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A neutron diffraction study of the non-linear optical (NLO) material 4-nitro-4′-methylbenzylidene aniline (NMBA) is presented. NMBA exhibits a large macroscopic second-order NLO susceptibility, χ
(2), and this study shows that hydrogen bonding is, in part, responsible for this. No hydrogen bonding was reported in the X-ray study [Ponomarev
et al. (1977).
Sov. Phys. Crystallogr. 22, 223–225], whereas the present work shows that C—H
X hydrogen bonds (where
X = N, O or π) direct the nature of the three-dimensional lattice. C—H
X (
X = N or O) hydrogen bonds are common; however, C—H
π hydrogen-bond motifs are relatively rare. Such intermolecular interactions help extend the molecular charge transfer into the supramolecular realm, the charge transfer originating as a consequence of the high level of molecular planarity and strong donor-to-acceptor interactions. Molecular planarity, coupled with the favourable nature of the hydrogen bonds, results in parallel stacking of molecules in both the
a and
c crystallographic directions with extremely close interplanar spacings. Such a combination of influential hydrogen-bonding characteristics accounts, in part, for the large second-order NLO output of the material since the phenomenon is so critically dependent upon the nature of the charge transfer.
Supporting information
CCDC reference: 166521
Alert A: < 85% complete (theta max?) revealed: given that this is a neutron
structure, completeness is much more resources demanding and is not necessary
since monochromatic neutron diffraction is intrinsically much more precise
than analogous XRD measurements. The completeness given here for this
experiment is satisfactory.
Data collection: MAD (Barthelemy, 1984); cell refinement: RAFIN (Fihol, 198?); data reduction: COLL5N (Lehmann & Wilson, 198?); program(s) used to solve structure: SHELXS86 (Sheldrick, 1990); program(s) used to refine structure: SHELXL93 (Sheldrick, 1993); molecular graphics: SHELXTL-Plus (Sheldrick, 1995); software used to prepare material for publication: SHELXL93 (Sheldrick, 1993).
Crystal data top
C14H12N2O2 | F(000) = 184 |
Mr = 240.00 | Dx = 1.393 Mg m−3 |
Monoclinic, Pc | Neutrons radiation, λ = 1.26170 Å |
a = 7.305 (4) Å | Cell parameters from 1349 reflections |
b = 11.495 (5) Å | θ = 15.4–70.4° |
c = 7.240 (3) Å | µ = 0.18 mm−1 |
β = 109.71 (5)° | T = 20 K |
V = 572.3 (5) Å3 | Block, yellow |
Z = 2 | 5.3 × 2.1 × 1.2 mm |
Data collection top
The single-crystal diffractometer, D10 | 1304 reflections with I > 2σ(I) |
Radiation source: Institut Laue Langevin Reactor, Grenoble, France | Rint = 0.017 |
Cu (200) monochromator | θmax = 70.4°, θmin = 15.5° |
ω–x–θ scans | h = −4→10 |
Absorption correction: integration DATAP (Coppens, 1970) | k = −16→16 |
Tmin = 0.618, Tmax = 0.806 | l = −10→10 |
1877 measured reflections | 1 standard reflections every 50 reflections |
1349 independent reflections | intensity decay: none |
Refinement top
Refinement on F2 | Hydrogen site location: inferred from neighbouring sites |
Least-squares matrix: full | All H-atom parameters refined |
R[F2 > 2σ(F2)] = 0.031 | Calculated w = 1/[σ2(Fo2) + (0.P)2] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.047 | (Δ/σ)max = −0.002 |
S = 1.96 | Δρmax = 0.52 e Å−3 |
1349 reflections | Δρmin = −0.50 e Å−3 |
272 parameters | Extinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
2 restraints | Extinction coefficient: 0.0071 (6) |
Primary atom site location: structure-invariant direct methods | Absolute structure: Flack H D (1983), Acta Cryst. A39, 876-881 |
Secondary atom site location: difference Fourier map | |
Crystal data top
C14H12N2O2 | V = 572.3 (5) Å3 |
Mr = 240.00 | Z = 2 |
Monoclinic, Pc | Neutrons radiation, λ = 1.26170 Å |
a = 7.305 (4) Å | µ = 0.18 mm−1 |
b = 11.495 (5) Å | T = 20 K |
c = 7.240 (3) Å | 5.3 × 2.1 × 1.2 mm |
β = 109.71 (5)° | |
Data collection top
The single-crystal diffractometer, D10 | 1304 reflections with I > 2σ(I) |
Absorption correction: integration DATAP (Coppens, 1970) | Rint = 0.017 |
Tmin = 0.618, Tmax = 0.806 | 1 standard reflections every 50 reflections |
1877 measured reflections | intensity decay: none |
1349 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.031 | 2 restraints |
wR(F2) = 0.047 | All H-atom parameters refined |
S = 1.96 | Δρmax = 0.52 e Å−3 |
1349 reflections | Δρmin = −0.50 e Å−3 |
272 parameters | Absolute structure: Flack H D (1983), Acta Cryst. A39, 876-881 |
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 on F2 for ALL reflections except for 0 with very negative
F2 or flagged by the user for potential systematic errors. Weighted
R-factors wR and all goodnesses of fit S are based on
F2, conventional R-factors R are based on F,
with F set to zero for negative F2. The observed criterion of
F2 > σ(F2) is used only for calculating R factor obs
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 | |
O1 | 1.1583 (4) | 0.9665 (2) | 0.6238 (3) | 0.0110 (4) | |
O2 | 1.2740 (4) | 0.8444 (2) | 0.4654 (3) | 0.0119 (4) | |
N1 | 0.3211 (2) | 0.70490 (12) | −0.1104 (2) | 0.0094 (3) | |
N2 | 1.1386 (2) | 0.89530 (12) | 0.4911 (2) | 0.0088 (2) | |
C1 | 0.6025 (3) | 0.9190 (2) | 0.2429 (2) | 0.0092 (4) | |
H1 | 0.4839 (10) | 0.9739 (5) | 0.2458 (7) | 0.0252 (10) | |
C2 | 0.5666 (3) | 0.8224 (2) | 0.1178 (2) | 0.0080 (4) | |
C3 | 0.7216 (3) | 0.7515 (2) | 0.1144 (2) | 0.0086 (4) | |
H3 | 0.6917 (9) | 0.6769 (4) | 0.0175 (6) | 0.0238 (10) | |
C4 | 0.9103 (3) | 0.7756 (2) | 0.2343 (2) | 0.0098 (4) | |
H4 | 1.0315 (9) | 0.7204 (5) | 0.2348 (7) | 0.0234 (10) | |
C5 | 0.9411 (3) | 0.8711 (2) | 0.3590 (2) | 0.0080 (3) | |
C6 | 0.7914 (3) | 0.9435 (2) | 0.3662 (2) | 0.0089 (4) | |
H6 | 0.8204 (10) | 1.0171 (5) | 0.4679 (7) | 0.0245 (10) | |
C7 | 0.3647 (3) | 0.7962 (2) | −0.0035 (2) | 0.0095 (4) | |
H7 | 0.2563 (8) | 0.8591 (5) | 0.0066 (7) | 0.0317 (11) | |
C8 | 0.1248 (3) | 0.6796 (2) | −0.2231 (2) | 0.0083 (4) | |
C9 | −0.0368 (3) | 0.7430 (2) | −0.2187 (2) | 0.0089 (4) | |
H9 | −0.0191 (10) | 0.8193 (5) | −0.1247 (7) | 0.0260 (10) | |
C10 | −0.2240 (3) | 0.7103 (2) | −0.3347 (2) | 0.0089 (4) | |
H10 | −0.3498 (9) | 0.7602 (5) | −0.3301 (7) | 0.0241 (10) | |
C11 | −0.2561 (3) | 0.6131 (2) | −0.4583 (2) | 0.0082 (3) | |
C12 | −0.0932 (3) | 0.5502 (2) | −0.4630 (2) | 0.0086 (4) | |
H12 | −0.1130 (9) | 0.4759 (5) | −0.5613 (7) | 0.0243 (10) | |
C13 | 0.0939 (3) | 0.5823 (2) | −0.3474 (2) | 0.0092 (4) | |
H13 | 0.2202 (9) | 0.5336 (5) | −0.3523 (7) | 0.0256 (10) | |
C14 | −0.4582 (4) | 0.5789 (2) | −0.5840 (2) | 0.0108 (4) | |
H14A | −0.4956 (11) | 0.4918 (5) | −0.5537 (8) | 0.0388 (14) | |
H14B | −0.4754 (12) | 0.5801 (7) | −0.7399 (6) | 0.041 (2) | |
H14C | −0.5674 (11) | 0.6380 (7) | −0.5675 (9) | 0.041 (2) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.0123 (11) | 0.0075 (10) | 0.0127 (7) | −0.0009 (9) | 0.0035 (7) | −0.0027 (6) |
O2 | 0.0091 (12) | 0.0123 (10) | 0.0142 (7) | 0.0002 (9) | 0.0036 (7) | −0.0008 (6) |
N1 | 0.0086 (8) | 0.0075 (6) | 0.0114 (5) | −0.0004 (6) | 0.0027 (5) | −0.0016 (4) |
N2 | 0.0098 (7) | 0.0061 (6) | 0.0113 (4) | −0.0009 (5) | 0.0045 (4) | −0.0001 (4) |
C1 | 0.0102 (11) | 0.0046 (8) | 0.0125 (6) | 0.0009 (8) | 0.0037 (7) | −0.0017 (5) |
H1 | 0.019 (3) | 0.022 (2) | 0.033 (2) | 0.008 (2) | 0.007 (2) | −0.0071 (15) |
C2 | 0.0088 (11) | 0.0047 (7) | 0.0103 (6) | −0.0005 (7) | 0.0030 (7) | −0.0008 (5) |
C3 | 0.0093 (11) | 0.0049 (9) | 0.0119 (6) | −0.0004 (8) | 0.0039 (7) | −0.0015 (5) |
H3 | 0.025 (3) | 0.018 (2) | 0.026 (2) | 0.001 (2) | 0.005 (2) | −0.0089 (14) |
C4 | 0.0109 (11) | 0.0081 (9) | 0.0114 (6) | −0.0004 (8) | 0.0051 (7) | −0.0011 (5) |
H4 | 0.018 (3) | 0.021 (2) | 0.031 (2) | 0.003 (2) | 0.008 (2) | −0.0051 (14) |
C5 | 0.0084 (10) | 0.0053 (8) | 0.0109 (6) | −0.0007 (7) | 0.0040 (6) | 0.0001 (5) |
C6 | 0.0091 (11) | 0.0058 (8) | 0.0119 (6) | 0.0010 (7) | 0.0037 (7) | −0.0006 (5) |
H6 | 0.025 (3) | 0.016 (2) | 0.032 (2) | −0.001 (2) | 0.010 (2) | −0.0091 (14) |
C7 | 0.0093 (11) | 0.0053 (8) | 0.0123 (6) | −0.0006 (8) | 0.0016 (7) | −0.0022 (5) |
H7 | 0.014 (3) | 0.027 (3) | 0.049 (2) | 0.004 (2) | 0.003 (2) | −0.015 (2) |
C8 | 0.0088 (11) | 0.0061 (8) | 0.0102 (6) | 0.0000 (8) | 0.0032 (6) | −0.0003 (5) |
C9 | 0.0081 (10) | 0.0067 (9) | 0.0119 (6) | 0.0005 (7) | 0.0035 (6) | −0.0014 (5) |
H9 | 0.024 (3) | 0.023 (2) | 0.031 (2) | 0.002 (2) | 0.008 (2) | −0.010 (2) |
C10 | 0.0089 (11) | 0.0051 (8) | 0.0124 (6) | −0.0003 (7) | 0.0033 (6) | −0.0001 (5) |
H10 | 0.022 (3) | 0.017 (2) | 0.034 (2) | 0.004 (2) | 0.010 (2) | −0.0054 (13) |
C11 | 0.0083 (10) | 0.0059 (7) | 0.0103 (6) | −0.0001 (7) | 0.0027 (6) | −0.0003 (5) |
C12 | 0.0091 (11) | 0.0055 (9) | 0.0109 (6) | −0.0003 (8) | 0.0028 (6) | −0.0018 (5) |
H12 | 0.023 (3) | 0.018 (2) | 0.028 (2) | −0.002 (2) | 0.005 (2) | −0.0118 (13) |
C13 | 0.0095 (11) | 0.0066 (8) | 0.0114 (6) | 0.0004 (7) | 0.0032 (7) | −0.0012 (5) |
H13 | 0.023 (3) | 0.023 (2) | 0.033 (2) | 0.004 (2) | 0.011 (2) | −0.0072 (15) |
C14 | 0.0104 (11) | 0.0082 (9) | 0.0124 (6) | −0.0019 (8) | 0.0019 (6) | 0.0003 (5) |
H14A | 0.028 (4) | 0.025 (3) | 0.051 (2) | −0.013 (3) | −0.002 (2) | 0.012 (2) |
H14B | 0.043 (4) | 0.062 (4) | 0.0186 (15) | −0.015 (3) | 0.009 (2) | −0.001 (2) |
H14C | 0.015 (3) | 0.039 (4) | 0.059 (3) | 0.009 (3) | 0.001 (2) | −0.022 (2) |
Geometric parameters (Å, º) top
O1—N2 | 1.233 (2) | C7—H7 | 1.093 (6) |
O2—N2 | 1.216 (3) | C8—C9 | 1.397 (3) |
N1—C7 | 1.278 (2) | C8—C13 | 1.405 (3) |
N1—C8 | 1.420 (3) | C9—C10 | 1.394 (3) |
N2—C5 | 1.464 (3) | C9—H9 | 1.091 (5) |
C1—C6 | 1.396 (3) | C10—C11 | 1.402 (3) |
C1—C2 | 1.401 (3) | C10—H10 | 1.093 (6) |
C1—H1 | 1.078 (6) | C11—C12 | 1.402 (3) |
C2—C3 | 1.402 (3) | C11—C14 | 1.502 (4) |
C2—C7 | 1.471 (3) | C12—C13 | 1.390 (3) |
C3—C4 | 1.387 (4) | C12—H12 | 1.089 (5) |
C3—H3 | 1.083 (4) | C13—H13 | 1.091 (6) |
C4—C5 | 1.390 (3) | C14—H14A | 1.081 (6) |
C4—H4 | 1.088 (6) | C14—H14B | 1.093 (4) |
C5—C6 | 1.389 (3) | C14—H14C | 1.084 (7) |
C6—H6 | 1.095 (5) | | |
| | | |
C7—N1—C8 | 120.9 (1) | C9—C8—C13 | 118.4 (2) |
O2—N2—O1 | 123.5 (2) | C9—C8—N1 | 125.3 (2) |
O2—N2—C5 | 118.8 (2) | C13—C8—N1 | 116.4 (2) |
O1—N2—C5 | 117.7 (2) | C10—C9—C8 | 120.7 (2) |
C6—C1—C2 | 120.1 (2) | C10—C9—H9 | 118.6 (4) |
C6—C1—H1 | 119.8 (3) | C8—C9—H9 | 120.7 (4) |
C2—C1—H1 | 120.0 (4) | C9—C10—C11 | 121.2 (2) |
C1—C2—C3 | 119.7 (2) | C9—C10—H10 | 120.3 (3) |
C1—C2—C7 | 118.7 (2) | C11—C10—H10 | 118.4 (3) |
C3—C2—C7 | 121.6 (2) | C10—C11—C12 | 117.8 (2) |
C4—C3—C2 | 120.8 (2) | C10—C11—C14 | 120.9 (2) |
C4—C3—H3 | 120.3 (4) | C12—C11—C14 | 121.3 (2) |
C2—C3—H3 | 119.0 (4) | C13—C12—C11 | 121.2 (2) |
C3—C4—C5 | 118.2 (2) | C13—C12—H12 | 119.2 (4) |
C3—C4—H4 | 121.4 (3) | C11—C12—H12 | 119.5 (4) |
C5—C4—H4 | 120.3 (4) | C12—C13—C8 | 120.7 (2) |
C6—C5—C4 | 122.7 (2) | C12—C13—H13 | 121.0 (3) |
C6—C5—N2 | 118.5 (2) | C8—C13—H13 | 118.3 (4) |
C4—C5—N2 | 118.8 (2) | C11—C14—H14A | 112.5 (4) |
C5—C6—C1 | 118.4 (2) | C11—C14—H14B | 111.7 (5) |
C5—C6—H6 | 120.8 (4) | H14A—C14—H14B | 105.8 (5) |
C1—C6—H6 | 120.7 (4) | C11—C14—H14C | 112.3 (4) |
N1—C7—C2 | 121.6 (2) | H14A—C14—H14C | 108.2 (6) |
N1—C7—H7 | 123.0 (3) | H14B—C14—H14C | 105.9 (6) |
C2—C7—H7 | 115.3 (3) | | |
Experimental details
Crystal data |
Chemical formula | C14H12N2O2 |
Mr | 240.00 |
Crystal system, space group | Monoclinic, Pc |
Temperature (K) | 20 |
a, b, c (Å) | 7.305 (4), 11.495 (5), 7.240 (3) |
β (°) | 109.71 (5) |
V (Å3) | 572.3 (5) |
Z | 2 |
Radiation type | Neutrons, λ = 1.26170 Å |
µ (mm−1) | 0.18 |
Crystal size (mm) | 5.3 × 2.1 × 1.2 |
|
Data collection |
Diffractometer | The single-crystal diffractometer, D10 |
Absorption correction | Integration DATAP (Coppens, 1970) |
Tmin, Tmax | 0.618, 0.806 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 1877, 1349, 1304 |
Rint | 0.017 |
(sin θ/λ)max (Å−1) | 0.747 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.031, 0.047, 1.96 |
No. of reflections | 1349 |
No. of parameters | 272 |
No. of restraints | 2 |
H-atom treatment | All H-atom parameters refined |
Δρmax, Δρmin (e Å−3) | 0.52, −0.50 |
Absolute structure | Flack H D (1983), Acta Cryst. A39, 876-881 |
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