Halogen trimer synthons in crystal engineering: low-temperature X-ray and neutron diffraction study of the 1:1 complex of 2,4,6-tris(4-chloro­phenoxy)-1,3,5-triazine with tribromobenzene

The title complex has been studied using low-temperature X-­ray (150 K) and neutron (100 K) diffraction. Molecules of the triazine host form a two-dimensional hexagonal network mediated by trigonally symmetric Cl₃ synthons having Cl...Cl interactions of 3.441 (3) Å, a C—Cl...Cl angle of 165° and a Cl...Cl—C angle of 105°, close to the ideal values of 180 and 90°, respectively. The guest molecules are of an appropriate size to fit the hexagonal networks and interact with the host via C—H...π (phenyl) and C—Br...π (phenyl) interactions which stabilize the overall structure. Both C-donor bond vectors are directed more closely towards the mid-point (X) of an individual aromatic bond, rather than the ring centroid, with H...X 2.817 (9) Å and C—H...X 174.0 (9)°, and Br...X 3.353 (4) Å and C—Br...X 158.1 (2)°.

Computing details

Data collection: Bruker SMART for (I). Cell refinement: Bruker SAINT for (I). Data reduction: Bruker SAINT for (I). For both compounds, program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997). Molecular graphics: Bruker SHELXTL for (I); Siemens SHELXTL for (II). Software used to prepare material for publication: Bruker SHELXTL for (I); Siemens SHELXTL for (II).

(I) 2,4,6-tris-(4-chlorophenoxy)-1,3,5-triazine tribromobenzene

Crystal data

C21H12Cl3N3O3·C6H3Br3	Dx = 1.876 Mg m^−3
Mr = 775.50	Mo Kα radiation, λ = 0.71073 Å
Hexagonal, P63	Cell parameters from 999 reflections
Hall symbol: P 6c	θ = 5.3–28.8°
a = 15.250 (2) Å	µ = 4.74 mm^−1
c = 6.8149 (14) Å	T = 150 K
V = 1372.6 (4) Å^3	Needle, colourless
Z = 2	0.35 × 0.27 × 0.27 mm
F(000) = 756

Data collection

Bruker SMART-CCD diffractometer	2568 independent reflections
Radiation source: fine-focus sealed tube	2283 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.030
/w scans	θmax = 30.5°, θmin = 1.5°
Absorption correction: multi-scan ?	h = −20→20
Tmin = 0.299, Tmax = 0.379	k = −21→21
17004 measured reflections	l = −9→9

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)] = 0.027	Only H-atom displacement parameters refined
wR(F^2) = 0.064	w = 1/[σ^2(Fo^2) + (0.0418P)^2 + 0.0942P] where P = (Fo^2 + 2Fc^2)/3
S = 1.04	(Δ/σ)max = 0.001
2568 reflections	Δρmax = 0.40 e Å^−3
122 parameters	Δρmin = −0.90 e Å^−3
1 restraint	Absolute structure: Flack H D (1983), Acta Cryst. A39, 876-881
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.015 (8)

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 (Ų)

	x	y	z	Uiso*/Ueq
Cl1	0.28248 (4)	0.51759 (4)	0.65111 (9)	0.02579 (10)
C1	0.33892 (13)	0.44198 (13)	0.6510 (4)	0.0202 (3)
C2	0.39612 (15)	0.44579 (15)	0.8120 (3)	0.0224 (4)
H2	0.4033	0.4869	0.9186	0.030 (7)*
C3	0.44300 (15)	0.38693 (15)	0.8123 (3)	0.0215 (4)
H3	0.4820	0.3884	0.9185	0.024 (6)*
C4	0.42989 (12)	0.32615 (12)	0.6503 (4)	0.0177 (3)
C5	0.37199 (14)	0.32150 (13)	0.4900 (4)	0.0217 (4)
H5A	0.3641	0.2796	0.3842	0.026*
C6	0.32559 (14)	0.38076 (14)	0.4893 (4)	0.0231 (4)
H6	0.2866	0.3793	0.3830	0.023 (6)*
O1	0.47036 (9)	0.26041 (9)	0.6491 (2)	0.0193 (3)
C7	0.57159 (12)	0.30103 (13)	0.6516 (3)	0.0169 (3)
N1	0.59961 (11)	0.23038 (11)	0.6523 (3)	0.0179 (3)
Br1	0.780866 (18)	0.98944 (2)	1.00678 (6)	0.04690 (9)
C8	0.90847 (16)	0.99571 (17)	1.0167 (5)	0.0292 (4)
C9	0.99560 (17)	1.09001 (16)	1.0164 (5)	0.0294 (4)
H9	0.9927	1.1495	1.0160	0.047 (8)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl1	0.0283 (2)	0.0257 (2)	0.0313 (2)	0.01943 (18)	0.0000 (2)	0.0004 (2)
C1	0.0174 (7)	0.0175 (8)	0.0270 (10)	0.0099 (7)	0.0016 (9)	0.0016 (9)
C2	0.0217 (9)	0.0205 (9)	0.0243 (10)	0.0101 (8)	−0.0005 (8)	−0.0034 (7)
C3	0.0186 (9)	0.0231 (9)	0.0235 (10)	0.0110 (8)	−0.0026 (7)	−0.0004 (8)
C4	0.0125 (7)	0.0150 (7)	0.0249 (9)	0.0064 (6)	0.0026 (8)	0.0011 (8)
C5	0.0223 (8)	0.0201 (8)	0.0244 (10)	0.0118 (7)	−0.0016 (9)	−0.0029 (8)
C6	0.0218 (8)	0.0255 (8)	0.0256 (11)	0.0145 (7)	−0.0031 (9)	−0.0004 (9)
O1	0.0139 (5)	0.0157 (5)	0.0292 (7)	0.0080 (5)	−0.0018 (6)	−0.0005 (6)
C7	0.0149 (7)	0.0184 (7)	0.0159 (8)	0.0072 (6)	−0.0005 (8)	0.0000 (8)
N1	0.0157 (6)	0.0162 (6)	0.0214 (8)	0.0076 (5)	0.0005 (7)	0.0003 (7)
Br1	0.03692 (13)	0.07222 (19)	0.04169 (14)	0.03488 (13)	−0.00008 (15)	−0.00118 (18)
C8	0.0291 (9)	0.0404 (10)	0.0202 (10)	0.0190 (8)	0.0012 (11)	0.0001 (11)
C9	0.0399 (10)	0.0317 (10)	0.0182 (9)	0.0191 (8)	0.0008 (10)	−0.0002 (10)

Geometric parameters (Å, º)

Cl1—C1	1.7501 (18)	C6—H6	0.9300
C1—C2	1.385 (3)	O1—C7	1.346 (2)
C1—C6	1.392 (3)	C7—N1^i	1.320 (2)
C2—C3	1.399 (3)	C7—N1	1.343 (2)
C2—H2	0.9300	N1—C7^ii	1.320 (2)
C3—C4	1.390 (3)	Br1—C8	1.901 (2)
C3—H3	0.9300	C8—C9^iii	1.386 (3)
C4—C5	1.384 (3)	C8—C9	1.387 (3)
C4—O1	1.416 (2)	C9—C8^iv	1.386 (3)
C5—C6	1.399 (3)	C9—H9	0.9300
C5—H5A	0.9300
C2—C1—C6	122.22 (17)	C1—C6—C5	118.7 (2)
C2—C1—Cl1	118.61 (17)	C1—C6—H6	120.7
C6—C1—Cl1	119.17 (16)	C5—C6—H6	120.7
C1—C2—C3	119.16 (19)	C7—O1—C4	118.67 (13)
C1—C2—H2	120.4	N1^i—C7—N1	127.70 (16)
C3—C2—H2	120.4	N1^i—C7—O1	119.79 (15)
C4—C3—C2	118.50 (19)	N1—C7—O1	112.50 (14)
C4—C3—H3	120.8	C7^ii—N1—C7	112.29 (16)
C2—C3—H3	120.8	C9^iii—C8—C9	123.1 (2)
C5—C4—C3	122.45 (17)	C9^iii—C8—Br1	118.31 (16)
C5—C4—O1	116.85 (18)	C9—C8—Br1	118.55 (16)
C3—C4—O1	120.56 (19)	C8^iv—C9—C8	116.9 (2)
C4—C5—C6	119.0 (2)	C8^iv—C9—H9	121.5
C4—C5—H5A	120.5	C8—C9—H9	121.5
C6—C5—H5A	120.5
C6—C1—C2—C3	0.6 (3)	C4—C5—C6—C1	−0.4 (3)
Cl1—C1—C2—C3	−178.97 (15)	C5—C4—O1—C7	118.43 (19)
C1—C2—C3—C4	−0.3 (3)	C3—C4—O1—C7	−65.7 (3)
C2—C3—C4—C5	−0.3 (3)	C4—O1—C7—N1^i	−1.0 (3)
C2—C3—C4—O1	−175.93 (17)	C4—O1—C7—N1	179.29 (19)
C3—C4—C5—C6	0.6 (3)	N1^i—C7—N1—C7^ii	−0.7 (4)
O1—C4—C5—C6	176.42 (17)	O1—C7—N1—C7^ii	178.97 (12)
C2—C1—C6—C5	−0.2 (3)	C9^iii—C8—C9—C8^iv	−0.3 (7)
Cl1—C1—C6—C5	179.31 (16)	Br1—C8—C9—C8^iv	−177.76 (16)

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

(II)

Crystal data

C21H12Cl3N3O3·C6H3Br3	F(000) = 43.57
Mr = 771.00	Dx = 1.906 Mg m^−3
Hexagonal, P63	Neutron radiation, λ = 0.5-5.0 Å
Hall symbol: P 6c	Cell parameters from 25 reflections
a = 15.166 (6) Å	µ = 1.08, at 1 Angstrom mm^−1
c = 6.743 (2) Å	T = 100 K
V = 1343 (1) Å^3	Irregular prism, colourless
Z = 2	6.0 × 1.5 × 1.0 mm

Data collection

SXD diffractometer	3102 independent reflections
Radiation source: ISIS spallation source	3102 reflections with I > 2σ(I)
None monochromator	Rint = 0.071
time–of–flight LAUE diffraction scans	θmax = 16.9°, θmin = 1.4°
Absorption correction: empirical (using intensity measurements) The linear absorption coefficient is wavelength dependent and it is calculated as: mu = 0.46 + 0.62 * lambda [cm^-1]	h = 0^→30
Tmin = 0.30, Tmax = 0.91	k = 0^→30
30681 measured reflections	l = 0^→15

Refinement

Refinement on F^2	Hydrogen site location: difference Fourier map
Least-squares matrix: full	All H-atom parameters refined
R[F^2 > 2σ(F^2)] = 0.083	w = 1/[σ^2(Fo^2) + (0.0383P)^2 + 59.851P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.212	(Δ/σ)max < 0.001
S = 1.23	Δρmax = 3.23 e Å^−3
3102 reflections	Δρmin = −3.98 e Å^−3
163 parameters	Extinction correction: Becker-Coppens Lorentzian model
1 restraint	Extinction coefficient: 0.560
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	Absolute structure parameter: 0 (10)

Special details

Experimental. For peak integration a local UB matrix refined for each frame, using approximately 25 reflections. Hence _cell_measurement_reflns_used 25

For final cell dimensions an average of all local cells was performed and estimated standard uncertainties were obtained from the spread of the local observations

Because of the nature of the experiment, it is not possible to give values of theta_min and theta_max for the cell determination.

Instead, we can give values of

_cell_measurement_sin(theta)/lambda_min 0.22 _cell_measurement_sin(theta)/lambda_max 0.83

The same applies for the wavelength used for the experiment. The range of wavelengths used was 0.5–5.0 Angstroms, BUT the bulk of the diffraction information is obtained from wavelengths in the range 0.7–2.5 Angstroms.

The data collection procedures on the SXD instrument used for the single-crystal neutron data collection are most recently summarized in the Appendix to the following paper Wilson, C·C. (1997). J. Mol. Struct. 405, 207–217.

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. The variable wavelength nature of the data collection procedure means that sensible values of _diffrn_reflns_theta_min & _diffrn_reflns_theta_max cannot be given

It is also difficult to estimate realistic values of maximum sin(theta)/lambda values for two reasons: (i) Different sin(theta)/lambda ranges are accessed in different parts of the detectors (ii) The nature of the data collection occasionally allows some reflections at very high sin(theta)/lambda to be observed even when no real attempt has been made to measure data in this region.

However, we can attempt to estimate the sin(theta)/lambda limits as follows:

_diffrn_reflns_sin(theta)/lambda_min 0.099 _diffrn_reflns_sin(theta)/lambda_max 1.162

Note also that reflections for which the standard profile fitting integration procedure fails are excluded from the data set, thus resulting in a high elimination rate of very weak or "unobserved" peaks from the final data set.

The extinction coefficient reported in _refine_ls_extinction_coef is in this case the refined value of the mosaic spread in units of 10^{-4 rad}-1 The reference for the extinction method used is: Becker, P. & Coppens, P. (1974). Acta Cryst. A30, 129–148.

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
Cl1	0.71822 (13)	0.48225 (13)	0.3485 (4)	0.0131 (2)
C1	0.66204 (15)	0.55789 (16)	0.3485 (6)	0.0105 (2)
C2	0.60324 (19)	0.55359 (19)	0.1864 (4)	0.0119 (3)
C3	0.55743 (19)	0.61318 (19)	0.1865 (4)	0.0115 (3)
C4	0.57032 (14)	0.67462 (15)	0.3491 (5)	0.0094 (2)
C5	0.62922 (19)	0.67932 (19)	0.5107 (4)	0.0110 (3)
C6	0.6756 (2)	0.6198 (2)	0.5114 (4)	0.0124 (3)
O1	0.52980 (16)	0.73975 (18)	0.3508 (7)	0.0104 (3)
C7	0.42892 (14)	0.69954 (15)	0.3479 (5)	0.0083 (2)
N1	0.40038 (10)	0.76978 (10)	0.3469 (4)	0.00947 (17)
Br1	0.2209 (3)	0.0124 (4)	−0.0057 (7)	0.0253 (7)
C8	0.0928 (3)	0.0049 (3)	−0.0148 (4)	0.0161 (4)
C9	0.0052 (3)	−0.0898 (3)	−0.0150 (5)	0.0166 (4)
H2	0.5946 (7)	0.5050 (7)	0.0621 (14)	0.0287 (15)
H3	0.5116 (8)	0.6117 (8)	0.0620 (14)	0.0308 (16)
H6	0.7213 (8)	0.6203 (8)	0.6358 (14)	0.0303 (16)
H5	0.6375 (8)	0.7286 (8)	0.6353 (14)	0.0296 (15)
H9	0.0092 (9)	−0.1591 (8)	−0.016 (2)	0.0358 (18)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl1	0.0146 (5)	0.0130 (5)	0.0154 (5)	0.0097 (4)	0.0000 (7)	−0.0001 (7)
C1	0.0097 (6)	0.0116 (6)	0.0120 (6)	0.0067 (5)	−0.0001 (9)	−0.0007 (9)
C2	0.0115 (7)	0.0123 (7)	0.0131 (8)	0.0069 (6)	−0.0024 (7)	−0.0040 (7)
C3	0.0111 (7)	0.0120 (7)	0.0125 (8)	0.0066 (6)	−0.0027 (7)	−0.0022 (7)
C4	0.0074 (5)	0.0081 (5)	0.0121 (6)	0.0035 (4)	0.0008 (8)	−0.0001 (8)
C5	0.0115 (7)	0.0127 (7)	0.0109 (7)	0.0077 (6)	−0.0032 (6)	−0.0028 (7)
C6	0.0149 (8)	0.0154 (8)	0.0114 (8)	0.0110 (7)	−0.0035 (7)	−0.0026 (7)
O1	0.0058 (5)	0.0092 (6)	0.0155 (8)	0.0032 (5)	−0.0011 (10)	−0.0007 (10)
C7	0.0070 (5)	0.0084 (5)	0.0098 (5)	0.0041 (4)	0.0000 (8)	0.0000 (8)
N1	0.0079 (4)	0.0080 (4)	0.0128 (4)	0.0042 (3)	−0.0004 (6)	−0.0007 (6)
Br1	0.0209 (12)	0.040 (2)	0.0220 (14)	0.0206 (14)	−0.0011 (12)	−0.0013 (15)
C8	0.0190 (10)	0.0230 (11)	0.0090 (8)	0.0125 (9)	0.0004 (8)	0.0007 (8)
C9	0.0206 (11)	0.0191 (10)	0.0111 (8)	0.0107 (9)	0.0002 (8)	0.0002 (8)
H2	0.034 (3)	0.033 (3)	0.026 (3)	0.021 (3)	−0.007 (3)	−0.015 (3)
H3	0.037 (4)	0.043 (4)	0.023 (3)	0.027 (4)	−0.013 (3)	−0.008 (3)
H6	0.034 (4)	0.041 (4)	0.025 (3)	0.026 (3)	−0.011 (3)	−0.006 (3)
H5	0.040 (4)	0.035 (4)	0.023 (3)	0.026 (3)	−0.011 (3)	−0.012 (3)
H9	0.041 (4)	0.032 (4)	0.044 (5)	0.025 (4)	−0.001 (4)	−0.002 (4)

Geometric parameters (Å, º)

Cl1—C1	1.737 (2)	C6—H6	1.085 (9)
C1—C2	1.392 (4)	O1—C7	1.334 (3)
C1—C6	1.392 (4)	C7—N1^i	1.320 (2)
C2—C3	1.388 (3)	C7—N1	1.335 (2)
C2—H2	1.080 (8)	N1—C7^ii	1.320 (2)
C3—C4	1.388 (4)	Br1—C8	1.890 (5)
C3—H3	1.083 (8)	C8—C9	1.386 (5)
C4—C5	1.388 (4)	C8—C9^iii	1.389 (5)
C4—O1	1.400 (3)	C9—C8^iv	1.389 (5)
C5—C6	1.395 (3)	C9—H9	1.083 (9)
C5—H5	1.089 (8)
C2—C1—C6	121.8 (2)	C1—C6—C5	118.8 (2)
C2—C1—Cl1	118.9 (2)	C1—C6—H6	119.6 (5)
C6—C1—Cl1	119.3 (2)	C5—C6—H6	121.6 (6)
C3—C2—C1	119.1 (2)	C7—O1—C4	119.0 (2)
C3—C2—H2	121.0 (6)	N1^i—C7—O1	119.64 (19)
C1—C2—H2	119.8 (6)	N1^i—C7—N1	127.38 (17)
C4—C3—C2	119.3 (3)	O1—C7—N1	112.98 (18)
C4—C3—H3	120.0 (5)	C7^ii—N1—C7	112.61 (17)
C2—C3—H3	120.7 (6)	C9—C8—C9^iii	122.3 (3)
C3—C4—C5	121.7 (2)	C9—C8—Br1	119.1 (3)
C3—C4—O1	121.1 (3)	C9^iii—C8—Br1	118.6 (3)
C5—C4—O1	117.1 (3)	C8—C9—C8^iv	117.7 (3)
C4—C5—C6	119.3 (2)	C8—C9—H9	121.1 (7)
C4—C5—H5	119.4 (5)	C8^iv—C9—H9	121.2 (7)
C6—C5—H5	121.3 (5)
C6—C1—C2—C3	0.4 (4)	C4—C5—C6—C1	0.5 (4)
Cl1—C1—C2—C3	179.4 (2)	C3—C4—O1—C7	65.3 (5)
C1—C2—C3—C4	−0.8 (4)	C5—C4—O1—C7	−118.8 (4)
C2—C3—C4—C5	1.0 (4)	C4—O1—C7—N1^i	1.2 (6)
C2—C3—C4—O1	176.7 (3)	C4—O1—C7—N1	−179.0 (4)
C3—C4—C5—C6	−0.9 (4)	N1^i—C7—N1—C7^ii	1.0 (7)
O1—C4—C5—C6	−176.7 (3)	O1—C7—N1—C7^ii	−178.8 (2)
C2—C1—C6—C5	−0.3 (4)	C9^iii—C8—C9—C8^iv	−0.2 (6)
Cl1—C1—C6—C5	−179.3 (2)	Br1—C8—C9—C8^iv	177.8 (2)

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