Structural verification of a tetra­hydro­tetra­zole compound

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.

Computing details

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-1H,2H,3H,10bH-[1,2,3,4]tetrazolo[5,1-a]isoquinoline-1,2-dicarboxylate

Crystal data

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) Å^3	Block, colourless
Z = 4	0.54 × 0.33 × 0.28 mm
F(000) = 960

Data collection

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

Refinement on F^2	Primary atom site location: dual
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.042	All H-atom parameters refined
wR(F^2) = 0.116	w = 1/[σ^2(Fo^2) + (0.0602P)^2 + 0.2083P] where P = (Fo^2 + 2Fc^2)/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

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 (Ų)

	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 (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
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)

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)