Di­cyano{[(1S)-(1-phenyl­ethyl)­aziridin-2-yl]­methano­lato-κ²N,O}boron

In the title compound, C₁₃H₁₄BN₃O, the aziridine ring is an almost equilateral triangle, the C—C distance being slightly shorter than the C—N distances, probably because of the dative B—N bond. The five-membered ring, composed of two C atoms and N, B and O atoms, is fused with the aziridine ring to form a six-membered ring with a chair conformation.

S1. Comment

During the course of the synthetic studies using the chiral aziridine 1-[(S)-1-phenylethyl]-2 − t-butyldimethylsilyloxymethylaziridine (Lee & Ha, 2003), we expected that the azidirine ring, known to be labile to Lewis acids (Pearson et al., 1996), would be opened by a nitrile nucleophile with the assistance of boron trifluoride. However, although the spectral data for the product, viz. the title compound, (I), do not allow an unambiguous structural assignment, they clearly show that (I) contains two cyano groups, with conservation of the three-membered aziridine ring, known to be labile with Lewis acids (Pearson, et al., 1996). Compound (I) is stable at room temperature in air for up to a month, and the structure determination described here was undertaken to establish its exact nature.

The structure of (I) is shown in Fig. 1. Contrary to our expectation, the nitrile nucleophiles have replaced the fluorides at the B atom instead of leading to ring opening, and the aziridine ring remains intact. Atoms N1, C1 and C2 form an almost equilateral triangle, the C1—C2 distance [1.468 (3) Å] being slightly shorter than the C—N distances [1.484 (2) and 1.506 (2) Å]. Usually, the C—C distances in aziridine rings are longer than the C—N distances (Hargreaves et al., 1997; Willems et al., 1997). However, the C—N bond distances in (I) are slightly longer than the C—C distances. This behaviour is probably due to the electron-donating nature of the N atom towards the B atom in forming the dative B—N bond. The geometry around atom N1 is distorted significantly from the ideal tetrahedron, with high strain.

A five-membered ring composed of atoms N1, B, O, C3 and C2 is observed in the product. This ring is fused with the aziridine ring, thus forming a six-membered ring that displays a chair conformation. The interplanar angle between the azidirine ring plane and the main plane of the chair (B/N1/C2/C3) is 68.96 (12)°, which is greater than that to the plane composed of atoms O, B and C3 [35.98 (17)°].

Compound (I) has a characteristic coordinative bond between the N and B atoms, with a bond distance of 1.608 (3) Å, which is significantly longer than the usual covalent bond distances (~1.4 Å; Allen et al., 1987) but agrees well with values for other dative B—N bonds, e.g. in NH₃BF₃ (Penner et al., 2002). The geometry around the B atom can be described as typical of tetrahedral coordination [ca 104.1 (1)–114.1 (2) °].

There is no strong hydrogen bond in (I) (Spek, 1990). However, there are some short C—H···N contacts that could be regarded as weak hydrogen bonds (Table 2). Additionally, there is an intermolecular contact between atoms C1 and N3(1 + x,y,z) [3.163 (4) Å].

S2. Experimental

The title compound was prepared from the reaction of 1-[(S)-1-phenylethyl]-2 −t-butyldimethylsilyloxymethylaziridine with three molar equivalents of cyanotrimethylsilane and one equivalent of boron trifluroride diethyl etherate at 233 K in CH₂Cl₂. The initial product (85% yield), a white solid, was recrystallized from dichloromethane to afford single crystals suitable for X-ray diffraction studies. Analysis found: C 65.2, H 5.77, N 17.5%; calculated: C 65.3, H 5.90, N 17.6

S3. Refinement

The absolute configuration cannot be determined in the absence of significant anomalous scattering and was therefore assigned by reference to the starting materials. Friedel opposite reflections were merged. The positions of the H atoms were generated geometically and refined as riding (SHELXL97; Sheldrick, 1997).

Computing details

Data collection: MXC3 (MacScience, 1994); cell refinement: MXC3; data reduction: MXC3; program(s) used to solve structure: SHELXS86 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

Figures

Fig. 1. The molecular structure of (I), showing 30% probability displacement ellipsoids.

Dicyano{[(1S)-(1-phenylethyl)aziridin-2-yl]methanolato-κ²N,O}boron

Crystal data

C13H14BN3O	Z = 1
Mr = 239.08	F(000) = 126
Triclinic, P1	Dx = 1.216 Mg m^−3
a = 6.710 (3) Å	Mo Kα radiation, λ = 0.71073 Å
b = 6.767 (4) Å	Cell parameters from 20 reflections
c = 8.059 (5) Å	θ = 10–14°
α = 71.51 (4)°	µ = 0.08 mm^−1
β = 84.68 (5)°	T = 293 K
γ = 70.16 (3)°	Rectangular, colourless
V = 326.4 (3) Å^3	0.5 × 0.4 × 0.3 mm

Data collection

MacScience MXC3 diffractometer	Rint = 0.020
Radiation source: fine-focus sealed tube	θmax = 27.5°, θmin = 2.7°
Graphite monochromator	h = −8→8
ω–2θ scans	k = −8→8
1595 measured reflections	l = 0→10
1483 independent reflections	2 standard reflections every 100 reflections
1435 reflections with I > 2σ(I)	intensity decay: none

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)] = 0.033	H-atom parameters constrained
wR(F^2) = 0.090	w = 1/[σ^2(Fo^2) + (0.0596P)^2 + 0.0238P] where P = (Fo^2 + 2Fc^2)/3
S = 1.08	(Δ/σ)max < 0.001
1483 reflections	Δρmax = 0.17 e Å^−3
165 parameters	Δρmin = −0.15 e Å^−3
3 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.09 (2)

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

	x	y	z	Uiso*/Ueq
C(1)	0.3951 (3)	0.1742 (3)	0.9006 (2)	0.0336 (4)
C(2)	0.3368 (3)	0.4116 (3)	0.8755 (2)	0.0305 (4)
C(3)	0.2319 (3)	0.4951 (3)	1.0258 (3)	0.0359 (4)
C(4)	0.1521 (3)	0.3504 (3)	0.6268 (2)	0.0282 (4)
C(5)	0.1412 (4)	0.1347 (4)	0.6139 (3)	0.0400 (5)
C(6)	0.3154 (3)	0.4337 (3)	0.5104 (2)	0.0301 (4)
C(7)	0.5046 (3)	0.2924 (4)	0.4686 (3)	0.0365 (4)
C(8)	0.6532 (4)	0.3785 (5)	0.3663 (3)	0.0515 (6)
C(9)	0.6140 (5)	0.6036 (5)	0.3084 (3)	0.0624 (8)
C(10)	0.4286 (6)	0.7424 (5)	0.3490 (3)	0.0667 (9)
C(11)	0.2776 (4)	0.6601 (4)	0.4471 (3)	0.0467 (6)
C(12)	−0.1921 (3)	0.5691 (3)	0.8498 (3)	0.0327 (4)
C(13)	−0.0846 (3)	0.1439 (3)	1.0175 (3)	0.0356 (4)
B	−0.0025 (3)	0.3523 (3)	0.9532 (3)	0.0285 (4)
N(1)	0.1875 (2)	0.3229 (2)	0.81644 (19)	0.0243 (3)
N(2)	−0.3255 (3)	0.7216 (3)	0.7767 (3)	0.0484 (5)
N(3)	−0.1448 (3)	−0.0010 (3)	1.0667 (3)	0.0525 (5)
O	0.0872 (2)	0.3772 (2)	1.09578 (18)	0.0359 (3)
H(1A)	0.3944	0.0779	1.0189	0.040*
H(1B)	0.5049	0.1113	0.8271	0.040*
H(2)	0.4106	0.4982	0.7875	0.037*
H(3A)	0.3362	0.4659	1.1138	0.043*
H(3B)	0.1573	0.6526	0.9847	0.043*
H(4)	0.0132	0.4626	0.5906	0.034*
H(5A)	0.0234	0.1021	0.6798	0.060*
H(5B)	0.2700	0.0177	0.6602	0.060*
H(5C)	0.1232	0.1482	0.4935	0.060*
H(7)	0.5320	0.1407	0.5089	0.044*
H(8)	0.7786	0.2841	0.3372	0.062*
H(9)	0.7140	0.6607	0.2417	0.075*
H(10)	0.4034	0.8938	0.3104	0.080*
H(11)	0.1502	0.7567	0.4709	0.056*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C(1)	0.0231 (8)	0.0399 (10)	0.0281 (9)	−0.0014 (7)	−0.0036 (7)	−0.0059 (8)
C(2)	0.0257 (8)	0.0423 (10)	0.0258 (8)	−0.0163 (8)	−0.0005 (7)	−0.0077 (7)
C(3)	0.0380 (10)	0.0446 (10)	0.0313 (9)	−0.0185 (8)	0.0020 (7)	−0.0149 (8)
C(4)	0.0251 (8)	0.0322 (8)	0.0245 (8)	−0.0053 (7)	−0.0019 (6)	−0.0086 (7)
C(5)	0.0408 (10)	0.0459 (11)	0.0429 (11)	−0.0203 (9)	0.0024 (8)	−0.0204 (9)
C(6)	0.0373 (9)	0.0312 (8)	0.0202 (8)	−0.0111 (7)	−0.0004 (7)	−0.0055 (7)
C(7)	0.0345 (10)	0.0436 (10)	0.0261 (9)	−0.0092 (8)	0.0013 (7)	−0.0074 (8)
C(8)	0.0374 (11)	0.0894 (19)	0.0291 (10)	−0.0248 (12)	0.0053 (9)	−0.0169 (11)
C(9)	0.086 (2)	0.097 (2)	0.0272 (11)	−0.0652 (19)	0.0153 (12)	−0.0160 (13)
C(10)	0.130 (3)	0.0584 (16)	0.0289 (11)	−0.0593 (19)	0.0161 (14)	−0.0104 (11)
C(11)	0.0759 (16)	0.0339 (10)	0.0259 (10)	−0.0167 (10)	0.0060 (10)	−0.0062 (8)
C(12)	0.0272 (9)	0.0318 (9)	0.0400 (10)	−0.0087 (8)	0.0058 (8)	−0.0147 (8)
C(13)	0.0292 (9)	0.0351 (10)	0.0397 (10)	−0.0120 (8)	0.0056 (7)	−0.0075 (8)
B	0.0232 (9)	0.0293 (9)	0.0310 (10)	−0.0073 (7)	0.0055 (8)	−0.0094 (8)
N(1)	0.0206 (6)	0.0251 (6)	0.0251 (7)	−0.0063 (5)	0.0000 (5)	−0.0063 (5)
N(2)	0.0383 (10)	0.0378 (9)	0.0615 (12)	0.0002 (8)	−0.0029 (9)	−0.0177 (9)
N(3)	0.0464 (11)	0.0452 (11)	0.0633 (13)	−0.0230 (9)	0.0067 (10)	−0.0061 (9)
O	0.0359 (7)	0.0468 (8)	0.0271 (6)	−0.0177 (6)	0.0069 (5)	−0.0114 (6)

Geometric parameters (Å, º)

C(1)—C(2)	1.468 (3)	C(6)—C(7)	1.393 (3)
C(1)—N(1)	1.484 (2)	C(7)—C(8)	1.396 (3)
C(1)—H(1A)	0.9700	C(7)—H(7)	0.9300
C(1)—H(1B)	0.9700	C(8)—C(9)	1.381 (5)
C(2)—N(1)	1.506 (2)	C(8)—H(8)	0.9300
C(2)—C(3)	1.513 (3)	C(9)—C(10)	1.365 (5)
C(2)—H(2)	0.9800	C(9)—H(9)	0.9300
C(3)—O	1.427 (3)	C(10)—C(11)	1.384 (4)
C(3)—H(3A)	0.9700	C(10)—H(10)	0.9300
C(3)—H(3B)	0.9700	C(11)—H(11)	0.9300
C(4)—N(1)	1.511 (2)	C(12)—N(2)	1.140 (3)
C(4)—C(6)	1.514 (3)	C(12)—B	1.618 (3)
C(4)—C(5)	1.523 (3)	C(13)—N(3)	1.128 (3)
C(4)—H(4)	0.9800	C(13)—B	1.604 (3)
C(5)—H(5A)	0.9600	B—O	1.425 (3)
C(5)—H(5B)	0.9600	B—N(1)	1.608 (3)
C(5)—H(5C)	0.9600	C(1)—N(3)^i	3.163 (4)
C(6)—C(11)	1.392 (3)	C(5)—N(1)	2.463 (3)
C(2)—C(1)—N(1)	61.34 (12)	C(7)—C(6)—C(4)	122.60 (17)
C(2)—C(1)—H(1A)	117.6	C(6)—C(7)—C(8)	120.1 (2)
N(1)—C(1)—H(1A)	117.6	C(6)—C(7)—H(7)	120.0
C(2)—C(1)—H(1B)	117.6	C(8)—C(7)—H(7)	120.0
N(1)—C(1)—H(1B)	117.6	C(9)—C(8)—C(7)	120.0 (2)
H(1A)—C(1)—H(1B)	114.7	C(9)—C(8)—H(8)	120.0
C(1)—C(2)—N(1)	59.85 (12)	C(7)—C(8)—H(8)	120.0
C(1)—C(2)—C(3)	117.62 (17)	C(10)—C(9)—C(8)	120.0 (2)
N(1)—C(2)—C(3)	106.74 (15)	C(10)—C(9)—H(9)	120.0
C(1)—C(2)—H(2)	119.2	C(8)—C(9)—H(9)	120.0
N(1)—C(2)—H(2)	119.2	C(9)—C(10)—C(11)	120.7 (2)
C(3)—C(2)—H(2)	119.2	C(9)—C(10)—H(10)	119.7
O—C(3)—C(2)	105.28 (16)	C(11)—C(10)—H(10)	119.7
O—C(3)—H(3A)	110.7	C(10)—C(11)—C(6)	120.4 (2)
C(2)—C(3)—H(3A)	110.7	C(10)—C(11)—H(11)	119.8
O—C(3)—H(3B)	110.7	C(6)—C(11)—H(11)	119.8
C(2)—C(3)—H(3B)	110.7	N(2)—C(12)—B	179.8 (2)
H(3A)—C(3)—H(3B)	108.8	N(3)—C(13)—B	178.1 (2)
N(1)—C(4)—C(6)	111.54 (14)	O—B—C(13)	110.71 (16)
N(1)—C(4)—C(5)	108.54 (16)	O—B—N(1)	104.08 (14)
C(6)—C(4)—C(5)	114.35 (16)	C(13)—B—N(1)	112.53 (15)
N(1)—C(4)—H(4)	107.4	O—B—C(12)	114.09 (16)
C(6)—C(4)—H(4)	107.4	C(13)—B—C(12)	109.59 (15)
C(5)—C(4)—H(4)	107.4	N(1)—B—C(12)	105.71 (15)
C(4)—C(5)—H(5A)	109.5	C(1)—N(1)—C(2)	58.81 (13)
C(4)—C(5)—H(5B)	109.5	C(1)—N(1)—C(4)	118.49 (14)
H(5A)—C(5)—H(5B)	109.5	C(2)—N(1)—C(4)	123.43 (14)
C(4)—C(5)—H(5C)	109.5	C(1)—N(1)—B	113.35 (15)
H(5A)—C(5)—H(5C)	109.5	C(2)—N(1)—B	102.86 (14)
H(5B)—C(5)—H(5C)	109.5	C(4)—N(1)—B	122.79 (14)
C(11)—C(6)—C(7)	118.8 (2)	B—O—C(3)	107.80 (15)
C(11)—C(6)—C(4)	118.59 (19)
N1—C1—C2—C3	94.14 (17)	C1—C2—N1—B	109.70 (15)
C1—C2—C3—O	−40.6 (2)	C3—C2—N1—B	−2.95 (17)
N1—C2—C3—O	23.63 (19)	C6—C4—N1—C1	−57.9 (2)
N1—C4—C6—C11	−86.3 (2)	C5—C4—N1—C1	69.0 (2)
C5—C4—C6—C11	150.03 (18)	C6—C4—N1—C2	11.8 (2)
N1—C4—C6—C7	91.6 (2)	C5—C4—N1—C2	138.65 (16)
C5—C4—C6—C7	−32.0 (2)	C6—C4—N1—B	149.74 (15)
C11—C6—C7—C8	0.6 (3)	C5—C4—N1—B	−83.40 (19)
C4—C6—C7—C8	−177.40 (17)	O—B—N1—C1	42.79 (19)
C6—C7—C8—C9	0.9 (3)	C13—B—N1—C1	−77.12 (19)
C7—C8—C9—C10	−0.9 (4)	C12—B—N1—C1	163.30 (15)
C8—C9—C10—C11	−0.5 (4)	O—B—N1—C2	−18.52 (16)
C9—C10—C11—C6	1.9 (4)	C13—B—N1—C2	−138.43 (16)
C7—C6—C11—C10	−2.0 (3)	C12—B—N1—C2	101.99 (16)
C4—C6—C11—C10	176.1 (2)	O—B—N1—C4	−163.54 (14)
N3—C13—B—O	44 (7)	C13—B—N1—C4	76.5 (2)
N3—C13—B—N1	160 (6)	C12—B—N1—C4	−43.0 (2)
N3—C13—B—C12	−83 (7)	C13—B—O—C3	155.89 (15)
N2—C12—B—O	154 (100)	N1—B—O—C3	34.75 (18)
N2—C12—B—C13	−81 (67)	C12—B—O—C3	−79.94 (18)
N2—C12—B—N1	40 (67)	C2—C3—O—B	−37.3 (2)
C2—C1—N1—C4	113.84 (17)	C1—C2—N1—B	109.70 (15)
C2—C1—N1—B	−91.26 (16)	C1—C2—N1—C3	112.66 (17)
C3—C2—N1—C1	−112.66 (17)	O—B—C3—N1	144.92 (19)
C1—C2—N1—C4	−105.57 (17)	O—B—C3—C2	143.0 (2)
C3—C2—N1—C4	141.77 (16)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1B···N3^i	0.97	2.92	3.163 (4)	95
C2—H2···N2^i	0.98	2.67	3.465 (3)	138
C1—H1B···N2^ii	0.97	2.64	3.404 (3)	136
C9—H9···N3^iii	0.93	2.70	3.553 (4)	152

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