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The synthesis, single-crystal X-ray structure, and 1H and 13C NMR spectrocopic analyses of an unyielding precursor mol­ecule to a cyclic (alk­yl)(amido)­carbene, 1-chloro-2-(2,6-diiso­propyl­phen­yl)-4,4-dimethyl-2-aza­spiro­[5.5]undecane-3,5-di­one, C24H34ClNO2 (1), is reported. Despite the use of several bases, 1 could not be deprotonated to afford the corresponding carbene. The crystal structure of 1 was compared to the crystal structures of two structurally similar HCl adducts of stable carbenes (compounds 4 and 5), which revealed no significant differences in the geometries about the `carbene' C atoms. To better understand the reactivity differences observed for 1 when compared to 4 and 5, modified percent buried volume (%Vbur) calculations were performed. These calculations revealed that the H atom bound to the carbene C atom is the most sterically hindered in compound 1 when compared to 4 and 5 (%Vbur = 84.9, 81.3, and 79.3% for 1, 4, and 5, respectively). Finally, close inspection of the quadrant-specific %Vbur values indicated that the approach of a deprotonating base to the H atom bound to the carbene C atom is significantly blocked in 1 (69.9%) when compared to 4 and 5 (50.4 and 56.5%, respectively).

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S2053229621006173/ov3151sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S2053229621006173/ov3151Isup2.hkl
Contains datablock I

cml

Chemical Markup Language (CML) file https://doi.org/10.1107/S2053229621006173/ov3151Isup3.cml
Supplementary material

CCDC reference: 2089913

Computing details top

Data collection: CrystalClear-SM Expert (Rigaku, 2011); cell refinement: CrysAlis PRO (Rigaku OD, 2021); data reduction: CrysAlis PRO (Rigaku OD, 2021); program(s) used to solve structure: SHELXT2014 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009) and publCIF (Westrip, 2010).

1-Chloro-2-(2,6-diisopropylphenyl)-4,4-dimethyl-2-azaspiro[5.5]undecane-3,5-dione top
Crystal data top
C24H34ClNO2F(000) = 872
Mr = 403.97Dx = 1.226 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
a = 13.4563 (12) ÅCell parameters from 5251 reflections
b = 10.7847 (9) Åθ = 2.3–24.8°
c = 15.5656 (13) ŵ = 0.19 mm1
β = 104.341 (9)°T = 223 K
V = 2188.5 (3) Å3Block, colourless
Z = 40.20 × 0.18 × 0.15 mm
Data collection top
Rigaku Oxford Diffraction SCXMini
diffractometer
3906 independent reflections
Radiation source: fine-focus sealed X-ray tube, fine-focus sealed X-ray tube2657 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.069
ω scansθmax = 25.1°, θmin = 2.3°
Absorption correction: multi-scan
(CrysAlis PRO; Rigaku OD, 2021)
h = 1616
Tmin = 0.817, Tmax = 1.000k = 1212
18492 measured reflectionsl = 1818
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.049H-atom parameters constrained
wR(F2) = 0.120 w = 1/[σ2(Fo2) + (0.0442P)2 + 0.7631P]
where P = (Fo2 + 2Fc2)/3
S = 1.02(Δ/σ)max = 0.001
3906 reflectionsΔρmax = 0.25 e Å3
259 parametersΔρmin = 0.20 e Å3
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Cl10.43370 (5)0.44683 (7)0.63217 (4)0.0511 (2)
N10.25026 (14)0.38737 (17)0.65933 (11)0.0332 (4)
O20.44537 (14)0.57847 (17)0.84324 (12)0.0591 (5)
O10.11081 (13)0.48115 (18)0.68275 (12)0.0577 (5)
C130.19290 (17)0.3359 (2)0.57562 (14)0.0355 (6)
C140.15945 (17)0.2133 (2)0.57282 (15)0.0389 (6)
C10.39847 (17)0.3735 (2)0.79079 (14)0.0337 (5)
C40.26869 (18)0.5526 (2)0.77415 (15)0.0381 (6)
C30.20270 (19)0.4700 (2)0.70309 (15)0.0379 (6)
C20.35582 (17)0.3562 (2)0.69067 (14)0.0346 (5)
H20.36350.26850.67710.041*
C50.37901 (19)0.5082 (2)0.80705 (15)0.0380 (6)
C180.17273 (18)0.4096 (2)0.49999 (16)0.0416 (6)
C150.1086 (2)0.1652 (2)0.49159 (17)0.0483 (7)
H150.08750.08290.48800.058*
C80.51193 (18)0.3389 (2)0.81789 (15)0.0417 (6)
H8A0.52070.25830.79300.050*
H8B0.55030.39870.79250.050*
C190.1728 (2)0.1327 (2)0.65362 (17)0.0469 (7)
H190.20740.18270.70490.056*
C120.34041 (18)0.2888 (2)0.84145 (15)0.0394 (6)
H12A0.26900.31380.82820.047*
H12B0.34300.20410.82120.047*
C220.2051 (2)0.5439 (2)0.49899 (17)0.0478 (7)
H220.24960.56290.55750.057*
C170.1188 (2)0.3570 (3)0.42126 (17)0.0527 (7)
H170.10280.40530.37020.063*
C110.3850 (2)0.2937 (3)0.94089 (15)0.0468 (7)
H11A0.37960.37750.96190.056*
H11B0.34610.23940.97000.056*
C160.0885 (2)0.2357 (3)0.41659 (17)0.0553 (8)
H160.05440.20150.36250.066*
C90.5568 (2)0.3343 (3)0.91765 (16)0.0517 (7)
H9A0.62640.30270.92950.062*
H9B0.55990.41780.94130.062*
C60.2212 (2)0.5630 (3)0.85335 (17)0.0547 (7)
H6A0.15330.59680.83420.082*
H6B0.26270.61640.89730.082*
H6C0.21780.48220.87840.082*
C100.4957 (2)0.2544 (3)0.96459 (17)0.0526 (7)
H10A0.52330.26131.02820.063*
H10B0.50080.16840.94790.063*
C70.2687 (2)0.6811 (2)0.73266 (19)0.0556 (7)
H7A0.29890.67610.68300.083*
H7B0.30770.73730.77590.083*
H7C0.19940.71060.71300.083*
C230.2672 (2)0.5659 (3)0.43050 (18)0.0692 (9)
H23A0.32350.50870.44050.104*
H23B0.29310.64930.43590.104*
H23C0.22400.55370.37200.104*
C240.1135 (2)0.6300 (3)0.4840 (2)0.0779 (10)
H24A0.06930.61510.42630.117*
H24B0.13660.71450.48800.117*
H24C0.07640.61490.52840.117*
C210.0701 (3)0.0950 (4)0.6678 (2)0.0919 (12)
H21A0.03390.16740.67920.138*
H21B0.08030.03980.71760.138*
H21C0.03080.05380.61580.138*
C200.2399 (4)0.0214 (3)0.6502 (3)0.1049 (14)
H20A0.20480.03400.60440.157*
H20B0.25450.02060.70630.157*
H20C0.30290.04820.63770.157*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl10.0452 (4)0.0693 (5)0.0417 (4)0.0070 (3)0.0163 (3)0.0042 (3)
N10.0351 (11)0.0339 (11)0.0304 (10)0.0008 (9)0.0076 (8)0.0048 (9)
O20.0544 (12)0.0471 (11)0.0682 (13)0.0104 (10)0.0011 (10)0.0182 (10)
O10.0370 (11)0.0695 (13)0.0646 (12)0.0060 (9)0.0090 (9)0.0174 (10)
C130.0324 (13)0.0395 (14)0.0336 (13)0.0006 (11)0.0062 (10)0.0060 (11)
C140.0346 (13)0.0423 (15)0.0386 (14)0.0005 (11)0.0064 (11)0.0057 (12)
C10.0336 (13)0.0370 (14)0.0305 (12)0.0027 (10)0.0078 (10)0.0044 (10)
C40.0434 (14)0.0343 (13)0.0381 (13)0.0006 (11)0.0129 (11)0.0056 (11)
C30.0378 (15)0.0389 (15)0.0375 (13)0.0014 (11)0.0104 (11)0.0008 (11)
C20.0367 (13)0.0338 (13)0.0342 (13)0.0002 (11)0.0106 (10)0.0008 (10)
C50.0440 (14)0.0415 (14)0.0299 (12)0.0066 (12)0.0114 (11)0.0065 (11)
C180.0395 (14)0.0466 (15)0.0376 (14)0.0004 (12)0.0074 (11)0.0006 (12)
C150.0516 (16)0.0438 (16)0.0475 (16)0.0096 (13)0.0083 (13)0.0103 (13)
C80.0368 (14)0.0475 (15)0.0398 (14)0.0014 (12)0.0073 (11)0.0018 (12)
C190.0546 (16)0.0391 (15)0.0443 (15)0.0116 (13)0.0070 (12)0.0038 (12)
C120.0423 (14)0.0384 (14)0.0377 (13)0.0006 (11)0.0101 (11)0.0011 (11)
C220.0525 (16)0.0449 (16)0.0414 (14)0.0007 (13)0.0033 (12)0.0062 (12)
C170.0549 (17)0.062 (2)0.0367 (14)0.0034 (15)0.0024 (12)0.0032 (13)
C110.0561 (17)0.0487 (16)0.0360 (14)0.0040 (13)0.0121 (12)0.0005 (12)
C160.0563 (18)0.068 (2)0.0374 (15)0.0116 (15)0.0029 (13)0.0138 (14)
C90.0427 (15)0.0641 (19)0.0435 (15)0.0016 (14)0.0018 (12)0.0046 (14)
C60.0583 (17)0.0557 (18)0.0558 (17)0.0019 (14)0.0251 (14)0.0154 (14)
C100.0574 (18)0.0576 (18)0.0382 (14)0.0050 (14)0.0034 (13)0.0005 (13)
C70.0648 (19)0.0373 (15)0.0652 (18)0.0007 (14)0.0172 (15)0.0006 (14)
C230.085 (2)0.072 (2)0.0501 (17)0.0153 (18)0.0170 (16)0.0120 (16)
C240.073 (2)0.056 (2)0.098 (3)0.0125 (17)0.0077 (19)0.0128 (19)
C210.084 (2)0.136 (3)0.0556 (19)0.050 (2)0.0171 (18)0.003 (2)
C200.155 (4)0.063 (2)0.100 (3)0.044 (2)0.037 (3)0.023 (2)
Geometric parameters (Å, º) top
Cl1—C21.832 (2)C22—H220.9800
N1—C131.450 (3)C22—C231.527 (4)
N1—C31.372 (3)C22—C241.515 (4)
N1—C21.423 (3)C17—H170.9300
O2—C51.200 (3)C17—C161.366 (4)
O1—C31.204 (3)C11—H11A0.9700
C13—C141.393 (3)C11—H11B0.9700
C13—C181.390 (3)C11—C101.504 (4)
C14—C151.381 (3)C16—H160.9300
C14—C191.503 (3)C9—H9A0.9700
C1—C21.533 (3)C9—H9B0.9700
C1—C51.509 (3)C9—C101.500 (4)
C1—C81.526 (3)C6—H6A0.9600
C1—C121.540 (3)C6—H6B0.9600
C4—C31.523 (3)C6—H6C0.9600
C4—C51.523 (3)C10—H10A0.9700
C4—C61.527 (3)C10—H10B0.9700
C4—C71.529 (3)C7—H7A0.9600
C2—H20.9800C7—H7B0.9600
C18—C221.514 (4)C7—H7C0.9600
C18—C171.382 (3)C23—H23A0.9600
C15—H150.9300C23—H23B0.9600
C15—C161.363 (4)C23—H23C0.9600
C8—H8A0.9700C24—H24A0.9600
C8—H8B0.9700C24—H24B0.9600
C8—C91.521 (3)C24—H24C0.9600
C19—H190.9800C21—H21A0.9600
C19—C211.508 (4)C21—H21B0.9600
C19—C201.511 (4)C21—H21C0.9600
C12—H12A0.9700C20—H20A0.9600
C12—H12B0.9700C20—H20B0.9600
C12—C111.516 (3)C20—H20C0.9600
C3—N1—C13118.99 (18)C24—C22—C23111.3 (2)
C3—N1—C2122.12 (18)C18—C17—H17119.2
C2—N1—C13118.78 (18)C16—C17—C18121.6 (3)
C14—C13—N1119.2 (2)C16—C17—H17119.2
C18—C13—N1119.4 (2)C12—C11—H11A109.4
C18—C13—C14121.5 (2)C12—C11—H11B109.4
C13—C14—C19123.5 (2)H11A—C11—H11B108.0
C15—C14—C13117.9 (2)C10—C11—C12111.0 (2)
C15—C14—C19118.6 (2)C10—C11—H11A109.4
C2—C1—C12109.81 (18)C10—C11—H11B109.4
C5—C1—C2104.52 (18)C15—C16—C17119.7 (2)
C5—C1—C8113.10 (19)C15—C16—H16120.2
C5—C1—C12110.74 (19)C17—C16—H16120.2
C8—C1—C2110.38 (18)C8—C9—H9A109.0
C8—C1—C12108.24 (19)C8—C9—H9B109.0
C3—C4—C6110.1 (2)H9A—C9—H9B107.8
C3—C4—C7106.5 (2)C10—C9—C8112.9 (2)
C5—C4—C3113.85 (19)C10—C9—H9A109.0
C5—C4—C6108.6 (2)C10—C9—H9B109.0
C5—C4—C7109.0 (2)C4—C6—H6A109.5
C6—C4—C7108.6 (2)C4—C6—H6B109.5
N1—C3—C4118.7 (2)C4—C6—H6C109.5
O1—C3—N1120.6 (2)H6A—C6—H6B109.5
O1—C3—C4120.5 (2)H6A—C6—H6C109.5
Cl1—C2—H2107.7H6B—C6—H6C109.5
N1—C2—Cl1110.43 (15)C11—C10—H10A109.6
N1—C2—C1114.23 (18)C11—C10—H10B109.6
N1—C2—H2107.7C9—C10—C11110.4 (2)
C1—C2—Cl1108.93 (15)C9—C10—H10A109.6
C1—C2—H2107.7C9—C10—H10B109.6
O2—C5—C1123.2 (2)H10A—C10—H10B108.1
O2—C5—C4120.6 (2)C4—C7—H7A109.5
C1—C5—C4116.2 (2)C4—C7—H7B109.5
C13—C18—C22124.0 (2)C4—C7—H7C109.5
C17—C18—C13117.8 (2)H7A—C7—H7B109.5
C17—C18—C22118.2 (2)H7A—C7—H7C109.5
C14—C15—H15119.2H7B—C7—H7C109.5
C16—C15—C14121.5 (3)C22—C23—H23A109.5
C16—C15—H15119.2C22—C23—H23B109.5
C1—C8—H8A108.7C22—C23—H23C109.5
C1—C8—H8B108.7H23A—C23—H23B109.5
H8A—C8—H8B107.6H23A—C23—H23C109.5
C9—C8—C1114.0 (2)H23B—C23—H23C109.5
C9—C8—H8A108.7C22—C24—H24A109.5
C9—C8—H8B108.7C22—C24—H24B109.5
C14—C19—H19107.3C22—C24—H24C109.5
C14—C19—C21110.8 (2)H24A—C24—H24B109.5
C14—C19—C20112.2 (2)H24A—C24—H24C109.5
C21—C19—H19107.3H24B—C24—H24C109.5
C21—C19—C20111.6 (3)C19—C21—H21A109.5
C20—C19—H19107.3C19—C21—H21B109.5
C1—C12—H12A109.1C19—C21—H21C109.5
C1—C12—H12B109.1H21A—C21—H21B109.5
H12A—C12—H12B107.9H21A—C21—H21C109.5
C11—C12—C1112.3 (2)H21B—C21—H21C109.5
C11—C12—H12A109.1C19—C20—H20A109.5
C11—C12—H12B109.1C19—C20—H20B109.5
C18—C22—H22107.6C19—C20—H20C109.5
C18—C22—C23111.4 (2)H20A—C20—H20B109.5
C18—C22—C24111.3 (2)H20A—C20—H20C109.5
C23—C22—H22107.6H20B—C20—H20C109.5
C24—C22—H22107.6
N1—C13—C14—C15177.5 (2)C5—C1—C2—N157.6 (2)
N1—C13—C14—C194.6 (3)C5—C1—C8—C972.1 (3)
N1—C13—C18—C221.4 (4)C5—C1—C12—C1169.9 (3)
N1—C13—C18—C17179.3 (2)C5—C4—C3—N116.9 (3)
C13—N1—C3—O114.7 (3)C5—C4—C3—O1166.7 (2)
C13—N1—C3—C4161.7 (2)C18—C13—C14—C152.4 (4)
C13—N1—C2—Cl178.2 (2)C18—C13—C14—C19175.5 (2)
C13—N1—C2—C1158.59 (19)C18—C17—C16—C152.2 (4)
C13—C14—C15—C162.0 (4)C15—C14—C19—C2160.7 (3)
C13—C14—C19—C21117.1 (3)C15—C14—C19—C2064.8 (3)
C13—C14—C19—C20117.3 (3)C8—C1—C2—Cl155.6 (2)
C13—C18—C22—C23125.7 (3)C8—C1—C2—N1179.55 (19)
C13—C18—C22—C24109.5 (3)C8—C1—C5—O24.9 (3)
C13—C18—C17—C161.8 (4)C8—C1—C5—C4174.74 (19)
C14—C13—C18—C22178.8 (2)C8—C1—C12—C1154.6 (3)
C14—C13—C18—C170.5 (4)C8—C9—C10—C1153.5 (3)
C14—C15—C16—C170.2 (4)C19—C14—C15—C16176.0 (2)
C1—C8—C9—C1052.3 (3)C12—C1—C2—Cl1174.82 (15)
C1—C12—C11—C1059.3 (3)C12—C1—C2—N161.2 (3)
C3—N1—C13—C14105.8 (3)C12—C1—C5—O2116.8 (2)
C3—N1—C13—C1874.3 (3)C12—C1—C5—C463.6 (2)
C3—N1—C2—Cl197.9 (2)C12—C1—C8—C951.0 (3)
C3—N1—C2—C125.2 (3)C12—C11—C10—C957.1 (3)
C3—C4—C5—O2159.4 (2)C22—C18—C17—C16178.9 (3)
C3—C4—C5—C120.2 (3)C17—C18—C22—C2355.1 (3)
C2—N1—C13—C1477.9 (3)C17—C18—C22—C2469.7 (3)
C2—N1—C13—C18101.9 (3)C6—C4—C3—N1139.2 (2)
C2—N1—C3—O1169.1 (2)C6—C4—C3—O144.4 (3)
C2—N1—C3—C414.4 (3)C6—C4—C5—O277.5 (3)
C2—C1—C5—O2125.0 (2)C6—C4—C5—C1102.9 (2)
C2—C1—C5—C454.6 (2)C7—C4—C3—N1103.3 (2)
C2—C1—C8—C9171.2 (2)C7—C4—C3—O173.1 (3)
C2—C1—C12—C11175.2 (2)C7—C4—C5—O240.6 (3)
C5—C1—C2—Cl166.36 (19)C7—C4—C5—C1139.0 (2)
Supramolecular contacts (Å, °) within the crystal structure of compound 1 top
Contact (C—H···X; X = Cl or O)DistanceAngle
C22—H22···Cl13.420 (3)125.08 (16)
C10—H10A···O2i3.413 (3)141.70 (17)
C10—H10B···Cl1ii3.858 (3)160.43 (16)
Symmetry codes: (i) -x+1, -y+1, -z+2; (ii) x, -y+1/2, z+1/2. [Please check added symmetry codes. Also, please check that the values in the final entry are correct. PLATON gives a contact with 3.645 (3)/160.18 (17) with symcode added]
 

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