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1 organic compounds Acta Crystallographica Section C Crystal Structure Communications ISSN ,6-Dimethylthio-1-[3-(4,6-dimethylthio-2H-pyrazolo[3,4-d]- pyrimidin-2-yl)propyl]-1h-pyrazolo[3,4-d]pyrimidine, (4), was prepared earlier as a co-product during the synthesis of (1). Disappearance of intramolecular stacking due to one-atom movement or increment of a `propylene linker' in pyrazolo[3,4-d]pyrimidine-based flexible models Prakas R. Maulik, a * Kamlakar Avasthi, b Sanjay Sarkhel, a Tilak Chandra, b Diwan S. Rawat, b Brad Logsdon c and Robert A. Jacobson c a Membrane Biology Division, Central Drug Research Institute, Lucknow , India, b Medicinal Chemistry Division, Central Drug Research Institute, Lucknow , India, and c Department of Chemistry, Iowa State University, Ames, Iowa , USA Correspondence root@cscdri.ren.nic.in Received 2 June 2000 Accepted 31 July 2000 In the crystal structures of 4,6-dimethylthio-1-[3-(4,6-dimethylthio-2H-pyrazolo[3,4-d]pyrimidin-2-yl)propyl]-1H-pyrazolo[3,4-d]pyrimidine, C 17 H 20 N 8 S 4, and 1-[4-(4-methoxy-6- methylthio-1h-pyrazolo[3,4-d]pyrimidin-1-yl)butyl]-5-meth- yl-6-methylthio-4,5-dihydro-1h-pyrazolo[3,4-d]pyrimidin-4- one, C 18 H 22 N 8 O 2 S 2, only intermolecular stacking due to aromatic ± interactions between pyrazolo[3,4-d]pyrimidine rings is present. Comment Interactions between aromatic units play a signi cant role in chemistry and biology. The use of a `propylene linker' was rst documented by Brown et al. (1968) for the promotion of intramolecular aromatic ± interactions (APPI). Recently, we have reported convenient synthesis, high resolution 1 H NMR analysis (Avasthi et al., 1995; Avasthi, Rawat, Chandra & Bhakuni, 1998) and X-ray studies (Biswas et al., 1995; Maulik et al., 1998) of three novel `propylene linker' compounds: 1,3-bis(4,6-dimethylthio-1H-pyrazolo[3,4-d]pyrimidin-1-yl)propane, (1), 1,1 0 -(1,3-propanediyl)bis(5-methyl- 6-methylthio-4,5-dihydro-1H-pyrazolo[3,4-d]pyrimidin-4-one, (2), and 1-[3-(4-methoxy-6-methylthio-1H-pyrazolo[3,4-d]- pyrimidin-1-yl)propyl]-5-methyl-6-methylthio-4,5-dihydro-1hpyrazolo[3,4-d]pyrimidin-4-one, (3). These three compounds show inter/intramolecular stacking due to APPI. In this communication, we report the crystal structures of two compounds, (4) and (5), which are very closely related to our earlier exible models (1)±(3). The conformation of (4) is shown in Fig. 1. The structure does not show any intramolecular stacking [N1 0 ÐN (3) A Ê ], although the angle at the centre of the bridge [C8ÐC9ÐC (3) ] is quite comparable to the corresponding angle in the structure of (1) (Biswas et al., 1995). This disappearance of intramolecular stacking compared with the structure of (1) may highlight the importance of speci c orientation for intramolecular stacking (Hobza & Sponer, 1999). Interestingly, intermolecular stacking due to APPI is still present (Fig. 2), as indicated by an average space of 3.67 (4) A Ê between two stacked rings [angle between the stacked rings: 6.32 (10) ]. The other compound, 1-[4-(4-methoxy-6-methyl- thio-1h-pyrazolo[3,4-d]pyrimidin-1-yl)butyl]-5-methyl-6- methylthio-4,5-dihydro-1h-pyrazolo[3,4-d]pyrimidin-4-one, (5), which differs from compound (3) in having an extra methylene group in its linker, has been synthesized by us recently (Avasthi, Rawat, Chandra & Bhakuni, 1998). The conformation of (5) is shown in Fig. 3. Once again, the crystal structure does not show any intramolecular stacking [N1ÐN (2) A Ê and torsion angle C8ÐC9ÐC10ÐC (2) ] con rming an earlier conclusion drawn on the basis of 1 H Figure 1 ORTEP (Johnson, 1965) diagram showing the molecular structure of (4) with labelling of the non-h atoms and displacement ellipsoids at the 50% probability level. Acta Cryst. (2000). C56, 1361±1363 # 2000 International Union of Crystallography Printed in Great Britain ± all rights reserved 1361

2 organic compounds We believe that the addition of these two new members, (4) and (5), to an already existing group of three pyrazolo- [3,4-d]pyrimidinyl compounds, (1)±(3), isomeric with biologically important purines, constitutes a unique family of ve compounds demonstrating very strong conformational (topological) preferences due mainly to APPI. Figure 2 View of the molecules of compound (4) showing the partial overlapping of the rings owing to intermolecular stacking. Experimental The synthesis of compound (4) was achieved by alkylation of 4,6- dimethylthio-1h-pyrazolo[3,4-d]pyrimidine with 1,3-dibromopropane in the presence of potassium carbonate in dimethylformamide (Avasthi et al., 1995). The synthesis of compound (5) was carried out by treatment of 1,4-bis(4,6-dimethylthio-1H-pyrazolo[3,4- d]pyrimidin-1-yl)butane with aqueous alkali followed by methylation (Avasthi, Rawat, Chandra & Bhakuni, 1998). Diffraction quality crystals of both compounds were obtained by slow evaporation of ethyl acetate/chloroform mixtures at room temperature. NMR data comparison (Avasthi, Rawat, Chandra & Bhakuni, 1998) with monomeric model compounds (Avasthi, Rawat & Bhakuni, 1998). Intermolecular stacking, due to APPI, however, is still present (Fig. 4), as revealed by the average intermolecular spacing of 3.64 (3) A Ê [angle between the stacked rings: 0.68 (12) ]. Thus, the crystal structures of (4) and (5) are stabilized mainly by intermolecular APPI and van der Waals forces. Figure 3 ORTEP (Johnson, 1965) diagram showing the molecular structure of (5) with labelling of the non-h atoms and displacement ellipsoids at the 50% probability level. Compound (4) Crystal data C 17 H 20 N 8 S 4 M r = Monoclinic, P2 1 =n a = (2) A Ê b = (2) A Ê c = (5) A Ê = (2) V = (8) A Ê 3 Z =4 Data collection Siemens P4 diffractometer! scans Absorption correction: scan (local program; Karcher, 1981) T min = 0.749, T max = measured re ections 3697 independent re ections 2893 re ections with I > 2(I) Re nement Re nement on F 2 R[F 2 >2(F 2 )] = wr(f 2 ) = S = re ections 267 parameters H-atom parameters constrained w = 1/[ 2 (F 2 o ) + (0.1195P) P] where P =(F 2 o +2F 2 c )/3 D x = Mg m 3 Mo K radiation Cell parameters from 42 re ections = 4.7±13.1 = mm 1 T = 293 (2) K Rhombohedral, colourless mm max = h =0! 9 k =0! 12 l = 31! 31 3 standard re ections every 97 re ections frequency: 60 min intensity decay: none (/) max < max = 0.50 e A Ê 3 min = 0.24 e A Ê 3 Extinction correction: SHELXL93 (Sheldrick, 1993) Extinction coef cient: (12) Figure 4 View of the molecules of compound (5) showing the partial overlapping of the rings owing to intermolecular stacking. Compound (5) Crystal data C 18 H 22 N 8 O 2 S 2 M r = Monoclinic, C2=c a = (7) A Ê b = (2) A Ê c = (4) A Ê = (2) V = (17) A Ê 3 Z =8 D x = Mg m 3 Mo K radiation Cell parameters from 39 re ections = 4.9±12.8 = mm 1 T = 293 (2) K Trapezoidal, colourless mm 1362 Prakas R. Maulik et al. C 17 H 20 N 8 S 4 and C 18 H 22 N 8 O 2 S 2 Acta Cryst. (2000). C56, 1361±1363

3 organic compounds Data collection Siemens P4 diffractometer! scans Absorption correction: scan (local program; Karcher, 1981) T min = 0.772, T max = measured re ections 3616 independent re ections 3189 re ections with I > 2(I) Re nement Re nement on F 2 R[F 2 >2(F 2 )] = wr(f 2 ) = S = re ections 276 parameters H-atom parameters constrained w = 1/[ 2 (F 2 o ) + (0.0685P) P] where P =(F 2 o +2F 2 c )/3 max = h =0! 37 k =0! 9 l = 20! 18 3 standard re ections every 97 re ections frequency: 60 min intensity decay: none (/) max < max = 0.28 e A Ê 3 min = 0.22 e A Ê 3 Extinction correction: SHELXL97 (Sheldrick, 1997) Extinction coef cient: (5) For both compounds, data collection: XSCANS (Siemens, 1992); cell re nement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS86 (Sheldrick, 1990); program(s) used to re ne structure: SHELXL93 (Sheldrick, 1993) for compound (4), SHELXL97 (Sheldrick, 1997) for compound (5). For both compounds; molecular graphics: NRCVAX (Gabe et al., 1989); software used to prepare material for publication: SHELXL93 for compound (4), SHELXL97 for compound (5). SS thanks CSIR, India, for a Senior Research Fellowship. Supplementary data for this paper are available from the IUCr electronic archives (Reference: VJ1110). Services for accessing these data are described at the back of the journal. References Avasthi, K., Chandra, T. & Bhakuni, D. S. (1995). Indian J. Chem. Ser. B, 34, 944±949. Avasthi, K., Rawat, D. S. & Bhakuni, D. S. (1998). Indian J. Chem. Ser. B, 37, 1228±1233. Avasthi, K., Rawat, D. S., Chandra, T. & Bhakuni, D. S. (1998). Indian J. Chem. Ser. B, 37, 754±759. Biswas, G., Chandra, T., Avasthi, K. & Maulik, P. R. (1995). Acta Cryst. C51, 2453±2455. Brown, D. T., Fisinger, J. & Leonard, N. J. (1968). J. Am. Chem. Soc. 90, 7300± Gabe, E. J., Le Page, Y., Charland, J.-P., Lee, F. L. & White, P. S. (1989). J. Appl. Cryst. 22, 384±387. Hobza, P. & Sponer, J. (1999). Chem. Rev. 99, 3247±3276. Johnson, C. K. (1965). ORTEP. Report ORNL Oak Ridge National Laboratory, Tennessee, USA. Karcher, B. (1981). PhD thesis, Iowa State University, USA, pp. 64±90. Maulik, P. R., Avasthi, K., Biswas, G., Biswas, S., Rawat, D. S., Sarkhel, S., Chandra, T. & Bhakuni, D. S. (1998). Acta Cryst. C54, 275±277. Sheldrick, G. M. (1990). Acta Cryst. A46, 467±473. Sheldrick, G. M. (1993). SHELXL93. University of GoÈttingen, Germany. Sheldrick, G. M. (1997). SHELXL97. University of GoÈttingen, Germany. Siemens (1992). XSCANS User's Manual. Version 2.0. Siemens Analytical X-ray Instruments Inc., Madison, Wisconsin, USA. Acta Cryst. (2000). C56, 1361±1363 Prakas R. Maulik et al. C 17 H 20 N 8 S 4 and C 18 H 22 N 8 O 2 S

4 supporting information [ Disappearance of intramolecular stacking due to one-atom movement or increment of a `propylene linker in pyrazolo[3,4-d]pyrimidine-based flexible models Prakas R. Maulik, Kamlakar Avasthi, Sanjay Sarkhel, Tilak Chandra, Diwan S. Rawat, Brad Logsdon and Robert A. Jacobson Computing details For both compounds, data collection: XSCANS (Siemens, 1992); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS86 (Sheldrick, 1990). Program(s) used to refine structure: SHELXL93 (Sheldrick, 1993) for (4); SHELXL97 (Sheldrick, 1997) for (5). For both compounds, molecular graphics: NRCVAX (Gabe et al., 1989). Software used to prepare material for publication: SHELXL93 for (4); SHELXL97 for (5). (4) 1-[4,6-dimethylthio-2H-pyrazolo[3,4-d]pyrimidin-2-yl]-4,6-dimethylthio-1H- pyrazolo[3,4-d]pyrimidine Crystal data C 17 H 20 N 8 S 4 M r = Monoclinic, P2 1 /n a = (2) Å b = (2) Å c = (5) Å β = (2) V = (8) Å 3 Z = 4 F(000) = 968 Data collection Siemens P4 diffractometer Radiation source: fine-focus sealed tube Graphite monochromator ω scan Absorption correction: ψ scan (local program; Karcher, 1981) T min = 0.749, T max = measured reflections Refinement Refinement on F 2 Least-squares matrix: full R[F 2 > 2σ(F 2 )] = wr(f 2 ) = D x = Mg m 3 Melting point: 180 K Mo Kα radiation, λ = Å Cell parameters from 42 reflections θ = µ = 0.47 mm 1 T = 293 K Rhombehedral, colourless mm 3697 independent reflections 2893 reflections with I > 2σ(I) R int = θ max = 25.0, θ min = 2.1 h = 0 9 k = 0 12 l = standard reflections every 97 reflections intensity decay: nil S = reflections 267 parameters 0 restraints sup-1

5 Primary atom site location: structure-invariant direct methods Secondary atom site location: difference Fourier map Hydrogen site location: inferred from neighbouring sites H-atom parameters constrained Calculated w = 1/[σ 2 (F o2 ) + (0.1195P) P] where P = (F o 2 + 2F c2 )/3 (Δ/σ) max < Δρ max = 0.50 e Å 3 Δρ min = 0.24 e Å 3 Extinction correction: SHELXL93 (Sheldrick, 1993), Fc * =kfc[ xfc 2 λ 3 /sin(2θ)] -1/4 Extinction coefficient: (12) 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 on F 2 for ALL reflections except for 13 with very negative F 2 or flagged by the user for potential systematic errors. Weighted R-factors wr and all goodnesses of fit S are based on F 2, conventional R-factors R are based on F, with F set to zero for negative F 2. The observed criterion of F 2 > σ(f 2 ) is used only for calculating _R_factor(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. All the H atoms were placed in geometrical idealized positions and allowed to ride on their parent atoms, to which each was bonded for the final cycles of refinement. Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 ) x y z U iso */U eq N (3) (2) (10) (6) N (3) (2) (9) (6) C (4) (3) (11) (7) H (4) (3) (11) 0.066* C3A (4) (3) (11) (6) C (4) (3) (11) (7) S (13) (8) (3) (3) CS (7) (4) (14) (13) HS4A (4) (12) (3) 0.137* HS4B (4) (2) (2) 0.137* HS4C (11) (3) (14) 0.137* N (4) (3) (9) (6) C (4) (3) (12) (7) S (15) (9) (3) (3) CS (6) (4) (2) (11) HS6A (13) (11) (11) 0.128* HS6B (4) (4) (5) 0.128* HS6C (3) (11) (7) 0.128* N (3) (2) (9) (6) C7A (4) (3) (11) (6) N (3) (2) (9) (6) N (4) (3) (9) (7) C (5) (3) (11) (8) H (5) (3) (11) 0.075* sup-2

6 C3 A (4) (3) (10) (6) C (4) (3) (10) (6) S (14) (8) (3) (3) CS (6) (3) (14) (10) HS4D (18) (12) (9) 0.118* HS4E (4) (3) (2) 0.118* HS4F (2) (12) (9) 0.118* N (3) (2) (8) (6) C (4) (3) (10) (6) S (11) (7) (3) (3) CS (5) (3) (13) (8) HS6D (4) (4) (4) 0.101* HS6E (11) (4) (10) 0.101* HS6F (2) (5) (6) 0.101* N (3) (2) (9) (6) C7 A (4) (3) (10) (6) C (4) (3) (11) (7) H8A (4) (3) (11) 0.073* H8B (4) (3) (11) 0.073* C (4) (3) (11) (7) H9A (4) (3) (11) 0.071* H9B (4) (3) (11) 0.071* C (4) (3) (12) (8) H10A (4) (3) (12) 0.072* H10B (4) (3) (12) 0.072* Atomic displacement parameters (Å 2 ) U 11 U 22 U 33 U 12 U 13 U 23 N (2) (12) (13) (11) (11) (10) N (15) (12) (13) (11) (11) (10) C (2) (14) (15) (13) (13) (12) C3A (2) (15) (14) (12) (12) (11) C (2) (2) (2) (13) (12) (12) S (6) (5) (5) (4) (4) (3) CS (4) (3) (2) (2) (2) (2) N (2) (14) (13) (12) (11) (11) C (2) (2) (2) (13) (13) (13) S (8) (6) (5) (5) (5) (4) CS (3) (2) (2) (2) (2) (2) N (15) (13) (13) (11) (11) (11) C7A (2) (15) (15) (12) (12) (12) N (2) (13) (12) (11) (11) (10) N (2) (14) (13) (13) (13) (11) C (2) (2) (14) (2) (14) (12) C3 A (2) (15) (13) (12) (12) (11) C (2) (15) (13) (12) (11) (11) S (8) (5) (4) (4) (4) (3) sup-3

7 CS (3) (2) (2) (2) (2) (2) N (14) (13) (12) (11) (10) (10) C (15) (2) (14) (12) (11) (11) S (5) (5) (4) (4) (3) (3) CS (2) (2) (2) (2) (2) (14) N (15) (13) (12) (11) (10) (9) C7 A (2) (14) (13) (12) (11) (11) C (2) (2) (2) (15) (14) (13) C (2) (14) (2) (14) (14) (12) C (2) (2) (2) (14) (14) (13) Geometric parameters (Å, º) N1 C7A (4) C3 C3 A (4) N1 N (3) C3 H N2 C (4) C3 A C (4) N2 C (4) C3 A C7 A (4) C3 C3A (4) C4 N (3) C3 H C4 S (3) C3A C7A (4) S4 CS (4) C3A C (4) CS4 HS4D 0.96 C4 N (4) CS4 HS4E 0.96 C4 S (3) CS4 HS4F 0.96 S4 CS (4) N5 C (4) CS4 HS4A 0.96 C6 N (4) CS4 HS4B 0.96 C6 S (3) CS4 HS4C 0.96 S6 CS (3) N5 C (4) CS6 HS6D 0.96 C6 N (4) CS6 HS6E 0.96 C6 S (3) CS6 HS6F 0.96 S6 CS (4) N7 C7 A (3) CS6 HS6A 0.96 C8 C (4) CS6 HS6B 0.96 C8 H8A 0.97 CS6 HS6C 0.96 C8 H8B 0.97 N7 C7A (4) C9 C (5) N1 C7 A (4) C9 H9A 0.97 N1 N (3) C9 H9B 0.97 N1 C (4) C10 H10A 0.97 N2 C (4) C10 H10B 0.97 C7A N1 N (2) C7 A C3 A C (3) C3 N2 N (2) N5 C4 C3 A (3) C3 N2 C (2) N5 C4 S (2) N1 N2 C (2) C3 A C4 S (2) N2 C3 C3A (3) C4 S4 CS (2) N2 C3 H (2) S4 CS4 HS4D (2) C3A C3 H (2) S4 CS4 HS4E (12) C3 C3A C7A (3) HS4D CS4 HS4E sup-4

8 C3 C3A C (3) S4 CS4 HS4F (13) C7A C3A C (3) HS4D CS4 HS4F N5 C4 C3A (3) HS4E CS4 HS4F N5 C4 S (2) C4 N5 C (2) C3A C4 S (2) N7 C6 N (3) C4 S4 CS (2) N7 C6 S (2) S4 CS4 HS4A (14) N5 C6 S (2) S4 CS4 HS4B (2) C6 S6 CS (2) HS4A CS4 HS4B S6 CS6 HS6D (11) S4 CS4 HS4C (2) S6 CS6 HS6E (12) HS4A CS4 HS4C HS6D CS6 HS6E HS4B CS4 HS4C S6 CS6 HS6F (12) C4 N5 C (3) HS6D CS6 HS6F N7 C6 N (3) HS6E CS6 HS6F N7 C6 S (2) C6 N7 C7 A (2) N5 C6 S (2) N7 C7 A N (3) C6 S6 CS (2) N7 C7 A C3 A (3) S6 CS6 HS6A (2) N1 C7 A C3 A (2) S6 CS6 HS6B (13) N2 C8 C (2) HS6A CS6 HS6B N2 C8 H8A (2) S6 CS6 HS6C (14) C9 C8 H8A (2) HS6A CS6 HS6C N2 C8 H8B (2) HS6B CS6 HS6C C9 C8 H8B (2) C6 N7 C7A (3) H8A C8 H8B N1 C7A N (3) C10 C9 C (3) N1 C7A C3A (2) C10 C9 H9A (2) N7 C7A C3A (3) C8 C9 H9A (2) C7 A N1 N (2) C10 C9 H9B (2) C7 A N1 C (2) C8 C9 H9B (2) N2 N1 C (2) H9A C9 H9B C3 N2 N (2) N1 C10 C (3) N2 C3 C3 A (3) N1 C10 H10A (2) N2 C3 H (2) C9 C10 H10A (2) C3 A C3 H (2) N1 C10 H10B (2) C4 C3 A C7 A (3) C9 C10 H10B (2) C4 C3 A C (3) H10A C10 H10B C7A N1 N2 C3 0.7 (3) N2 C3 C3 A C7 A 0.1 (4) C7A N1 N2 C (2) C7 A C3 A C4 N5 0.2 (4) N1 N2 C3 C3A 0.4 (3) C3 C3 A C4 N (4) C8 N2 C3 C3A (3) C7 A C3 A C4 S (2) N2 C3 C3A C7A 0.1 (3) C3 C3 A C4 S4 1.3 (6) N2 C3 C3A C (3) N5 C4 S4 CS4 5.0 (3) C3 C3A C4 N (3) C3 A C4 S4 CS (3) C7A C3A C4 N5 0.3 (4) C3 A C4 N5 C6 1.0 (4) C3 C3A C4 S4 0.8 (5) S4 C4 N5 C (2) C7A C3A C4 S (2) C4 N5 C6 N7 1.8 (4) N5 C4 S4 CS4 8.3 (3) C4 N5 C6 S (2) sup-5

9 C3A C4 S4 CS (3) N7 C6 S6 CS (2) C3A C4 N5 C6 0.1 (4) N5 C6 S6 CS6 4.4 (3) S4 C4 N5 C (2) N5 C6 N7 C7 A 1.0 (4) C4 N5 C6 N7 0.8 (5) S6 C6 N7 C7 A (2) C4 N5 C6 S (2) C6 N7 C7 A N (3) N7 C6 S6 CS6 6.5 (3) C6 N7 C7 A C3 A 0.5 (4) N5 C6 S6 CS (2) N2 N1 C7 A N (3) N5 C6 N7 C7A 0.9 (5) C10 N1 C7 A N7 7.9 (5) S6 C6 N7 C7A (2) N2 N1 C7 A C3 A 0.8 (3) N2 N1 C7A N (3) C10 N1 C7 A C3 A (3) N2 N1 C7A C3A 0.7 (3) C4 C3 A C7 A N7 1.0 (5) C6 N7 C7A N (3) C3 C3 A C7 A N (3) C6 N7 C7A C3A 0.3 (4) C4 C3 A C7 A N (3) C3 C3A C7A N1 0.5 (3) C3 C3 A C7 A N1 0.5 (3) C4 C3A C7A N (3) C3 N2 C8 C (3) C3 C3A C7A N (3) N1 N2 C8 C (4) C4 C3A C7A N7 0.2 (4) N2 C8 C9 C (3) C7 A N1 N2 C3 0.7 (4) C7 A N1 C10 C (4) C10 N1 N2 C (3) N2 N1 C10 C (4) N1 N2 C3 C3 A 0.4 (4) C8 C9 C10 N (3) N2 C3 C3 A C (4) (5) 1-[4-(4-methoxy-6-methylthio-1H-pyrazolo[3,4-d]pyrimidin-1-yl)butyl]- 5-methyl-6-methylthio-4,5- dihydro-1h-pyrazolo[3,4-d]pyrimidin-4-one Crystal data C 18 H 22 N 8 O 2 S 2 M r = Monoclinic, C2/c a = (7) Å b = (2) Å c = (4) Å β = (2) V = (17) Å 3 Z = 8 F(000) = 1872 Data collection Siemens P4 diffractometer Radiation source: fine-focus sealed tube Graphite monochromator ω scan Absorption correction: ψ scan (local program; Karcher, 1981) T min = 0.772, T max = measured reflections D x = Mg m 3 Melting point: 150 K Mo Kα radiation, λ = Å Cell parameters from 39 reflections θ = µ = 0.29 mm 1 T = 293 K Trapezoidal, colourless mm 3616 independent reflections 3189 reflections with I > 2σ(I) R int = θ max = 25.0, θ min = 2.4 h = 0 37 k = 0 9 l = standard reflections every 97 reflections intensity decay: nil sup-6

10 Refinement Refinement on F 2 Least-squares matrix: full R[F 2 > 2σ(F 2 )] = wr(f 2 ) = S = reflections 276 parameters 0 restraints Primary atom site location: structure-invariant direct methods Secondary atom site location: difference Fourier map Hydrogen site location: inferred from neighbouring sites H-atom parameters constrained w = 1/[σ 2 (F o2 ) + (0.0685P) P] where P = (F o 2 + 2F c2 )/3 (Δ/σ) max < Δρ max = 0.28 e Å 3 Δρ min = 0.22 e Å 3 Extinction correction: SHELXL97 (Sheldrick, 1997), Fc * =kfc[ xfc 2 λ 3 /sin(2θ)] -1/4 Extinction coefficient: (5) 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 F 2 against ALL reflections. The weighted R-factor wr and goodness of fit S are based on F 2, conventional R-factors R are based on F, with F set to zero for negative F 2. The threshold expression of F 2 > σ(f 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 ) x y z U iso */U eq N (6) (18) (10) (4) N (6) (2) (11) (4) C (8) (3) (14) (5) H * C3A (6) (2) (12) (4) C (6) (2) (12) (4) O (5) (15) (10) (4) CO (8) (3) (15) (6) HO4A * HO4B * HO4C * N (5) (17) (10) (4) C (6) (2) (11) (4) S (2) (6) (4) (2) CS (9) (3) (16) (7) HS6A * HS6B * HS6C * N (5) (18) (10) (4) C7A (6) (2) (11) (4) N (5) (19) (9) (4) N (6) (2) (10) (4) C (7) (3) (12) (5) sup-7

11 H * C3 A (6) (2) (11) (4) C (7) (2) (12) (5) O (6) (18) (11) (5) N (5) (18) (9) (4) C (9) (3) (15) (6) H * H * H * C (6) (2) (10) (4) S (17) (6) (3) (19) CS (8) (3) (14) (5) HS6D * HS6E * HS6F * N (5) (18) (9) (3) C7 A (6) (2) (10) (4) C (7) (2) (13) (5) H8A * H8B * C (7) (2) (12) (5) H9A * H9B * C (6) (2) (11) (4) H10A * H10B * C (6) (2) (12) (4) H11A * H11B * Atomic displacement parameters (Å 2 ) U 11 U 22 U 33 U 12 U 13 U 23 N (9) (9) (9) (7) (7) (7) N (11) (11) (10) (8) (9) (8) C (13) (12) (12) (9) (11) (9) C3A (9) (10) (10) (7) (8) (8) C (9) (10) (10) (7) (8) (7) O (9) (7) (10) (6) (8) (6) CO (15) (11) (14) (10) (12) (10) N (8) (8) (9) (6) (7) (6) C (9) (10) (10) (7) (8) (7) S (4) (3) (4) (2) (3) (2) CS (18) (15) (14) (13) (14) (12) N (9) (8) (9) (6) (7) (6) C7A (9) (10) (9) (7) (7) (7) N (9) (9) (8) (7) (7) (7) N (10) (11) (9) (8) (8) (8) sup-8

12 C (12) (13) (10) (10) (9) (9) C3 A (10) (10) (9) (8) (8) (8) C (11) (11) (10) (8) (9) (8) O (12) (8) (11) (8) (10) (7) N (9) (8) (8) (6) (7) (6) C (15) (12) (14) (10) (12) (10) C (9) (9) (8) (7) (7) (7) S (3) (3) (3) (2) (2) (19) CS (13) (11) (12) (9) (10) (9) N (8) (8) (7) (6) (6) (6) C7 A (9) (10) (8) (7) (7) (7) C (11) (11) (11) (9) (9) (9) C (11) (10) (11) (8) (9) (8) C (11) (10) (10) (8) (9) (8) C (10) (11) (10) (8) (9) (8) Geometric parameters (Å, º) N1 C7A (2) N1 C (2) N1 N (2) N2 C (3) N1 C (2) C3 C3 A (3) N2 C (3) C3 A C7 A (3) C3 C3A (3) C3 A C (3) C3A C7A (3) C4 O (3) C3A C (3) C4 N (2) C4 N (2) N5 C (2) C4 O (2) N5 C (3) O4 CO (2) C6 N (2) N5 C (2) C6 S (17) C6 N (2) S6 CS (2) C6 S (18) N7 C7 A (2) S6 CS (2) C8 C (3) N7 C7A (2) C9 C (2) N1 C7 A (2) C10 C (3) N1 N (2) C7A N1 N (14) C3 N2 N (15) C7A N1 C (16) N2 C3 C3 A (17) N2 N1 C (16) C7 A C3 A C (18) C3 N2 N (16) C7 A C3 A C (16) N2 C3 C3A (18) C3 C3 A C (18) C7A C3A C (16) O4 C4 C3 A (19) C7A C3A C (17) O4 C4 N (19) C4 C3A C (18) C3 A C4 N (16) N5 C4 O (16) C6 N5 C (16) N5 C4 C3A (16) C6 N5 C (16) O4 C4 C3A (16) C4 N5 C (16) C4 O4 CO (15) N7 C6 N (15) sup-9

13 C4 N5 C (16) N7 C6 S (13) N7 C6 N (16) N5 C6 S (13) N7 C6 S (13) C6 S6 CS (9) N5 C6 S (13) C6 N7 C7 A (15) C6 S6 CS (10) N1 C7 A N (16) C6 N7 C7A (15) N1 C7 A C3 A (15) N7 C7A N (16) N7 C7 A C3 A (17) N7 C7A C3A (17) N1 C8 C (16) N1 C7A C3A (15) C8 C9 C (16) C7 A N1 N (15) C11 C10 C (15) C7 A N1 C (14) N1 C11 C (15) N2 N1 C (15) C7A N1 N2 C3 0.6 (2) C7 A C3 A C4 O (2) C8 N1 N2 C (18) C3 C3 A C4 O4 1.7 (4) N1 N2 C3 C3A 0.2 (2) C7 A C3 A C4 N5 1.6 (2) N2 C3 C3A C7A 0.8 (2) C3 C3 A C4 N (2) N2 C3 C3A C (2) O4 C4 N5 C (18) C7A C3A C4 N5 2.9 (2) C3 A C4 N5 C6 1.0 (2) C3 C3A C4 N (2) O4 C4 N5 C5 2.8 (3) C7A C3A C4 O (16) C3 A C4 N5 C (16) C3 C3A C4 O4 0.3 (4) C4 N5 C6 N7 3.0 (3) N5 C4 O4 CO4 3.4 (3) C5 N5 C6 N (17) C3A C4 O4 CO (17) C4 N5 C6 S (13) O4 C4 N5 C (15) C5 N5 C6 S6 5.8 (2) C3A C4 N5 C6 0.7 (2) N7 C6 S6 CS (16) C4 N5 C6 N7 2.1 (3) N5 C6 S6 CS (14) C4 N5 C6 S (12) N5 C6 N7 C7 A 1.9 (2) N7 C6 S6 CS (14) S6 C6 N7 C7 A (11) N5 C6 S6 CS (17) N2 N1 C7 A N (15) N5 C6 N7 C7A 2.2 (3) C11 N1 C7 A N7 0.5 (3) S6 C6 N7 C7A (12) N2 N1 C7 A C3 A 0.9 (2) C6 N7 C7A N (16) C11 N1 C7 A C3 A (16) C6 N7 C7A C3A 0.5 (3) C6 N7 C7 A N (15) N2 N1 C7A N (16) C6 N7 C7 A C3 A 1.0 (3) C8 N1 C7A N7 0.5 (3) C3 C3 A C7 A N1 0.7 (2) N2 N1 C7A C3A 1.1 (2) C4 C3 A C7 A N (15) C8 N1 C7A C3A (17) C3 C3 A C7 A N (17) C4 C3A C7A N7 2.9 (3) C4 C3 A C7 A N7 2.8 (3) C3 C3A C7A N (17) C7A N1 C8 C (2) C4 C3A C7A N (14) N2 N1 C8 C (2) C3 C3A C7A N1 1.2 (2) N1 C8 C9 C (2) C7 A N1 N2 C3 0.7 (2) C8 C9 C10 C (16) C11 N1 N2 C (16) C7 A N1 C11 C (2) N1 N2 C3 C3 A 0.2 (2) N2 N1 C11 C (2) N2 C3 C3 A C7 A 0.3 (2) C9 C10 C11 N (2) N2 C3 C3 A C (2) sup-10