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Acta Crystallogr Sect E Struct Rep Online. 2008 August 1; 64(Pt 8): o1447.
Published online 2008 July 9. doi:  10.1107/S160053680802076X
PMCID: PMC2962078

A monoclinic polymorph of N,N′-bis­(2,6-diisopropyl­phen­yl)formamidine

Abstract

A new polymorph of N,N′-bis­(2,6-diisopropyl­phen­yl)formamidine, C25H36N2, is reported, which is different from the previously reported ortho­rhom­bic structure. The mol­ecule crystallizes in the Eanti configuration, with tautomeric disorder of the N-bonded H atoms and no clear distinction between imine and amine functionalities. The mol­ecules form hydrogen-bonded dimers with inter­molecular N(...)N distances shorter than those in the ortho­rhom­bic polymorph.

Related literature

For the ortho­rhom­bic polymorph, see: Stibrany & Potenza (2006 [triangle]). For synthetic details and related literature, see: Krahulic et al. (2005 [triangle]); Perrin (1991 [triangle]).

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Object name is e-64-o1447-scheme1.jpg

Experimental

Crystal data

  • C25H36N2
  • M r = 364.56
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-64-o1447-efi1.jpg
  • a = 24.169 (4) Å
  • b = 12.7881 (18) Å
  • c = 19.479 (3) Å
  • β = 126.735 (2)°
  • V = 4824.8 (12) Å3
  • Z = 8
  • Mo Kα radiation
  • μ = 0.06 mm−1
  • T = 291 (2) K
  • 0.45 × 0.34 × 0.30 mm

Data collection

  • Bruker SMART 1K CCD diffractometer
  • Absorption correction: none
  • 12048 measured reflections
  • 4242 independent reflections
  • 2237 reflections with I > 2σ(I)
  • R int = 0.036

Refinement

  • R[F 2 > 2σ(F 2)] = 0.051
  • wR(F 2) = 0.161
  • S = 1.02
  • 4242 reflections
  • 252 parameters
  • H-atom parameters constrained
  • Δρmax = 0.18 e Å−3
  • Δρmin = −0.17 e Å−3

Data collection: SMART (Bruker, 2003 [triangle]); cell refinement: SAINT (Bruker, 2003 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 [triangle]); software used to prepare material for publication: publCIF (Westrip, 2008 [triangle]).

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S160053680802076X/bi2287sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S160053680802076X/bi2287Isup2.hkl

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

Acknowledgments

The author thanks Saint Mary’s University for funding.

supplementary crystallographic information

Comment

Crystals of the title compound were grown from toluene solution and were found to crystallize in the monoclinic space group C2/c, different from the previously published polymorph which crystallizes in the orthorhombic space group C2221 (Stibrany & Potenza, 2006). The molecule crystallizes in the E-anti configuration (Perrin, 1991), with tautomeric disorder of the N-bonded H atoms. The molecules form hydrogen-bonded dimers with N···N distances of 2.882 (4) and 2.910 (3) Å (Table 1). These distances are slightly shorter than that seen in the orthorhombic polymorph (2.947 Å). The two core amidine (NCNH) fragments are non-coplanar as a result of interaction between the sterically bulky 2,6-diisopropylphenyl fragments. The N1—C(1) (1.313 (3) Å) and N2—C1 (1.311 (3) Å) distances are similar in length, whereas in the orthorhombic polymorph there are distinct imine (1.288 Å) and amine (1.325 Å) functionalities.

Experimental

The title compound was prepared according to the literature procedure (Krahulic et al., 2005). Crystals were grown by evaporation of a toluene solution at room temperature.

Refinement

H atoms bonded to C and N atoms were refined in geometrically idealized positions with the riding-model approximation. The difference map showed equivalent electron density for the H atoms bonded to the formamidine N atoms. Thus, the H atom was refined as disordered over two positions, each with site occupancy factor 0.5.

Figures

Fig. 1.
Molecular structure showing displacement ellipsoids at the 30% probability level for non-H atoms. H atoms bound to C (except for H1) are omitted, and only one of the disordered H atoms (H1A & H1B) is shown.
Fig. 2.
A plot of the hydrogen-bonded dimer in the title compound, showing displacement ellipsoids at the 30% probability level for non-H atoms. H atoms bound to C (except for H1) are omitted, and only one of the disordered H atoms (H1A & H1B) is shown. ...

Crystal data

C25H36N2F000 = 1600
Mr = 364.56Dx = 1.004 Mg m3
Monoclinic, C2/cMo Kα radiation λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 2205 reflections
a = 24.169 (4) Åθ = 2.6–21.8º
b = 12.7881 (18) ŵ = 0.06 mm1
c = 19.479 (3) ÅT = 291 (2) K
β = 126.735 (2)ºBlock, colourless
V = 4824.8 (12) Å30.45 × 0.34 × 0.30 mm
Z = 8

Data collection

Bruker SMART 1K CCD diffractometer2237 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.036
Monochromator: graphiteθmax = 25.0º
T = 291(2) Kθmin = 2.1º
[var phi] and ω scansh = −28→28
Absorption correction: nonek = −7→15
12048 measured reflectionsl = −23→23
4242 independent reflections

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.051H-atom parameters constrained
wR(F2) = 0.161  w = 1/[σ2(Fo2) + (0.065P)2 + 2.1873P] where P = (Fo2 + 2Fc2)/3
S = 1.02(Δ/σ)max < 0.001
4242 reflectionsΔρmax = 0.18 e Å3
252 parametersΔρmin = −0.17 e Å3
Primary atom site location: structure-invariant direct methodsExtinction correction: none

Special details

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)

xyzUiso*/UeqOcc. (<1)
N20.02590 (9)0.18752 (13)0.69910 (11)0.0465 (5)
H2A0.01130.19190.72990.056*0.50
N10.00186 (10)0.01071 (13)0.67743 (12)0.0502 (5)
H1A−0.00420.00870.71670.060*0.50
C2−0.00791 (13)−0.08218 (17)0.63024 (16)0.0509 (6)
C10.01996 (11)0.09893 (17)0.66139 (14)0.0468 (6)
H10.02900.09850.62120.056*
C140.05632 (11)0.27673 (17)0.68974 (14)0.0463 (6)
C150.01510 (13)0.36571 (18)0.64789 (15)0.0554 (6)
C190.12706 (12)0.27631 (19)0.72640 (16)0.0569 (6)
C70.03995 (14)−0.16434 (18)0.67252 (17)0.0607 (7)
C3−0.06573 (14)−0.0910 (2)0.54441 (16)0.0612 (7)
C110.10007 (15)−0.1590 (2)0.76716 (17)0.0705 (8)
H11A0.0904−0.10150.79170.085*
C8−0.12183 (15)−0.0076 (2)0.50015 (18)0.0746 (8)
H8A−0.10930.04740.54220.090*
C60.03099 (18)−0.2520 (2)0.6239 (2)0.0797 (9)
H6A0.0627−0.30640.64990.096*
C4−0.07140 (17)−0.1813 (2)0.50041 (19)0.0781 (9)
H4A−0.1090−0.18840.44320.094*
C20−0.06095 (13)0.3655 (2)0.60888 (18)0.0692 (8)
H20A−0.06730.31220.63970.083*
C160.04601 (16)0.4528 (2)0.64050 (19)0.0776 (8)
H16A0.01960.51200.61200.093*
C170.11450 (18)0.4525 (2)0.6744 (2)0.0902 (10)
H17A0.13410.51130.66880.108*
C230.17226 (13)0.1832 (2)0.77905 (18)0.0719 (8)
H23A0.14490.12000.75020.086*
C180.15455 (15)0.3660 (2)0.7168 (2)0.0803 (9)
H18A0.20110.36730.73960.096*
C5−0.0236 (2)−0.2596 (2)0.5387 (2)0.0874 (10)
H5A−0.0279−0.31790.50720.105*
C250.23851 (14)0.1727 (3)0.7863 (2)0.0935 (10)
H25A0.22760.17490.73020.140*
H25B0.26050.10740.81330.140*
H25C0.26910.22930.82010.140*
C130.10778 (19)−0.2581 (3)0.8163 (2)0.1084 (12)
H13A0.1433−0.24780.87640.163*
H13B0.1200−0.31580.79630.163*
H13C0.0649−0.27300.80710.163*
C120.16764 (18)−0.1332 (3)0.7815 (2)0.1097 (12)
H12A0.1630−0.06820.75390.165*
H12B0.1788−0.18790.75790.165*
H12C0.2038−0.12730.84180.165*
C10−0.12660 (19)0.0421 (3)0.4259 (2)0.1045 (11)
H10A−0.08230.06970.44610.157*
H10B−0.15990.09760.40210.157*
H10C−0.1406−0.00970.38270.157*
C240.18908 (18)0.1848 (3)0.8679 (2)0.1184 (14)
H24A0.14700.18160.86270.178*
H24B0.21330.24820.89680.178*
H24C0.21750.12580.90020.178*
C21−0.08718 (19)0.4678 (3)0.6196 (3)0.1195 (13)
H21A−0.05740.48920.67850.179*
H21B−0.13320.45810.60260.179*
H21C−0.08750.52070.58440.179*
C9−0.19216 (18)−0.0515 (3)0.4695 (3)0.1260 (14)
H9A−0.1900−0.07400.51810.189*
H9B−0.2038−0.10990.43210.189*
H9C−0.22670.00180.43920.189*
C22−0.10306 (17)0.3317 (4)0.5178 (2)0.1415 (17)
H22A−0.08550.26660.51350.212*
H22B−0.10070.38390.48420.212*
H22C−0.15020.32260.49690.212*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
N20.0542 (12)0.0376 (11)0.0561 (12)−0.0011 (9)0.0376 (10)−0.0006 (9)
N10.0740 (14)0.0368 (11)0.0566 (12)0.0004 (10)0.0481 (11)−0.0005 (9)
C20.0741 (17)0.0376 (13)0.0615 (16)−0.0029 (12)0.0516 (15)−0.0020 (12)
C10.0513 (14)0.0483 (14)0.0475 (13)0.0015 (11)0.0330 (12)0.0025 (12)
C140.0511 (14)0.0420 (13)0.0495 (13)−0.0059 (11)0.0322 (12)−0.0040 (11)
C150.0612 (16)0.0429 (14)0.0589 (16)−0.0023 (12)0.0342 (14)0.0009 (12)
C190.0550 (16)0.0551 (15)0.0616 (16)−0.0068 (13)0.0355 (13)−0.0058 (13)
C70.089 (2)0.0415 (14)0.0725 (18)0.0033 (14)0.0599 (17)0.0001 (13)
C30.0817 (19)0.0557 (16)0.0582 (17)−0.0070 (14)0.0483 (16)−0.0065 (14)
C110.090 (2)0.0576 (17)0.074 (2)0.0200 (15)0.0539 (18)0.0119 (15)
C80.078 (2)0.080 (2)0.0591 (17)−0.0008 (17)0.0373 (16)−0.0067 (15)
C60.120 (3)0.0427 (16)0.100 (3)0.0088 (16)0.079 (2)−0.0006 (16)
C40.106 (2)0.069 (2)0.0666 (19)−0.0134 (18)0.0555 (18)−0.0150 (17)
C200.0616 (17)0.0590 (17)0.079 (2)0.0106 (14)0.0379 (16)0.0132 (15)
C160.086 (2)0.0506 (16)0.095 (2)−0.0034 (15)0.0534 (19)0.0093 (16)
C170.093 (2)0.0605 (19)0.125 (3)−0.0231 (18)0.069 (2)0.003 (2)
C230.0534 (16)0.0719 (18)0.083 (2)0.0030 (14)0.0369 (15)0.0051 (16)
C180.0636 (18)0.076 (2)0.101 (2)−0.0171 (16)0.0493 (18)−0.0044 (18)
C50.139 (3)0.0538 (19)0.096 (3)−0.009 (2)0.084 (2)−0.0201 (18)
C250.0622 (18)0.117 (3)0.094 (2)0.0095 (18)0.0426 (17)−0.009 (2)
C130.146 (3)0.089 (2)0.107 (3)0.024 (2)0.085 (3)0.034 (2)
C120.099 (3)0.127 (3)0.105 (3)0.010 (2)0.062 (2)0.019 (2)
C100.127 (3)0.099 (3)0.088 (2)0.021 (2)0.064 (2)0.022 (2)
C240.097 (2)0.168 (4)0.099 (3)0.056 (3)0.063 (2)0.052 (3)
C210.109 (3)0.097 (3)0.158 (4)0.034 (2)0.084 (3)0.006 (3)
C90.096 (3)0.149 (4)0.137 (3)−0.001 (3)0.071 (3)0.009 (3)
C220.067 (2)0.214 (5)0.096 (3)0.005 (3)0.023 (2)−0.040 (3)

Geometric parameters (Å, °)

N2—C11.310 (3)C16—H16A0.930
N2—C141.427 (3)C17—C181.373 (4)
N2—H2A0.860C17—H17A0.930
N1—C11.313 (3)C23—C241.523 (4)
N1—C21.432 (3)C23—C251.527 (4)
N1—H1A0.860C23—H23A0.980
C2—C31.402 (3)C18—H18A0.930
C2—C71.407 (3)C5—H5A0.930
C1—H10.930C25—H25A0.960
C14—C191.404 (3)C25—H25B0.960
C14—C151.407 (3)C25—H25C0.960
C15—C161.395 (3)C13—H13A0.960
C15—C201.512 (3)C13—H13B0.960
C19—C181.392 (3)C13—H13C0.960
C19—C231.524 (3)C12—H12A0.960
C7—C61.398 (3)C12—H12B0.960
C7—C111.520 (4)C12—H12C0.960
C3—C41.395 (4)C10—H10A0.960
C3—C81.523 (4)C10—H10B0.960
C11—C121.519 (4)C10—H10C0.960
C11—C131.531 (4)C24—H24A0.960
C11—H11A0.980C24—H24B0.960
C8—C101.520 (4)C24—H24C0.960
C8—C91.532 (4)C21—H21A0.960
C8—H8A0.980C21—H21B0.960
C6—C51.373 (4)C21—H21C0.960
C6—H6A0.930C9—H9A0.960
C4—C51.365 (4)C9—H9B0.960
C4—H4A0.930C9—H9C0.960
C20—C221.487 (4)C22—H22A0.960
C20—C211.522 (4)C22—H22B0.960
C20—H20A0.980C22—H22C0.960
C16—C171.367 (4)
C1—N2—C14120.78 (18)C19—C23—C25114.9 (2)
C1—N2—H2A119.6C24—C23—H23A107.0
C14—N2—H2A119.6C19—C23—H23A107.0
C1—N1—C2120.68 (18)C25—C23—H23A107.0
C1—N1—H1A119.7C17—C18—C19121.5 (3)
C2—N1—H1A119.7C17—C18—H18A119.3
C3—C2—C7121.5 (2)C19—C18—H18A119.3
C3—C2—N1119.7 (2)C4—C5—C6119.7 (3)
C7—C2—N1118.8 (2)C4—C5—H5A120.2
N2—C1—N1123.3 (2)C6—C5—H5A120.2
N2—C1—H1118.3C23—C25—H25A109.5
N1—C1—H1118.3C23—C25—H25B109.5
C19—C14—C15121.5 (2)H25A—C25—H25B109.5
C19—C14—N2119.7 (2)C23—C25—H25C109.5
C15—C14—N2118.7 (2)H25A—C25—H25C109.5
C16—C15—C14117.9 (2)H25B—C25—H25C109.5
C16—C15—C20121.0 (2)C11—C13—H13A109.5
C14—C15—C20121.1 (2)C11—C13—H13B109.5
C18—C19—C14117.5 (2)H13A—C13—H13B109.5
C18—C19—C23121.8 (2)C11—C13—H13C109.5
C14—C19—C23120.6 (2)H13A—C13—H13C109.5
C6—C7—C2117.5 (3)H13B—C13—H13C109.5
C6—C7—C11120.4 (3)C11—C12—H12A109.5
C2—C7—C11122.1 (2)C11—C12—H12B109.5
C4—C3—C2117.4 (3)H12A—C12—H12B109.5
C4—C3—C8120.3 (3)C11—C12—H12C109.5
C2—C3—C8122.2 (2)H12A—C12—H12C109.5
C12—C11—C7112.1 (2)H12B—C12—H12C109.5
C12—C11—C13110.4 (3)C8—C10—H10A109.5
C7—C11—C13113.1 (3)C8—C10—H10B109.5
C12—C11—H11A107.0H10A—C10—H10B109.5
C7—C11—H11A107.0C8—C10—H10C109.5
C13—C11—H11A107.0H10A—C10—H10C109.5
C10—C8—C3111.5 (3)H10B—C10—H10C109.5
C10—C8—C9110.4 (3)C23—C24—H24A109.5
C3—C8—C9111.6 (3)C23—C24—H24B109.5
C10—C8—H8A107.7H24A—C24—H24B109.5
C3—C8—H8A107.7C23—C24—H24C109.5
C9—C8—H8A107.7H24A—C24—H24C109.5
C5—C6—C7121.6 (3)H24B—C24—H24C109.5
C5—C6—H6A119.2C20—C21—H21A109.5
C7—C6—H6A119.2C20—C21—H21B109.5
C5—C4—C3122.1 (3)H21A—C21—H21B109.5
C5—C4—H4A118.9C20—C21—H21C109.5
C3—C4—H4A118.9H21A—C21—H21C109.5
C22—C20—C15111.0 (2)H21B—C21—H21C109.5
C22—C20—C21111.7 (3)C8—C9—H9A109.5
C15—C20—C21114.2 (2)C8—C9—H9B109.5
C22—C20—H20A106.4H9A—C9—H9B109.5
C15—C20—H20A106.4C8—C9—H9C109.5
C21—C20—H20A106.4H9A—C9—H9C109.5
C17—C16—C15121.1 (3)H9B—C9—H9C109.5
C17—C16—H16A119.5C20—C22—H22A109.5
C15—C16—H16A119.5C20—C22—H22B109.5
C16—C17—C18120.5 (3)H22A—C22—H22B109.5
C16—C17—H17A119.7C20—C22—H22C109.5
C18—C17—H17A119.7H22A—C22—H22C109.5
C24—C23—C19110.5 (2)H22B—C22—H22C109.5
C24—C23—C25110.1 (2)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N1—H1A···N1i0.862.032.882 (4)171
N2—H2A···N2i0.862.052.910 (3)175

Symmetry codes: (i) −x, y, −z+3/2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BI2287).

References

  • Bruker (2003). SMART and SAINT Bruker AXS Inc., Madison, Wisconsin, USA.
  • Farrugia, L. J. (1997). J. Appl. Cryst.30, 565.
  • Krahulic, K. E., Enright, G. D., Parvez, M. & Roesler, R. (2005). J. Am. Chem. Soc.127, 4142–4143. [PubMed]
  • Perrin, C. L. (1991). The Chemistry of Amidines and Imidates, Vol. 2, edited by S. Patai & Z. Rappoport, pp. 147–229. Chichester: Wiley.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Stibrany, R. T. & Potenza, J. A. (2006). Private communication (refcode: TEVJOU). CCDC, Cambridge, England.
  • Westrip, S. J. (2008). publCIF In preparation.

Articles from Acta Crystallographica Section E: Structure Reports Online are provided here courtesy of International Union of Crystallography