organic compounds
1,3-Bis(2,6-diisopropylphenyl)imidazolidin-2-ylidene
aThe Maritime Centre for Green Chemistry (MCGC), Department of Chemistry, Saint Mary's University, 923 Robie Street, Halifax, NS B3H 3C3, Canada
*Correspondence e-mail: jason.masuda@smu.ca
The title compound, C27H38N2, is the first reported free imidazolidin-2-ylidene carbene with 2,6-diisopropylphenyl groups in the 1,3-positions. The five-membered ring adopts a twisted conformation and the dihedral angle between the aromatic rings is 48.81 (6)°. Both isopropyl groups attached to one of the benzene rings are disordered over two sets of sites in 0.74 (2):0.26 (2) and 0.599 (8):0.401 (8) ratios.
Related literature
There are few examples in the literature of crystallographically characterized free ylidenes with ortho-alkyl substituted phenyl groups in the 1,3-positions: for related structures see: Arduengo et al. (1991, 1992, 1995, 1999). For background to free see: Igau et al. (1989) and for Arduengo-type see: Pauling (1980).
Experimental
Crystal data
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Data collection: APEX2 (Bruker, 2008); cell SAINT (Bruker, 2008); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).
Supporting information
https://doi.org/10.1107/S1600536810029922/hb5563sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810029922/hb5563Isup2.hkl
1,3-bis(2,6-diisopropylphenyl)imidazolidin-2-ylidene was prepared through the addition of 0.466 g of potassium bis-hexamethyl disilazide to a solution of 1.00 g (0.234 mmol) of 1,3-bis(2,6-diisopropylphenyl) imidazolidinium chloride (0.234 mmol) in diethylether. Volatiles were removed under reduced pressure and the remaining solid was dissolved in pentane, filtered through diatomaceous earth and cooled to 243 K yielding colorless blocks of (I). The proton NMR matched that in the literature of the title ylidene (Arduengo et al., 1999).
The H atoms were placed in geometrically idealized positions with C—H distances of 0.95Å (aromatic),0.98Å (idealized tertiary), 0.99Å (Idealized secondary) and 0.98Å (Idealized methyl). H atoms were constrained to ride on the parent C atom with Uiso(H) = 1.2Ueq(C) for aromatic, Uiso(H) = 1.5Ueq(C) for the idealized methyl protons, Uiso(H) = 1.2Ueq(C) for the idealized tertiary protons and Uiso(H) = 1.2Ueq(C) for the idealized secondary protons. A short contact distance of 1.89 Angstroms is observed between H31B and H2B, where H31B lies in the disordered part of the model. Tests for
and missed symmetry were preformed and no laws or change of spacegroup were suggested. The short contact is believed to arise from the disorder present in the crystal. In order to obtain satisfactory thermal parametersthe use of SIMU and DELU restraints were applied to carbon atoms C21 to C27.Free
have received substantial attention in the literature since their introduction by Igau et al. (1989). Arduengo-type described by Linus Pauling as push-push, mesomeric pull-pull (Pauling, 1980) are electronically stabilized through donating amino-substituents and sterically protected by alkyl substituted phenyl groups in the 1,3-positions. Beginning in 1991, free diamino such as the 1,3-bis(1-adamantyl)imidazol-2-ylidiene (Arduengo et al., 1991) have garnered substantial notoriety across chemical disciplines.As a result of the increased steric bulk associated with the flanking 2,6-diisopropylphenyl substiuents the title free carbene exibits a N1—C1—N2 bond angle of 104.98 (11)°. This angle represents substantial relaxation when compared to the IPr carbene, 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidiene, 101.4 (2)° and the IMes carbene 1,3-bis (2,4,6-trimethylphenyl)imidazolidin-2-ylidiene, 101.4 (3)° (Arduengo et al., 1999). However, the N1—C1—N2 angle in the title molecule is similar to that of the saturated analogue of IMes, 1,3-bis(2,4,6-trimethylphenyl)imidazolidin-2-ylidiene, 104.7 (3)° (Arduengo et al., 1995). It should be noted that the unit-cell parameters are nearly identical to those reported for the analagous IPr carbene (Arduengo et al., 1999). This is not surprising as the addition of two Hydrogen atoms to the C=C bond in the backbone of the molecule will casue little change in the overall molecular volume and shape of the parent molecule relative to that of the imidazol-2-ylidiene.
There are few examples in the literature of crystallographically characterized free ylidenes with ortho-alkyl substituted phenyl groups in the 1,3-positions: for related structures see: Arduengo et al. (1991, 1992, 1995, 1999). For background to free
see: Igau et al. (1989) and for Arduengo-type see: Pauling (1980).Data collection: APEX2 (Bruker, 2008); cell
SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).Fig. 1. The molecular structure of (I) with 30% probability displacement ellipsoids for non-H atoms. Perspective is down the 010 axis and H atoms are removed for clarity. |
C27H38N2 | F(000) = 856 |
Mr = 390.59 | Dx = 1.069 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 9396 reflections |
a = 20.835 (7) Å | θ = 2.2–28.4° |
b = 5.922 (2) Å | µ = 0.06 mm−1 |
c = 19.694 (7) Å | T = 150 K |
β = 93.090 (4)° | Block, colourless |
V = 2426.2 (14) Å3 | 0.50 × 0.34 × 0.12 mm |
Z = 4 |
Bruker APEXII CCD diffractometer | 4259 independent reflections |
Radiation source: fine-focus sealed tube | 3326 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.033 |
φ and ω scans | θmax = 25.0°, θmin = 2.1° |
Absorption correction: multi-scan (SADABS; Bruker, 2008) | h = −24→24 |
Tmin = 0.716, Tmax = 0.746 | k = −7→7 |
22607 measured reflections | l = −23→23 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.037 | H-atom parameters constrained |
wR(F2) = 0.097 | w = 1/[σ2(Fo2) + (0.0419P)2 + 0.6416P] where P = (Fo2 + 2Fc2)/3 |
S = 1.01 | (Δ/σ)max = 0.002 |
4259 reflections | Δρmax = 0.18 e Å−3 |
319 parameters | Δρmin = −0.14 e Å−3 |
168 restraints | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0031 (6) |
C27H38N2 | V = 2426.2 (14) Å3 |
Mr = 390.59 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 20.835 (7) Å | µ = 0.06 mm−1 |
b = 5.922 (2) Å | T = 150 K |
c = 19.694 (7) Å | 0.50 × 0.34 × 0.12 mm |
β = 93.090 (4)° |
Bruker APEXII CCD diffractometer | 4259 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2008) | 3326 reflections with I > 2σ(I) |
Tmin = 0.716, Tmax = 0.746 | Rint = 0.033 |
22607 measured reflections |
R[F2 > 2σ(F2)] = 0.037 | 168 restraints |
wR(F2) = 0.097 | H-atom parameters constrained |
S = 1.01 | Δρmax = 0.18 e Å−3 |
4259 reflections | Δρmin = −0.14 e Å−3 |
319 parameters |
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. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
N1 | 0.21083 (5) | 0.66151 (18) | 0.15446 (5) | 0.0270 (3) | |
N2 | 0.30506 (5) | 0.79278 (17) | 0.17711 (5) | 0.0263 (3) | |
C1 | 0.24262 (6) | 0.8528 (2) | 0.17156 (6) | 0.0252 (3) | |
C2 | 0.25298 (6) | 0.4697 (2) | 0.13858 (8) | 0.0379 (4) | |
H2A | 0.2557 | 0.4496 | 0.0889 | 0.046* | |
H2B | 0.2382 | 0.3272 | 0.1589 | 0.046* | |
C3 | 0.31647 (6) | 0.5471 (2) | 0.17175 (8) | 0.0369 (4) | |
H3A | 0.3248 | 0.4771 | 0.2170 | 0.044* | |
H3B | 0.3528 | 0.5136 | 0.1429 | 0.044* | |
C4 | 0.35630 (6) | 0.9431 (2) | 0.19756 (6) | 0.0251 (3) | |
C5 | 0.36374 (6) | 1.0164 (2) | 0.26515 (7) | 0.0286 (3) | |
C6 | 0.41414 (6) | 1.1635 (2) | 0.28223 (7) | 0.0327 (3) | |
H6A | 0.4197 | 1.2172 | 0.3276 | 0.039* | |
C7 | 0.45624 (6) | 1.2329 (2) | 0.23476 (7) | 0.0330 (3) | |
H7A | 0.4904 | 1.3331 | 0.2475 | 0.040* | |
C8 | 0.44864 (6) | 1.1564 (2) | 0.16868 (7) | 0.0301 (3) | |
H8A | 0.4779 | 1.2043 | 0.1363 | 0.036* | |
C9 | 0.39891 (6) | 1.0107 (2) | 0.14862 (6) | 0.0268 (3) | |
C10 | 0.39200 (6) | 0.9307 (2) | 0.07521 (7) | 0.0324 (3) | |
H10A | 0.3536 | 0.8297 | 0.0707 | 0.039* | |
C11 | 0.45050 (7) | 0.7930 (3) | 0.05695 (8) | 0.0427 (4) | |
H11A | 0.4566 | 0.6670 | 0.0889 | 0.064* | |
H11B | 0.4888 | 0.8896 | 0.0596 | 0.064* | |
H11C | 0.4437 | 0.7340 | 0.0106 | 0.064* | |
C12 | 0.38055 (8) | 1.1287 (3) | 0.02624 (7) | 0.0461 (4) | |
H12A | 0.3424 | 1.2128 | 0.0387 | 0.069* | |
H12B | 0.3739 | 1.0714 | −0.0203 | 0.069* | |
H12C | 0.4180 | 1.2290 | 0.0290 | 0.069* | |
C13 | 0.31902 (7) | 0.9415 (3) | 0.31916 (7) | 0.0366 (3) | |
H13A | 0.2890 | 0.8257 | 0.2984 | 0.044* | |
C14 | 0.27892 (8) | 1.1385 (3) | 0.34266 (9) | 0.0580 (5) | |
H14A | 0.2547 | 1.2044 | 0.3035 | 0.087* | |
H14B | 0.3073 | 1.2533 | 0.3639 | 0.087* | |
H14C | 0.2489 | 1.0847 | 0.3757 | 0.087* | |
C15 | 0.35625 (8) | 0.8326 (3) | 0.37951 (8) | 0.0608 (5) | |
H15A | 0.3810 | 0.7042 | 0.3636 | 0.091* | |
H15B | 0.3260 | 0.7799 | 0.4125 | 0.091* | |
H15C | 0.3856 | 0.9438 | 0.4011 | 0.091* | |
C16 | 0.14366 (6) | 0.6519 (2) | 0.13366 (6) | 0.0268 (3) | |
C17 | 0.10301 (6) | 0.5242 (2) | 0.17292 (7) | 0.0320 (3) | |
C18 | 0.03883 (6) | 0.5047 (3) | 0.15029 (8) | 0.0390 (4) | |
H18A | 0.0104 | 0.4177 | 0.1759 | 0.047* | |
C19 | 0.01594 (7) | 0.6089 (3) | 0.09170 (8) | 0.0431 (4) | |
H19A | −0.0280 | 0.5931 | 0.0770 | 0.052* | |
C20 | 0.05626 (7) | 0.7360 (3) | 0.05408 (7) | 0.0408 (4) | |
H20A | 0.0396 | 0.8082 | 0.0138 | 0.049* | |
C21 | 0.12121 (6) | 0.7610 (2) | 0.07385 (7) | 0.0317 (3) | |
C22B | 0.1629 (5) | 0.9020 (16) | 0.0300 (6) | 0.0390 (10) | 0.74 (2) |
H22A | 0.2022 | 0.9410 | 0.0591 | 0.047* | 0.74 (2) |
C23B | 0.1861 (4) | 0.7654 (14) | −0.0289 (4) | 0.0624 (15) | 0.74 (2) |
H23A | 0.2075 | 0.6282 | −0.0116 | 0.094* | 0.74 (2) |
H23B | 0.2164 | 0.8558 | −0.0539 | 0.094* | 0.74 (2) |
H23C | 0.1493 | 0.7240 | −0.0595 | 0.094* | 0.74 (2) |
C24B | 0.1334 (4) | 1.1277 (10) | 0.0058 (4) | 0.0546 (15) | 0.74 (2) |
H24A | 0.1183 | 1.2108 | 0.0449 | 0.082* | 0.74 (2) |
H24B | 0.0972 | 1.0989 | −0.0269 | 0.082* | 0.74 (2) |
H24C | 0.1660 | 1.2175 | −0.0161 | 0.082* | 0.74 (2) |
C22A | 0.1707 (15) | 0.880 (4) | 0.0293 (14) | 0.037 (2) | 0.26 (2) |
H22B | 0.2152 | 0.8825 | 0.0512 | 0.045* | 0.26 (2) |
C23A | 0.1669 (12) | 0.755 (4) | −0.0425 (9) | 0.056 (3) | 0.26 (2) |
H23D | 0.1970 | 0.8264 | −0.0726 | 0.083* | 0.26 (2) |
H23E | 0.1231 | 0.7667 | −0.0630 | 0.083* | 0.26 (2) |
H23F | 0.1783 | 0.5958 | −0.0361 | 0.083* | 0.26 (2) |
C24A | 0.1448 (11) | 1.106 (3) | 0.0164 (12) | 0.044 (3) | 0.26 (2) |
H24D | 0.1483 | 1.1944 | 0.0585 | 0.066* | 0.26 (2) |
H24E | 0.0995 | 1.0942 | 0.0006 | 0.066* | 0.26 (2) |
H24F | 0.1690 | 1.1802 | −0.0185 | 0.066* | 0.26 (2) |
C25B | 0.1227 (4) | 0.4253 (16) | 0.2422 (5) | 0.0339 (9) | 0.599 (8) |
H25A | 0.1698 | 0.4534 | 0.2505 | 0.041* | 0.599 (8) |
C26B | 0.1126 (4) | 0.1722 (14) | 0.2434 (5) | 0.0444 (11) | 0.599 (8) |
H26A | 0.1338 | 0.1030 | 0.2053 | 0.067* | 0.599 (8) |
H26B | 0.0665 | 0.1392 | 0.2392 | 0.067* | 0.599 (8) |
H26C | 0.1310 | 0.1106 | 0.2864 | 0.067* | 0.599 (8) |
C27B | 0.0885 (3) | 0.5341 (5) | 0.30107 (14) | 0.0470 (10) | 0.599 (8) |
H27A | 0.0932 | 0.6986 | 0.2989 | 0.070* | 0.599 (8) |
H27B | 0.1077 | 0.4787 | 0.3445 | 0.070* | 0.599 (8) |
H27C | 0.0428 | 0.4945 | 0.2974 | 0.070* | 0.599 (8) |
C25A | 0.1323 (7) | 0.398 (2) | 0.2352 (7) | 0.0383 (16) | 0.401 (8) |
H25B | 0.1779 | 0.3604 | 0.2266 | 0.046* | 0.401 (8) |
C26A | 0.0966 (7) | 0.178 (2) | 0.2496 (10) | 0.065 (3) | 0.401 (8) |
H26D | 0.1186 | 0.0995 | 0.2882 | 0.097* | 0.401 (8) |
H26E | 0.0961 | 0.0802 | 0.2094 | 0.097* | 0.401 (8) |
H26F | 0.0523 | 0.2121 | 0.2606 | 0.097* | 0.401 (8) |
C27A | 0.1321 (4) | 0.5605 (9) | 0.2935 (2) | 0.0548 (18) | 0.401 (8) |
H27D | 0.1528 | 0.4903 | 0.3340 | 0.082* | 0.401 (8) |
H27E | 0.0876 | 0.6000 | 0.3024 | 0.082* | 0.401 (8) |
H27F | 0.1556 | 0.6974 | 0.2821 | 0.082* | 0.401 (8) |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0214 (5) | 0.0227 (6) | 0.0366 (6) | 0.0006 (5) | −0.0017 (4) | 0.0014 (5) |
N2 | 0.0228 (5) | 0.0192 (6) | 0.0366 (6) | 0.0009 (4) | −0.0017 (4) | 0.0016 (5) |
C1 | 0.0237 (6) | 0.0264 (7) | 0.0252 (6) | 0.0000 (5) | 0.0002 (5) | 0.0032 (5) |
C2 | 0.0277 (7) | 0.0221 (7) | 0.0631 (10) | 0.0019 (6) | −0.0051 (7) | −0.0008 (7) |
C3 | 0.0273 (7) | 0.0222 (7) | 0.0604 (10) | 0.0013 (6) | −0.0051 (6) | 0.0017 (7) |
C4 | 0.0214 (6) | 0.0200 (6) | 0.0333 (7) | 0.0017 (5) | −0.0039 (5) | 0.0019 (5) |
C5 | 0.0268 (7) | 0.0271 (7) | 0.0314 (7) | 0.0055 (6) | −0.0025 (5) | 0.0023 (6) |
C6 | 0.0329 (7) | 0.0307 (8) | 0.0335 (7) | 0.0045 (6) | −0.0076 (6) | −0.0036 (6) |
C7 | 0.0271 (7) | 0.0255 (7) | 0.0454 (8) | −0.0016 (6) | −0.0087 (6) | −0.0008 (6) |
C8 | 0.0236 (7) | 0.0277 (7) | 0.0390 (8) | −0.0006 (6) | 0.0004 (5) | 0.0050 (6) |
C9 | 0.0234 (6) | 0.0242 (7) | 0.0323 (7) | 0.0035 (5) | −0.0020 (5) | 0.0023 (6) |
C10 | 0.0300 (7) | 0.0345 (8) | 0.0328 (7) | −0.0010 (6) | 0.0016 (6) | −0.0018 (6) |
C11 | 0.0435 (9) | 0.0424 (9) | 0.0427 (9) | 0.0055 (7) | 0.0069 (7) | −0.0045 (7) |
C12 | 0.0572 (10) | 0.0485 (10) | 0.0323 (8) | 0.0104 (8) | −0.0014 (7) | 0.0008 (7) |
C13 | 0.0358 (8) | 0.0432 (9) | 0.0308 (7) | 0.0016 (7) | 0.0011 (6) | 0.0052 (6) |
C14 | 0.0544 (10) | 0.0698 (12) | 0.0518 (10) | 0.0190 (9) | 0.0202 (8) | 0.0124 (9) |
C15 | 0.0571 (11) | 0.0747 (13) | 0.0510 (10) | 0.0123 (10) | 0.0059 (8) | 0.0300 (10) |
C16 | 0.0222 (6) | 0.0249 (7) | 0.0329 (7) | 0.0004 (5) | −0.0017 (5) | −0.0027 (6) |
C17 | 0.0276 (7) | 0.0295 (7) | 0.0389 (7) | −0.0019 (6) | 0.0014 (6) | −0.0008 (6) |
C18 | 0.0272 (7) | 0.0397 (9) | 0.0505 (9) | −0.0065 (6) | 0.0053 (6) | −0.0013 (7) |
C19 | 0.0238 (7) | 0.0504 (10) | 0.0542 (10) | −0.0020 (7) | −0.0073 (7) | −0.0055 (8) |
C20 | 0.0354 (8) | 0.0459 (9) | 0.0397 (8) | 0.0025 (7) | −0.0100 (7) | 0.0000 (7) |
C21 | 0.0302 (7) | 0.0328 (7) | 0.0317 (7) | 0.0006 (6) | −0.0023 (5) | −0.0022 (6) |
C22B | 0.029 (2) | 0.048 (2) | 0.0391 (18) | 0.0014 (14) | −0.0040 (14) | 0.0110 (14) |
C23B | 0.071 (3) | 0.055 (2) | 0.064 (3) | 0.016 (2) | 0.032 (3) | 0.016 (2) |
C24B | 0.075 (4) | 0.0357 (17) | 0.054 (3) | 0.0053 (15) | 0.009 (2) | 0.0093 (14) |
C22A | 0.047 (6) | 0.037 (5) | 0.027 (4) | −0.004 (4) | −0.005 (5) | 0.011 (3) |
C23A | 0.088 (8) | 0.045 (5) | 0.035 (4) | 0.006 (6) | 0.014 (5) | 0.001 (4) |
C24A | 0.053 (6) | 0.034 (4) | 0.044 (6) | −0.003 (4) | −0.003 (5) | 0.002 (3) |
C25B | 0.024 (2) | 0.0335 (19) | 0.0445 (17) | 0.0001 (19) | 0.0031 (16) | 0.0070 (17) |
C26B | 0.044 (3) | 0.0332 (15) | 0.057 (3) | 0.0022 (19) | 0.009 (2) | 0.0067 (13) |
C27B | 0.063 (3) | 0.0396 (15) | 0.0390 (12) | 0.0043 (16) | 0.0089 (15) | 0.0040 (11) |
C25A | 0.040 (5) | 0.035 (4) | 0.041 (3) | 0.003 (3) | 0.012 (2) | 0.0096 (16) |
C26A | 0.073 (7) | 0.044 (3) | 0.079 (5) | −0.010 (4) | 0.018 (5) | 0.020 (3) |
C27A | 0.075 (5) | 0.052 (2) | 0.0371 (18) | 0.009 (3) | −0.001 (2) | 0.005 (2) |
N1—C1 | 1.3458 (16) | C18—C19 | 1.371 (2) |
N1—C16 | 1.4380 (16) | C18—H18A | 0.9500 |
N1—C2 | 1.4793 (17) | C19—C20 | 1.374 (2) |
N2—C1 | 1.3474 (16) | C19—H19A | 0.9500 |
N2—C4 | 1.4309 (16) | C20—C21 | 1.3959 (19) |
N2—C3 | 1.4790 (17) | C20—H20A | 0.9500 |
C2—C3 | 1.5144 (19) | C21—C22B | 1.509 (9) |
C2—H2A | 0.9900 | C21—C22A | 1.56 (3) |
C2—H2B | 0.9900 | C22B—C23B | 1.515 (9) |
C3—H3A | 0.9900 | C22B—C24B | 1.537 (6) |
C3—H3B | 0.9900 | C22B—H22A | 1.0000 |
C4—C5 | 1.4007 (18) | C23B—H23A | 0.9800 |
C4—C9 | 1.4034 (18) | C23B—H23B | 0.9800 |
C5—C6 | 1.3915 (19) | C23B—H23C | 0.9800 |
C5—C13 | 1.5176 (19) | C24B—H24A | 0.9800 |
C6—C7 | 1.379 (2) | C24B—H24B | 0.9800 |
C6—H6A | 0.9500 | C24B—H24C | 0.9800 |
C7—C8 | 1.3791 (19) | C22A—C24A | 1.458 (17) |
C7—H7A | 0.9500 | C22A—C23A | 1.59 (3) |
C8—C9 | 1.3894 (18) | C22A—H22B | 1.0000 |
C8—H8A | 0.9500 | C23A—H23D | 0.9800 |
C9—C10 | 1.5205 (19) | C23A—H23E | 0.9800 |
C10—C11 | 1.526 (2) | C23A—H23F | 0.9800 |
C10—C12 | 1.529 (2) | C24A—H24D | 0.9800 |
C10—H10A | 1.0000 | C24A—H24E | 0.9800 |
C11—H11A | 0.9800 | C24A—H24F | 0.9800 |
C11—H11B | 0.9800 | C25B—C26B | 1.514 (11) |
C11—H11C | 0.9800 | C25B—C27B | 1.535 (6) |
C12—H12A | 0.9800 | C25B—H25A | 1.0000 |
C12—H12B | 0.9800 | C26B—H26A | 0.9800 |
C12—H12C | 0.9800 | C26B—H26B | 0.9800 |
C13—C14 | 1.521 (2) | C26B—H26C | 0.9800 |
C13—C15 | 1.527 (2) | C27B—H27A | 0.9800 |
C13—H13A | 1.0000 | C27B—H27B | 0.9800 |
C14—H14A | 0.9800 | C27B—H27C | 0.9800 |
C14—H14B | 0.9800 | C25A—C27A | 1.497 (10) |
C14—H14C | 0.9800 | C25A—C26A | 1.537 (18) |
C15—H15A | 0.9800 | C25A—H25B | 1.0000 |
C15—H15B | 0.9800 | C26A—H26D | 0.9800 |
C15—H15C | 0.9800 | C26A—H26E | 0.9800 |
C16—C17 | 1.3992 (19) | C26A—H26F | 0.9800 |
C16—C21 | 1.4015 (18) | C27A—H27D | 0.9800 |
C17—C18 | 1.3913 (19) | C27A—H27E | 0.9800 |
C17—C25B | 1.521 (11) | C27A—H27F | 0.9800 |
C17—C25A | 1.534 (18) | ||
C1—N1—C16 | 124.27 (10) | C18—C19—C20 | 120.34 (13) |
C1—N1—C2 | 114.15 (10) | C18—C19—H19A | 119.8 |
C16—N1—C2 | 119.28 (10) | C20—C19—H19A | 119.8 |
C1—N2—C4 | 124.14 (11) | C19—C20—C21 | 121.30 (14) |
C1—N2—C3 | 114.32 (10) | C19—C20—H20A | 119.3 |
C4—N2—C3 | 120.77 (10) | C21—C20—H20A | 119.3 |
N1—C1—N2 | 104.98 (11) | C20—C21—C16 | 117.39 (13) |
N1—C2—C3 | 101.04 (11) | C20—C21—C22B | 118.6 (4) |
N1—C2—H2A | 111.6 | C16—C21—C22B | 124.0 (4) |
C3—C2—H2A | 111.6 | C20—C21—C22A | 123.5 (12) |
N1—C2—H2B | 111.6 | C16—C21—C22A | 118.7 (11) |
C3—C2—H2B | 111.6 | C21—C22B—C23B | 111.1 (7) |
H2A—C2—H2B | 109.4 | C21—C22B—C24B | 115.2 (6) |
N2—C3—C2 | 100.85 (10) | C23B—C22B—C24B | 111.4 (8) |
N2—C3—H3A | 111.6 | C21—C22B—H22A | 106.2 |
C2—C3—H3A | 111.6 | C23B—C22B—H22A | 106.2 |
N2—C3—H3B | 111.6 | C24B—C22B—H22A | 106.2 |
C2—C3—H3B | 111.6 | C22B—C23B—H23A | 109.5 |
H3A—C3—H3B | 109.4 | C22B—C23B—H23B | 109.5 |
C5—C4—C9 | 121.50 (12) | H23A—C23B—H23B | 109.5 |
C5—C4—N2 | 120.20 (11) | C22B—C23B—H23C | 109.5 |
C9—C4—N2 | 118.29 (11) | H23A—C23B—H23C | 109.5 |
C6—C5—C4 | 117.85 (12) | H23B—C23B—H23C | 109.5 |
C6—C5—C13 | 119.82 (12) | C22B—C24B—H24A | 109.5 |
C4—C5—C13 | 122.33 (12) | C22B—C24B—H24B | 109.5 |
C7—C6—C5 | 121.48 (13) | H24A—C24B—H24B | 109.5 |
C7—C6—H6A | 119.3 | C22B—C24B—H24C | 109.5 |
C5—C6—H6A | 119.3 | H24A—C24B—H24C | 109.5 |
C6—C7—C8 | 119.80 (12) | H24B—C24B—H24C | 109.5 |
C6—C7—H7A | 120.1 | C24A—C22A—C21 | 105.2 (18) |
C8—C7—H7A | 120.1 | C24A—C22A—C23A | 106 (2) |
C7—C8—C9 | 121.22 (13) | C21—C22A—C23A | 107 (2) |
C7—C8—H8A | 119.4 | C24A—C22A—H22B | 112.9 |
C9—C8—H8A | 119.4 | C21—C22A—H22B | 112.9 |
C8—C9—C4 | 118.13 (12) | C23A—C22A—H22B | 112.9 |
C8—C9—C10 | 119.64 (12) | C22A—C23A—H23D | 109.5 |
C4—C9—C10 | 122.22 (11) | C22A—C23A—H23E | 109.5 |
C9—C10—C11 | 110.78 (11) | H23D—C23A—H23E | 109.5 |
C9—C10—C12 | 111.37 (12) | C22A—C23A—H23F | 109.5 |
C11—C10—C12 | 111.15 (12) | H23D—C23A—H23F | 109.5 |
C9—C10—H10A | 107.8 | H23E—C23A—H23F | 109.5 |
C11—C10—H10A | 107.8 | C22A—C24A—H24D | 109.5 |
C12—C10—H10A | 107.8 | C22A—C24A—H24E | 109.5 |
C10—C11—H11A | 109.5 | H24D—C24A—H24E | 109.5 |
C10—C11—H11B | 109.5 | C22A—C24A—H24F | 109.5 |
H11A—C11—H11B | 109.5 | H24D—C24A—H24F | 109.5 |
C10—C11—H11C | 109.5 | H24E—C24A—H24F | 109.5 |
H11A—C11—H11C | 109.5 | C26B—C25B—C17 | 111.3 (7) |
H11B—C11—H11C | 109.5 | C26B—C25B—C27B | 109.5 (7) |
C10—C12—H12A | 109.5 | C17—C25B—C27B | 113.7 (6) |
C10—C12—H12B | 109.5 | C26B—C25B—H25A | 107.4 |
H12A—C12—H12B | 109.5 | C17—C25B—H25A | 107.4 |
C10—C12—H12C | 109.5 | C27B—C25B—H25A | 107.4 |
H12A—C12—H12C | 109.5 | C25B—C26B—H26A | 109.5 |
H12B—C12—H12C | 109.5 | C25B—C26B—H26B | 109.5 |
C5—C13—C14 | 110.94 (12) | H26A—C26B—H26B | 109.5 |
C5—C13—C15 | 111.32 (12) | C25B—C26B—H26C | 109.5 |
C14—C13—C15 | 110.57 (13) | H26A—C26B—H26C | 109.5 |
C5—C13—H13A | 108.0 | H26B—C26B—H26C | 109.5 |
C14—C13—H13A | 108.0 | C25B—C27B—H27A | 109.5 |
C15—C13—H13A | 108.0 | C25B—C27B—H27B | 109.5 |
C13—C14—H14A | 109.5 | H27A—C27B—H27B | 109.5 |
C13—C14—H14B | 109.5 | C25B—C27B—H27C | 109.5 |
H14A—C14—H14B | 109.5 | H27A—C27B—H27C | 109.5 |
C13—C14—H14C | 109.5 | H27B—C27B—H27C | 109.5 |
H14A—C14—H14C | 109.5 | C27A—C25A—C17 | 106.4 (9) |
H14B—C14—H14C | 109.5 | C27A—C25A—C26A | 112.5 (11) |
C13—C15—H15A | 109.5 | C17—C25A—C26A | 112.7 (12) |
C13—C15—H15B | 109.5 | C27A—C25A—H25B | 108.4 |
H15A—C15—H15B | 109.5 | C17—C25A—H25B | 108.4 |
C13—C15—H15C | 109.5 | C26A—C25A—H25B | 108.4 |
H15A—C15—H15C | 109.5 | C25A—C26A—H26D | 109.5 |
H15B—C15—H15C | 109.5 | C25A—C26A—H26E | 109.5 |
C17—C16—C21 | 121.95 (12) | H26D—C26A—H26E | 109.5 |
C17—C16—N1 | 118.22 (11) | C25A—C26A—H26F | 109.5 |
C21—C16—N1 | 119.78 (11) | H26D—C26A—H26F | 109.5 |
C18—C17—C16 | 117.89 (13) | H26E—C26A—H26F | 109.5 |
C18—C17—C25B | 117.6 (4) | C25A—C27A—H27D | 109.5 |
C16—C17—C25B | 124.2 (4) | C25A—C27A—H27E | 109.5 |
C18—C17—C25A | 123.3 (6) | H27D—C27A—H27E | 109.5 |
C16—C17—C25A | 118.6 (6) | C25A—C27A—H27F | 109.5 |
C19—C18—C17 | 121.12 (13) | H27D—C27A—H27F | 109.5 |
C19—C18—H18A | 119.4 | H27E—C27A—H27F | 109.5 |
C17—C18—H18A | 119.4 |
Experimental details
Crystal data | |
Chemical formula | C27H38N2 |
Mr | 390.59 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 150 |
a, b, c (Å) | 20.835 (7), 5.922 (2), 19.694 (7) |
β (°) | 93.090 (4) |
V (Å3) | 2426.2 (14) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.06 |
Crystal size (mm) | 0.50 × 0.34 × 0.12 |
Data collection | |
Diffractometer | Bruker APEXII CCD |
Absorption correction | Multi-scan (SADABS; Bruker, 2008) |
Tmin, Tmax | 0.716, 0.746 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 22607, 4259, 3326 |
Rint | 0.033 |
(sin θ/λ)max (Å−1) | 0.595 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.037, 0.097, 1.01 |
No. of reflections | 4259 |
No. of parameters | 319 |
No. of restraints | 168 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.18, −0.14 |
Computer programs: APEX2 (Bruker, 2008), SAINT (Bruker, 2008), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997), SHELXTL (Sheldrick, 2008).
Acknowledgements
The authors would like to thank Saint Mary's University for providing funding in the form of initial operating funds, the Natural Sciences and Engineering Research Council for a Discovery Grant and a Research Tools and Instruments Grant (JDM), the Canadian Foundation for Innovation for a Leaders Opportunity Fund Grant and the Nova Scotia Research and Innovation Trust (JDM). Student funding was provided through the Saint Mary's University Summer Employment Experience Program (ADH) and the office of the Dean of Sciences Summer Research Award (NAG).
References
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Free carbenes have received substantial attention in the literature since their introduction by Igau et al. (1989). Arduengo-type carbenes, described by Linus Pauling as push-push, mesomeric pull-pull (Pauling, 1980) are electronically stabilized through donating amino-substituents and sterically protected by alkyl substituted phenyl groups in the 1,3-positions. Beginning in 1991, free diamino carbenes such as the 1,3-bis(1-adamantyl)imidazol-2-ylidiene (Arduengo et al., 1991) have garnered substantial notoriety across chemical disciplines.
As a result of the increased steric bulk associated with the flanking 2,6-diisopropylphenyl substiuents the title free carbene exibits a N1—C1—N2 bond angle of 104.98 (11)°. This angle represents substantial relaxation when compared to the IPr carbene, 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidiene, 101.4 (2)° and the IMes carbene 1,3-bis (2,4,6-trimethylphenyl)imidazolidin-2-ylidiene, 101.4 (3)° (Arduengo et al., 1999). However, the N1—C1—N2 angle in the title molecule is similar to that of the saturated analogue of IMes, 1,3-bis(2,4,6-trimethylphenyl)imidazolidin-2-ylidiene, 104.7 (3)° (Arduengo et al., 1995). It should be noted that the unit-cell parameters are nearly identical to those reported for the analagous IPr carbene (Arduengo et al., 1999). This is not surprising as the addition of two Hydrogen atoms to the C=C bond in the backbone of the molecule will casue little change in the overall molecular volume and shape of the parent molecule relative to that of the imidazol-2-ylidiene.