2-(3-Cyano-4-methyl-5,5-diphenyl-5H-furan-2-yl­idene)malono­nitrile

M Delower H Bhuiyan; Graeme J Gainsford; Andrew Kay; Jack Anderson

doi:10.1107/S1600536813020849

. 2013 Aug 3;69(Pt 9):o1365–o1366. doi: 10.1107/S1600536813020849

2-(3-Cyano-4-methyl-5,5-diphenyl-5H-furan-2-ylidene)malononitrile

M Delower H Bhuiyan ^a, Graeme J Gainsford ^a,^*, Andrew Kay ^a, Jack Anderson ^b

PMCID: PMC3884449 PMID: 24427012

Abstract

The title compound, C₂₁H₁₃N₃O, crystallizes with two independent molecules with similar conformations per asymmetric unit. The dihydrofuran rings are essentially planar with maximum deviations of 0.017 (1) and 0.006 (1) Å for the O atoms. The dihedral angles between the dihydrofuran ring and the attached phenyl rings are 79.90 (6) and 82.07 (6)° in one molecule and 79.36 (6) and 72.26 (6)° in the other. In the crystal, the molecules are linked by weak C—H⋯π and C—H⋯N interactions similar to those in other closely related crystals. The replacement of appended methyl by phenyl groups has not significantly affected the dihydrofuran ring structure or the crystal packing interactions.

Related literature

For general background to NLO chromophores, see: Smith et al. (2006 ▶, 2010 ▶); Carey et al. (2002 ▶); Kay et al. (2004 ▶). For details of the synthesis, see: Anderson (2009 ▶). For related structures, see: Anderson (2009 ▶); Gainsford et al. (2011 ▶); Li et al. (2005 ▶); Liao et al. (2005 ▶). For geometric analysis of structures, see: Spek (2009 ▶). For a description of the Cambridge Structural Database, see: Allen (2002 ▶).

Experimental

Crystal data

C₂₁H₁₃N₃O
M _r = 323.34
Triclinic,
a = 9.2308 (3) Å
b = 12.5991 (4) Å
c = 14.3043 (4) Å
α = 89.954 (2)°
β = 89.052 (2)°
γ = 79.233 (2)°
V = 1634.07 (9) Å³
Z = 4
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 123 K
0.36 × 0.32 × 0.29 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.651, T _max = 0.746
45305 measured reflections
9930 independent reflections
7329 reflections with I > 2σ(I)
R _int = 0.042

Refinement

R[F ² > 2σ(F ²)] = 0.045
wR(F ²) = 0.119
S = 1.04
9930 reflections
453 parameters
H-atom parameters constrained
Δρ_max = 0.35 e Å⁻³
Δρ_min = −0.24 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT (Bruker, 2005 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012 ▶) and Mercury (Macrae et al., 2006 ▶); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536813020849/rz5081sup1.cif

e-69-o1365-sup1.cif^{(28.7KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536813020849/rz5081Isup2.hkl

e-69-o1365-Isup2.hkl^{(475.8KB, hkl)}

Click here for additional data file.^{(6.1KB, cml)}

Supplementary material file. DOI: 10.1107/S1600536813020849/rz5081Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

Cg1 is the centroid of the C10–C15 phenyl ring

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C20′—H20′⋯Cg1ⁱ	0.95	2.69	3.4041 (14)	133
C9—H9B⋯N3′	0.98	2.70	3.4560 (14)	134

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Symmetry code: (i) Inline graphic .

Acknowledgments

This work was supported by a New Zealand Foundation for Research Science and Technology grant (contract No. C08X0704). We thank Dr C. Fitchett of the University of Canterbury, New Zealand, for his assistance.

supplementary crystallographic information

1. Comment

Organic non-linear optical (NLO) chromophores consist of donor and acceptor units connecting through π-conjugation. To realise a strong NLO response, chromophores need to be in uniform alignment. Unfortunately organic chromophores have a tendency to aggregate rather than align due to their highly polar nature (Smith et al., 2006). These push-pull chromophores can also exist as two rotomeric (cis and trans) forms (Kay et al., 2004). As a result, these chromophores are difficult to crystallize, therefore they may not be able to be used in devices that require crystals such as terahertz wave emitters (Carey et al., 2002). Consequently it is of interest to design and synthesize molecules which will be much less prone to aggregation and isomerization. It has been found that through changing the shape of the chromophore molecules, aggregation can be minimized. The most successful strategy has been to add bulky pendant groups onto the donor end (Smith et al., 2010). We have reported our previous attempts with two benzyloxyphenyl groups (Gainsford et al., 2011; Anderson, 2009) and report here the structure of a related acceptor unit with two phenyl groups.

The asymmetric unit of the title compound (I) contains two independent, nearly identical, 2-(3-cyano-4-methyl-5,5-diphenyl-5H-furan-2-ylidene)malononitrile molecules (Fig. 1). The second molecule (1') has identical labels with an appended prime (e.g. C10 and C10'); the r.m.s. bond and angle fits are 0.003 Å and 0.48° (Spek, 2009). The five-membered dihydrofuran rings (atoms C4-C7/O1, hereafter plane 1) are planar (maximum deviation 0.017 (1) Å for O1) with the appended cyano groups almost coplanar (maximum deviation 0.093 (1) Å for N1). The 5,5-dimethyl adduct (Li et al., 2005; CSD refcode PANLUM), in which plane 1 was constrained to a crystallographic mirror plane, has identical ring dimensions with the exception of the C4–C5 bond which is just significantly longer here (by 0.013 (4) Å). This marginally longer distance seems the exception and is not observed in related molecules [Allen (2002); CSD version 5.34 with May 2013 updates: e.g. KAJCII and KATCEE, 1.518 and 1.536, 1.537 Å respectively (Liao et al., 2005); YAHKUP 1.512 Å (Gainsford et al., 2011)].

The only significant conformational differences between the two molecules concern the interplanar angles between the phenyl rings and plane 1, corresponding to the different torsion angles (C4–C5–C10–C15 = -21.21 (15)°; O1–C5–C16–C17 = -30.62 (13)°; C4'–C5'–C10'–C15' = -30.22 (14)°; O1'–C5'–C16'–C17' = -21.91 (15)°). The plane 1 angle to phenyl plane (C10–C15) is 79.90 (6) and 82.07 (6)° for molecules 1 and 1' while the other phenyl plane (C16–C21) makes interplane angle of 79.36 (6) and 72.26 (6)° for molecules 1 and 1'.

Lattice binding is provided mainly by one non-classical C–H···π interaction (Table 1, Figure 2 where Cg1 is the centroid of the C10–C15 ring), the dominant binding interaction type in related compound YAHKUP (Gainsford et al., 2011). As in PANLUM, a weak methylC–H···N(cyano) interaction is observed. Other C–H···N(cyano), C–H···π and cyano···cyano very weak interactions even closer to van der Waal's contact distances are also present. Overall, the effect of the phenyl for methyl replacement on C5 has given insignificant molecular structural and cystal packing alignment affects.

2. Experimental

The title compound was prepared by the condensation of 1-hydroxy-1,1-diphenylpropan-2-one with 4 equivalents of malononitrile over 10 days as described in Anderson (2009). A small portion was recrystallized in dichloromethane and acetone (1:1) mixture to give colourless crystals. M.p. 223 °C. Found: C, 77.70; H, 3.91; N, 13.06, C₂₁H₁₃N₃O requires C, 78.00; H, 4.05; N, 13.00%. Found: M⁺ m/z 323.1059 C₂₁H₁₃N₃O requires: M+ m/z 323.1056 (Δ 0.9 p.p.m.). ¹H NMR– (300 MHz, CDCl₃) δ (p.p.m.): 2.41 (s, 3H), 7.18 (d, J 9.6 Hz, 4H), 7.51–7.47 (m, 6H). ¹³C NMR– (75 MHz, CDCl₃) δ (p.p.m.): 16.2 (CH₃), 59.5 (C_Q), 105.6 (C_Q), 106.4 (C_Q), 109.0 (C_Q), 110.2 (C_Q), 110.7 (C_Q), 127.3 (CH), 129.5 (CH), 130.6 (CH), 134.9 (C_Q), 175.1 (C_Q), 180.2 (C_Q).