1-(4-Ethynylphen­yl)-3,5-dimethyl­biuret

In the title compound, C₁₂H₁₃N₃O₂, an intra­molecular N—H...O bond helps to establish the near-planar conformation; the two –NH–CO–N– fragments of the biuret backbone are twisted by 4.96 (10)°. An acute inter­molecular N—H...O hydrogen bond helps to define the crystal packing.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.037
• wR factor = 0.105
• Data-to-parameter ratio = 13.4

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT371_ALERT_2_C Long   C(sp2)-C(sp1) Bond  C2     -   C3     ...       1.44 Ang.

Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   1 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

The title compound, (I), was prepared as an intermediate in the synthesis of new multidentate porphyrin-like ligands.

On progressing along the chain formed by atoms N1, C9, N2, C11, and N3 (Fig. 1), the C–N bond lengths in (I) show a short-long-long-short pattern, although all of them are intermediate between typical C–N single (1.47 Å) and C=N double (1.30 Å) bonds. Bond-angle sums about the three N atoms in (I) yielded values of 360.0° in each case suggesting that all these species can be regarded as being sp² hybridized, indicating a significant degree of electronic delocalization over the entire biuret fragment (Carugo et al., 1992).

Similar variations in C–N bond-lengths to those of (I) were seen in biuret monohydrate (Craven, 1973), although other biurets show a distinctly different pattern, such as the monoclinic polymorph of 1-(2,6-difluorobenzoyl)-5-(4-chlorophenyl)biuret (Deschamps et al., 1998) in which a short-long-short-long sequence [C–N = 1.344 (4), 1.412 (4), 1.352 (4) and 1.407 (4) Å] occurs.

The two –NH—CO—N– fragments making up the biuret unit in (I) are planar within experimental error. The dihedral angle between these two groupings is 4.96 (10)°, which is at the lower end of the range of this parameter observed in related compounds (Carugo et al., 1992).

The ethynylphenyl moiety (atoms C1—C8) in (I) is twisted by 11.23 (7)° with respect to the N1/C9/O1/N2, grouping, although the C6—N1 bond [1.4026 (19) Å] appears to have significant double bond character. A PLATON analysis (Spek, 2003) of (I) suggested that the C2—C3 bond is unusually long [1.443 (2) Å] for a C(sp)—C(sp²) contact. However, a similar bond length (1.445 Å; s.u. not stated) has been seen for the equivalent bond in 1,4-diethynylbenzene (Ahmed et al., 1972).

A bent, intramolecular, N1—H1···O2 bond is present in (I) (Table 1), with the component atoms making up a six-ring loop, this being a common motif in biurets (Carugo et al., 1992).

In the crystal of (I), the molecules are linked into infinite chains which propagate in [010] by way of the N3—H3···O1ⁱ bond (see Table 1). There are no significant π-π, C—H···O or C—H···π interactions in (I).

Related literature

For related structures, see: Ahmed et al. (1972); Craven (1973); Carugo et al. (1992); Deschamps et al. (1998). For geometric analysis, see Spek (2003).

S2. Experimental

The title compound was prepared by reacting 1-(4-ethynylphenyl)biuret with MeI in THF (Aiken & Plater, 2007, unpublished work).

S3. Refinement

The H atoms were placed geometrically (N—H = 0.86 Å; C—H = 0.93–0.96 Å) and refined as riding with U_iso(H) = 1.2U_eq(carrier) or 1.5U_eq(methyl C). The methyl group was allowed to rotate, but not to tip, to best fit the electron density.

Computing details

Data collection: SMART (Bruker, 1999); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT (Bruker, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures

Fig. 1. The molecular structure of (I) (50% displacement ellipsoids, arbitrary spheres for the H atoms, hydrogen bond indicated by a double dashed line).

1-(4-Ethynylphenyl)-3,5-dimethylbiuret

Crystal data

C12H13N3O2	F(000) = 488
Mr = 231.25	Dx = 1.285 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 2287 reflections
a = 6.7870 (5) Å	θ = 2.2–25.0°
b = 11.1876 (8) Å	µ = 0.09 mm^−1
c = 15.8669 (11) Å	T = 293 K
β = 97.180 (2)°	Block, colourless
V = 1195.33 (15) Å^3	0.36 × 0.30 × 0.20 mm
Z = 4

Data collection

Bruker SMART1000 CCD diffractometer	1465 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.024
Graphite monochromator	θmax = 25.0°, θmin = 2.2°
ω scans	h = −6→8
6817 measured reflections	k = −12→13
2101 independent reflections	l = −18→18

Refinement

Refinement on F^2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.037	w = 1/[σ^2(Fo^2) + (0.0645P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.105	(Δ/σ)max = 0.001
S = 0.98	Δρmax = 0.15 e Å^−3
2101 reflections	Δρmin = −0.11 e Å^−3
157 parameters	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.016 (3)
Primary atom site location: structure-invariant direct methods

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
O1	0.24431 (16)	0.54995 (11)	0.34396 (7)	0.0731 (4)
O2	0.71481 (14)	0.32197 (11)	0.35264 (7)	0.0689 (4)
N1	0.56872 (18)	0.51965 (11)	0.39439 (8)	0.0569 (4)
H1	0.6618	0.4672	0.3961	0.068*
N2	0.38323 (17)	0.37021 (12)	0.31831 (7)	0.0527 (3)
N3	0.51702 (19)	0.19015 (13)	0.27910 (9)	0.0709 (4)
H3	0.4021	0.1736	0.2524	0.085*
C1	0.8880 (3)	1.02491 (19)	0.60840 (13)	0.0836 (6)
H1A	0.9375	1.0915	0.6391	0.100*
C2	0.8256 (3)	0.94085 (17)	0.56966 (10)	0.0660 (5)
C3	0.7550 (2)	0.83572 (14)	0.52261 (10)	0.0577 (4)
C4	0.8886 (2)	0.74785 (15)	0.50449 (10)	0.0643 (5)
H4	1.0236	0.7579	0.5218	0.077*
C5	0.8221 (2)	0.64615 (15)	0.46107 (10)	0.0619 (4)
H5	0.9131	0.5885	0.4489	0.074*
C6	0.6211 (2)	0.62841 (14)	0.43513 (9)	0.0523 (4)
C7	0.4871 (2)	0.71615 (15)	0.45250 (10)	0.0588 (4)
H7	0.3521	0.7063	0.4351	0.071*
C8	0.5556 (2)	0.81836 (15)	0.49591 (10)	0.0617 (4)
H8	0.4650	0.8767	0.5074	0.074*
C9	0.3921 (2)	0.48661 (15)	0.35301 (9)	0.0528 (4)
C10	0.1859 (2)	0.32878 (16)	0.28153 (10)	0.0676 (5)
H10A	0.0862	0.3805	0.2995	0.101*
H10B	0.1651	0.2487	0.3003	0.101*
H10C	0.1772	0.3300	0.2207	0.101*
C11	0.5479 (2)	0.29428 (15)	0.31843 (9)	0.0535 (4)
C12	0.6776 (3)	0.1042 (2)	0.28120 (15)	0.0998 (7)
H12A	0.6411	0.0422	0.2404	0.150*
H12B	0.7028	0.0698	0.3369	0.150*
H12C	0.7953	0.1436	0.2677	0.150*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0518 (7)	0.0721 (8)	0.0894 (9)	0.0121 (6)	−0.0144 (6)	0.0026 (6)
O2	0.0386 (6)	0.0772 (8)	0.0882 (8)	−0.0008 (5)	−0.0033 (5)	−0.0225 (6)
N1	0.0416 (7)	0.0594 (8)	0.0672 (8)	0.0029 (6)	−0.0024 (6)	−0.0024 (6)
N2	0.0377 (7)	0.0630 (8)	0.0552 (7)	−0.0028 (5)	−0.0020 (5)	0.0025 (6)
N3	0.0439 (8)	0.0824 (10)	0.0832 (10)	−0.0021 (7)	−0.0045 (7)	−0.0281 (8)
C1	0.0899 (15)	0.0771 (14)	0.0814 (13)	0.0077 (11)	0.0013 (10)	−0.0222 (11)
C2	0.0683 (11)	0.0668 (12)	0.0612 (10)	0.0097 (9)	0.0014 (8)	−0.0029 (9)
C3	0.0613 (11)	0.0577 (10)	0.0525 (8)	0.0066 (8)	0.0013 (7)	0.0027 (8)
C4	0.0501 (10)	0.0674 (11)	0.0724 (10)	0.0016 (8)	−0.0040 (8)	−0.0068 (9)
C5	0.0473 (10)	0.0647 (11)	0.0716 (10)	0.0090 (7)	−0.0009 (7)	−0.0074 (8)
C6	0.0484 (9)	0.0567 (10)	0.0507 (8)	0.0004 (7)	0.0016 (7)	0.0057 (7)
C7	0.0466 (9)	0.0670 (11)	0.0616 (10)	0.0075 (7)	0.0015 (7)	0.0043 (8)
C8	0.0596 (11)	0.0625 (11)	0.0627 (10)	0.0137 (8)	0.0064 (8)	0.0018 (8)
C9	0.0448 (9)	0.0625 (11)	0.0498 (8)	0.0004 (7)	0.0014 (7)	0.0092 (7)
C10	0.0412 (9)	0.0819 (12)	0.0763 (11)	−0.0047 (8)	−0.0061 (7)	−0.0012 (9)
C11	0.0402 (9)	0.0687 (10)	0.0509 (8)	−0.0046 (7)	0.0035 (7)	−0.0054 (8)
C12	0.0613 (12)	0.0988 (16)	0.1354 (18)	0.0114 (10)	−0.0029 (12)	−0.0533 (14)

Geometric parameters (Å, º)

C9—O1	1.2220 (18)	C3—C4	1.391 (2)
C11—O2	1.2328 (17)	C4—C5	1.376 (2)
N1—C9	1.3444 (19)	C4—H4	0.9300
N1—C6	1.4026 (19)	C5—C6	1.389 (2)
N1—H1	0.8600	C5—H5	0.9300
N2—C11	1.404 (2)	C6—C7	1.389 (2)
N2—C9	1.412 (2)	C7—C8	1.385 (2)
N2—C10	1.4677 (18)	C7—H7	0.9300
N3—C11	1.326 (2)	C8—H8	0.9300
N3—C12	1.451 (2)	C10—H10A	0.9600
N3—H3	0.8600	C10—H10B	0.9600
C1—C2	1.173 (2)	C10—H10C	0.9600
C1—H1A	0.9300	C12—H12A	0.9600
C2—C3	1.443 (2)	C12—H12B	0.9600
C3—C8	1.381 (2)	C12—H12C	0.9600
C9—N1—C6	128.52 (13)	C8—C7—H7	120.2
C9—N1—H1	115.7	C6—C7—H7	120.2
C6—N1—H1	115.7	C3—C8—C7	121.61 (15)
C11—N2—C9	124.21 (12)	C3—C8—H8	119.2
C11—N2—C10	119.76 (14)	C7—C8—H8	119.2
C9—N2—C10	116.02 (12)	O1—C9—N1	124.52 (16)
C11—N3—C12	119.84 (15)	O1—C9—N2	119.63 (14)
C11—N3—H3	120.1	N1—C9—N2	115.85 (13)
C12—N3—H3	120.1	N2—C10—H10A	109.5
C2—C1—H1A	180.0	N2—C10—H10B	109.5
C1—C2—C3	178.2 (2)	H10A—C10—H10B	109.5
C8—C3—C4	118.44 (15)	N2—C10—H10C	109.5
C8—C3—C2	121.54 (15)	H10A—C10—H10C	109.5
C4—C3—C2	120.01 (15)	H10B—C10—H10C	109.5
C5—C4—C3	120.42 (15)	O2—C11—N3	120.71 (14)
C5—C4—H4	119.8	O2—C11—N2	122.42 (15)
C3—C4—H4	119.8	N3—C11—N2	116.87 (13)
C4—C5—C6	120.97 (14)	N3—C12—H12A	109.5
C4—C5—H5	119.5	N3—C12—H12B	109.5
C6—C5—H5	119.5	H12A—C12—H12B	109.5
C5—C6—C7	118.91 (15)	N3—C12—H12C	109.5
C5—C6—N1	116.33 (13)	H12A—C12—H12C	109.5
C7—C6—N1	124.74 (14)	H12B—C12—H12C	109.5
C8—C7—C6	119.64 (15)
N1—C9—N2—C11	−5.7 (2)	O2—C11—N2—C10	−175.88 (14)
C9—N2—C11—N3	−176.34 (13)	O1—C9—N2—C11	174.09 (14)
N2—C11—N3—C12	−176.20 (16)	C9—N2—C11—O2	3.2 (2)
N1—C9—N2—C10	173.37 (12)	O2—C11—N3—C12	4.3 (3)
O1—C9—N2—C10	−6.8 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O2	0.86	1.82	2.5451 (17)	141
N3—H3···O1^i	0.86	2.20	2.9245 (17)	141

Symmetry code: (i) −x+1/2, y−1/2, −z+1/2.