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Tetrahydrotetrazoles are five-membered-ring heterocycles containing four contiguous saturated nitrogen atoms. Very few examples of such compounds have been reported in the literature. Our previous attempt at the synthesis of a member of this class of compound suggested that the N—N bonds may be more labile than expected. This finding raised the question as to whether the structures of any of the previously reported tetrahydrotetrazoles had been properly assigned. We have reproduced the synthesis of a reported tetrahydrotetrazole, namely 1,2-di-tert-butyl 3-phenyl-1H,2H,3H,10bH-[1,2,3,4]tetrazolo[5,1-a]isoquinoline-1,2-dicarboxylate, C25H30N4O4, and have now confidently confirmed its structure via X-ray crystallography. However, while sufficiently stable in the crystal phase, we discovered that it remains very labile in solution (having a half-life of only 15 min at 20 °C in CDCl3). A tentative reaction pathway for its dissociation based on 1H NMR spectral evidence is provided.
Supporting information
CCDC reference: 1941061
Data collection: CrysAlis PRO (Rigaku OD, 2018); cell refinement: CrysAlis PRO (Rigaku OD, 2018); data reduction: CrysAlis PRO (Rigaku OD, 2018); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2017 (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).
1,2-Di-
tert-butyl
3-phenyl-1
H,2
H,3
H,10b
H-[1,2,3,4]tetrazolo[5,1-
a]isoquinoline-1,2-dicarboxylate
top
Crystal data top
C25H30N4O4 | Dx = 1.265 Mg m−3 |
Mr = 450.53 | Melting point: 369 K |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 9.2613 (19) Å | Cell parameters from 79687 reflections |
b = 10.882 (2) Å | θ = 1.7–49.2° |
c = 23.583 (5) Å | µ = 0.09 mm−1 |
β = 95.54 (3)° | T = 90 K |
V = 2365.7 (8) Å3 | Block, colourless |
Z = 4 | 0.54 × 0.33 × 0.28 mm |
F(000) = 960 | |
Data collection top
XtaLAB Synergy Dualflex HyPix diffractometer | 24326 independent reflections |
Radiation source: micro-focus sealed X-ray tube, PhotonJet (Mo) X-ray Source | 19422 reflections with I > 2σ(I) |
Mirror monochromator | Rint = 0.036 |
ω scans | θmax = 49.8°, θmin = 1.7° |
Absorption correction: gaussian (CrysAlis PRO; Rigaku OD, 2018) | h = −19→19 |
Tmin = 0.372, Tmax = 1.000 | k = −21→23 |
183544 measured reflections | l = −45→50 |
Refinement top
Refinement on F2 | Primary atom site location: dual |
Least-squares matrix: full | Hydrogen site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.042 | All H-atom parameters refined |
wR(F2) = 0.116 | w = 1/[σ2(Fo2) + (0.0602P)2 + 0.2083P] where P = (Fo2 + 2Fc2)/3 |
S = 1.03 | (Δ/σ)max = 0.003 |
24326 reflections | Δρmax = 0.71 e Å−3 |
418 parameters | Δρmin = −0.25 e Å−3 |
0 restraints | |
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 | x | y | z | Uiso*/Ueq | |
O1 | 0.27581 (3) | 0.73921 (3) | 0.78541 (2) | 0.01366 (4) | |
O2 | 0.42718 (3) | 0.60049 (3) | 0.83311 (2) | 0.01571 (5) | |
O3 | 0.31619 (3) | 0.67435 (3) | 0.96733 (2) | 0.01277 (4) | |
O4 | 0.20284 (4) | 0.49959 (3) | 0.99317 (2) | 0.01693 (5) | |
N1 | 0.02413 (3) | 0.52644 (3) | 0.82967 (2) | 0.01196 (4) | |
N2 | 0.05946 (3) | 0.65338 (3) | 0.83777 (2) | 0.01109 (4) | |
N3 | 0.20532 (3) | 0.65133 (3) | 0.86364 (2) | 0.01050 (4) | |
N4 | 0.21584 (3) | 0.54738 (3) | 0.89982 (2) | 0.01086 (4) | |
C1 | 0.06390 (4) | 0.48733 (4) | 0.77611 (2) | 0.01436 (5) | |
H1 | 0.0390 (9) | 0.5467 (8) | 0.7462 (4) | 0.0192 (18)* | |
C2 | 0.12033 (4) | 0.37654 (4) | 0.76764 (2) | 0.01607 (6) | |
H2 | 0.1349 (10) | 0.3516 (8) | 0.7285 (4) | 0.024 (2)* | |
C3 | 0.15273 (4) | 0.29276 (3) | 0.81520 (2) | 0.01501 (5) | |
C4 | 0.20068 (5) | 0.17264 (4) | 0.80703 (2) | 0.01941 (7) | |
H4 | 0.2127 (11) | 0.1439 (9) | 0.7668 (4) | 0.030 (2)* | |
C5 | 0.22737 (5) | 0.09330 (4) | 0.85290 (2) | 0.02194 (7) | |
H5 | 0.2610 (11) | 0.0096 (9) | 0.8470 (4) | 0.032 (2)* | |
C6 | 0.20595 (5) | 0.13303 (4) | 0.90772 (2) | 0.02048 (7) | |
H6 | 0.2238 (11) | 0.0772 (10) | 0.9406 (4) | 0.033 (2)* | |
C7 | 0.15994 (4) | 0.25292 (3) | 0.91666 (2) | 0.01655 (6) | |
H7 | 0.1493 (10) | 0.2814 (8) | 0.9553 (4) | 0.0203 (18)* | |
C8 | 0.13412 (4) | 0.33298 (3) | 0.87069 (2) | 0.01338 (5) | |
C9 | 0.09017 (4) | 0.46394 (3) | 0.88103 (2) | 0.01160 (4) | |
H9 | 0.0233 (8) | 0.4678 (7) | 0.9109 (3) | 0.0129 (15)* | |
C10 | −0.03570 (4) | 0.71725 (3) | 0.87237 (2) | 0.01151 (4) | |
C11 | −0.17551 (4) | 0.67480 (4) | 0.87762 (2) | 0.01539 (5) | |
H11 | −0.2052 (10) | 0.5941 (9) | 0.8611 (4) | 0.025 (2)* | |
C12 | −0.27025 (5) | 0.74630 (4) | 0.90630 (2) | 0.01872 (6) | |
H12 | −0.3665 (11) | 0.7162 (9) | 0.9081 (4) | 0.029 (2)* | |
C13 | −0.22630 (5) | 0.85958 (4) | 0.92885 (2) | 0.02054 (7) | |
H13 | −0.2939 (11) | 0.9094 (9) | 0.9488 (4) | 0.030 (2)* | |
C14 | −0.08583 (5) | 0.90087 (4) | 0.92372 (2) | 0.02242 (8) | |
H14 | −0.0504 (12) | 0.9823 (10) | 0.9386 (5) | 0.042 (3)* | |
C15 | 0.00991 (5) | 0.82997 (4) | 0.89583 (2) | 0.01805 (6) | |
H15 | 0.1076 (11) | 0.8593 (9) | 0.8916 (4) | 0.028 (2)* | |
C16 | 0.31477 (4) | 0.65636 (3) | 0.82525 (2) | 0.01128 (4) | |
C17 | 0.37557 (4) | 0.77151 (3) | 0.74242 (2) | 0.01410 (5) | |
C18 | 0.29049 (5) | 0.86999 (4) | 0.70787 (2) | 0.02097 (7) | |
H18A | 0.2746 (11) | 0.9417 (10) | 0.7332 (4) | 0.034 (2)* | |
H18B | 0.3474 (11) | 0.9002 (10) | 0.6766 (4) | 0.035 (2)* | |
H18C | 0.2004 (10) | 0.8343 (9) | 0.6905 (4) | 0.027 (2)* | |
C19 | 0.51594 (5) | 0.82367 (5) | 0.77147 (2) | 0.02137 (7) | |
H19A | 0.5774 (10) | 0.7599 (9) | 0.7902 (4) | 0.028 (2)* | |
H19B | 0.4928 (11) | 0.8866 (9) | 0.8007 (4) | 0.033 (2)* | |
H19C | 0.5667 (12) | 0.8615 (9) | 0.7433 (4) | 0.034 (2)* | |
C20 | 0.40079 (6) | 0.65914 (4) | 0.70642 (2) | 0.02022 (7) | |
H20A | 0.4617 (11) | 0.6004 (9) | 0.7289 (4) | 0.032 (2)* | |
H20B | 0.4554 (10) | 0.6840 (9) | 0.6749 (4) | 0.026 (2)* | |
H20C | 0.3125 (10) | 0.6246 (9) | 0.6886 (4) | 0.026 (2)* | |
C21 | 0.24080 (4) | 0.57102 (3) | 0.95807 (2) | 0.01159 (4) | |
C22 | 0.35314 (4) | 0.71857 (3) | 1.02605 (2) | 0.01257 (5) | |
C23 | 0.21485 (5) | 0.73970 (5) | 1.05462 (2) | 0.02044 (7) | |
H23A | 0.2402 (11) | 0.7858 (9) | 1.0910 (4) | 0.031 (2)* | |
H23B | 0.1726 (12) | 0.6633 (10) | 1.0646 (5) | 0.037 (3)* | |
H23C | 0.1452 (10) | 0.7857 (9) | 1.0287 (4) | 0.028 (2)* | |
C24 | 0.42713 (5) | 0.84033 (4) | 1.01594 (2) | 0.01948 (6) | |
H24A | 0.4558 (11) | 0.8803 (9) | 1.0528 (4) | 0.030 (2)* | |
H24B | 0.5160 (12) | 0.8251 (10) | 0.9961 (4) | 0.035 (2)* | |
H24C | 0.3600 (12) | 0.8944 (10) | 0.9927 (5) | 0.036 (2)* | |
C25 | 0.45844 (5) | 0.62985 (4) | 1.05809 (2) | 0.01855 (6) | |
H25A | 0.4965 (10) | 0.6665 (9) | 1.0944 (4) | 0.028 (2)* | |
H25B | 0.4113 (11) | 0.5510 (9) | 1.0645 (4) | 0.028 (2)* | |
H25C | 0.5397 (11) | 0.6167 (9) | 1.0358 (4) | 0.031 (2)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.01323 (9) | 0.01518 (10) | 0.01316 (9) | 0.00325 (7) | 0.00428 (7) | 0.00513 (7) |
O2 | 0.01207 (9) | 0.01753 (11) | 0.01774 (10) | 0.00354 (8) | 0.00256 (8) | 0.00487 (8) |
O3 | 0.01592 (10) | 0.01261 (9) | 0.00963 (8) | −0.00433 (7) | 0.00040 (7) | −0.00066 (7) |
O4 | 0.02262 (12) | 0.01558 (11) | 0.01255 (9) | −0.00587 (9) | 0.00139 (8) | 0.00363 (8) |
N1 | 0.01166 (9) | 0.01191 (10) | 0.01202 (9) | 0.00010 (7) | −0.00027 (7) | −0.00217 (7) |
N2 | 0.01000 (9) | 0.01155 (9) | 0.01165 (9) | 0.00056 (7) | 0.00063 (7) | −0.00086 (7) |
N3 | 0.01013 (9) | 0.01134 (9) | 0.00999 (8) | −0.00032 (7) | 0.00076 (7) | 0.00175 (7) |
N4 | 0.01248 (9) | 0.01003 (9) | 0.00980 (8) | −0.00225 (7) | −0.00029 (7) | 0.00090 (7) |
C1 | 0.01354 (12) | 0.01697 (13) | 0.01221 (11) | 0.00117 (10) | −0.00055 (9) | −0.00345 (9) |
C2 | 0.01536 (13) | 0.01701 (13) | 0.01575 (12) | 0.00058 (10) | 0.00109 (10) | −0.00531 (10) |
C3 | 0.01249 (11) | 0.01263 (12) | 0.01995 (13) | −0.00107 (9) | 0.00180 (10) | −0.00415 (10) |
C4 | 0.01706 (14) | 0.01319 (13) | 0.02859 (18) | −0.00098 (10) | 0.00533 (13) | −0.00574 (12) |
C5 | 0.01895 (15) | 0.01170 (13) | 0.0358 (2) | −0.00012 (11) | 0.00599 (15) | −0.00189 (13) |
C6 | 0.01834 (15) | 0.01174 (13) | 0.0312 (2) | −0.00076 (11) | 0.00164 (13) | 0.00242 (12) |
C7 | 0.01558 (13) | 0.01189 (12) | 0.02187 (15) | −0.00184 (10) | 0.00032 (11) | 0.00124 (10) |
C8 | 0.01170 (11) | 0.01050 (11) | 0.01775 (12) | −0.00152 (8) | 0.00054 (9) | −0.00148 (9) |
C9 | 0.01114 (10) | 0.01069 (10) | 0.01283 (10) | −0.00145 (8) | 0.00041 (8) | −0.00070 (8) |
C10 | 0.01197 (10) | 0.01124 (10) | 0.01148 (10) | 0.00070 (8) | 0.00191 (8) | 0.00019 (8) |
C11 | 0.01255 (11) | 0.01596 (13) | 0.01807 (13) | −0.00103 (9) | 0.00365 (9) | −0.00334 (10) |
C12 | 0.01477 (13) | 0.02046 (16) | 0.02190 (15) | −0.00054 (11) | 0.00680 (11) | −0.00420 (12) |
C13 | 0.01936 (15) | 0.01922 (16) | 0.02430 (17) | 0.00141 (12) | 0.00862 (13) | −0.00541 (13) |
C14 | 0.02111 (17) | 0.01592 (15) | 0.0315 (2) | −0.00126 (12) | 0.00915 (15) | −0.00849 (14) |
C15 | 0.01639 (13) | 0.01323 (13) | 0.02544 (16) | −0.00203 (10) | 0.00671 (12) | −0.00486 (11) |
C16 | 0.01117 (10) | 0.01158 (10) | 0.01117 (10) | 0.00015 (8) | 0.00149 (8) | 0.00151 (8) |
C17 | 0.01572 (12) | 0.01339 (12) | 0.01403 (11) | 0.00324 (9) | 0.00582 (9) | 0.00371 (9) |
C18 | 0.02573 (18) | 0.02020 (16) | 0.01822 (14) | 0.01002 (14) | 0.00849 (13) | 0.00857 (12) |
C19 | 0.01873 (15) | 0.02050 (16) | 0.02546 (18) | −0.00404 (12) | 0.00518 (13) | 0.00382 (13) |
C20 | 0.02767 (19) | 0.01729 (15) | 0.01667 (14) | 0.00551 (13) | 0.00709 (13) | 0.00060 (11) |
C21 | 0.01299 (11) | 0.01130 (10) | 0.01033 (9) | −0.00198 (8) | 0.00034 (8) | 0.00086 (8) |
C22 | 0.01253 (11) | 0.01427 (12) | 0.01080 (10) | −0.00043 (9) | 0.00060 (8) | −0.00206 (8) |
C23 | 0.01573 (14) | 0.02806 (19) | 0.01812 (14) | 0.00095 (13) | 0.00463 (11) | −0.00534 (13) |
C24 | 0.02259 (16) | 0.01579 (14) | 0.01981 (15) | −0.00553 (12) | 0.00075 (12) | −0.00359 (11) |
C25 | 0.01928 (15) | 0.02031 (16) | 0.01514 (13) | 0.00355 (12) | −0.00306 (11) | −0.00109 (11) |
Geometric parameters (Å, º) top
O1—C16 | 1.3268 (5) | C3—C8 | 1.4062 (6) |
O1—C17 | 1.4784 (6) | C4—C5 | 1.3875 (8) |
O2—C16 | 1.2044 (5) | C5—C6 | 1.3953 (8) |
O3—C21 | 1.3305 (5) | C6—C7 | 1.3948 (6) |
O3—C22 | 1.4748 (5) | C7—C8 | 1.3933 (6) |
O4—C21 | 1.2120 (5) | C8—C9 | 1.5085 (6) |
N1—N2 | 1.4282 (5) | C10—C11 | 1.3915 (6) |
N1—C1 | 1.4148 (6) | C10—C15 | 1.3943 (6) |
N1—C9 | 1.4700 (6) | C11—C12 | 1.3955 (6) |
N2—N3 | 1.4277 (6) | C12—C13 | 1.3879 (7) |
N2—C10 | 1.4369 (5) | C13—C14 | 1.3926 (7) |
N3—N4 | 1.4146 (4) | C14—C15 | 1.3880 (6) |
N3—C16 | 1.4237 (6) | C17—C18 | 1.5196 (6) |
N4—C9 | 1.5086 (5) | C17—C19 | 1.5197 (7) |
N4—C21 | 1.3949 (5) | C17—C20 | 1.5195 (6) |
C1—C2 | 1.3367 (6) | C22—C23 | 1.5211 (7) |
C2—C3 | 1.4541 (6) | C22—C24 | 1.5210 (6) |
C3—C4 | 1.3998 (6) | C22—C25 | 1.5204 (6) |
| | | |
C16—O1—C17 | 120.13 (3) | C8—C9—N4 | 113.80 (3) |
C21—O3—C22 | 120.02 (3) | C11—C10—N2 | 121.12 (4) |
N2—N1—C9 | 105.40 (3) | C11—C10—C15 | 120.38 (3) |
C1—N1—N2 | 109.53 (3) | C15—C10—N2 | 118.16 (3) |
C1—N1—C9 | 118.23 (3) | C10—C11—C12 | 119.47 (4) |
N1—N2—C10 | 113.49 (3) | C13—C12—C11 | 120.41 (4) |
N3—N2—N1 | 103.72 (3) | C12—C13—C14 | 119.68 (4) |
N3—N2—C10 | 111.82 (3) | C15—C14—C13 | 120.44 (4) |
N4—N3—N2 | 106.11 (3) | C14—C15—C10 | 119.61 (4) |
N4—N3—C16 | 113.73 (3) | O1—C16—N3 | 108.34 (3) |
C16—N3—N2 | 115.47 (3) | O2—C16—O1 | 128.61 (4) |
N3—N4—C9 | 107.33 (3) | O2—C16—N3 | 122.73 (3) |
C21—N4—N3 | 116.22 (3) | O1—C17—C18 | 102.08 (3) |
C21—N4—C9 | 116.75 (3) | O1—C17—C19 | 110.10 (4) |
C2—C1—N1 | 122.96 (4) | O1—C17—C20 | 109.37 (4) |
C1—C2—C3 | 120.32 (4) | C18—C17—C19 | 110.80 (4) |
C4—C3—C2 | 121.60 (4) | C20—C17—C18 | 111.58 (4) |
C4—C3—C8 | 119.19 (4) | C20—C17—C19 | 112.42 (4) |
C8—C3—C2 | 119.21 (4) | O3—C21—N4 | 110.60 (3) |
C5—C4—C3 | 120.59 (4) | O4—C21—O3 | 127.75 (3) |
C4—C5—C6 | 119.92 (4) | O4—C21—N4 | 121.53 (3) |
C7—C6—C5 | 120.18 (4) | O3—C22—C23 | 109.65 (4) |
C8—C7—C6 | 119.95 (4) | O3—C22—C24 | 101.79 (3) |
C3—C8—C9 | 120.25 (3) | O3—C22—C25 | 109.81 (4) |
C7—C8—C3 | 120.14 (4) | C24—C22—C23 | 110.43 (4) |
C7—C8—C9 | 119.59 (4) | C25—C22—C23 | 113.77 (4) |
N1—C9—N4 | 102.20 (3) | C25—C22—C24 | 110.73 (4) |
N1—C9—C8 | 113.65 (3) | | |
| | | |
N1—N2—N3—N4 | −35.80 (3) | C4—C3—C8—C9 | 176.78 (3) |
N1—N2—N3—C16 | 91.19 (3) | C4—C5—C6—C7 | −1.01 (7) |
N1—N2—C10—C11 | −23.78 (5) | C5—C6—C7—C8 | 0.53 (6) |
N1—N2—C10—C15 | 162.85 (3) | C6—C7—C8—C3 | 0.73 (6) |
N1—C1—C2—C3 | −4.16 (6) | C6—C7—C8—C9 | −177.57 (3) |
N2—N1—C1—C2 | 141.94 (4) | C7—C8—C9—N1 | −162.30 (3) |
N2—N1—C9—N4 | −27.23 (3) | C7—C8—C9—N4 | 81.25 (5) |
N2—N1—C9—C8 | −150.29 (3) | C8—C3—C4—C5 | 1.04 (6) |
N2—N3—N4—C9 | 18.43 (3) | C9—N1—N2—N3 | 39.42 (4) |
N2—N3—N4—C21 | −114.35 (4) | C9—N1—N2—C10 | −82.14 (4) |
N2—N3—C16—O1 | 42.68 (4) | C9—N1—C1—C2 | 21.26 (5) |
N2—N3—C16—O2 | −143.34 (4) | C9—N4—C21—O3 | −158.24 (3) |
N2—C10—C11—C12 | −172.86 (4) | C9—N4—C21—O4 | 25.47 (5) |
N2—C10—C15—C14 | 172.36 (4) | C10—N2—N3—N4 | 86.87 (4) |
N3—N2—C10—C11 | −140.69 (3) | C10—N2—N3—C16 | −146.14 (3) |
N3—N2—C10—C15 | 45.94 (4) | C10—C11—C12—C13 | 0.80 (7) |
N3—N4—C9—N1 | 5.38 (3) | C11—C10—C15—C14 | −1.06 (7) |
N3—N4—C9—C8 | 128.33 (3) | C11—C12—C13—C14 | −1.24 (8) |
N3—N4—C21—O3 | −29.91 (4) | C12—C13—C14—C15 | 0.53 (8) |
N3—N4—C21—O4 | 153.80 (4) | C13—C14—C15—C10 | 0.62 (8) |
N4—N3—C16—O1 | 165.71 (3) | C15—C10—C11—C12 | 0.36 (6) |
N4—N3—C16—O2 | −20.31 (5) | C16—O1—C17—C18 | −178.18 (4) |
C1—N1—N2—N3 | −88.77 (4) | C16—O1—C17—C19 | −60.47 (5) |
C1—N1—N2—C10 | 149.67 (3) | C16—O1—C17—C20 | 63.53 (5) |
C1—N1—C9—N4 | 95.55 (4) | C16—N3—N4—C9 | −109.59 (3) |
C1—N1—C9—C8 | −27.50 (4) | C16—N3—N4—C21 | 117.63 (4) |
C1—C2—C3—C4 | 174.71 (4) | C17—O1—C16—O2 | 1.27 (6) |
C1—C2—C3—C8 | −4.67 (6) | C17—O1—C16—N3 | 174.78 (3) |
C2—C3—C4—C5 | −178.34 (4) | C21—O3—C22—C23 | −59.09 (5) |
C2—C3—C8—C7 | 177.88 (3) | C21—O3—C22—C24 | −176.04 (3) |
C2—C3—C8—C9 | −3.83 (5) | C21—O3—C22—C25 | 66.61 (4) |
C3—C4—C5—C6 | 0.21 (7) | C21—N4—C9—N1 | 137.87 (3) |
C3—C8—C9—N1 | 19.40 (5) | C21—N4—C9—C8 | −99.17 (4) |
C3—C8—C9—N4 | −97.05 (5) | C22—O3—C21—O4 | −5.01 (6) |
C4—C3—C8—C7 | −1.51 (5) | C22—O3—C21—N4 | 178.99 (3) |
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