related precursors (Gainsford et al., 2007). In this case the C4—C7—C11 angle has increased [by 9.7 (2)°], possibly in response to packing interactions involving atoms H11 and N3 (see below).

The comparable planar groups in (I) and (II) are the `CDFP' five-membered ring (atoms O1 and C4–C7), with an r.m.s. deviation (r.m.s.d.) of 0.0018 (11) Å for (I) and 0.0099 (7) Å for (II), and the `polyene' plane defined by atoms N4, C11, C12 and C4 [r.m.s.d. of 0.0023 (9) Å for (I) and 0.0019 (6) Å for (II)]. These two planes are twisted slightly with respect to each other by 2.56 (6) and 2.31 (16)° for (I) and (II), respectively. The phenyl ring in (I) makes an angle of 82.99 (11)° with the polyene plane. The piperidin-1-yl group in (II) adopts a pure chair conformation [Cremer & Pople (1975) parameters Q = 0.5611 (14) Å, θ = 179.00 (14)° and ϕ = 358 (12)°], with an r.m.s.d. of 0.0003 (7) Å for the `seat' atoms C13, C14, C16 and C17, and with the head and foot atoms N4 and C15 lying on opposite sides of this plane at distances of 0.6307 (16) and 0.664 (2) Å. The `seat' atom plane is at 53.48 (6)° to the CDFP plane. The angle between the mean plane through the piperidin-1-yl ring and the CDFP plane is 36.02 (5)°.

The essentially planar 2-dicyanomethylene-4,5,5- trimethyl-2,5-dihyrofuran-3-carbonitrile fragments (i.e. excluding the phenyl ring) in (I) form layers approximately parallel to the ac plane linked by the (phenyl)C18—H18···O2(x, -y + 3/2, z - 1/2) interaction (Table 2 and Fig. 3). Intra-layer binding is provided by one (phenyl)C— H···N(cyano) and one (phenyl)C—H···O═C hydrogen bond. Both of these interaction types have been observed before. Few meta-phenyl C—H···N interactions have been reported [e.g. from the Cambridge Structural Database (Version 5.28 with May 2007 updates; Allen, 2002), refcodes ETIDAM (Lu et al., 2004) with H···N = 2.59 Å and C—H···N = 145°, and SOXRAY (Quinn et al., 1991) with H···N = 2.52 Å and C—H···N = 130°]. There are many examples of the (phenyl)C—H···O═C interaction (see Gainsford et al., 2007, and references therein). There are no intermolecular interactions in (I) involving the vinyl H atoms (H11 and H12), as both are effectively shielded by the adjacent atoms.

The crystal packing in (II) is dominated by strong C—H···N(cyano) hydrogen bonds, which link molecules into undulating layers approximately parallel to the ac plane (Table 4 and Fig. 4). The C11—H11···N1(x, -y + 1/2, z - 1/2) interaction binds molecules into these layers; we have observed this strong interaction before (H···N = 2.57 Å and C—H···N = 156°; Gainsford et al., 2007). A hydrogen bond involving a methylene group, C13—H13A···N1(-x + 1, -y, -z + 1), provides a strong cross-link to the layers. Atom N1 also has two further contacts (not shown in Fig. 4 for clarity) to the same molecule as the stronger hydrogen bond (entry 3, Table 4) which are shorter than the sum of the van der Waals radii (2.75 Å) within the layer structure, viz. to the methylene atom H17A (entry 5) on the piperidin-1-yl ring and to the methyl atom H8B [entry 6; this interaction type is observed in the packing of the parent structure PANLUM (Li et al., 2005), (III), with H···N = 2.55 Å]. The water molecule is bound between molecules in adjacent layers by cyano N donor atoms; it does not provide the key attractive binding force, but fits neatly into a hole in the cyrstal structure (see Fig. 4), which explains its partial occupancy of 0.376 (6).

A comparison of key bond lengths and angles with those in (III) is given in Table 5. Note that all the atoms of (III) are constrained to a crystallographic mirror plane, except for the (mirror-related) 5,5-dimethyl groups. Examination of the endocyclic dihydrofuranylidene double bonds (C4═ C7) shows that in (I) and (II) these bonds exhibit more single-bond character than the corresponding bond in (III). On the other hand, the adjacent endocyclic nominally single bond (C6—C7) in (II) is shorter than that in (III) by 0.035 (5) Å. Notably, when comparing these two bonds (within each structure), we find that in (II) they are indistinguishable in length, while they differ significantly in (I) and (III), by 0.069 (4) and 0.102 (6) Å, respectively. Furthermore, the dicyanomethylidene bonds (C2═C6) in both (I) and (II) are longer than those reported for (III); again the difference is marginal in (I) but significant in (II) [0.031 (4) Å]. The exocyclic nominally single bond in (I) (C4—C11) is some 0.039 (3) Å longer than the analogous bond in (II). The polyene double bond in (I) is shorter [0.053 (4) Å] than the analogous bond in (II). Finally the C—N bond (C12—N4) in (I) is longer by 0.069 (3) Å than the C—N bond in (II) (Tables 1 and 3).

Taken together, these observations clearly indicate that charge from the N donor atoms in (I) and (II) is delocalized across the molecules to the dicyanomethylidene C atom, with the delocalization being more pronounced in (II), as reflected in the larger changes in bond length and hence bond order observed for this molecule. This is to be expected given the greater donor strength of the piperidine nucleus in comparison with the acetanilido functional group. Indeed, the virtual homogeneity of bond orders across the π-conjugated system in (II) would suggest the charge is evenly delocalized, and hence the ground state is moderately (~50%) zwitterionic. We are currently undertaking theoretical studies to model the geometries of these molecules in order to establish the efficacy of the (DFT) calculations and to predict the hyperpolarizabilities of these, and related, systems.

Related literature

For related literature, see: Allen (2002); Cremer & Pople (1975); Dalton (2002); Gainsford et al. (2007); Kay et al. (2004); Li et al. (2005); Lu et al. (2004); Quinn et al. (1991).

S2. Experimental

Compound (I) was prepared as previously described (compound 11a; Kay et al., 2004) and recrystallized from ethanol. To a solution of (I) (5.8 mmol) in 30 ml of ethanol was added an equimolar quantity of piperidine. The solution was refluxed for 1 h and then cooled, and the product was collected by filtration and washed with ethanol. The product (II) was recrystallized from ethanol.

S3. Refinement

All H atoms bound to C atoms were constrained to their expected geometries (C—H = 0.95–0.99 Å). The positions of H atoms on the water atom O2 in (II) were refined freely after assignment from difference maps, consistent with the N···H—O bonds. The occupancy of the water molecule was found by refinement with an isotropic U_O value of 0.03 Ų; this parameter was then refined with O2 allowed anisotropic displacement parameters. Attempts to force the O2—H atom distances to longer values were not supported by the data. All U_iso(H) values were set at 1.5 (methyl) or 1.2 (other H atoms) times U_eq of the parent atom. Outlier reflections in (I) (020 and 040) and (II) (112) were omitted from the refinements.

Computing details

For both compounds, data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005) and SADABS (Sheldrick, 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP (Farrugia, 1997) and PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2003).

Figures

	Fig. 1. The molecular structure of the independent molecule of (I) (Farrugia, 1997); displacement ellipsoids are shown at the 50% probability level.
	Fig. 2. The molecular structure of the independent molecule of (II) (Farrugia, 1997); displacement ellipsoids are shown at the 50% probability level. One hydrogen bond is shown by dashed lines (Table 4).
	Fig. 3. A partial packing diagram of (I) (Mercury; Bruno et al., (2002). Only H atoms involved in selected hydrogen bonds (dashed lines) are shown. For symmetry codes see Table 2.
	Fig. 4. The packing of (II) (Farrugia, 1997), viewed down the b axis. Only H atoms involved in selected hydrogen bonds (dashed lines) are shown. [Symmetry code: (iv) -x + 1, -y + 1, -z + 1; for other symmetry designations see Table 4.]

(I) N-[2-(4-cyano-5-dicyanomethylene-2,2-dimethyl-2,5-dihydrofuran-3-yl)vinyl]- N-phenylacetamide

Crystal data

C20H16N4O2	F(000) = 720
Mr = 344.37	Dx = 1.290 Mg m^−3 Dm = 0 Mg m^−3 Dm measured by not measured
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 2017 reflections
a = 14.417 (3) Å	θ = 2.9–25.9°
b = 6.9224 (12) Å	µ = 0.09 mm^−1
c = 18.508 (4) Å	T = 120 K
β = 106.334 (6)°	Plate, yellow
V = 1772.5 (6) Å^3	0.53 × 0.15 × 0.04 mm
Z = 4

Data collection

Bruker–Nonius APEXII CCD area-detector diffractometer	2017 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.174
Graphite monochromator	θmax = 30.0°, θmin = 2.9°
Detector resolution: 8.192 pixels mm^-1	h = −19→20
phi and ω scans	k = −5→9
19450 measured reflections	l = −26→25
5152 independent reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.061	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.132	H-atom parameters constrained
S = 0.83	w = 1/[σ^2(Fo^2) + (0.0373P)^2] where P = (Fo^2 + 2Fc^2)/3
5152 reflections	(Δ/σ)max = 0.001
233 parameters	Δρmax = 0.47 e Å^−3
0 restraints	Δρmin = −0.39 e Å^−3

Special details

Experimental. 5 reflections were OMIT-ted from the refinement; two were clearly outliers and three were affected by mismeasurement (low theta).

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 (Ų)

	x	y	z	Uiso*/Ueq
O1	0.50288 (9)	0.77836 (18)	0.66535 (8)	0.0305 (4)
O2	0.02436 (10)	0.78610 (19)	0.55598 (8)	0.0351 (4)
N1	0.71406 (13)	0.7430 (3)	0.50805 (11)	0.0430 (5)
N2	0.74799 (12)	0.7785 (2)	0.75187 (11)	0.0382 (5)
N3	0.46542 (13)	0.7265 (3)	0.40148 (11)	0.0405 (5)
N4	0.10516 (11)	0.7511 (2)	0.46770 (9)	0.0246 (4)
C1	0.67723 (14)	0.7524 (3)	0.55556 (13)	0.0309 (5)
C2	0.63414 (13)	0.7639 (3)	0.61608 (11)	0.0270 (5)
C3	0.69740 (14)	0.7723 (3)	0.69170 (13)	0.0306 (5)
C4	0.37196 (14)	0.7630 (3)	0.55738 (11)	0.0241 (4)
C5	0.39507 (13)	0.7771 (3)	0.64203 (11)	0.0259 (5)
C6	0.53670 (14)	0.7659 (3)	0.60571 (11)	0.0258 (5)
C7	0.45710 (13)	0.7569 (3)	0.53814 (11)	0.0245 (4)
C8	0.36481 (15)	0.9649 (3)	0.67019 (12)	0.0355 (6)
H8A	0.3872	1.0734	0.6454	0.053*
H8B	0.3934	0.9742	0.7248	0.053*
H8C	0.2942	0.9691	0.6586	0.053*
C9	0.36604 (15)	0.6001 (3)	0.67818 (12)	0.0367 (6)
H9A	0.3943	0.6068	0.7329	0.055*
H9B	0.3896	0.4841	0.6586	0.055*
H9C	0.2954	0.5947	0.6665	0.055*
C10	0.46440 (13)	0.7407 (3)	0.46297 (12)	0.0271 (5)
C11	0.27894 (13)	0.7530 (2)	0.50442 (11)	0.0252 (4)
H11	0.2767	0.7383	0.4529	0.030*
C12	0.19414 (13)	0.7626 (2)	0.52081 (11)	0.0256 (5)
H12	0.1953	0.7783	0.5721	0.031*
C13	0.01988 (14)	0.7612 (3)	0.48994 (11)	0.0259 (4)
C14	−0.07292 (13)	0.7402 (3)	0.42905 (11)	0.0310 (5)
H14A	−0.1274	0.7581	0.4503	0.047*
H14B	−0.0763	0.6110	0.4068	0.047*
H14C	−0.0760	0.8377	0.3901	0.047*
C15	0.10380 (13)	0.7220 (3)	0.38995 (10)	0.0237 (4)
C16	0.09608 (14)	0.5377 (3)	0.36115 (12)	0.0313 (5)
H16	0.0886	0.4302	0.3909	0.038*
C17	0.09951 (15)	0.5121 (3)	0.28721 (13)	0.0406 (6)
H17	0.0929	0.3861	0.2660	0.049*
C18	0.11228 (15)	0.6662 (4)	0.24500 (13)	0.0446 (6)
H18	0.1155	0.6465	0.1950	0.054*
C19	0.12047 (16)	0.8494 (3)	0.27444 (13)	0.0429 (6)*
H19	0.1292	0.9559	0.2446	0.051*
C20	0.11608 (14)	0.8798 (3)	0.34766 (11)	0.0330 (5)
H20	0.1214	1.0064	0.3682	0.040*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0181 (7)	0.0433 (8)	0.0277 (8)	0.0002 (6)	0.0025 (6)	0.0000 (7)
O2	0.0294 (8)	0.0520 (9)	0.0245 (8)	−0.0004 (7)	0.0083 (7)	−0.0006 (7)
N1	0.0337 (11)	0.0495 (11)	0.0492 (13)	0.0045 (10)	0.0174 (10)	0.0050 (11)
N2	0.0264 (10)	0.0455 (11)	0.0410 (12)	0.0014 (9)	0.0069 (9)	−0.0030 (9)
N3	0.0415 (11)	0.0489 (12)	0.0342 (12)	−0.0014 (9)	0.0159 (9)	−0.0030 (10)
N4	0.0216 (8)	0.0305 (8)	0.0210 (9)	−0.0007 (8)	0.0048 (7)	−0.0012 (8)
C1	0.0204 (10)	0.0284 (11)	0.0422 (13)	0.0003 (10)	0.0058 (10)	0.0009 (11)
C2	0.0212 (10)	0.0252 (10)	0.0333 (12)	−0.0004 (9)	0.0054 (9)	0.0005 (9)
C3	0.0194 (10)	0.0322 (11)	0.0407 (13)	−0.0008 (9)	0.0093 (10)	−0.0016 (10)
C4	0.0258 (10)	0.0197 (9)	0.0258 (11)	0.0008 (9)	0.0056 (9)	0.0019 (9)
C5	0.0154 (9)	0.0347 (11)	0.0263 (11)	−0.0015 (9)	0.0041 (8)	−0.0001 (9)
C6	0.0261 (11)	0.0219 (9)	0.0296 (11)	0.0007 (9)	0.0080 (9)	0.0008 (9)
C7	0.0240 (11)	0.0209 (9)	0.0269 (11)	0.0011 (9)	0.0043 (9)	0.0015 (9)
C8	0.0290 (13)	0.0442 (12)	0.0313 (13)	0.0002 (10)	0.0051 (11)	−0.0087 (10)
C9	0.0289 (13)	0.0461 (13)	0.0328 (14)	−0.0024 (10)	0.0051 (11)	0.0104 (10)
C10	0.0207 (10)	0.0241 (10)	0.0359 (13)	−0.0005 (9)	0.0072 (9)	−0.0003 (10)
C11	0.0252 (10)	0.0254 (10)	0.0234 (11)	0.0007 (10)	0.0042 (9)	0.0004 (9)
C12	0.0251 (10)	0.0261 (10)	0.0215 (10)	0.0000 (9)	−0.0001 (9)	−0.0004 (9)
C13	0.0251 (11)	0.0258 (10)	0.0262 (11)	0.0001 (9)	0.0061 (9)	0.0029 (10)
C14	0.0215 (10)	0.0404 (12)	0.0291 (12)	0.0001 (10)	0.0039 (9)	−0.0013 (10)
C15	0.0171 (9)	0.0330 (11)	0.0203 (10)	0.0006 (9)	0.0043 (8)	0.0010 (9)
C16	0.0254 (12)	0.0345 (11)	0.0325 (13)	0.0028 (9)	0.0056 (11)	−0.0012 (10)
C17	0.0261 (13)	0.0597 (15)	0.0335 (14)	0.0039 (11)	0.0042 (11)	−0.0136 (12)
C18	0.0259 (13)	0.0823 (18)	0.0264 (13)	−0.0002 (12)	0.0087 (11)	−0.0011 (13)
C20	0.0289 (13)	0.0398 (12)	0.0274 (12)	−0.0073 (10)	0.0032 (10)	0.0010 (10)

Geometric parameters (Å, º)

O1—C6	1.329 (2)	C9—H9A	0.9800
O1—C5	1.492 (2)	C9—H9B	0.9800
O2—C13	1.218 (2)	C9—H9C	0.9800
N1—C1	1.150 (3)	C11—C12	1.342 (3)
N2—C3	1.148 (2)	C11—H11	0.9500
N3—C10	1.147 (3)	C12—H12	0.9500
N4—C12	1.382 (2)	C13—C14	1.494 (2)
N4—C13	1.404 (2)	C14—H14A	0.9800
N4—C15	1.448 (2)	C14—H14B	0.9800
C1—C2	1.428 (3)	C14—H14C	0.9800
C2—C6	1.363 (3)	C15—C16	1.375 (3)
C2—C3	1.441 (3)	C15—C20	1.384 (3)
C4—C7	1.372 (3)	C16—C17	1.394 (3)
C4—C11	1.423 (2)	C16—H16	0.9500
C4—C5	1.510 (3)	C17—C18	1.365 (3)
C5—C9	1.510 (3)	C17—H17	0.9500
C5—C8	1.510 (3)	C18—C19	1.372 (3)
C6—C7	1.441 (2)	C18—H18	0.9500
C7—C10	1.429 (3)	C19—C20	1.390 (3)
C8—H8A	0.9800	C19—H19	0.9500
C8—H8B	0.9800	C20—H20	0.9500
C8—H8C	0.9800
C6—O1—C5	110.80 (14)	H9B—C9—H9C	109.5
C12—N4—C13	120.19 (16)	N3—C10—C7	176.6 (2)
C12—N4—C15	117.75 (16)	C12—C11—C4	125.74 (19)
C13—N4—C15	122.02 (15)	C12—C11—H11	117.1
N1—C1—C2	178.4 (2)	C4—C11—H11	117.1
C6—C2—C1	123.28 (18)	C11—C12—N4	123.99 (19)
C6—C2—C3	118.8 (2)	C11—C12—H12	118.0
C1—C2—C3	117.90 (17)	N4—C12—H12	118.0
N2—C3—C2	179.8 (3)	O2—C13—N4	119.85 (17)
C7—C4—C11	123.95 (18)	O2—C13—C14	123.65 (19)
C7—C4—C5	108.60 (16)	N4—C13—C14	116.50 (18)
C11—C4—C5	127.44 (18)	C13—C14—H14A	109.5
O1—C5—C9	105.83 (15)	C13—C14—H14B	109.5
O1—C5—C8	105.87 (15)	H14A—C14—H14B	109.5
C9—C5—C8	113.74 (18)	C13—C14—H14C	109.5
O1—C5—C4	102.03 (15)	H14A—C14—H14C	109.5
C9—C5—C4	113.55 (16)	H14B—C14—H14C	109.5
C8—C5—C4	114.37 (16)	C16—C15—C20	121.5 (2)
O1—C6—C2	119.20 (18)	C16—C15—N4	119.44 (17)
O1—C6—C7	109.57 (16)	C20—C15—N4	118.95 (17)
C2—C6—C7	131.2 (2)	C15—C16—C17	118.5 (2)
C4—C7—C10	124.86 (17)	C15—C16—H16	120.8
C4—C7—C6	109.00 (18)	C17—C16—H16	120.8
C10—C7—C6	126.13 (18)	C18—C17—C16	120.7 (2)
C5—C8—H8A	109.5	C18—C17—H17	119.7
C5—C8—H8B	109.5	C16—C17—H17	119.7
H8A—C8—H8B	109.5	C17—C18—C19	120.4 (2)
C5—C8—H8C	109.5	C17—C18—H18	119.8
H8A—C8—H8C	109.5	C19—C18—H18	119.8
H8B—C8—H8C	109.5	C18—C19—C20	120.3 (2)
C5—C9—H9A	109.5	C18—C19—H19	119.8
C5—C9—H9B	109.5	C20—C19—H19	119.8
H9A—C9—H9B	109.5	C15—C20—C19	118.7 (2)
C5—C9—H9C	109.5	C15—C20—H20	120.7
H9A—C9—H9C	109.5	C19—C20—H20	120.7
C6—O1—C5—C9	118.61 (17)	C2—C6—C7—C10	0.8 (3)
C6—O1—C5—C8	−120.35 (17)	C7—C4—C11—C12	−178.49 (19)
C6—O1—C5—C4	−0.40 (19)	C5—C4—C11—C12	3.0 (3)
C7—C4—C5—O1	0.19 (19)	C4—C11—C12—N4	−179.55 (17)
C11—C4—C5—O1	178.89 (16)	C13—N4—C12—C11	179.57 (18)
C7—C4—C5—C9	−113.21 (18)	C15—N4—C12—C11	1.6 (3)
C11—C4—C5—C9	65.5 (2)	C12—N4—C13—O2	2.2 (3)
C7—C4—C5—C8	113.98 (18)	C15—N4—C13—O2	−179.90 (16)
C11—C4—C5—C8	−67.3 (2)	C12—N4—C13—C14	−177.83 (16)
C5—O1—C6—C2	−179.62 (16)	C15—N4—C13—C14	0.0 (3)
C5—O1—C6—C7	0.5 (2)	C12—N4—C15—C16	94.3 (2)
C1—C2—C6—O1	−179.50 (17)	C13—N4—C15—C16	−83.6 (2)
C3—C2—C6—O1	1.0 (3)	C12—N4—C15—C20	−81.9 (2)
C1—C2—C6—C7	0.4 (3)	C13—N4—C15—C20	100.2 (2)
C3—C2—C6—C7	−179.14 (18)	C20—C15—C16—C17	−0.9 (3)
C11—C4—C7—C10	0.3 (3)	N4—C15—C16—C17	−177.00 (17)
C5—C4—C7—C10	179.06 (17)	C15—C16—C17—C18	1.3 (3)
C11—C4—C7—C6	−178.69 (17)	C16—C17—C18—C19	−1.0 (3)
C5—C4—C7—C6	0.1 (2)	C17—C18—C19—C20	0.2 (3)
O1—C6—C7—C4	−0.3 (2)	C16—C15—C20—C19	0.1 (3)
C2—C6—C7—C4	179.8 (2)	N4—C15—C20—C19	176.21 (18)
O1—C6—C7—C10	−179.32 (17)	C18—C19—C20—C15	0.3 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C16—H16···O2^i	0.95	2.60	3.448 (3)	149
C18—H18···O2^ii	0.95	2.58	3.385 (3)	143
C19—H19···N2^iii	0.95	2.54	3.315 (3)	139

Symmetry codes: (i) −x, −y+1, −z+1; (ii) x, −y+3/2, z−1/2; (iii) −x+1, −y+2, −z+1.

(II) 2-{3-cyano-5,5-dimethyl-4-[2-(piperidin-1-yl)vinyl]-2,5-dihydrofuran-2- ylidene}malononitrile 0.376-hydrate

Crystal data

C17H18N4O·0.376H2O	F(000) = 639
Mr = 301.13	Dx = 1.195 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 8133 reflections
a = 11.3193 (3) Å	θ = 2.5–32.5°
b = 8.8981 (3) Å	µ = 0.08 mm^−1
c = 16.9338 (5) Å	T = 99 K
β = 101.298 (2)°	Block, yellow
V = 1672.53 (9) Å^3	0.65 × 0.32 × 0.15 mm
Z = 4

Data collection

Bruker–Nonius APEXII CCD area-detector diffractometer	4855 independent reflections
Radiation source: fine-focus sealed tube	3607 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.035
Detector resolution: 8.192 pixels mm^-1	θmax = 30.0°, θmin = 2.9°
phi and ω scans	h = −15→15
Absorption correction: multi-scan (Blessing, 1995)	k = −12→12
Tmin = 0.775, Tmax = 0.988	l = −23→23
28794 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.042	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.118	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0575P)^2 + 0.3738P] where P = (Fo^2 + 2Fc^2)/3
4855 reflections	(Δ/σ)max < 0.001
217 parameters	Δρmax = 0.41 e Å^−3
0 restraints	Δρmin = −0.19 e Å^−3

Special details

Experimental. Crystal decay was monitored by repeating the initial 10 frames at the end of the data collection and analyzing duplicate reflections. The standard 1.0 mm diameter collimator was used.

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 (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
O1	0.04537 (7)	0.25023 (10)	0.44570 (5)	0.02325 (18)
O2	0.6324 (3)	0.2834 (5)	0.6144 (3)	0.0646 (16)	0.376 (6)
H2A	0.590 (6)	0.211 (8)	0.612 (4)	0.078*	0.376 (6)
H2B	0.694 (7)	0.258 (7)	0.611 (4)	0.078*	0.376 (6)
N1	0.21333 (10)	0.01224 (13)	0.69463 (6)	0.0286 (2)
N2	−0.14555 (10)	0.15463 (12)	0.57564 (7)	0.0316 (2)
N3	0.43041 (10)	0.08343 (15)	0.58294 (7)	0.0369 (3)
N4	0.53892 (8)	0.31485 (11)	0.36566 (6)	0.0232 (2)
C1	0.15513 (10)	0.06691 (12)	0.63887 (6)	0.0210 (2)
C2	0.07963 (10)	0.13476 (12)	0.57160 (6)	0.0196 (2)
C3	−0.04518 (10)	0.14620 (12)	0.57293 (7)	0.0220 (2)
C4	0.24028 (10)	0.26626 (12)	0.41719 (6)	0.0197 (2)
C5	0.10933 (10)	0.30249 (13)	0.38289 (7)	0.0210 (2)
C6	0.12471 (10)	0.18920 (12)	0.50647 (6)	0.0187 (2)
C7	0.24285 (10)	0.19424 (12)	0.49147 (6)	0.0185 (2)
C8	0.08534 (11)	0.46991 (14)	0.37234 (7)	0.0266 (2)
H8A	−0.0013	0.4870	0.3544	0.040*
H8B	0.1285	0.5096	0.3320	0.040*
H8C	0.1134	0.5212	0.4238	0.040*
C9	0.06030 (11)	0.21253 (14)	0.30722 (7)	0.0271 (3)
H9A	0.0775	0.1056	0.3176	0.041*
H9B	0.0988	0.2466	0.2633	0.041*
H9C	−0.0270	0.2274	0.2920	0.041*
C10	0.34547 (10)	0.13279 (13)	0.54283 (7)	0.0235 (2)
C11	0.32832 (10)	0.30601 (13)	0.37476 (7)	0.0229 (2)
H11	0.3040	0.3539	0.3240	0.027*
C12	0.45091 (10)	0.27947 (13)	0.40248 (7)	0.0217 (2)
H12	0.4729	0.2308	0.4532	0.026*
C13	0.66476 (10)	0.28076 (14)	0.40176 (8)	0.0265 (2)
H13A	0.6972	0.2070	0.3678	0.032*
H13B	0.6690	0.2356	0.4557	0.032*
C14	0.74004 (11)	0.42279 (16)	0.40936 (8)	0.0319 (3)
H14A	0.8256	0.3972	0.4302	0.038*
H14B	0.7133	0.4917	0.4483	0.038*
C15	0.72838 (12)	0.50106 (16)	0.32841 (9)	0.0348 (3)
H15A	0.7639	0.4371	0.2913	0.042*
H15B	0.7732	0.5972	0.3355	0.042*
C16	0.59654 (12)	0.53131 (15)	0.29227 (8)	0.0331 (3)
H16A	0.5638	0.6049	0.3262	0.040*
H16B	0.5900	0.5754	0.2379	0.040*
C17	0.52328 (11)	0.38757 (17)	0.28644 (7)	0.0316 (3)
H17A	0.4370	0.4109	0.2667	0.038*
H17B	0.5497	0.3183	0.2475	0.038*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0199 (4)	0.0302 (4)	0.0199 (4)	0.0007 (3)	0.0044 (3)	0.0074 (3)
O2	0.035 (2)	0.071 (3)	0.096 (3)	−0.0076 (17)	0.0316 (19)	−0.023 (2)
N1	0.0302 (5)	0.0368 (6)	0.0196 (5)	0.0031 (4)	0.0066 (4)	0.0010 (4)
N2	0.0290 (6)	0.0312 (5)	0.0366 (6)	0.0006 (4)	0.0114 (5)	0.0031 (5)
N3	0.0279 (5)	0.0514 (7)	0.0325 (6)	0.0066 (5)	0.0085 (5)	0.0154 (5)
N4	0.0201 (5)	0.0286 (5)	0.0207 (5)	−0.0031 (4)	0.0033 (4)	0.0031 (4)
C1	0.0241 (5)	0.0223 (5)	0.0180 (5)	−0.0016 (4)	0.0080 (4)	−0.0026 (4)
C2	0.0224 (5)	0.0196 (5)	0.0174 (5)	−0.0007 (4)	0.0050 (4)	−0.0007 (4)
C3	0.0268 (6)	0.0188 (5)	0.0211 (5)	−0.0007 (4)	0.0068 (4)	0.0009 (4)
C4	0.0219 (5)	0.0185 (5)	0.0181 (5)	−0.0021 (4)	0.0028 (4)	−0.0008 (4)
C5	0.0201 (5)	0.0251 (5)	0.0181 (5)	−0.0025 (4)	0.0045 (4)	0.0039 (4)
C6	0.0215 (5)	0.0168 (4)	0.0172 (5)	−0.0007 (4)	0.0025 (4)	−0.0012 (4)
C7	0.0200 (5)	0.0175 (4)	0.0179 (5)	−0.0011 (4)	0.0036 (4)	0.0002 (4)
C8	0.0266 (6)	0.0264 (6)	0.0261 (6)	0.0016 (5)	0.0037 (5)	0.0059 (4)
C9	0.0263 (6)	0.0326 (6)	0.0210 (5)	−0.0077 (5)	0.0016 (4)	0.0014 (5)
C10	0.0242 (5)	0.0263 (5)	0.0214 (5)	−0.0003 (4)	0.0079 (4)	0.0046 (4)
C11	0.0214 (5)	0.0270 (5)	0.0199 (5)	−0.0027 (4)	0.0036 (4)	0.0035 (4)
C12	0.0235 (5)	0.0228 (5)	0.0191 (5)	−0.0025 (4)	0.0048 (4)	0.0009 (4)
C13	0.0210 (5)	0.0280 (6)	0.0306 (6)	0.0035 (5)	0.0056 (5)	0.0045 (5)
C14	0.0234 (6)	0.0384 (7)	0.0316 (7)	−0.0057 (5)	−0.0003 (5)	0.0015 (5)
C15	0.0303 (7)	0.0347 (7)	0.0382 (7)	−0.0126 (5)	0.0040 (5)	0.0054 (6)
C16	0.0359 (7)	0.0317 (6)	0.0319 (7)	0.0014 (5)	0.0075 (5)	0.0109 (5)
C17	0.0243 (6)	0.0487 (8)	0.0208 (6)	−0.0083 (5)	0.0017 (5)	0.0082 (5)

Geometric parameters (Å, º)

O1—C6	1.3410 (13)	C8—H8C	0.9800
O1—C5	1.4742 (13)	C9—H9A	0.9800
O2—H2A	0.80 (8)	C9—H9B	0.9800
O2—H2B	0.75 (7)	C9—H9C	0.9800
N1—C1	1.1482 (15)	C11—C12	1.3951 (16)
N2—C3	1.1485 (16)	C11—H11	0.9500
N3—C10	1.1502 (15)	C12—H12	0.9500
N4—C12	1.3130 (14)	C13—C14	1.5156 (17)
N4—C13	1.4675 (15)	C13—H13A	0.9900
N4—C17	1.4684 (15)	C13—H13B	0.9900
C1—C2	1.4182 (15)	C14—C15	1.5202 (19)
C2—C6	1.3899 (15)	C14—H14A	0.9900
C2—C3	1.4210 (16)	C14—H14B	0.9900
C4—C11	1.3837 (15)	C15—C16	1.5219 (19)
C4—C7	1.4070 (15)	C15—H15A	0.9900
C4—C5	1.5170 (15)	C15—H15B	0.9900
C5—C8	1.5185 (17)	C16—C17	1.5170 (19)
C5—C9	1.5206 (16)	C16—H16A	0.9900
C6—C7	1.4099 (15)	C16—H16B	0.9900
C7—C10	1.4173 (15)	C17—H17A	0.9900
C8—H8A	0.9800	C17—H17B	0.9900
C8—H8B	0.9800
C6—O1—C5	109.37 (8)	N3—C10—C7	178.22 (13)
H2A—O2—H2B	108 (7)	C4—C11—C12	123.50 (11)
C12—N4—C13	121.16 (10)	C4—C11—H11	118.2
C12—N4—C17	124.93 (10)	C12—C11—H11	118.2
C13—N4—C17	113.90 (9)	N4—C12—C11	126.64 (11)
N1—C1—C2	177.84 (12)	N4—C12—H12	116.7
C6—C2—C1	121.91 (10)	C11—C12—H12	116.7
C6—C2—C3	120.56 (10)	N4—C13—C14	110.29 (10)
C1—C2—C3	117.53 (10)	N4—C13—H13A	109.6
N2—C3—C2	178.60 (13)	C14—C13—H13A	109.6
C11—C4—C7	133.61 (11)	N4—C13—H13B	109.6
C11—C4—C5	119.74 (10)	C14—C13—H13B	109.6
C7—C4—C5	106.65 (9)	H13A—C13—H13B	108.1
O1—C5—C4	103.76 (8)	C13—C14—C15	110.94 (11)
O1—C5—C8	107.01 (9)	C13—C14—H14A	109.5
C4—C5—C8	113.10 (9)	C15—C14—H14A	109.5
O1—C5—C9	106.99 (9)	C13—C14—H14B	109.5
C4—C5—C9	112.25 (10)	C15—C14—H14B	109.5
C8—C5—C9	112.95 (10)	H14A—C14—H14B	108.0
O1—C6—C2	117.08 (10)	C14—C15—C16	110.41 (11)
O1—C6—C7	111.41 (9)	C14—C15—H15A	109.6
C2—C6—C7	131.51 (10)	C16—C15—H15A	109.6
C4—C7—C6	108.75 (9)	C14—C15—H15B	109.6
C4—C7—C10	126.53 (10)	C16—C15—H15B	109.6
C6—C7—C10	124.71 (10)	H15A—C15—H15B	108.1
C5—C8—H8A	109.5	C17—C16—C15	110.95 (11)
C5—C8—H8B	109.5	C17—C16—H16A	109.4
H8A—C8—H8B	109.5	C15—C16—H16A	109.4
C5—C8—H8C	109.5	C17—C16—H16B	109.4
H8A—C8—H8C	109.5	C15—C16—H16B	109.4
H8B—C8—H8C	109.5	H16A—C16—H16B	108.0
C5—C9—H9A	109.5	N4—C17—C16	110.22 (10)
C5—C9—H9B	109.5	N4—C17—H17A	109.6
H9A—C9—H9B	109.5	C16—C17—H17A	109.6
C5—C9—H9C	109.5	N4—C17—H17B	109.6
H9A—C9—H9C	109.5	C16—C17—H17B	109.6
H9B—C9—H9C	109.5	H17A—C17—H17B	108.1
C6—O1—C5—C4	−1.42 (11)	C5—C4—C7—C10	176.30 (11)
C6—O1—C5—C8	−121.25 (10)	O1—C6—C7—C4	1.47 (13)
C6—O1—C5—C9	117.43 (10)	C2—C6—C7—C4	−177.87 (11)
C11—C4—C5—O1	−177.51 (10)	O1—C6—C7—C10	−177.15 (10)
C7—C4—C5—O1	2.25 (11)	C2—C6—C7—C10	3.50 (19)
C11—C4—C5—C8	−61.91 (14)	C7—C4—C11—C12	−0.9 (2)
C7—C4—C5—C8	117.84 (10)	C5—C4—C11—C12	178.80 (11)
C11—C4—C5—C9	67.33 (13)	C13—N4—C12—C11	179.82 (11)
C7—C4—C5—C9	−112.92 (10)	C17—N4—C12—C11	−1.2 (2)
C5—O1—C6—C2	179.51 (9)	C4—C11—C12—N4	−179.60 (11)
C5—O1—C6—C7	0.06 (12)	C12—N4—C13—C14	−123.80 (12)
C1—C2—C6—O1	179.50 (10)	C17—N4—C13—C14	57.15 (14)
C3—C2—C6—O1	−0.78 (15)	N4—C13—C14—C15	−55.19 (14)
C1—C2—C6—C7	−1.19 (18)	C13—C14—C15—C16	55.00 (15)
C3—C2—C6—C7	178.53 (11)	C14—C15—C16—C17	−54.96 (15)
C11—C4—C7—C6	177.41 (12)	C12—N4—C17—C16	123.93 (13)
C5—C4—C7—C6	−2.29 (12)	C13—N4—C17—C16	−57.07 (14)
C11—C4—C7—C10	−4.0 (2)	C15—C16—C17—N4	55.05 (15)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2A···N3	0.80 (8)	2.111 (s.u.?)	2.864	157
O2—H2B···N2^i	0.75 (7)	2.217 (s.u.?)	2.950	166
C11—H11···N1^ii	0.95	2.53	3.4725 (16)	172
C13—H13A···N1^iii	0.99	2.52	3.4997 (17)	169
C17—H17A···N1^ii	0.99	2.68	3.6584 (17)	172
C8—H8B···N1^ii	0.98	2.69	3.5900 (16)	153

Symmetry codes: (i) x+1, y, z; (ii) x, −y+1/2, z−1/2; (iii) −x+1, −y, −z+1.