The high-anti conformation of 8-aza-1,3-dide­aza-2′-deoxy­adenosine

In the title compound, 4-amino-1-(2-deoxy-β-D-erythro-pento­furan­osyl)-1H-benzotriazole, C₁₁H₁₄N₄O₃, the conformation of the N-glycosidic bond is in the high-anti range [χ = −77.1 (4)°] and the 2′-deoxy­ribo­furan­ose moiety adopts a 2′-­endo (²E) sugar puckering. The 5′-hydroxyl group is disordered and has conformations ap with γ = 171.1 (3)° [occupation of 61.4 (3)%] and +sc with γ = 52.4 (6)° [occupation of 38.6 (3)%]. The nucleobases are stacked in the crystal state.

S1. Comment

8-Aza-1,3-dideaza-2'-deoxyadenosine, (I), can be considered as an analogue of the DNA constituent dA, (II). It shows a similar shape to the parent DNA constitutent but cannot develop bidentate Watson-Crick hydrogen bonds with dT. Nevertheless, it should be well accommodated in a DNA duplex. Its preparation from 4-amino- or 4-nitrobenzotriazole has been described (Kazimierczuk & Seela, 1990). The kinetics and mechanism of its acid-catalyzed hydrolysis have been investigated (Käppi et al., 1991). \sch

The structure of (I) is shown in Fig. 1. Some geometrical parameters are summarized in Table 1 (systematic numbering is used throughout). For the normal purine nucleosides, the orientation of the base relative to the sugar (syn/anti) is defined by the torsion angle χ (O4'-C1'-N9—C4) (IUPAC-IUB Joint Commission on Biochemical Nomenclature, 1983). The preferred conformation around the N-glycosidic bond of purine 2'-deoxynucleosides is usually anti. 2'-Deoxyadenosine, (II), shows a χ value of -165.1° (Sato, 1984). In the case of compound (I) the torsion angle χ (O4'-C1'-N1—C7A) (systematic numbering) is -77.1 (4)°. This indicates that the title compound adopts a high-anti conformation. As it contains a nitrogen atom at position 8 (purine numbering), the particular conformation is in accordance with the high-anti conformation of other ortho azanucleosides (Abola & Sundaralingam, 1973; Schwalbe & Saenger, 1973; Singh & Hodgson, 1974a,b, 1977; Seela, Becher et al., 1999). 8-Aza-7-deaza-7-iodo-2'-deoxyadenosine (χ = -73.2°) and 8-aza-7-bromo-7-deaza-2'-deoxyadenosine (χ = -74.1°) show similar values (Seela et al., 2000). The high-anti conformation results from Coulomb repulsion between non-bonding electron pairs of O4' and N8 (Seela et al., 2000). In contrast, the conformation of 8-aza-7-deaza-2'-deoxyadenosine (χ = -106.3°) (Seela, Zulauf et al., 1999) belongs to the anti-range. The glycosidic bond length (N1—C1') of (I) is 1.454 (3) Å, which is shorter than the corresponding bond of compound (II) (1.474 Å) (Sato, 1984). The shortening of the glycosidic bond of ortho azanucleosides has already been discussed (Sundaralingam, 1966; Lin et al., 1971). The puckering of the deoxyribose ring of (I) is C2'-endo (²E) with P = 163.3 (3)° and τ_m = 41.9 (2)°, observed for anomers of 8-aza-7-deaza-2'-deoxyadenosine (Seela, Zulauf et al., 1999) but not for 2'-deoxyadenosine (C3'-endo) (Sato, 1984). This is the typical South conformation. The sugar moiety of the title compound shows a disorder of the hydroxyl group. There are two alternative conformations, defined as conformation 1 and conformation 2; both are staggered. The γ(O5'1-C5'-C4'-C3') value of conformation 1 [occupation factor: 0.614 (3)] is 171.1 (3)°, which corresponds to ap. For conformation 2 [occupation factor: 0.386 (3)], the γ(O5'2-C5'-C4'-C3') value is 52.4 (6)°, which corresponds to +sc. The preponderant ap conformation means that the nucleobase and the CH₂OH group undergo a disrotatory motion so that the Coulomb repulsion between N8 (purine numbering) and O5' as well as O4' is minimized.

Another distinct attribute of the structure is a nearly parallel orientation of the base moieties, which is probably caused by π electron interactions between the aromatic ring systems of adjacent molecules. The least-squares plane of the base moiety (N1, N2, N3, C3A, C4, N4, C5, C6, C7, C7A) results in a plane nearly orthogonal to the a axis [89.10 (6)°]. Because of the space group symmetry, the molecules can take two alternative orientations, here called (a) and (b). The asymmetric unit and translation equivalent molecules are in orientation (a). The molecules generated by the screw-axis have orientation (b). The base moieties of molecules of the same orientation are naturally parallel. The base moieties of molecules of different orientation [(a) and (b)] form an interplanar angle of 1.80 (12)°. A view along the a axis shows the stacking of the base moieties (Fig. 2). Interestingly, the average distance between those nearly parallel base moieties stacked along the a axis is 3.48 Å (=0.5*a), very close to the distance between adjacent base pairs in DNA duplexes (3.4 Å). However, there is no helical twist in the crystal structure of (I) as is found for the base pairs in a DNA duplex.

The molecules of the title compound are linked by several hydrogen bonds (Table 2) forming two-dimensional networks perpendicular to the c axis. The molecules are linked along the screw-axis parallel to a by the bifurcated hydrogen bond system N4—H41.·O5'1/O4'. A further hydrogen bond is found linking molecules parallel to the a axis (O5'1-H5'1···O3'). Finally, there are further hydrogen bonds that connect molecules along the b axis or via the screw-axis parallel to b, namely O3'-H3'.·N3, the N4—H42.·O3' and the bifurcated contact O5'2-H5'2.·N2/N3.

Related literature

For related literature, see: Abola & Sundaralingam (1973); IUPAC-IUB (1983); Käppi et al. (1991); Kazimierczuk & Seela (1990); Lin et al. (1971); Sato (1984); Schwalbe & Saenger (1973); Seela et al. (2000); Seela, Becher, Rosemeyer, Reuter, Kastner & Mikhailopulo (1999); Seela, Zulauf, Reuter & Kastner (1999); Singh & Hodgson (1974a, 1974b, 1977); Sundaralingam (1966).

S2. Refinement

In the absence of suitable anomalous scatterers, the measured Friedel data could not be used to determine the absolute structure. Because of this the Friedel reflections were merged. Comparison with the known configuration of the parent molecule indicates that the proposed configuration is correct. All hydrogen atoms except H511 and H521 were located in difference Fourier synthesis. Localization of H511 and H521 failed because their electron density is hidden behind the electron density of the disordered O5' (H511 is covered by O5'2, H21 is covered by O5'1). In order to optimize the data/parameter ratio all H atoms were calculated at geometrically reasonable positions and refined as riding on the parent atoms. Their displacement parameters were fixed at 1.2 times the (equivalent) isotropic displacement parameter of the parent atoms.

Computing details

Data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS; data reduction: SHELXTL (Sheldrick, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL and DIAMOND (Brandenburg, 1999); software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. Perspective view of (I). Displacement ellipsoids of non-H atoms are drawn at 25% probability level. H atoms are shown as spheres of an arbitrary size. Conformation (1) of the C4'-C5' bond is represented by full bonds and an O5'1 atom with octants. Conformation (2) is represented by open bonds and an O5'2 atom without octants.
	Fig. 2. The stacking of the base moieties of (I). View against the a axis.

4-amino-1-(2-deoxy-β-D-erythro-pentofuranosyl) -1H-benzotriazole

Crystal data

C11H14N4O3	Dx = 1.489 Mg m^−3
Mr = 250.26	Melting point: not measured K
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
a = 6.959 (1) Å	Cell parameters from 38 reflections
b = 8.564 (1) Å	θ = 2.6–17.3°
c = 18.734 (3) Å	µ = 0.11 mm^−1
V = 1116.5 (3) Å^3	T = 293 K
Z = 4	Prism, colourless
F(000) = 528	0.48 × 0.16 × 0.15 mm

Data collection

Bruker P4 diffractometer	Rint = 0.041
Radiation source: fine-focus sealed tube	θmax = 25.0°, θmin = 2.2°
Graphite monochromator	h = −8→8
2θ/ω scans	k = −10→10
1169 measured reflections	l = −22→22
1169 independent reflections	3 standard reflections every 97 reflections
1058 reflections with I > 2σ(I)	intensity decay: none

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)] = 0.041	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.113	H-atom parameters constrained
S = 1.10	w = 1/[σ^2(Fo^2) + (0.0756P)^2 + 0.0595P] where P = (Fo^2 + 2Fc^2)/3
1169 reflections	(Δ/σ)max < 0.001
179 parameters	Δρmax = 0.28 e Å^−3
1 restraint	Δρmin = −0.22 e Å^−3

Special details

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.

To make the refinememt strategy more clearly the last INS-file is given: TITL Xy002 in P2(1)2(1)2(1) CELL 0.710730 6.959300 8.563900 18.733601 90.000000 90.000000 90.000000 ZERR 4.00 0.001400 0.001400 0.002600 0.000000 0.000000 0.000000 L A T T -1 SYMM 0.5-X, –Y, 0.5+Z SYMM –X, 0.5+Y, 0.5-Z SYMM 0.5+X, 0.5-Y, –Z SFAC C H N O UNIT 44 56 16 12 L·S. 15 EXYZ C5'1 C5'2 EADP C5'1 C5'2 SUMP 1.00 0.00 1.00 2 1.00 3 BOND $H FMAP 2 acta conf eqiv $1 x - 1/2, -y + 3/2, -z + 1 eqiv $2 x, y + 1, z eqiv $3 x, y - 1, z eqiv $4 x + 1, y, z eqiv $5 - x + 1, y - 1/2, -z + 1/2 eqiv $6 x - 0.5, -y + 1.5, -z + 1 eqiv $7 x + 0.5, -y + 1.5, -z + 1 htab N4 o5'1_$1 htab n4 o4'_$1 htab N4 O3'_$2 htab o3' n3_$3 htab o5'1 o3'_$4 htab o5'2 n2_$5 htab o5'2 n3_$5 mpla n1 n2 n3 c3a c4 c5 c6 c7 c7a mpla n1_$6 n2_$6 n3_$6 c3a_$6 c4_$6 c5_$6 c6_$6 c7_$6 c7a_$6 mpla n1_$7 n2_$7 n3_$7 c3a_$7 c4_$7 c5_$7 c6_$7 c7_$7 c7a_$7

PLAN 10

WGHT 0.076400 0.126900 FVAR 0.32742 0.61441 0.38559 0.06275 0.83469 N1 3 0.168371 0.574033 0.401715 11.00000 0.04112 0.02738 = 0.03462 0.00213 0.00086 0.00142 N2 3 0.164102 0.690225 0.352679 11.00000 0.04653 0.03004 = 0.03747 0.00136 0.00476 0.00174 N3 3 0.166683 0.822658 0.386873 11.00000 0.04420 0.02980 = 0.04002 - 0.00012 0.00561 0.00067 C3A 1 0.171177 0.794614 0.459028 11.00000 0.03140 0.02856 = 0.03823 - 0.00009 0.00547 0.00081 C4 1 0.169420 0.899213 0.517657 11.00000 0.03578 0.03312 = 0.04315 - 0.00566 0.00674 0.00076 N4 3 0.169336 1.058198 0.507950 11.00000 0.07423 0.03173 = 0.05497 - 0.01094 0.01997 - 0.00512 AFIX 93 H41 2 0.169802 1.119480 0.544318 11.00000 - 1.20000 H42 2 0.168817 1.096454 0.465505 11.00000 - 1.20000 AFIX 0 C5 1 0.170237 0.829747 0.584563 11.00000 0.04208 0.05083 = 0.03790 - 0.00982 0.00417 - 0.00364 AFIX 43 H5 2 0.167654 0.892886 0.624942 11.00000 - 1.20000 AFIX 0 C6 1 0.174869 0.666176 0.593124 11.00000 0.04911 0.05297 = 0.03397 0.00482 - 0.00178 0.00423 AFIX 43 H6 2 0.177504 0.625866 0.639211 11.00000 - 1.20000 AFIX 0 C7 1 0.175681 0.563742 0.537026 11.00000 0.04498 0.03822 = 0.04091 0.00632 - 0.00136 0.00195 AFIX 43 H7 2 0.178018 0.456042 0.543329 11.00000 - 1.20000 AFIX 0 C7A 1 0.172727 0.633448 0.469476 11.00000 0.03147 0.03107 = 0.03760 - 0.00316 0.00319 0.00133 C1' 1 0.150653 0.409845 0.383162 11.00000 0.03934 0.02579 = 0.03880 0.00053 0.00004 0.00567 AFIX 13 H1' 2 0.055066 0.361037 0.414432 11.00000 - 1.20000 AFIX 0 C2' 1 0.098150 0.377187 0.306072 11.00000 0.04724 0.02997 = 0.04136 0.00103 - 0.01396 0.00026 AFIX 23 H2'1 2 0.166487 0.445423 0.273461 11.00000 - 1.20000 H2'2 2 - 0.039029 0.386632 0.297982 11.00000 - 1.20000 AFIX 0 C3' 1 0.165478 0.209184 0.299771 11.00000 0.04570 0.02909 = 0.03493 - 0.00047 - 0.00474 0.00180 AFIX 13 H3'1 2 0.187604 0.179233 0.249956 11.00000 - 1.20000 AFIX 0 O3' 4 0.025252 0.112339 0.332919 11.00000 0.03920 0.02798 = 0.06201 0.00261 - 0.00689 - 0.00019 AFIX 147 H3' 2 0.075039 0.029626 0.344926 11.00000 - 1.20000 AFIX 0 C4' 1 0.353032 0.210571 0.343016 11.00000 0.03973 0.02769 = 0.03785 - 0.00083 - 0.00089 0.00069 AFIX 13 H4' 2 0.363758 0.111858 0.369177 11.00000 - 1.20000 AFIX 0 O4' 4 0.330907 0.336032 0.393678 11.00000 0.05277 0.04938 = 0.04666 - 0.01859 - 0.01827 0.02145 PART 1 C5'1 1 0.532587 0.234616 0.300400 21.00000 0.05072 0.06557 = 0.05641 - 0.00665 0.00993 - 0.00771 AFIX 23 H511 2 0.557346 0.144212 0.270592 21.00000 - 1.20000 H512 2 0.519323 0.325433 0.269852 21.00000 - 1.20000 AFIX 0 O5'1 4 0.681316 0.256153 0.347935 21.00000 0.03330 0.08156 = 0.08786 - 0.01950 0.00266 - 0.00316 AFIX 147 H5'1 2 0.777816 0.211934 0.333029 21.00000 - 1.20000 AFIX 0 PART 2 C5'2 1 0.532587 0.234616 0.300400 31.00000 0.05072 0.06557 = 0.05641 - 0.00665 0.00993 - 0.00771 AFIX 23 H521 2 0.637871 0.241548 0.334182 31.00000 - 1.20000 H522 2 0.552985 0.140133 0.272867 31.00000 - 1.20000 AFIX 0 O5'2 4 0.551140 0.352579 0.256082 31.00000 0.06718 0.08478 = 0.05829 0.01585 0.02538 0.00050 AFIX 147 H5'2 2 0.637786 0.333999 0.227661 31.00000 - 1.20000 PART 0 HKLF 4 END

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
N1	0.1684 (4)	0.5740 (2)	0.40172 (11)	0.0344 (5)
N2	0.1641 (4)	0.6902 (2)	0.35268 (12)	0.0380 (5)
N3	0.1667 (4)	0.8227 (2)	0.38687 (12)	0.0380 (5)
C3A	0.1712 (4)	0.7946 (3)	0.45903 (13)	0.0327 (6)
C4	0.1694 (4)	0.8992 (3)	0.51766 (15)	0.0374 (6)
N4	0.1693 (5)	1.0582 (3)	0.50795 (15)	0.0536 (7)
H41	0.1698	1.1195	0.5443	0.064*
H42	0.1688	1.0965	0.4655	0.064*
C5	0.1702 (5)	0.8297 (4)	0.58456 (15)	0.0436 (7)
H5	0.1677	0.8929	0.6249	0.052*
C6	0.1749 (5)	0.6662 (4)	0.59312 (15)	0.0454 (7)
H6	0.1775	0.6259	0.6392	0.054*
C7	0.1757 (5)	0.5637 (3)	0.53703 (15)	0.0414 (6)
H7	0.1780	0.4560	0.5433	0.050*
C7A	0.1727 (4)	0.6334 (3)	0.46948 (14)	0.0334 (6)
C1'	0.1507 (4)	0.4098 (3)	0.38316 (14)	0.0346 (6)
H1'	0.0551	0.3610	0.4144	0.042*
C2'	0.0981 (4)	0.3772 (3)	0.30607 (15)	0.0395 (7)
H2'1	0.1665	0.4454	0.2735	0.047*
H2'2	−0.0390	0.3866	0.2980	0.047*
C3'	0.1655 (4)	0.2092 (3)	0.29977 (15)	0.0366 (6)
H3'1	0.1876	0.1792	0.2500	0.044*
O3'	0.0253 (3)	0.1123 (2)	0.33292 (12)	0.0431 (5)
H3'	0.0750	0.0296	0.3449	0.052*
C4'	0.3530 (4)	0.2106 (3)	0.34302 (14)	0.0351 (6)
H4'	0.3638	0.1119	0.3692	0.042*
O4'	0.3309 (4)	0.3360 (2)	0.39368 (10)	0.0496 (6)
C5'1	0.5326 (5)	0.2346 (5)	0.3004 (2)	0.0576 (9)	0.614 (3)
H511	0.5573	0.1442	0.2706	0.069*	0.614 (3)
H512	0.5193	0.3254	0.2699	0.069*	0.614 (3)
O5'1	0.6813 (5)	0.2562 (5)	0.3479 (2)	0.0676 (12)	0.614 (3)
H5'1	0.7778	0.2119	0.3330	0.081*	0.614 (3)
C5'2	0.5326 (5)	0.2346 (5)	0.3004 (2)	0.0576 (9)	0.386 (3)
H521	0.6379	0.2415	0.3342	0.069*	0.386 (3)
H522	0.5530	0.1401	0.2729	0.069*	0.386 (3)
O5'2	0.5511 (10)	0.3526 (9)	0.2561 (3)	0.070 (2)	0.386 (3)
H5'2	0.6378	0.3340	0.2277	0.084*	0.386 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0411 (12)	0.0274 (10)	0.0346 (10)	0.0014 (12)	0.0009 (11)	0.0021 (9)
N2	0.0465 (13)	0.0300 (11)	0.0375 (11)	0.0017 (13)	0.0048 (12)	0.0014 (9)
N3	0.0442 (12)	0.0298 (10)	0.0400 (11)	0.0007 (12)	0.0056 (12)	−0.0001 (9)
C3A	0.0314 (12)	0.0286 (13)	0.0382 (13)	0.0008 (14)	0.0055 (13)	−0.0001 (10)
C4	0.0358 (13)	0.0331 (13)	0.0432 (14)	0.0008 (13)	0.0067 (14)	−0.0057 (11)
N4	0.0742 (19)	0.0317 (12)	0.0550 (14)	−0.0051 (15)	0.0200 (16)	−0.0109 (11)
C5	0.0421 (15)	0.0508 (16)	0.0379 (13)	−0.0036 (17)	0.0042 (14)	−0.0098 (13)
C6	0.0491 (16)	0.0530 (17)	0.0340 (12)	0.0042 (17)	−0.0018 (15)	0.0048 (13)
C7	0.0450 (15)	0.0382 (14)	0.0409 (13)	0.0019 (16)	−0.0014 (15)	0.0063 (12)
C7A	0.0315 (12)	0.0311 (13)	0.0376 (13)	0.0013 (13)	0.0032 (14)	−0.0032 (11)
C1'	0.0393 (15)	0.0258 (12)	0.0388 (13)	0.0057 (12)	0.0000 (13)	0.0005 (11)
C2'	0.0472 (16)	0.0300 (13)	0.0414 (15)	0.0003 (13)	−0.0140 (13)	0.0010 (12)
C3'	0.0457 (14)	0.0291 (13)	0.0349 (13)	0.0018 (14)	−0.0047 (13)	−0.0005 (11)
O3'	0.0392 (10)	0.0280 (10)	0.0620 (12)	−0.0002 (9)	−0.0069 (10)	0.0026 (10)
C4'	0.0397 (14)	0.0277 (12)	0.0378 (13)	0.0007 (13)	−0.0009 (12)	−0.0008 (11)
O4'	0.0528 (12)	0.0494 (12)	0.0467 (11)	0.0215 (12)	−0.0183 (11)	−0.0186 (10)
C5'1	0.0507 (17)	0.066 (2)	0.0564 (19)	−0.0077 (18)	0.0099 (16)	−0.0066 (19)
O5'1	0.0333 (18)	0.082 (3)	0.088 (3)	−0.003 (2)	0.003 (2)	−0.020 (3)
C5'2	0.0507 (17)	0.066 (2)	0.0564 (19)	−0.0077 (18)	0.0099 (16)	−0.0066 (19)
O5'2	0.067 (5)	0.085 (5)	0.058 (4)	0.001 (4)	0.025 (4)	0.016 (4)

Geometric parameters (Å, º)

N1—N2	1.355 (3)	C1'—H1'	0.9800
N1—C7A	1.368 (3)	C2'—C3'	1.518 (4)
N1—C1'	1.454 (3)	C2'—H2'1	0.9700
N2—N3	1.303 (3)	C2'—H2'2	0.9700
N3—C3A	1.373 (3)	C3'—O3'	1.423 (4)
C3A—C7A	1.394 (3)	C3'—C4'	1.536 (4)
C3A—C4	1.417 (4)	C3'—H3'1	0.9800
C4—N4	1.374 (4)	O3'—H3'	0.8200
C4—C5	1.387 (4)	C4'—O4'	1.442 (3)
N4—H41	0.8600	C4'—C5'1	1.497 (4)
N4—H42	0.8600	C4'—H4'	0.9800
C5—C6	1.410 (4)	C5'1—O5'1	1.378 (5)
C5—H5	0.9300	C5'1—H511	0.9700
C6—C7	1.369 (4)	C5'1—H512	0.9700
C6—H6	0.9300	C5'2—O5'2	1.314 (8)
C7—C7A	1.399 (4)	C5'2—H521	0.9700
C7—H7	0.9300	C5'2—H522	0.9700
C1'—O4'	1.418 (4)	O5'1—H5'1	0.8200
C1'—C2'	1.516 (4)	O5'2—H5'2	0.8200
N2—N1—C7A	110.9 (2)	C1'—C2'—C3'	100.1 (2)
N2—N1—C1'	123.1 (2)	C1'—C2'—H2'1	111.8
C7A—N1—C1'	125.7 (2)	C3'—C2'—H2'1	111.8
N3—N2—N1	107.8 (2)	C1'—C2'—H2'2	111.8
N2—N3—C3A	109.4 (2)	C3'—C2'—H2'2	111.8
N3—C3A—C7A	108.2 (2)	H2'1—C2'—H2'2	109.5
N3—C3A—C4	130.7 (2)	O3'—C3'—C2'	107.9 (2)
C7A—C3A—C4	121.1 (2)	O3'—C3'—C4'	110.9 (2)
N4—C4—C5	123.0 (3)	C2'—C3'—C4'	102.4 (2)
N4—C4—C3A	121.6 (3)	O3'—C3'—H3'1	111.8
C5—C4—C3A	115.4 (2)	C2'—C3'—H3'1	111.8
C4—N4—H41	120.0	C4'—C3'—H3'1	111.8
C4—N4—H42	120.0	C3'—O3'—H3'	109.5
H41—N4—H42	120.0	O4'—C4'—C5'1	109.7 (3)
C4—C5—C6	121.9 (3)	O4'—C4'—C3'	105.2 (2)
C4—C5—H5	119.0	C5'1—C4'—C3'	115.4 (2)
C6—C5—H5	119.0	O4'—C4'—H4'	108.8
C7—C6—C5	123.3 (3)	C5'1—C4'—H4'	108.8
C7—C6—H6	118.3	C3'—C4'—H4'	108.8
C5—C6—H6	118.3	C1'—O4'—C4'	109.6 (2)
C6—C7—C7A	114.9 (3)	C4'—C5'1—H511	110.2
C6—C7—H7	122.6	C4'—C5'1—H512	110.2
C7A—C7—H7	122.6	O5'1—C5'1—C4'	107.5 (3)
N1—C7A—C3A	103.8 (2)	O5'1—C5'1—H511	110.2
N1—C7A—C7	132.9 (2)	O5'1—C5'1—H512	110.2
C3A—C7A—C7	123.3 (2)	H511—C5'1—H512	108.5
O4'—C1'—N1	108.8 (2)	C4'—C5'2—H521	106.9
O4'—C1'—C2'	105.3 (2)	C4'—C5'2—H522	106.9
N1—C1'—C2'	115.3 (2)	O5'2—C5'2—C4'	121.6 (6)
O4'—C1'—H1'	109.1	O5'2—C5'2—H521	106.9
N1—C1'—H1'	109.1	O5'2—C5'2—H522	106.9
C2'—C1'—H1'	109.1	H521—C5'2—H522	106.7
C7A—N1—N2—N3	0.4 (3)	C6—C7—C7A—C3A	0.7 (5)
C1'—N1—N2—N3	174.6 (3)	N2—N1—C1'—O4'	109.5 (3)
N1—N2—N3—C3A	−0.5 (3)	C7A—N1—C1'—O4'	−77.1 (4)
N2—N3—C3A—C7A	0.4 (4)	N2—N1—C1'—C2'	−8.4 (4)
N2—N3—C3A—C4	−177.8 (3)	C7A—N1—C1'—C2'	164.9 (3)
N3—C3A—C4—N4	−2.4 (6)	O4'—C1'—C2'—C3'	39.7 (3)
C7A—C3A—C4—N4	179.5 (3)	N1—C1'—C2'—C3'	159.6 (3)
N3—C3A—C4—C5	178.3 (3)	C1'—C2'—C3'—O3'	77.9 (3)
C7A—C3A—C4—C5	0.3 (5)	C1'—C2'—C3'—C4'	−39.1 (3)
N4—C4—C5—C6	−178.5 (4)	O3'—C3'—C4'—O4'	−88.7 (3)
C3A—C4—C5—C6	0.7 (5)	C2'—C3'—C4'—O4'	26.1 (3)
C4—C5—C6—C7	−1.1 (6)	O3'—C3'—C4'—C5'1	150.2 (3)
C5—C6—C7—C7A	0.4 (5)	O3'—C3'—C4'—C5'2	150.2 (3)
N2—N1—C7A—C3A	−0.1 (3)	C2'—C3'—C4'—C5'1	−95.0 (3)
C1'—N1—C7A—C3A	−174.2 (3)	N1—C1'—O4'—C4'	−148.6 (2)
N2—N1—C7A—C7	179.1 (3)	C2'—C1'—O4'—C4'	−24.5 (3)
C1'—N1—C7A—C7	5.0 (5)	C5'1—C4'—O4'—C1'	123.5 (3)
N3—C3A—C7A—N1	−0.2 (4)	C3'—C4'—O4'—C1'	−1.2 (3)
C4—C3A—C7A—N1	178.3 (3)	O4'—C4'—C5'1—O5'1	52.5 (4)
N3—C3A—C7A—C7	−179.5 (3)	C3'—C4'—C5'1—O5'1	171.1 (3)
C4—C3A—C7A—C7	−1.0 (5)	O4'—C4'—C5'1—O5'2	−66.2 (5)
C6—C7—C7A—N1	−178.4 (4)	C3'—C4'—C5'1—O5'2	52.4 (6)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N4—H41···O5′1^i	0.86	2.28	3.134 (5)	170
N4—H41···O4′^i	0.86	2.66	3.125 (4)	116
N4—H42···O3′^ii	0.86	2.68	3.460 (4)	151
O3′—H3′···N3^iii	0.82	2.04	2.854 (3)	171
O5′1—H5′1···O3′^iv	0.82	1.92	2.706 (4)	160
O5′2—H5′2···N2^v	0.82	2.38	3.164 (7)	159
O5′2—H5′2···N3^v	0.82	2.54	3.331 (7)	162

Symmetry codes: (i) x−1/2, −y+3/2, −z+1; (ii) x, y+1, z; (iii) x, y−1, z; (iv) x+1, y, z; (v) −x+1, y−1/2, −z+1/2.