1,3,5-Tris(4-meth­­oxy­phen­yl)-1,3,5-triazinane-2,4,6-trione

The complete mol­ecule of the title compound, C₂₄H₂₁N₃O₆, is generated by the application of threefold rotation symmetry about an axis perpendicular to the central ring. The mol­ecule exhibits a propeller-like shape. The dihedral angle between each benzene ring and the heterocyclic ring is 74.0 (1)°. The mol­ecules pack with no specific inter­molecular inter­actions between them. The SQUEEZE procedure in PLATON [Spek (2009). Acta Cryst. D65, 148–155] was used to model disordered solvent mol­ecules, presumed to be acetone; the calculated unit-cell data do not take into account the presence of these.

Related literature

For general background to trimerization of aromatic iso­cyanates, see: Raders & Verkade (2010); Duong et al. (2004); Tang et al. (1994); Zhitinkina et al. (1985); Nawata et al. (1975); Nicholas & Gmitter (1965).

Experimental

Crystal data

• C₂₄H₂₁N₃O₆

• M_r = 447.44

• Trigonal, R 3c

• a = 13.2008 (14) Å

• c = 26.695 (3) Å

• V = 4028.7 (8) ų

• Z = 6

• Mo Kα radiation

• μ = 0.08 mm⁻¹

• T = 200 K

• 0.51 × 0.49 × 0.04 mm

Data collection

• Bruker SMART CCD area-detector diffractometer

• Absorption correction: multi-scan (SADABS; Sheldrick, 1996) T_min = 0.960, T_max = 0.997

• 6995 measured reflections

• 1577 independent reflections

• 1142 reflections with I > 2σ(I)

• R_int = 0.031

Refinement

• R[F² > 2σ(F²)] = 0.044

• wR(F²) = 0.122

• S = 1.05

• 1577 reflections

• 101 parameters

• 1 restraint

• H-atom parameters constrained

• Δρ_max = 0.16 e Å⁻³

• Δρ_min = −0.12 e Å⁻³

Data collection: SMART (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009).

Supporting information

S1. Experimental

S1.1. Synthesis and crystallization

To a stirred solution of lithium di­benzyl­amide (0.04 g) in di­ethyl ether was added 4-meth­oxy­phenyl iso­thio­cyanate (29.8 g). After stirring for 2 min, the mixture afforded a white precipitate. The resulting precipitate was collected by suction filtration and recrystallized from acetone to obtain white crystals of 1,3,5-tris-(4-meth­oxy­phenyl)-1,3,5-triazinane-2,4,6-trione (yield: 90%), m.p. 530–531 K.

S1.2. Refinement

The H atoms were placed in their idealised positions with C—H = 0.95–0.98 Å, and refined as riding with U_iso(H) = 1.2–1.5U_eq. The structure contains solvent accessible voids of 153 A³. The SQUEEZE procedure in PLATON (Spek, 2009) was used to model the disordered solvent molecules, presumed to be 4–6 acetone molecules per unit cell.

S2. Results and discussion

Trimerization of aromatic iso­cyanates, manufactured by cyclo­trimerizing corresponding iso­cyanates, has been known to enhance the properties of polyurethanes or coating materials (Raders & Verkade, 2010; Duong et al., 2004; Tang et al., 1994; Zhitinkina et al., 1985; Nawata et al., 1975; Nicholas & Gmitter, 1965). Polymers, such as polyurethanes incorporated with isocyanurates, have enhanced thermal resistance, flame retardation, chemical resistance and film-forming characteristics. Isocyanurates are also used in the synthesis of co-polymer resins to improve their water-resistance, transparency and impact resistance. During research on the properties of lithium di­benzyl­amide, a simple and efficient catalyst for iso­cyanate cyclo­trimerization to isocyanurate, we obtained crystals of 1,3,5-tris-(4-meth­oxy­phenyl)-1,3,5-triazinane-2,4,6-trione.

In the title compound, C₂₄H₂₁N₃O₆, the six-membered heterocyclic ring lies on a threefold rotation axis and adopts a planar conformation. The molecule exhibits a propeller-like shape. The dihedral angle between each benzene ring and the heterocyclic ring is 74.0 (1).

Related literature

For general background to trimerization of aromatic isocyanates, see: Raders & Verkade (2010); Duong et al. (2004); Tang et al. (1994); Zhitinkina et al. (1985); Nawata et al. (1975); Nicholas & Gmitter (1965).

Structure description

Trimerization of aromatic iso­cyanates, manufactured by cyclo­trimerizing corresponding iso­cyanates, has been known to enhance the properties of polyurethanes or coating materials (Raders & Verkade, 2010; Duong et al., 2004; Tang et al., 1994; Zhitinkina et al., 1985; Nawata et al., 1975; Nicholas & Gmitter, 1965). Polymers, such as polyurethanes incorporated with isocyanurates, have enhanced thermal resistance, flame retardation, chemical resistance and film-forming characteristics. Isocyanurates are also used in the synthesis of co-polymer resins to improve their water-resistance, transparency and impact resistance. During research on the properties of lithium di­benzyl­amide, a simple and efficient catalyst for iso­cyanate cyclo­trimerization to isocyanurate, we obtained crystals of 1,3,5-tris-(4-meth­oxy­phenyl)-1,3,5-triazinane-2,4,6-trione.

In the title compound, C₂₄H₂₁N₃O₆, the six-membered heterocyclic ring lies on a threefold rotation axis and adopts a planar conformation. The molecule exhibits a propeller-like shape. The dihedral angle between each benzene ring and the heterocyclic ring is 74.0 (1).

For general background to trimerization of aromatic isocyanates, see: Raders & Verkade (2010); Duong et al. (2004); Tang et al. (1994); Zhitinkina et al. (1985); Nawata et al. (1975); Nicholas & Gmitter (1965).

Synthesis and crystallization

To a stirred solution of lithium di­benzyl­amide (0.04 g) in di­ethyl ether was added 4-meth­oxy­phenyl iso­thio­cyanate (29.8 g). After stirring for 2 min, the mixture afforded a white precipitate. The resulting precipitate was collected by suction filtration and recrystallized from acetone to obtain white crystals of 1,3,5-tris-(4-meth­oxy­phenyl)-1,3,5-triazinane-2,4,6-trione (yield: 90%), m.p. 530–531 K.

Refinement details

The H atoms were placed in their idealised positions with C—H = 0.95–0.98 Å, and refined as riding with U_iso(H) = 1.2–1.5U_eq. The structure contains solvent accessible voids of 153 A³. The SQUEEZE procedure in PLATON (Spek, 2009) was used to model the disordered solvent molecules, presumed to be 4–6 acetone molecules per unit cell.

Computing details

Data collection: SMART (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures

Fig. 1. Molecular structure of I showing 30% probability displacement ellipsoids. The hydrogen atoms are omitted for clarity.

1,3,5-Tris(4-methoxyphenyl)-1,3,5-triazinane-2,4,6-trione

Crystal data

C24H21N3O6	Dx = 1.107 Mg m^−3
Mr = 447.44	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3c	Cell parameters from 1247 reflections
Hall symbol: R 3 -2"c	θ = 2.3–20.4°
a = 13.2008 (14) Å	µ = 0.08 mm^−1
c = 26.695 (3) Å	T = 200 K
V = 4028.7 (8) Å^3	Block, colourless
Z = 6	0.51 × 0.49 × 0.04 mm
F(000) = 1404

Data collection

Bruker SMART CCD area-detector diffractometer	1577 independent reflections
Radiation source: fine-focus sealed tube	1142 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.031
phi and ω scans	θmax = 25.0°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −9→15
Tmin = 0.960, Tmax = 0.997	k = −15→14
6995 measured reflections	l = −31→31

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.044	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.122	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0687P)^2] where P = (Fo^2 + 2Fc^2)/3
1577 reflections	(Δ/σ)max = 0.001
101 parameters	Δρmax = 0.16 e Å^−3
1 restraint	Δρmin = −0.12 e Å^−3

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
N1	0.24317 (15)	0.68853 (16)	0.06336 (8)	0.0507 (6)
O1	0.37628 (17)	0.88360 (16)	0.06161 (9)	0.0710 (6)
O2	−0.1275 (2)	0.7774 (3)	0.06263 (12)	0.1146 (9)
C1	0.1470 (2)	0.7108 (2)	0.06541 (11)	0.0552 (7)
C2	0.0864 (2)	0.6942 (2)	0.10907 (12)	0.0652 (7)
H2	0.1090	0.6709	0.1387	0.078*
C3	−0.0104 (3)	0.7124 (3)	0.10944 (13)	0.0768 (9)
H3	−0.0565	0.6970	0.1388	0.092*
C4	−0.0369 (2)	0.7525 (3)	0.06691 (14)	0.0724 (8)
C5	0.0253 (3)	0.7708 (3)	0.02514 (15)	0.0878 (10)
H5	0.0050	0.7983	−0.0039	0.105*
C6	0.1168 (3)	0.7514 (3)	0.02308 (12)	0.0729 (8)
H6	0.1600	0.7654	−0.0071	0.088*
C7	0.3566 (2)	0.7838 (2)	0.06225 (11)	0.0566 (7)
C8	−0.2060 (4)	0.7446 (5)	0.1028 (2)	0.1312 (17)
H8A	−0.2414	0.6604	0.1087	0.197*
H8B	−0.2674	0.7631	0.0948	0.197*
H8C	−0.1641	0.7874	0.1329	0.197*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0390 (12)	0.0406 (12)	0.0734 (15)	0.0206 (10)	0.0029 (11)	0.0033 (11)
O1	0.0571 (12)	0.0488 (12)	0.1124 (15)	0.0306 (10)	−0.0006 (11)	−0.0036 (10)
O2	0.0943 (19)	0.158 (3)	0.127 (2)	0.0896 (19)	0.0056 (17)	0.0234 (18)
C1	0.0452 (16)	0.0456 (15)	0.0770 (18)	0.0242 (14)	0.0011 (15)	−0.0026 (14)
C2	0.0608 (17)	0.0636 (18)	0.0762 (19)	0.0350 (14)	0.0076 (14)	0.0051 (15)
C3	0.0591 (18)	0.080 (2)	0.089 (2)	0.0331 (16)	0.0207 (15)	0.0075 (17)
C4	0.0538 (16)	0.078 (2)	0.098 (2)	0.0429 (16)	−0.0027 (18)	0.0036 (17)
C5	0.071 (2)	0.111 (3)	0.093 (3)	0.054 (2)	−0.008 (2)	0.0187 (19)
C6	0.0654 (19)	0.079 (2)	0.081 (2)	0.0410 (16)	0.0038 (16)	0.0179 (16)
C7	0.0465 (16)	0.0472 (16)	0.0751 (19)	0.0227 (11)	0.0012 (14)	−0.0021 (14)
C8	0.085 (3)	0.174 (4)	0.166 (4)	0.088 (3)	0.016 (3)	−0.011 (4)

Geometric parameters (Å, º)

N1—C7^i	1.384 (3)	C3—C4	1.370 (5)
N1—C7	1.393 (3)	C3—H3	0.9500
N1—C1	1.440 (3)	C4—C5	1.333 (4)
O1—C7	1.209 (3)	C5—C6	1.356 (4)
O2—C4	1.395 (4)	C5—H5	0.9500
O2—C8	1.400 (5)	C6—H6	0.9500
C1—C2	1.368 (4)	C7—N1^ii	1.384 (3)
C1—C6	1.392 (4)	C8—H8A	0.9800
C2—C3	1.413 (4)	C8—H8B	0.9800
C2—H2	0.9500	C8—H8C	0.9800
C7^i—N1—C7	124.2 (3)	C4—C5—C6	121.7 (3)
C7^i—N1—C1	117.35 (19)	C4—C5—H5	119.2
C7—N1—C1	118.43 (19)	C6—C5—H5	119.2
C4—O2—C8	117.0 (3)	C5—C6—C1	119.6 (3)
C2—C1—C6	119.7 (2)	C5—C6—H6	120.2
C2—C1—N1	120.3 (3)	C1—C6—H6	120.2
C6—C1—N1	120.0 (2)	O1—C7—N1^ii	122.2 (2)
C1—C2—C3	119.1 (3)	O1—C7—N1	122.1 (2)
C1—C2—H2	120.5	N1^ii—C7—N1	115.7 (3)
C3—C2—H2	120.5	O2—C8—H8A	109.5
C4—C3—C2	119.1 (3)	O2—C8—H8B	109.5
C4—C3—H3	120.4	H8A—C8—H8B	109.5
C2—C3—H3	120.4	O2—C8—H8C	109.5
C5—C4—C3	120.7 (3)	H8A—C8—H8C	109.5
C5—C4—O2	114.3 (3)	H8B—C8—H8C	109.5
C3—C4—O2	125.0 (3)

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