Azido­tri­phenyl­silane: a new determination

The title compound, (I), C₁₈H₁₅N₃Si, is monomeric with quasi-tetrahedral geometry around Si. The azide group (—N_α—N_β—N_γ) is disordered. One form has (N_α—N_β) > d(N_β—N_γ); the other has d(N_α—N_β) < d(N_β—N_γ). In contrast, the mesityl analogue, (II), has d(N_α—N_β) only slightly less than d(N_β—N_γ). As expected, on going from (I) to (II), d(Si—N_α), d(Si—C)_ave and angle (C—Si—C)_ave increase, while angle (C—Si—N_α)_ave decreases.

Key indicators

• Single-crystal X-ray study
• T = 220 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.039
• wR factor = 0.121
• Data-to-parameter ratio = 14.6

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT241_ALERT_2_B Check High   U(eq) as Compared to Neighbors  for        N32

Alert level C
PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density ....       2.17
PLAT241_ALERT_2_C Check High   U(eq) as Compared to Neighbors  for        N31
PLAT242_ALERT_2_C Check Low    U(eq) as Compared to Neighbors  for        N21
PLAT301_ALERT_3_C Main Residue  Disorder .........................       8.00 Perc.

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

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

---

Computing details

Data collection: SMART (Bruker, 1999b); cell refinement: SMART; data reduction: SAINT (Bruker, 1999a); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997a); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997b); molecular graphics: SHELXTL (Bruker, 1997); software used to prepare material for publication: UdMX (local program).

azidotriphenylsilane

Crystal data

C18H15N3Si	F(000) = 632
Mr = 301.42	Dx = 1.248 Mg m^−3
Monoclinic, P21/n	Cu Kα radiation, λ = 1.54178 Å
Hall symbol: -P 2yn	Cell parameters from 14448 reflections
a = 9.6708 (2) Å	θ = 2.6–72.6°
b = 17.0961 (3) Å	µ = 1.28 mm^−1
c = 10.3028 (2) Å	T = 220 K
β = 109.665 (1)°	Block, colourless
V = 1604.04 (5) Å^3	0.40 × 0.26 × 0.13 mm
Z = 4

Data collection

Bruker AXS Smart 2K/Platform diffractometer	3164 independent reflections
Radiation source: Sealed Tube	2756 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.022
Detector resolution: 5.5 pixels mm^-1	θmax = 72.8°, θmin = 5.2°
ω scans	h = −11→11
Absorption correction: multi-scan (SADABS; Sheldrick,1996)	k = −21→21
Tmin = 0.705, Tmax = 0.847	l = −12→11
19377 measured reflections

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)] = 0.039	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.121	H-atom parameters constrained
S = 1.04	w = 1/[σ^2(Fo^2) + (0.0873P)^2 + 0.1083P] where P = (Fo^2 + 2Fc^2)/3
3164 reflections	(Δ/σ)max < 0.001
217 parameters	Δρmax = 0.39 e Å^−3
48 restraints	Δρmin = −0.18 e Å^−3

Special details

Experimental. X-ray crystallographic data for (I) were collected from a single-crystal sample, which was mounted on a loop fiber. Data were collected using a Bruker Platform diffractometer, equipped with a Bruker SMART 2 K Charged-Coupled Device (CCD) Area Detector using the program SMART and normal focus sealed tube source graphite monochromated Cu—Kα radiation. The crystal-to-detector distance was 4.908 cm, and the data collection was carried out in 512 x 512 pixel mode, utilizing 4 x 4 pixel binning. The initial unit-cell parameters were determined by a least-squares fit of the angular setting of strong reflections, collected by a 9.0 degree scan in 30 frames over four different parts of the reciprocal space (120 frames total). One complete sphere of data was collected, to better than 0.8 Å resolution. Upon completion of the data collection, the first 101 frames were recollected in order to improve the decay correction analysis.

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	Occ. (<1)
Si	0.61309 (4)	0.15538 (2)	0.24537 (4)	0.03702 (15)
N1	0.61329 (18)	0.08411 (8)	0.12173 (14)	0.0489 (3)
N21	0.7299 (18)	0.0628 (10)	0.0982 (18)	0.0476 (18)	0.50
N31	0.8232 (14)	0.0361 (7)	0.0844 (13)	0.089 (3)	0.50
N22	0.706 (2)	0.0718 (12)	0.087 (2)	0.069 (4)	0.50
N32	0.8016 (15)	0.0592 (7)	0.0344 (12)	0.103 (3)	0.50
C11	0.41429 (16)	0.17277 (9)	0.21162 (15)	0.0420 (3)
C12	0.30740 (17)	0.11889 (11)	0.14131 (17)	0.0520 (4)
H12	0.3359	0.0715	0.1115	0.062*
C13	0.1597 (2)	0.13401 (14)	0.1146 (2)	0.0684 (6)
H13	0.0889	0.0972	0.0661	0.082*
C14	0.1164 (2)	0.20253 (15)	0.1588 (2)	0.0752 (7)
H14	0.0161	0.2126	0.1404	0.090*
C15	0.2194 (2)	0.25641 (13)	0.2298 (2)	0.0698 (6)
H15	0.1896	0.3031	0.2609	0.084*
C16	0.3681 (2)	0.24195 (11)	0.25588 (18)	0.0543 (4)
H16	0.4380	0.2793	0.3039	0.065*
C21	0.70772 (14)	0.24442 (8)	0.21288 (14)	0.0372 (3)
C22	0.69210 (16)	0.26758 (9)	0.07887 (15)	0.0425 (3)
H22	0.6386	0.2359	0.0043	0.051*
C23	0.75434 (19)	0.33670 (9)	0.05369 (18)	0.0490 (4)
H23	0.7435	0.3513	−0.0372	0.059*
C24	0.83220 (17)	0.38395 (9)	0.16252 (18)	0.0487 (4)
H24	0.8737	0.4310	0.1457	0.058*
C25	0.84907 (18)	0.36218 (9)	0.29594 (17)	0.0502 (4)
H25	0.9020	0.3944	0.3699	0.060*
C26	0.78815 (17)	0.29298 (9)	0.32095 (15)	0.0451 (3)
H26	0.8011	0.2784	0.4123	0.054*
C31	0.70732 (15)	0.11334 (8)	0.41866 (15)	0.0389 (3)
C32	0.86034 (17)	0.10542 (10)	0.47027 (18)	0.0506 (4)
H32	0.9167	0.1245	0.4185	0.061*
C33	0.92994 (19)	0.07000 (11)	0.59584 (19)	0.0591 (5)
H33	1.0329	0.0658	0.6291	0.071*
C34	0.84953 (19)	0.04096 (11)	0.67239 (18)	0.0581 (4)
H34	0.8970	0.0163	0.7573	0.070*
C35	0.69901 (19)	0.04817 (11)	0.62415 (18)	0.0560 (4)
H35	0.6437	0.0282	0.6763	0.067*
C36	0.62843 (17)	0.08465 (9)	0.49911 (16)	0.0462 (4)
H36	0.5257	0.0901	0.4683	0.055*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Si	0.0348 (2)	0.0372 (2)	0.0365 (2)	−0.00288 (14)	0.00865 (17)	−0.00112 (14)
N1	0.0461 (8)	0.0489 (8)	0.0497 (8)	−0.0050 (6)	0.0135 (6)	−0.0115 (6)
N21	0.030 (4)	0.049 (3)	0.062 (3)	0.000 (3)	0.014 (3)	−0.023 (2)
N31	0.052 (3)	0.091 (5)	0.121 (7)	0.001 (3)	0.024 (4)	−0.040 (4)
N22	0.051 (7)	0.063 (5)	0.086 (5)	0.000 (4)	0.012 (4)	−0.032 (4)
N32	0.079 (6)	0.110 (8)	0.135 (9)	−0.018 (5)	0.055 (6)	−0.066 (6)
C11	0.0376 (7)	0.0459 (8)	0.0402 (7)	−0.0002 (6)	0.0102 (6)	0.0107 (6)
C12	0.0418 (8)	0.0579 (9)	0.0505 (9)	−0.0073 (7)	0.0079 (7)	0.0111 (7)
C13	0.0402 (9)	0.0886 (14)	0.0669 (12)	−0.0110 (9)	0.0054 (8)	0.0256 (11)
C14	0.0412 (9)	0.1020 (17)	0.0829 (14)	0.0146 (10)	0.0217 (10)	0.0466 (13)
C15	0.0625 (12)	0.0729 (12)	0.0845 (14)	0.0268 (10)	0.0385 (11)	0.0321 (11)
C16	0.0519 (9)	0.0522 (9)	0.0609 (10)	0.0067 (7)	0.0217 (8)	0.0113 (7)
C21	0.0324 (7)	0.0391 (7)	0.0390 (7)	−0.0012 (5)	0.0105 (6)	−0.0009 (5)
C22	0.0415 (7)	0.0467 (8)	0.0375 (7)	−0.0029 (6)	0.0109 (6)	−0.0030 (6)
C23	0.0517 (9)	0.0516 (9)	0.0474 (8)	0.0002 (7)	0.0216 (7)	0.0061 (6)
C24	0.0442 (8)	0.0423 (8)	0.0629 (10)	−0.0043 (6)	0.0224 (7)	0.0039 (7)
C25	0.0463 (9)	0.0445 (8)	0.0532 (9)	−0.0091 (7)	0.0083 (7)	−0.0065 (7)
C26	0.0486 (8)	0.0445 (8)	0.0384 (7)	−0.0042 (6)	0.0094 (6)	−0.0015 (6)
C31	0.0379 (7)	0.0345 (7)	0.0414 (7)	−0.0005 (5)	0.0097 (6)	−0.0001 (5)
C32	0.0389 (8)	0.0557 (9)	0.0555 (9)	0.0001 (7)	0.0136 (7)	0.0076 (7)
C33	0.0400 (8)	0.0628 (10)	0.0645 (11)	0.0051 (7)	0.0046 (8)	0.0130 (8)
C34	0.0561 (10)	0.0554 (10)	0.0529 (9)	0.0030 (8)	0.0053 (8)	0.0156 (8)
C35	0.0564 (10)	0.0585 (10)	0.0522 (9)	−0.0032 (8)	0.0170 (8)	0.0130 (8)
C36	0.0387 (8)	0.0482 (8)	0.0494 (8)	−0.0008 (6)	0.0120 (7)	0.0044 (6)

Geometric parameters (Å, º)

Si—N1	1.7632 (15)	C22—C23	1.390 (2)
Si—C31	1.8546 (15)	C22—H22	0.94
Si—C11	1.8588 (15)	C23—C24	1.382 (2)
Si—C21	1.8636 (14)	C23—H23	0.94
N1—N22	1.09 (2)	C24—C25	1.380 (2)
N1—N21	1.284 (17)	C24—H24	0.94
N21—N31	1.06 (2)	C25—C26	1.384 (2)
N22—N32	1.24 (3)	C25—H25	0.94
C11—C12	1.392 (2)	C26—H26	0.94
C11—C16	1.394 (2)	C31—C36	1.391 (2)
C12—C13	1.385 (3)	C31—C32	1.400 (2)
C12—H12	0.94	C32—C33	1.381 (2)
C13—C14	1.372 (3)	C32—H32	0.94
C13—H13	0.94	C33—C34	1.373 (3)
C14—C15	1.373 (3)	C33—H33	0.94
C14—H14	0.94	C34—C35	1.376 (2)
C15—C16	1.393 (3)	C34—H34	0.94
C15—H15	0.94	C35—C36	1.387 (2)
C16—H16	0.94	C35—H35	0.94
C21—C22	1.395 (2)	C36—H36	0.94
C21—C26	1.397 (2)
N1—Si—C31	107.94 (7)	C23—C22—H22	119.4
N1—Si—C11	103.17 (7)	C21—C22—H22	119.4
C31—Si—C11	112.60 (6)	C24—C23—C22	119.85 (15)
N1—Si—C21	108.34 (7)	C24—C23—H23	120.1
C31—Si—C21	112.18 (6)	C22—C23—H23	120.1
C11—Si—C21	112.04 (6)	C25—C24—C23	120.02 (14)
N22—N1—Si	124.70 (11)	C25—C24—H24	120
N21—N1—Si	123.2 (8)	C23—C24—H24	120
N31—N21—N1	170.70 (17)	C24—C25—C26	120.07 (14)
N1—N22—N32	173 (2)	C24—C25—H25	120
C12—C11—C16	117.90 (15)	C26—C25—H25	120
C12—C11—Si	122.12 (13)	C25—C26—C21	121.16 (14)
C16—C11—Si	119.98 (12)	C25—C26—H26	119.4
C13—C12—C11	121.03 (19)	C21—C26—H26	119.4
C13—C12—H12	119.5	C36—C31—C32	117.45 (14)
C11—C12—H12	119.5	C36—C31—Si	121.33 (11)
C14—C13—C12	120.18 (19)	C32—C31—Si	121.14 (12)
C14—C13—H13	119.9	C33—C32—C31	121.18 (15)
C12—C13—H13	119.9	C33—C32—H32	119.4
C13—C14—C15	120.13 (18)	C31—C32—H32	119.4
C13—C14—H14	119.9	C34—C33—C32	120.32 (16)
C15—C14—H14	119.9	C34—C33—H33	119.8
C14—C15—C16	120.0 (2)	C32—C33—H33	119.8
C14—C15—H15	120	C33—C34—C35	119.65 (15)
C16—C15—H15	120	C33—C34—H34	120.2
C15—C16—C11	120.74 (18)	C35—C34—H34	120.2
C15—C16—H16	119.6	C34—C35—C36	120.39 (15)
C11—C16—H16	119.6	C34—C35—H35	119.8
C22—C21—C26	117.78 (13)	C36—C35—H35	119.8
C22—C21—Si	120.90 (11)	C35—C36—C31	121.00 (14)
C26—C21—Si	121.18 (11)	C35—C36—H36	119.5
C23—C22—C21	121.12 (14)	C31—C36—H36	119.5
C31—Si—N1—N22	−80.60 (13)	C31—Si—C21—C26	−28.86 (14)
C11—Si—N1—N22	160.00 (13)	C11—Si—C21—C26	98.94 (13)
C21—Si—N1—N22	41.10 (13)	C26—C21—C22—C23	−0.1 (2)
C31—Si—N1—N21	−69.8 (9)	Si—C21—C22—C23	175.64 (12)
C11—Si—N1—N21	170.8 (9)	C21—C22—C23—C24	−0.5 (2)
C21—Si—N1—N21	51.9 (9)	C22—C23—C24—C25	0.5 (2)
N1—Si—C11—C12	20.35 (14)	C23—C24—C25—C26	0.1 (2)
C31—Si—C11—C12	−95.76 (14)	C24—C25—C26—C21	−0.7 (2)
C21—Si—C11—C12	136.67 (12)	C22—C21—C26—C25	0.7 (2)
N1—Si—C11—C16	−158.94 (13)	Si—C21—C26—C25	−175.04 (12)
C31—Si—C11—C16	84.95 (13)	N1—Si—C31—C36	−101.42 (13)
C21—Si—C11—C16	−42.62 (14)	C11—Si—C31—C36	11.80 (14)
C16—C11—C12—C13	0.8 (2)	C21—Si—C31—C36	139.29 (12)
Si—C11—C12—C13	−178.47 (13)	N1—Si—C31—C32	75.08 (14)
C11—C12—C13—C14	−0.7 (3)	C11—Si—C31—C32	−171.71 (12)
C12—C13—C14—C15	−0.1 (3)	C21—Si—C31—C32	−44.21 (14)
C13—C14—C15—C16	0.7 (3)	C36—C31—C32—C33	0.4 (2)
C14—C15—C16—C11	−0.6 (3)	Si—C31—C32—C33	−176.21 (14)
C12—C11—C16—C15	−0.2 (2)	C31—C32—C33—C34	0.7 (3)
Si—C11—C16—C15	179.12 (13)	C32—C33—C34—C35	−0.8 (3)
N1—Si—C21—C22	36.53 (13)	C33—C34—C35—C36	−0.1 (3)
C31—Si—C21—C22	155.58 (11)	C34—C35—C36—C31	1.2 (3)
C11—Si—C21—C22	−76.63 (13)	C32—C31—C36—C35	−1.4 (2)
N1—Si—C21—C26	−147.91 (12)	Si—C31—C36—C35	175.27 (13)