2,6-Bis­[1-(phenyl­imino)­ethyl]­pyridine

The structure of the title compound, C₂₁H₁₉N₃ (BIP1), has been determined. The mol­ecule lies on a crystallographic mirror plane. The terminal phenyl groups are rotated 60.2 (2)° from the plane of the ethyl­idene­pyridine system.

Key indicators

• Single-crystal X-ray study
• T = 290 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.049
• wR factor = 0.151
• Data-to-parameter ratio = 8.4

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



PLAT_030  Alert C Refined Extinction parameter within range ....       2.84 Sigma

PLAT_741  Alert C Bond    Calc    1.390(3), Rep     1.39000 ....    Missing s.u.
                     C6   -C7      1.555   1.555

PLAT_741  Alert C Bond    Calc    1.390(4), Rep     1.39000 ....    Missing s.u.
                     C6   -C11     1.555   1.555

PLAT_741  Alert C Bond    Calc    1.390(3), Rep     1.39000 ....    Missing s.u.
                     C7   -C8      1.555   1.555

PLAT_741  Alert C Bond    Calc    1.390(4), Rep     1.39000 ....    Missing s.u.
                     C8   -C9      1.555   1.555

PLAT_741  Alert C Bond    Calc    1.390(4), Rep     1.39000 ....    Missing s.u.
                     C9   -C10     1.555   1.555

PLAT_741  Alert C Bond    Calc    1.390(3), Rep     1.39000 ....    Missing s.u.
                     C10  -C11     1.555   1.555

PLAT_742  Alert C Angle   Calc  119.99(19), Rep      120.00 ....    Missing s.u.
                     C7   -C6   -C11     1.555   1.555   1.555

PLAT_742  Alert C Angle   Calc    120.0(2), Rep      120.00 ....    Missing s.u.
                     C8   -C7   -C6      1.555   1.555   1.555

PLAT_742  Alert C Angle   Calc    120.0(2), Rep      120.00 ....    Missing s.u.
                     C7   -C8   -C9      1.555   1.555   1.555

PLAT_742  Alert C Angle   Calc    120.0(2), Rep      120.00 ....    Missing s.u.
                     C10  -C9   -C8      1.555   1.555   1.555

PLAT_742  Alert C Angle   Calc    120.0(3), Rep      120.00 ....    Missing s.u.
                     C11  -C10  -C9      1.555   1.555   1.555

PLAT_742  Alert C Angle   Calc    120.0(2), Rep      120.00 ....    Missing s.u.
                     C10  -C11  -C6      1.555   1.555   1.555

General Notes



REFLT_03
         From the CIF: _diffrn_reflns_theta_max           24.97
         From the CIF: _reflns_number_total                849
         Count of symmetry unique reflns          851
         Completeness (_total/calc)             99.76%
         TEST3: Check Friedels for noncentro structure
         Estimate of Friedel pairs measured         0
         Fraction of Friedel pairs measured     0.000
         Are heavy atom types Z>Si present           no
          Please check that the estimate of the number of Friedel pairs is
          correct. If it is not, please give the correct count in the
          _publ_section_exptl_refinement section of the submitted CIF.


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 13 Alert Level C = Please check

---

S1. Comment

The title compound, (I) or BIP1, was previously described (Blake et al., 1989). Platinum complexes of the type fac-[PtXMe₃(BIP1)] (X = Cl, Br, I) have been recently reported (Orrell et al., 1998), the crystal structure of the iodine derivative, fac-[PtIMe₃(BIP1)], was determined to confirm the proposed stereochemistry.

Pentacoordinate complexes of iron, {[(ArN═C(Me)]₂C₅H₃N}FeCl₂ (Ar= alkyl substituted aryl ring), have been used for the isospecific polymerization of propylene (Small & Brookhart, 1999). [Please check that the above formula has the correct format as the original parentheses were confusing]

Our interest in tetracarbonyl complexes of molybdenum and tungsten with chelating nitrogen-donor ligands (Mentes, 1999; Mentes et al., 1999) lead us to investigate in situ reactions of 2,6-diacetylpyridine with aniline in the presence of [Mo(CO)₄(pip)₂] (pip is ?), from which reaction crystals of BIP1 were obtained.

The molecular structure of BIP1 is shown in Fig. 1 and selected bond distances and angles are given in Table 1. Atoms C1 and N1 lie on a crystallographic mirror plane which is orthogonal to the ring. The terminal phenyl groups are rotated by 60.2 (2)° from the plane of the ethylidenepyridine system. The bond length of the symmetric imine group (C4—N2) of 1.266 (4) Å is similar to that in fac-[PtIMe₃(BIP1)], 1.277 (8) (coordinated to Pt) and 1.291 (9) Å (uncoordinated), and also in [FeCl₂[(BIP2)] (BIP2 is ?) 1.273 (3) and 1.284 (3) Å. The C═N bond lengths in [Mo(CO)₄{C₅H₄NC(CH₃)═ NCH₃}] and [Mo(CO)₄{C₅H₄NC(C₆H₅)═NCH₃}] are 1.289 (5) and 1.283 (4) Å, respectively.

S2. Experimental

The Schiff base compound (BIP1) was isolated by refluxing 2,6-diacetylpyridine (0.489 g, 3 mmol) and excess of aniline (5 ml, 55 mmol) in propan-2-ol (10 ml) for 2 h. cis-[Mo(CO)₄(pip)₂] (1.134 g, 3 mmol) was added to the reaction. The reaction mixture was cooled to room temperature and the solvent removed by rotary evaporation. The intermediate (BIP1) was isolated and recrystallized as pale-yellow crystals from an acetone–methanol (50:50) mixture.

S3. Refinement

The absolute configuration could not be determined from the Flack parameter and the structure was refined using merged Friedels pairs. Insufficient data to refine all atom positional and anisotropic displacement parameters therefore the phenyl ring was refined as a rigid group with C—C bond distances and C—C—C idealized.

Computing details

Data collection: XSCANS (Fait, 1991); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXL97; software used to prepare material for publication: SHELXL97.

Figures

Fig. 1. The molecular structure of BIP1 showing the atom-numbering scheme. Displacement ellipsoids are shown at the 30% probability level. H atoms are shown as spheres of arbitrary radii. Primed atoms are generated by the symmetry operation -x, y, z.

2,6-Bis[1-(phenylimino)ethyl]pyridine

Crystal data

C21H19N3	Dx = 1.199 Mg m^−3
Mr = 313.39	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Cmc21	Cell parameters from 33 reflections
a = 33.805 (5) Å	θ = 5.3–12.4°
b = 7.1247 (9) Å	µ = 0.07 mm^−1
c = 7.2074 (10) Å	T = 290 K
V = 1735.9 (4) Å^3	Block, yellow
Z = 4	0.46 × 0.39 × 0.31 mm
F(000) = 664

Data collection

Bruker P4 diffractometer	Rint = 0.043
Radiation source: fine-focus sealed tube	θmax = 25.0°, θmin = 2.9°
Graphite monochromator	h = −1→40
ω scans	k = 0→8
1096 measured reflections	l = −8→1
849 independent reflections	3 standard reflections every 100 reflections
663 reflections with I > 2σ(I)	intensity decay: <1%

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)] = 0.049	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.151	w = 1/[σ^2(Fo^2) + (0.0779P)^2 + 0.947P] where P = (Fo^2 + 2Fc^2)/3
S = 1.07	(Δ/σ)max < 0.001
849 reflections	Δρmax = 0.18 e Å^−3
101 parameters	Δρmin = −0.19 e Å^−3
1 restraint	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0054 (19)

Special details

Experimental. The compound was also characterized by NMR (250 MHz, CDCl₃), δ: 2.32 (6H, s, CH₃—C), 6.73–8.35 (13H, m, arom.) p.p.m., IR (NaCl plates in Nujol): 1640 ν(C=N) cm^-1, Mass spectrum (FAB)m [MH]⁺ 314, and microanalysis Found: C, 80.0; H,6.1; N, 13.3%. calc.: C, 80.5; H, 6.1; N, 13.4 C₂₁H₁₉N₃

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 based on F.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
N1	0.5000	0.2468 (5)	0.3061 (6)	0.0388 (11)
N2	0.39677 (8)	0.2700 (5)	0.3834 (5)	0.0508 (10)
C1	0.5000	0.3046 (9)	0.6858 (10)	0.0553 (15)
H1B	0.5000	0.3259	0.8131	0.066*
C2	0.46513 (10)	0.2886 (6)	0.5903 (7)	0.0503 (10)
H2B	0.4411	0.2959	0.6525	0.060*
C3	0.46603 (10)	0.2616 (5)	0.4008 (6)	0.0402 (10)
C4	0.42839 (9)	0.2462 (5)	0.2923 (6)	0.0401 (9)
C5	0.43096 (10)	0.2059 (7)	0.0878 (7)	0.0580 (12)
H5A	0.4048	0.1993	0.0365	0.087*
H5B	0.4442	0.0883	0.0688	0.087*
H5C	0.4455	0.3043	0.0276	0.087*
C6	0.35871 (5)	0.2606 (4)	0.2992 (4)	0.0458 (10)
C7	0.33256 (6)	0.1237 (3)	0.3611 (4)	0.0534 (11)
H7A	0.3407	0.0365	0.4493	0.064*
C8	0.29426 (6)	0.1171 (3)	0.2913 (5)	0.0587 (11)
H8A	0.2768	0.0255	0.3327	0.070*
C9	0.28210 (5)	0.2474 (4)	0.1596 (5)	0.0584 (13)
H9A	0.2565	0.2430	0.1129	0.070*
C10	0.30825 (7)	0.3843 (4)	0.0977 (5)	0.0617 (12)
H10A	0.3001	0.4715	0.0096	0.074*
C11	0.34655 (6)	0.3909 (3)	0.1675 (4)	0.0573 (12)
H11A	0.3640	0.4826	0.1261	0.069*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.033 (2)	0.044 (2)	0.040 (3)	0.000	0.000	−0.004 (2)
N2	0.0307 (17)	0.077 (2)	0.045 (2)	0.0018 (14)	0.0002 (16)	0.002 (2)
C1	0.045 (3)	0.077 (4)	0.044 (3)	0.000	0.000	−0.006 (4)
C2	0.036 (2)	0.069 (3)	0.046 (2)	0.0012 (18)	0.007 (2)	−0.001 (3)
C3	0.032 (2)	0.041 (2)	0.048 (3)	0.0010 (14)	0.0004 (16)	−0.0019 (19)
C4	0.0324 (19)	0.043 (2)	0.045 (2)	−0.0036 (14)	0.0004 (18)	0.0007 (19)
C5	0.0362 (19)	0.084 (3)	0.054 (3)	0.0027 (19)	−0.001 (2)	−0.023 (3)
C6	0.0293 (16)	0.068 (3)	0.040 (2)	0.0031 (16)	0.0042 (17)	−0.003 (2)
C7	0.0399 (18)	0.071 (3)	0.050 (2)	0.0045 (18)	0.003 (2)	0.007 (2)
C8	0.0405 (19)	0.072 (3)	0.063 (3)	−0.0063 (19)	0.004 (2)	0.000 (3)
C9	0.0363 (19)	0.083 (3)	0.056 (3)	0.0059 (19)	−0.0018 (19)	−0.013 (3)
C10	0.0396 (19)	0.085 (3)	0.061 (3)	0.0098 (19)	0.000 (2)	0.013 (3)
C11	0.0403 (19)	0.074 (3)	0.057 (3)	0.0000 (19)	0.004 (2)	0.018 (3)

Geometric parameters (Å, º)

N1—C3	1.340 (4)	C4—C5	1.504 (7)
N1—C3^i	1.340 (4)	C6—C7	1.3900
N2—C4	1.266 (4)	C6—C11	1.3900
N2—C6	1.424 (3)	C7—C8	1.3900
C1—C2	1.370 (5)	C8—C9	1.3900
C1—C2^i	1.370 (5)	C9—C10	1.3900
C2—C3	1.379 (7)	C10—C11	1.3900
C3—C4	1.497 (5)
C3—N1—C3^i	117.9 (4)	C3—C4—C5	118.5 (3)
C4—N2—C6	122.4 (3)	C7—C6—C11	120.0
C2—C1—C2^i	118.7 (6)	C7—C6—N2	118.1 (2)
C1—C2—C3	119.4 (4)	C11—C6—N2	121.8 (2)
N1—C3—C2	122.3 (4)	C8—C7—C6	120.0
N1—C3—C4	117.2 (3)	C7—C8—C9	120.0
C2—C3—C4	120.5 (3)	C10—C9—C8	120.0
N2—C4—C3	115.9 (3)	C11—C10—C9	120.0
N2—C4—C5	125.6 (4)	C10—C11—C6	120.0

Symmetry code: (i) −x+1, y, z.