Geometry and bond-length alternation in nonlinear optical materials. I. Standard parameters in two precursors

2-{3-Cyano-4-[4-(N-formyl­anilino)-trans-1,3-butadien­yl]-5,5-dimethyl-2,5-dihydro­furan-2-yl­idene}propane­dinitrile, C₂₂H₁₈N₄O₂, (I), and 2-{3-cyano-4-[6-(N-formyl­anilino)-trans,trans-1,3,5-hexa­trien­yl]-5,5-dimethyl-2,5-dihydro­furan-2-yl­idene}propane­dinitrile, C₂₄H₂₀N₄O₂, (II), show the alternating single/double-bond behaviour of push–pull chromophores. In the two structures, the planar polyene chains are twisted with respect to the furanyl­idene ring by 18.2 (2) and 12.4 (2)°, respectively. Comparison with structures of related and parent mol­ecules shows subtle but consistent bond-length variations consistent with charge-delocalized structures. Crystal cohesion is provided by various sets of hydrogen bonds, viz. C—H_methyl...N_cyano and bifurcated (C=C—H)₂...O=C in (I), and C—H_{methyl/phenyl}...O and C=C—H...N_cyano in (II).

S1. Comment

The development of organic nonlinear optical (NLO) polymers continues to attract considerable interest because of their potential application in a number of photonic and optoelectronic devices (Dalton, 2002). Polymeric organic materials offer a number of advantages over conventional inorganic electro-optic materials such as lithium niobate. These include better performance, the ability to be processed in a range of solvents, lower cost and lower drive voltages (Ma et al., 2002). Crucial to the creation of such materials is the preparation of high figure of merit (µ.β) chromophores which can be incorporated into the polymer system and which act as the active component. Recently, we reported the synthesis of a suite of such compounds using a range of acetanilido-based precursors (Kay et al., 2004). The methodology permits a flexible route to `right-hand side' (RHS) chromophore systems, with chromophores derived from the two title compounds affording the highest figures of merit (µ.β₀ 6400–9400 × 10⁻⁴⁸ s.u.). RHS NLO materials are readily differentiated from their left-hand side counterparts as they have an aromatizable donor system which leads to zwitterionic, charge-separated ground states and high figure of merit molecules (Marder et al., 1993). Owing to this charge delocalization, RHS molecules are expected to exhibit large changes in bond order across the conjugated π system. As part of our ongoing interest, we intend to study a range of NLO compounds containing a variety of donor systems, to examine the effect of the donor on bond order within these molecules. In order to establish some standard parameters, we have characterized the two title precursor compounds. These contain a weak donor system, which permits us to establish standard geometrical parameters for analogues derived from the powerful electron acceptor [3-cyano-5,5-dimethyl-2(5H)-furanylidene]propanedinitrile (hereafter CDFP).

The asymmetric units of (I) and (II), each consisting of one molecule, are shown in Figs. 1 and 2, with selected dimensions in Tables 1 and 3. A comparison of some key bond lengths with those of related structures (Scheme 2) containing the CDFP group with bound alkene moieties at the C4 position is given in Table 5 [sourced from the Cambridge Structural Database; Version 5.38, May 2007 updates (Allen, 2002; hereafter CSD); refcodes KAJBUT, (III), and KAJCAA, (IV) (Liao et al., 2005), HESKIA, (V) (Kinnibrugh et al., 2006), JETGEV, (VI) (Wang et al., 2007), and PANLUM, (VII) (Li et al., 2005)]. The consistency of the CDFP dimensions for (I) and (II) is remarkable, with only insignificant changes also noted in comparison with compounds (III)–(VI). The first double-bond lengths in the donor–acceptor chains (C11═C12) are similar, except for that in structure (II), which is marginally longer by 0.012 (4)° [the mean of (I) and (III)–(VI) is 1.354 (1) Å]. The `extra' alkene bond length in (II) (C13═C14) appears normal.

Both structures contain three major planar groups, viz. the CDFP five-membered ring [with average out-of-plane deviations, hereafter ADs, for (I) and (II), respectively, of 0.005 (2) and 0.016 (2) Å], the alternating alkene/alkane (polyene) chain, hereafter AC [C12–C14 for (I) and C12–C16 for (II); ADs 0 (three atoms) and 0.005 (2) Å] and the planar phenyl rings [C17–C22 for (I) and C19–C24 for (II)]. The CDFP five-membered ring and the AC planes are twisted at atom C11, with interplanar angles of 18.17 (19) and 12.4 (2)° in (I) and (II), respectively. Similar twisting has been noted before [e.g. 14.15 (3)° in HESKIA; Kinnibrugh et al., 2006]. Atom C11 is almost coplanar with the CDFP five-membered ring in (I), with a deviation of 0.018 (2) Å, but definitely out of this plane in (II) [the deviation is 0.142 (6) Å]. The phenyl ring plane is approximately normal to the AC plane; the dihedral angles are 79.49 (18) and 83.4 (2)°, respectively, in (I) and (II). The capping acetanilido atoms (N4 and O2 with C14 {C15?} for (I) and C17 for (II)] are tilted slightly with respect to the AC plane by 2.2 (2) and 10.6 (4)° respectively. The minor distortions of cyano groups bound to C2 probably reflect packing considerations [e.g. the methyl hydrogen bond H8···N2ⁱ in (I) (Table 2)].

There are also two major geometrical differences between (I) and (II). The phenyl rings are oriented differently with respect to the CDFP five-membered ring, at interplanar angles of 80.23 (16) and 68.31 (9)°, respectively. However, an even more noteworthy feature is the different configuration of the alkene/alkane (polyene) chain binding to the CDFP group, (I) being synperiplanar while (II) is antiperiplanar with respect to the atom sequence C7—C4—C11—C12 (see torsion angles in Tables 1 and 3, and Figs. 1 and 2). The two possible orientations of the precursor molecule are very similar in energy (within 2 kcal mol⁻¹; Kay et al., 2004) and so crystal packing forces can determine which isomer (rotamer) crystallizes out. Tables 2 and 4 list the important intermolecular interactions shown in Figs. 3 and 4 and confirm that different hydrogen-bonding regimes exist in (I) and (II) (see below).

Both compounds are derived from 2-dicyanomethylene-4,5,5-trimethyl-2,5-dihydrofuran-3-carbonitrile, (VII). Comparison of the bond lengths in (VII) with the corresponding bonds in (I) and (II) reveals some subtle variations. The endocyclic double-bond lengths in (I) and (II) (C4═C7, entry 1 in Table 5) averaging 1.370 (3) Å, indicate more single-bond character in comparison with the parent (VII) molecule [1.343 (4) Å] with a significant bond difference [0.027 (5) Å]. Conversely, the adjacent endocyclic single-bond lengths (C6—C7, entry 2), averaging 1.437 (3) Å, are marginally shorter than the corresponding bond in (VII) [1.445 (4) Å]. Finally, the dicyanomethylene bonds (C2—C6, entry 3), with average 1.370 (3) Å, are also marginally longer than that observed in (VII) [1.359 (4) Å]. The bond lengths in (VII) observed at 298 K would be expected to be longer than the low-temperature values presented here. Taking all these observations together it appears to us that charge from the acetanildo N atoms of both compounds is delocalized throughout the molecules from N4 to the dicyanomethylene C atom (C2), resulting in a consistent change in bond lengths across the conjugated π systems. The scale of this change is small, which is not surprising given the weak donating power of atom N4 as a result of the presence of the adjacent electron-withdrawing carbonyl group.

For (I), the crystal packing is dominated by strong C═C—H···O═C interactions of molecules related by inversion symmetry, involving a bifurcated carbonyl O atom (O2), and a C—H_methyl···N_cyano hydrogen bond (Table 2 and Fig. 3). These three interactions result in layers lying approximately parallel to the bc plane. C—H···N_cyano bonding has been noted before in the related structure HESKIA (Kinnibrugh et al., 2006), with H···N distances of 2.42 and 2.50 Å and C—H···N angles of 147 and 160°. Similar (C═C—H)₂···O bifurcated interactions are found in the CSD [e.g. GAMFOP (Krasnaya et al., 1987), with H···O = 2.60 and 2.39 Å and H···O···H = 50°, compared with 59° here].

In (II), the molecules pack in layers parallel to the (101) plane (Fig. 4), the layers being joined by bifurcated C—H···O hydrogen bonds with phenyl and methyl atoms as donors and carbonyl atom O2 as acceptor (entries 2 and 3 in Table 4). A survey of C—H_methyl···O interactions in the CSD indicates that these interactions are stronger than those commonly found, with typical H···O distances greater than 2.43 Å [e.g. DEFYOD (Bream et al., 2006), with H···O = 2.45 Å and C—H···O = 155°]. C—H_phenyl···O intermolecular interactions are more common, with H···O distances ranging upwards from 2.33 Å [e.g. YABFIR (Carella et al., 2004), with H···O = 2.49 Å and C—H···O = 177°]. One C═C—H···N_cyano hydrogen bond provides the linkage between molecules within the layer (Fig. 4); such interactions occur with H···N distances ranging from 2.51 to 2.61 Å [e.g. CISDEN, with H···N = 2.56 Å and C—H···N = 150° (Murata et al., 1984)].

These two structures are representive of our nonlinear optical chromophore precursors (Kay et al., 2004), where the donor effect is observable but not large. Our future work will include examples where the acetanilido group is replaced with a more powerful donor, such as piperidine, and the magnitude of bond-length alternation in comparison with (I), (II) and (VII) is examined.

Related literature

For related literature, see: Allen (2002); Bream et al. (2006); Carella et al. (2004); Dalton (2002); Kay et al. (2004); Kinnibrugh et al. (2006); Krasnaya et al. (1987); Li et al. (2005); Liao et al. (2005); Ma et al. (2002); Marder et al. (1993); Murata et al. (1984); Wang et al. (2007).

S2. Experimental

The compounds were prepared as described by Kay et al. (2004; compounds 11b and 11c, p. 1328). The crystals were recrystallized from dichloromethane/hexane for (I) and dichloromethane/ethylacetate for (II).

S3. Refinement

All H atoms in (I) were freely refined with isotropic displacement parameters. All H atoms in (II) were positioned geometrically and allowed to ride on their respective parent atoms [C—H = 0.95 and 0.98 Å, with U_iso(H) = 1.2U_eq(phenyl C) or 1.5U_eq(methyl C)], in response to a weaker data set with fewer observed data.

Computing details

For both compounds, data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT (Siemens, 1996) and SADABS (Sheldrick, 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997) and Mercury (Bruno et al., 2002); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997) and PLATON (Spek, 2003).

Figures

	Fig. 1. The molecular structure of (I) (ORTEP-3; Farrugia, 1997); displacement ellipsoids are shown at the 50% probability level.
	Fig. 2. The molecular structure (II) (ORTEP-3; Farrugia, 1997); displacement ellipsoids are shown at the 50% probability level.
	Fig. 3. A partial packing diagram of (I) (Mercury; Bruno et al., 2002), normal to the hydrogen-bonded layers, showing key intermolecular contacts (dotted lines between ball-shaped atoms). For symmetry designations see Table 2.
	Fig. 4. A partial packing diagram of (II) (Mercury; Bruno et al., 2002), showing the layer structure with key intermolecular contacts (dotted lines). H atoms not involved in hydrogen bonding have been omitted for clarity. For symmetry designations see Table 4.

(I) 2-{4-[4-(N-Formylanilino)-trans-1,3-butadienyl]-3-cyano-5,5-dimethyl-2,5-dihydrofuranylidene}propanedinitrile

Crystal data

C22H18N4O2	F(000) = 1552
Mr = 370.40	Dx = 1.273 Mg m^−3
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 3326 reflections
a = 17.5731 (14) Å	θ = 2.3–27.8°
b = 9.6510 (8) Å	µ = 0.08 mm^−1
c = 22.7965 (19) Å	T = 105 K
V = 3866.2 (5) Å^3	Lath, red
Z = 8	0.75 × 0.20 × 0.04 mm

Data collection

Bruker–Nonius APEXII CCD area-detector diffractometer	5714 independent reflections
Radiation source: fine-focus sealed tube	3318 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.062
Detector resolution: 8.192 pixels mm^-1	θmax = 30.4°, θmin = 2.6°
phi and ω scans	h = −25→22
Absorption correction: multi-scan (Blessing, 1995)	k = −9→13
Tmin = 0.744, Tmax = 0.997	l = −31→31
23770 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)] = 0.047	Hydrogen site location: difference Fourier map
wR(F^2) = 0.113	All H-atom parameters refined
S = 1.00	w = 1/[σ^2(Fo^2) + (0.0367P)^2 + 1.4135P] where P = (Fo^2 + 2Fc^2)/3
5714 reflections	(Δ/σ)max < 0.001
325 parameters	Δρmax = 0.36 e Å^−3
0 restraints	Δρmin = −0.27 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
O1	0.57691 (7)	0.65974 (11)	0.64788 (5)	0.0202 (3)
O2	0.51046 (7)	−0.10836 (12)	0.42583 (5)	0.0260 (3)
N1	0.69207 (9)	1.08654 (16)	0.58975 (8)	0.0351 (4)
N2	0.55684 (9)	0.94290 (16)	0.73727 (7)	0.0295 (4)
N3	0.69492 (9)	0.82311 (15)	0.47278 (7)	0.0288 (4)
N4	0.59423 (7)	0.05630 (13)	0.39591 (6)	0.0176 (3)
C1	0.65852 (10)	0.99579 (17)	0.60898 (8)	0.0234 (4)
C2	0.61752 (9)	0.88722 (16)	0.63727 (7)	0.0192 (3)
C3	0.58407 (9)	0.91744 (16)	0.69274 (8)	0.0213 (4)
C4	0.61660 (9)	0.55819 (16)	0.56013 (7)	0.0168 (3)
C5	0.57722 (9)	0.52427 (15)	0.61703 (7)	0.0179 (3)
C6	0.61094 (9)	0.75571 (16)	0.61509 (7)	0.0177 (3)
C7	0.63486 (9)	0.69665 (15)	0.56056 (7)	0.0178 (3)
C8	0.49452 (10)	0.48343 (18)	0.61068 (8)	0.0216 (4)
C9	0.62228 (12)	0.42638 (19)	0.65540 (8)	0.0253 (4)
C10	0.66940 (9)	0.76917 (16)	0.51293 (7)	0.0201 (3)
C11	0.63278 (10)	0.46498 (17)	0.51365 (7)	0.0198 (3)
C12	0.60781 (9)	0.33293 (16)	0.50881 (7)	0.0188 (3)
C13	0.62202 (9)	0.25230 (16)	0.45747 (7)	0.0190 (3)
C14	0.58615 (10)	0.13197 (16)	0.44747 (7)	0.0194 (3)
C15	0.55459 (9)	−0.06747 (16)	0.38848 (7)	0.0198 (3)
C16	0.57003 (12)	−0.14550 (18)	0.33306 (8)	0.0242 (4)
C17	0.64761 (9)	0.10562 (16)	0.35258 (7)	0.0171 (3)
C18	0.62521 (10)	0.20863 (16)	0.31372 (7)	0.0199 (3)
C19	0.67758 (10)	0.25824 (17)	0.27342 (7)	0.0235 (4)
C20	0.75074 (11)	0.20560 (18)	0.27211 (8)	0.0249 (4)
C21	0.77218 (10)	0.10279 (18)	0.31103 (8)	0.0252 (4)
C22	0.72078 (10)	0.05326 (17)	0.35202 (8)	0.0214 (4)
H8A	0.4695 (10)	0.5525 (19)	0.5874 (8)	0.027 (5)*
H8B	0.4907 (10)	0.3898 (19)	0.5915 (8)	0.024 (5)*
H8C	0.4700 (10)	0.4806 (18)	0.6505 (8)	0.026 (5)*
H9A	0.5978 (11)	0.4182 (19)	0.6943 (9)	0.033 (5)*
H9B	0.6235 (11)	0.334 (2)	0.6355 (8)	0.034 (5)*
H9C	0.6731 (13)	0.459 (2)	0.6597 (9)	0.039 (6)*
H11	0.6627 (10)	0.5037 (18)	0.4831 (8)	0.024 (5)*
H12	0.5775 (9)	0.2896 (17)	0.5391 (7)	0.016 (4)*
H13	0.6576 (10)	0.2916 (18)	0.4294 (8)	0.024 (5)*
H14	0.5503 (11)	0.0921 (18)	0.4764 (8)	0.027 (5)*
H16A	0.5750 (11)	−0.086 (2)	0.2993 (9)	0.034 (5)*
H16B	0.5272 (12)	−0.211 (2)	0.3269 (8)	0.040 (6)*
H16C	0.6180 (14)	−0.193 (2)	0.3387 (10)	0.058 (7)*
H18	0.5736 (10)	0.2438 (18)	0.3152 (7)	0.023 (5)*
H19	0.6627 (10)	0.3295 (19)	0.2457 (8)	0.028 (5)*
H20	0.7894 (11)	0.242 (2)	0.2434 (8)	0.035 (5)*
H21	0.8240 (12)	0.067 (2)	0.3108 (8)	0.036 (5)*
H22	0.7348 (9)	−0.0180 (17)	0.3795 (7)	0.017 (4)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0295 (6)	0.0131 (5)	0.0179 (6)	−0.0010 (5)	0.0026 (5)	−0.0011 (4)
O2	0.0245 (6)	0.0206 (6)	0.0331 (7)	−0.0058 (5)	0.0092 (5)	−0.0020 (5)
N1	0.0315 (9)	0.0219 (8)	0.0520 (11)	−0.0030 (7)	0.0024 (8)	0.0033 (8)
N2	0.0304 (9)	0.0291 (8)	0.0290 (9)	0.0021 (7)	−0.0017 (7)	−0.0076 (7)
N3	0.0288 (8)	0.0260 (8)	0.0316 (9)	−0.0002 (7)	0.0047 (7)	0.0070 (7)
N4	0.0189 (7)	0.0130 (6)	0.0208 (7)	0.0006 (5)	0.0038 (5)	−0.0020 (5)
C1	0.0215 (8)	0.0167 (8)	0.0319 (10)	0.0036 (7)	−0.0018 (7)	−0.0023 (7)
C2	0.0193 (8)	0.0153 (8)	0.0231 (8)	0.0001 (6)	−0.0017 (7)	−0.0012 (7)
C3	0.0219 (8)	0.0155 (8)	0.0265 (9)	−0.0005 (7)	−0.0055 (7)	−0.0044 (7)
C4	0.0177 (8)	0.0157 (7)	0.0171 (8)	0.0015 (6)	−0.0026 (6)	0.0010 (6)
C5	0.0250 (8)	0.0110 (7)	0.0176 (8)	−0.0004 (6)	0.0010 (6)	−0.0016 (6)
C6	0.0178 (8)	0.0161 (8)	0.0192 (8)	0.0015 (6)	−0.0021 (6)	0.0020 (6)
C7	0.0187 (8)	0.0148 (7)	0.0198 (8)	0.0009 (6)	−0.0001 (6)	0.0007 (6)
C8	0.0253 (9)	0.0159 (8)	0.0237 (9)	−0.0005 (7)	0.0025 (7)	−0.0003 (7)
C9	0.0321 (11)	0.0222 (9)	0.0215 (9)	0.0050 (8)	−0.0009 (8)	0.0044 (7)
C10	0.0209 (8)	0.0145 (8)	0.0249 (9)	0.0012 (7)	−0.0002 (7)	0.0003 (7)
C11	0.0224 (8)	0.0177 (8)	0.0193 (8)	0.0006 (7)	0.0020 (7)	0.0005 (6)
C12	0.0217 (8)	0.0164 (8)	0.0183 (8)	0.0013 (7)	0.0009 (7)	0.0008 (6)
C13	0.0209 (8)	0.0157 (7)	0.0205 (8)	0.0006 (7)	0.0027 (7)	−0.0009 (7)
C14	0.0218 (9)	0.0153 (8)	0.0212 (8)	0.0028 (7)	0.0025 (7)	−0.0017 (7)
C15	0.0179 (8)	0.0142 (8)	0.0272 (9)	0.0013 (6)	0.0009 (7)	0.0011 (7)
C16	0.0297 (10)	0.0161 (8)	0.0268 (10)	−0.0036 (8)	0.0035 (8)	−0.0034 (7)
C17	0.0193 (8)	0.0134 (7)	0.0186 (8)	−0.0032 (6)	0.0028 (6)	−0.0044 (6)
C18	0.0232 (9)	0.0143 (7)	0.0223 (8)	−0.0005 (7)	−0.0011 (7)	−0.0038 (6)
C19	0.0346 (10)	0.0158 (8)	0.0200 (8)	−0.0040 (7)	−0.0015 (7)	−0.0010 (7)
C20	0.0296 (9)	0.0213 (8)	0.0238 (9)	−0.0091 (7)	0.0070 (8)	−0.0050 (7)
C21	0.0220 (9)	0.0209 (9)	0.0327 (10)	−0.0021 (7)	0.0047 (8)	−0.0049 (8)
C22	0.0235 (9)	0.0149 (8)	0.0257 (9)	0.0006 (7)	0.0016 (7)	0.0006 (7)

Geometric parameters (Å, º)

O1—C6	1.3320 (19)	C9—H9C	0.95 (2)
O1—C5	1.4846 (18)	C11—C12	1.352 (2)
O2—C15	1.2174 (19)	C11—H11	0.949 (18)
N1—C1	1.143 (2)	C12—C13	1.427 (2)
N2—C3	1.149 (2)	C12—H12	0.968 (17)
N3—C10	1.144 (2)	C13—C14	1.341 (2)
N4—C14	1.391 (2)	C13—H13	0.972 (18)
N4—C15	1.393 (2)	C14—H14	0.991 (18)
N4—C17	1.443 (2)	C15—C16	1.496 (2)
C1—C2	1.426 (2)	C16—H16A	0.96 (2)
C2—C6	1.371 (2)	C16—H16B	0.99 (2)
C2—C3	1.425 (2)	C16—H16C	0.97 (2)
C4—C7	1.374 (2)	C17—C22	1.382 (2)
C4—C11	1.419 (2)	C17—C18	1.389 (2)
C4—C5	1.506 (2)	C18—C19	1.386 (2)
C5—C9	1.512 (2)	C18—H18	0.969 (17)
C5—C8	1.513 (2)	C19—C20	1.383 (3)
C6—C7	1.431 (2)	C19—H19	0.969 (18)
C7—C10	1.427 (2)	C20—C21	1.383 (3)
C8—H8A	0.959 (19)	C20—H20	1.005 (19)
C8—H8B	1.006 (18)	C21—C22	1.385 (2)
C8—H8C	1.004 (18)	C21—H21	0.97 (2)
C9—H9A	0.99 (2)	C22—H22	0.962 (17)
C9—H9B	1.00 (2)
C6—O1—C5	110.18 (11)	C12—C11—H11	119.4 (11)
C14—N4—C15	120.12 (13)	C4—C11—H11	114.2 (11)
C14—N4—C17	118.14 (13)	C11—C12—C13	121.59 (16)
C15—N4—C17	121.64 (13)	C11—C12—H12	121.8 (10)
N1—C1—C2	175.63 (19)	C13—C12—H12	116.5 (10)
C6—C2—C3	118.82 (15)	C14—C13—C12	121.96 (16)
C6—C2—C1	123.79 (15)	C14—C13—H13	121.9 (10)
C3—C2—C1	117.36 (14)	C12—C13—H13	116.1 (10)
N2—C3—C2	179.38 (19)	C13—C14—N4	123.39 (15)
C7—C4—C11	125.11 (15)	C13—C14—H14	121.5 (10)
C7—C4—C5	108.20 (13)	N4—C14—H14	115.1 (10)
C11—C4—C5	126.69 (14)	O2—C15—N4	120.76 (15)
O1—C5—C4	102.61 (12)	O2—C15—C16	122.90 (15)
O1—C5—C9	106.15 (13)	N4—C15—C16	116.34 (14)
C4—C5—C9	113.18 (14)	C15—C16—H16A	113.1 (11)
O1—C5—C8	105.74 (13)	C15—C16—H16B	107.5 (11)
C4—C5—C8	114.56 (13)	H16A—C16—H16B	109.5 (16)
C9—C5—C8	113.32 (14)	C15—C16—H16C	106.6 (13)
O1—C6—C2	118.34 (14)	H16A—C16—H16C	108.1 (17)
O1—C6—C7	110.02 (13)	H16B—C16—H16C	112.0 (17)
C2—C6—C7	131.64 (15)	C22—C17—C18	121.31 (15)
C4—C7—C10	124.79 (15)	C22—C17—N4	119.39 (14)
C4—C7—C6	108.97 (14)	C18—C17—N4	119.25 (14)
C10—C7—C6	126.20 (14)	C19—C18—C17	118.83 (16)
C5—C8—H8A	108.2 (11)	C19—C18—H18	121.6 (10)
C5—C8—H8B	109.9 (10)	C17—C18—H18	119.6 (10)
H8A—C8—H8B	110.6 (14)	C20—C19—C18	120.32 (16)
C5—C8—H8C	109.5 (10)	C20—C19—H19	119.8 (11)
H8A—C8—H8C	108.8 (15)	C18—C19—H19	119.9 (11)
H8B—C8—H8C	109.8 (14)	C19—C20—C21	120.19 (17)
C5—C9—H9A	109.9 (11)	C19—C20—H20	121.0 (11)
C5—C9—H9B	107.8 (11)	C21—C20—H20	118.8 (11)
H9A—C9—H9B	110.2 (15)	C20—C21—C22	120.19 (17)
C5—C9—H9C	110.4 (12)	C20—C21—H21	120.4 (11)
H9A—C9—H9C	110.0 (17)	C22—C21—H21	119.3 (11)
H9B—C9—H9C	108.5 (16)	C17—C22—C21	119.15 (16)
N3—C10—C7	176.43 (18)	C17—C22—H22	119.6 (10)
C12—C11—C4	126.40 (16)	C21—C22—H22	121.2 (10)
C6—O1—C5—C4	−0.64 (16)	C7—C4—C11—C12	−171.59 (17)
C6—O1—C5—C9	118.35 (14)	C5—C4—C11—C12	8.6 (3)
C6—O1—C5—C8	−121.00 (14)	C4—C11—C12—C13	174.27 (16)
C7—C4—C5—O1	−0.27 (16)	C11—C12—C13—C14	−167.40 (16)
C11—C4—C5—O1	179.57 (15)	C12—C13—C14—N4	174.85 (15)
C7—C4—C5—C9	−114.22 (16)	C15—N4—C14—C13	−179.47 (15)
C11—C4—C5—C9	65.6 (2)	C17—N4—C14—C13	4.0 (2)
C7—C4—C5—C8	113.79 (15)	C14—N4—C15—O2	2.7 (2)
C11—C4—C5—C8	−66.4 (2)	C17—N4—C15—O2	179.08 (15)
C5—O1—C6—C2	−178.52 (14)	C14—N4—C15—C16	−176.80 (15)
C5—O1—C6—C7	1.30 (17)	C17—N4—C15—C16	−0.4 (2)
C3—C2—C6—O1	−3.5 (2)	C14—N4—C17—C22	94.74 (18)
C1—C2—C6—O1	174.19 (15)	C15—N4—C17—C22	−81.72 (19)
C3—C2—C6—C7	176.74 (16)	C14—N4—C17—C18	−82.83 (18)
C1—C2—C6—C7	−5.6 (3)	C15—N4—C17—C18	100.72 (17)
C11—C4—C7—C10	3.4 (3)	C22—C17—C18—C19	0.6 (2)
C5—C4—C7—C10	−176.71 (15)	N4—C17—C18—C19	178.09 (14)
C11—C4—C7—C6	−178.82 (15)	C17—C18—C19—C20	0.1 (2)
C5—C4—C7—C6	1.03 (18)	C18—C19—C20—C21	0.1 (3)
O1—C6—C7—C4	−1.48 (18)	C19—C20—C21—C22	−0.8 (3)
C2—C6—C7—C4	178.31 (17)	C18—C17—C22—C21	−1.3 (2)
O1—C6—C7—C10	176.21 (15)	N4—C17—C22—C21	−178.82 (15)
C2—C6—C7—C10	−4.0 (3)	C20—C21—C22—C17	1.4 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C8—H8C···N2^i	1.005 (18)	2.627 (18)	3.603 (2)	163.8 (14)
C12—H12···O2^ii	0.967 (16)	2.467 (16)	3.352 (2)	152.0 (13)
C14—H14···O2^ii	0.990 (19)	2.476 (18)	3.358 (2)	148.2 (14)

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

(II) 2-{4-[6-(N-Formylanilino)-trans,trans-1,3,5-hexatrienyl]-3-cyano-5,5-dimethyl-2,5-dihydrofuranylidene}propanedinitrile

Crystal data

C24H20N4O2	F(000) = 832
Mr = 396.44	Dx = 1.219 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1328 reflections
a = 12.7040 (15) Å	θ = 2.3–21.3°
b = 15.154 (2) Å	µ = 0.08 mm^−1
c = 11.7651 (14) Å	T = 95 K
β = 107.440 (7)°	Needle, red
V = 2160.8 (5) Å^3	0.40 × 0.10 × 0.04 mm
Z = 4

Data collection

Bruker–Nonius APEXII CCD area-detector diffractometer	6628 independent reflections
Radiation source: fine-focus sealed tube	1966 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.155
Detector resolution: 8.192 pixels mm^-1	θmax = 31.9°, θmin = 2.7°
phi and ω scans	h = −14→18
Absorption correction: multi-scan (Blessing, 1995)	k = −22→22
Tmin = 0.743, Tmax = 0.997	l = −17→17
22431 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.067	H-atom parameters constrained
wR(F^2) = 0.169	w = 1/[σ^2(Fo^2) + (0.0474P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 0.92	(Δ/σ)max = 0.001
6628 reflections	Δρmax = 0.29 e Å^−3
275 parameters	Δρmin = −0.25 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0039 (6)

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
O1	0.30751 (16)	0.63758 (13)	0.93494 (17)	0.0333 (5)
O2	0.87796 (17)	0.45183 (14)	0.30379 (19)	0.0443 (6)
N1	0.2994 (2)	0.32575 (18)	0.9781 (2)	0.0429 (8)
N2	0.2025 (2)	0.55275 (17)	1.1555 (3)	0.0463 (8)
N3	0.4622 (2)	0.38497 (18)	0.8042 (2)	0.0418 (7)
N4	0.86660 (19)	0.58441 (16)	0.3875 (2)	0.0292 (6)
C1	0.2959 (2)	0.4010 (2)	0.9870 (3)	0.0298 (7)
C2	0.2884 (2)	0.49398 (19)	0.9973 (3)	0.0278 (7)
C3	0.2388 (2)	0.5270 (2)	1.0836 (3)	0.0335 (8)
C4	0.4169 (2)	0.61577 (19)	0.8096 (2)	0.0272 (7)
C5	0.3587 (2)	0.6872 (2)	0.8569 (2)	0.0300 (7)
C6	0.3268 (2)	0.55154 (19)	0.9294 (3)	0.0278 (7)
C7	0.3924 (2)	0.53625 (19)	0.8501 (2)	0.0262 (7)
C8	0.4353 (2)	0.75372 (19)	0.9357 (3)	0.0378 (8)
H8A	0.3927	0.7932	0.9712	0.057*
H8B	0.4717	0.7883	0.8880	0.057*
H8C	0.4910	0.7228	0.9990	0.057*
C9	0.2667 (2)	0.7304 (2)	0.7598 (3)	0.0415 (9)
H9A	0.2169	0.6848	0.7143	0.062*
H9B	0.2982	0.7637	0.7065	0.062*
H9C	0.2254	0.7705	0.7960	0.062*
C10	0.4299 (2)	0.4514 (2)	0.8254 (2)	0.0309 (7)
C11	0.4858 (2)	0.6389 (2)	0.7391 (2)	0.0316 (7)
H11	0.4947	0.7002	0.7280	0.038*
C12	0.5410 (2)	0.5832 (2)	0.6854 (2)	0.0331 (8)
H12	0.5304	0.5214	0.6898	0.040*
C13	0.6138 (2)	0.6147 (2)	0.6233 (2)	0.0325 (8)
H13	0.6253	0.6766	0.6229	0.039*
C14	0.6682 (2)	0.5636 (2)	0.5646 (3)	0.0345 (8)
H14	0.6577	0.5015	0.5630	0.041*
C15	0.7407 (2)	0.6005 (2)	0.5052 (2)	0.0315 (7)
H15	0.7519	0.6626	0.5083	0.038*
C16	0.7938 (2)	0.5510 (2)	0.4449 (2)	0.0321 (7)
H16	0.7808	0.4891	0.4411	0.039*
C17	0.9093 (2)	0.5279 (2)	0.3197 (3)	0.0344 (8)
C18	0.9930 (3)	0.5642 (2)	0.2667 (3)	0.0511 (10)
H18A	1.0287	0.5157	0.2373	0.077*
H18B	1.0487	0.5973	0.3276	0.077*
H18C	0.9568	0.6036	0.2005	0.077*
C19	0.8994 (2)	0.6763 (2)	0.4031 (3)	0.0293 (7)
C20	0.9802 (2)	0.7011 (2)	0.5048 (3)	0.0375 (8)
H20	1.0116	0.6592	0.5655	0.045*
C21	1.0153 (3)	0.7888 (2)	0.5175 (3)	0.0423 (9)
H21	1.0711	0.8069	0.5873	0.051*
C22	0.9691 (3)	0.8490 (2)	0.4292 (3)	0.0434 (9)
H22	0.9938	0.9085	0.4373	0.052*
C23	0.8876 (3)	0.8231 (2)	0.3298 (3)	0.0443 (9)
H23	0.8555	0.8652	0.2696	0.053*
C24	0.8512 (3)	0.7366 (2)	0.3153 (3)	0.0392 (8)
H24	0.7941	0.7192	0.2463	0.047*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0403 (13)	0.0212 (12)	0.0419 (12)	0.0041 (10)	0.0176 (11)	0.0029 (10)
O2	0.0547 (15)	0.0287 (14)	0.0508 (14)	−0.0015 (12)	0.0176 (12)	−0.0070 (12)
N1	0.0534 (19)	0.0284 (17)	0.0525 (18)	−0.0026 (15)	0.0244 (15)	0.0000 (14)
N2	0.0565 (19)	0.0342 (18)	0.0598 (19)	0.0045 (15)	0.0350 (16)	0.0041 (15)
N3	0.0545 (19)	0.0323 (18)	0.0446 (17)	0.0047 (14)	0.0240 (15)	0.0054 (14)
N4	0.0327 (15)	0.0258 (15)	0.0317 (14)	−0.0017 (12)	0.0135 (12)	−0.0012 (12)
C1	0.0301 (18)	0.031 (2)	0.0299 (17)	0.0004 (16)	0.0109 (14)	−0.0015 (15)
C2	0.0298 (18)	0.0237 (18)	0.0331 (17)	0.0016 (14)	0.0141 (15)	0.0016 (14)
C3	0.0327 (19)	0.0266 (19)	0.0428 (19)	−0.0003 (15)	0.0137 (16)	0.0056 (16)
C4	0.0234 (17)	0.0286 (18)	0.0266 (15)	−0.0023 (14)	0.0029 (13)	0.0014 (14)
C5	0.0335 (18)	0.0242 (18)	0.0343 (17)	−0.0031 (15)	0.0131 (15)	0.0049 (14)
C6	0.0269 (17)	0.0213 (17)	0.0334 (16)	0.0026 (15)	0.0062 (14)	−0.0013 (14)
C7	0.0285 (17)	0.0217 (17)	0.0290 (15)	−0.0012 (14)	0.0094 (14)	−0.0003 (14)
C8	0.043 (2)	0.0274 (19)	0.0425 (19)	0.0007 (16)	0.0130 (16)	−0.0041 (16)
C9	0.041 (2)	0.0278 (19)	0.050 (2)	0.0062 (16)	0.0051 (17)	0.0069 (16)
C10	0.0361 (19)	0.029 (2)	0.0295 (17)	0.0009 (16)	0.0129 (14)	0.0058 (15)
C11	0.0348 (19)	0.0258 (18)	0.0324 (16)	−0.0028 (15)	0.0071 (15)	0.0044 (15)
C12	0.0375 (19)	0.0340 (19)	0.0262 (16)	−0.0036 (16)	0.0070 (15)	0.0052 (15)
C13	0.0351 (19)	0.029 (2)	0.0312 (17)	−0.0034 (15)	0.0073 (15)	0.0058 (15)
C14	0.0377 (19)	0.0332 (19)	0.0328 (16)	−0.0013 (16)	0.0108 (15)	0.0039 (15)
C15	0.0351 (19)	0.0285 (18)	0.0305 (16)	−0.0027 (15)	0.0091 (15)	0.0017 (15)
C16	0.0333 (18)	0.0299 (19)	0.0336 (17)	−0.0028 (16)	0.0106 (15)	0.0024 (15)
C17	0.039 (2)	0.030 (2)	0.0339 (18)	0.0017 (16)	0.0114 (16)	0.0023 (16)
C18	0.061 (2)	0.046 (2)	0.060 (2)	−0.0036 (19)	0.038 (2)	−0.0083 (19)
C19	0.0319 (18)	0.0255 (18)	0.0327 (17)	−0.0027 (15)	0.0131 (15)	−0.0030 (15)
C20	0.042 (2)	0.031 (2)	0.0363 (18)	−0.0009 (16)	0.0065 (16)	0.0041 (16)
C21	0.044 (2)	0.031 (2)	0.0412 (19)	−0.0028 (17)	−0.0035 (17)	0.0012 (16)
C22	0.050 (2)	0.030 (2)	0.044 (2)	−0.0071 (17)	0.0045 (18)	0.0016 (16)
C23	0.058 (2)	0.029 (2)	0.0398 (19)	−0.0016 (18)	0.0051 (18)	0.0103 (16)
C24	0.046 (2)	0.034 (2)	0.0316 (17)	−0.0049 (17)	0.0017 (16)	0.0026 (16)

Geometric parameters (Å, º)

O1—C6	1.332 (3)	C11—H11	0.9500
O1—C5	1.480 (3)	C12—C13	1.422 (4)
O2—C17	1.215 (3)	C12—H12	0.9500
N1—C1	1.147 (4)	C13—C14	1.357 (4)
N2—C3	1.147 (4)	C13—H13	0.9500
N3—C10	1.142 (4)	C14—C15	1.428 (4)
N4—C17	1.387 (4)	C14—H14	0.9500
N4—C16	1.394 (3)	C15—C16	1.344 (4)
N4—C19	1.449 (4)	C15—H15	0.9500
C1—C2	1.420 (4)	C16—H16	0.9500
C2—C6	1.368 (4)	C17—C18	1.490 (4)
C2—C3	1.435 (4)	C18—H18A	0.9800
C4—C7	1.366 (4)	C18—H18B	0.9800
C4—C11	1.419 (4)	C18—H18C	0.9800
C4—C5	1.508 (4)	C20—C19	1.375 (4)
C5—C8	1.510 (4)	C20—C21	1.395 (4)
C5—C9	1.516 (4)	C20—H20	0.9500
C6—C7	1.443 (4)	C21—C22	1.375 (4)
C7—C10	1.432 (4)	C21—H21	0.9500
C8—H8A	0.9800	C22—C23	1.366 (4)
C8—H8B	0.9800	C22—H22	0.9500
C8—H8C	0.9800	C23—C24	1.383 (4)
C9—H9A	0.9800	C23—H23	0.9500
C9—H9B	0.9800	C24—C19	1.378 (4)
C9—H9C	0.9800	C24—H24	0.9500
C11—C12	1.367 (4)
C6—O1—C5	110.2 (2)	C11—C12—H12	118.9
C17—N4—C16	119.0 (3)	C13—C12—H12	118.9
C17—N4—C19	121.3 (3)	C14—C13—C12	125.4 (3)
C16—N4—C19	119.7 (2)	C14—C13—H13	117.3
N1—C1—C2	178.5 (3)	C12—C13—H13	117.3
C6—C2—C1	122.5 (3)	C13—C14—C15	121.8 (3)
C6—C2—C3	120.0 (3)	C13—C14—H14	119.1
C1—C2—C3	117.5 (3)	C15—C14—H14	119.1
N2—C3—C2	177.6 (3)	C16—C15—C14	122.6 (3)
C7—C4—C11	131.9 (3)	C16—C15—H15	118.7
C7—C4—C5	108.4 (3)	C14—C15—H15	118.7
C11—C4—C5	119.6 (3)	C15—C16—N4	124.2 (3)
O1—C5—C4	102.6 (2)	C15—C16—H16	117.9
O1—C5—C8	106.2 (2)	N4—C16—H16	117.9
C4—C5—C8	114.1 (2)	O2—C17—N4	120.5 (3)
O1—C5—C9	107.7 (2)	O2—C17—C18	121.9 (3)
C4—C5—C9	112.6 (2)	N4—C17—C18	117.6 (3)
C8—C5—C9	112.6 (3)	C17—C18—H18A	109.5
O1—C6—C2	119.5 (3)	C17—C18—H18B	109.5
O1—C6—C7	109.8 (3)	H18A—C18—H18B	109.5
C2—C6—C7	130.6 (3)	C17—C18—H18C	109.5
C4—C7—C10	126.6 (3)	H18A—C18—H18C	109.5
C4—C7—C6	108.7 (3)	H18B—C18—H18C	109.5
C10—C7—C6	124.6 (3)	C19—C20—C21	119.1 (3)
C5—C8—H8A	109.5	C19—C20—H20	120.5
C5—C8—H8B	109.5	C21—C20—H20	120.5
H8A—C8—H8B	109.5	C22—C21—C20	120.0 (3)
C5—C8—H8C	109.5	C22—C21—H21	120.0
H8A—C8—H8C	109.5	C20—C21—H21	120.0
H8B—C8—H8C	109.5	C23—C22—C21	119.9 (3)
C5—C9—H9A	109.5	C23—C22—H22	120.1
C5—C9—H9B	109.5	C21—C22—H22	120.1
H9A—C9—H9B	109.5	C22—C23—C24	121.2 (3)
C5—C9—H9C	109.5	C22—C23—H23	119.4
H9A—C9—H9C	109.5	C24—C23—H23	119.4
H9B—C9—H9C	109.5	C19—C24—C23	118.7 (3)
N3—C10—C7	177.9 (3)	C19—C24—H24	120.7
C12—C11—C4	127.6 (3)	C23—C24—H24	120.7
C12—C11—H11	116.2	C20—C19—C24	121.2 (3)
C4—C11—H11	116.2	C20—C19—N4	119.0 (3)
C11—C12—C13	122.2 (3)	C24—C19—N4	119.8 (3)
C6—O1—C5—C4	−3.0 (3)	C5—C4—C11—C12	−177.2 (3)
C6—O1—C5—C8	−123.1 (3)	C4—C11—C12—C13	−175.7 (3)
C6—O1—C5—C9	116.0 (3)	C11—C12—C13—C14	−177.6 (3)
C7—C4—C5—O1	4.3 (3)	C12—C13—C14—C15	−179.5 (3)
C11—C4—C5—O1	−173.8 (2)	C13—C14—C15—C16	−178.8 (3)
C7—C4—C5—C8	118.8 (3)	C14—C15—C16—N4	−178.8 (2)
C11—C4—C5—C8	−59.3 (3)	C17—N4—C16—C15	−174.6 (3)
C7—C4—C5—C9	−111.2 (3)	C19—N4—C16—C15	7.6 (4)
C11—C4—C5—C9	70.7 (3)	C16—N4—C17—O2	5.0 (4)
C5—O1—C6—C2	178.6 (2)	C19—N4—C17—O2	−177.3 (3)
C5—O1—C6—C7	0.7 (3)	C16—N4—C17—C18	−175.7 (3)
C1—C2—C6—O1	173.3 (3)	C19—N4—C17—C18	2.0 (4)
C3—C2—C6—O1	−7.0 (4)	C19—C20—C21—C22	0.1 (5)
C1—C2—C6—C7	−9.3 (5)	C20—C21—C22—C23	1.0 (5)
C3—C2—C6—C7	170.4 (3)	C21—C22—C23—C24	−0.8 (5)
C11—C4—C7—C10	−2.8 (5)	C22—C23—C24—C19	−0.5 (5)
C5—C4—C7—C10	179.5 (3)	C21—C20—C19—C24	−1.4 (5)
C11—C4—C7—C6	173.7 (3)	C21—C20—C19—N4	177.2 (3)
C5—C4—C7—C6	−4.1 (3)	C23—C24—C19—C20	1.6 (5)
O1—C6—C7—C4	2.2 (3)	C23—C24—C19—N4	−177.0 (3)
C2—C6—C7—C4	−175.4 (3)	C17—N4—C19—C20	−97.7 (3)
O1—C6—C7—C10	178.8 (3)	C16—N4—C19—C20	80.1 (3)
C2—C6—C7—C10	1.2 (5)	C17—N4—C19—C24	81.0 (4)
C7—C4—C11—C12	5.2 (5)	C16—N4—C19—C24	−101.3 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C15—H15···N1^i	0.95	2.57	3.466 (4)	156
C9—H9A···O2^ii	0.98	2.37	3.277 (4)	153
C20—H20···O2^iii	0.95	2.42	3.355 (4)	167

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