Supporting Information Selective Synthesis of [6]-, [8]-, and [10]Cycloparaphenylenes Eiichi Kayahara, 1,2 Takahiro Iwamoto, 1 Toshiyasu Suzuki, 2,3 and Shigeru Yamago* 1,2 1 Institute for Chemical Research, Kyoto University, Kyoto 611-0011 2 CREST, Japan Science and Technology Agency, Tokyo 102-0076 3 Institute for Molecular Science, Myodaiji, Okazaki, Aichi 444-8787 (Received March 5, 2013; CL-130188; E-mail: yamago@scl.kyoto-u.ac.jp) Copyright The Chemical Society of Japan
Supporting Information General. All reactions dealing with air- and moisture sensitive compounds were carried out in a dry reaction vessel under nitrogen atmosphere. Water content in solvents was determined by Karl-Fisher water titrator. 1 H (400 MHz) and 13 C NMR (100 MHz) spectra were measured for a CDCl 3 solution of a sample and are reported in parts per million ( ) from internal tetramethylsilane or residual solvent peak. 31 P NMR (162 MHz) spectrum was measured for a CDCl 3 solution of a sample and chemical shifts are given relative to 85% H 3 PO 4, which is used as an external standard. IR spectrum (absorption) was reported in cm -1. Electro spray ionization time-of-flight mass (ESI-TOF MS) spectrum was recorded on a spectrometer in the positive mode. A sample was injected as a CH 2 Cl 2 /isopropanol solution. Matrix-assisted laser-desorption ionization time-of-flight mass (MALDI-TOF MS) spectrum was obtained on a spectrometer in the positive reflection mode and at 20 kv acceleration voltage. Samples were prepared from a tetrahydrofuran (THF) solution by mixing a sample (1 mg/ml) and dithranol (1 mg/ml) in a 1:1 ratio. UV-vis and emission spectra were measured in CHCl 3 at room temperature. Cyclic voltammetry (CV) and differential pulse voltammogram (DPV) were measured with a Pt electrode for 1,1,2,2-tetrachloroethane solution of a sample (1 mm) in the presence of an supporting electrolyte (Bu 4 NPF 6, 0.10 M) at room temperature under nitrogen atmosphere. The scan rates of 100 and 20 mv s 1 were employed for CV and DPV, respectively. After the measurement, ferrocene was added to the sample solution, and the potentials were calibrated with respect to the ferrocene/ferrocenium couple (Fc/Fc + ). Materials. Unless otherwise noted, commercially available materials were used without purification. Dichloromethane (CH 2 Cl 2 ) was distilled successively from P 2 O 5 and K 2 CO 3 and stored over molecular sieves. Toluene, 1,5-cyclooctadiene (cod), and acryronitrile were distilled from CaH 2 and stored over molecular sieves. Triphenylphosphine (PPh 3 ) was recrystallized from hot ethanol. Dichloro(1,5- cyclooctadiene)platinum; Pt(cod)Cl 2, 1 1,1 -bis(diphenylphosphino)ferrocene (dppf), 2 S1 --
bis(1,5-cyclo-octadiene)nickel [Ni(cod) 2 ], 3 4,4 -bis(trimethylstannyl)-p-biphenyl 4b, 4 4,4 -bis(trimethylstannyl)-p-terphenyl 4c, 4 dichlorobis(1,5-cyclooctadiene)-p-biphenylenediplatinum 5b, 4 dichlorobis(1,5- cyclooctadiene)-p-terphenylenediplatinum 5c, 4 5 and P[OCH(CF 3 ) 2 ] 3 were synthesized as reported. Synthesis of 1,4-bis(trimethylstannyl)benzene (4a). To a suspension of Mg (0.61 g, 25 mmol) and a small crystal of I 2 in dry THF (200 ml) was added a solution of 1,4-dibromobenzene 3a (2.36 g, 10 mmol) in THF (50 ml) over 0.5 h at rt. The resulting mixture was refluxed for 24 h under nitrogen atmosphere. After cooling to rt, a solution of trimethylstannyl chloride (1.99 g, 22 mmol) in THF (20 ml) was slowly added through a cannula at -78 o C, and the resulting mixture was slowly warmed to rt. After stirring for 6 h at same temperature, the reaction mixture was quenched with saturated aqueous NH 4 Cl solution, and extracted with ethyl acetate. The combined organic layers were washed with brine, dried over Na 2 SO 4, filtered and concentrated under reduced pressure. The crude product was purified by passing it over neutral alumina with hexane as the eluent, to give the title compound (3.79 g, 94%) as a white solid. 1 H NMR (CDCl 3, 400 MHz) 0.56 (s, 18H, SnMe 3 ), 7.50 (s, 4H, Ar-H); 13 C NMR (CDCl 3, 100 MHz,) -9.52 (CH 3 ), 135.93 (C), 142.60 (CH). The NMR spectra were consistent with literature data. 6,7 Synthesis of dichloro[1,1 -bis(diphenylphosphino)ferrocene]1,4-phenylenediplatinum (6a). Pt(cod)Cl 2 (0.82 g, 2.20 mmol) and 4a (0.45 g, 1.10 mmol) were dissolved in THF (110 ml), and the mixture was heated at 60 C for 8 h under nitrogen atmosphere. The solvent was removed under reduced pressure, and the residue was washed with toluene to give crude 5a (0.75 g, 92%) as a white solid. A suspension of the crude product (0.75 g, 1.0 mmol) and dppf (1.11 g, 2.0 mmol) in CH 2 Cl 2 (100 ml) was stirred at rt for 8 h under nitrogen atmosphere. The solvent was removed under reduced pressure, and the residue was washed with ethyl acetate to give the title compound (1.49 g, 91%) as an orange solid. 1 H NMR (CDCl 3, 400 MHz) 3.74 (s, 4H, Cp-H), 4.07 (s, 4H, Cp-H), 4.36 (s, 4H, Cp-H), 4.52 (s, 4H, Cp-H), 6.26 (m, 4H, PtAr-H), 7.30 7.54 (m, 40H, PAr 2 -H); 31 P NMR (CDCl 3, 162 MHz) 13.20 (d, 4P, J PP = 21.02 Hz, J PPt = 1776 Hz), 15.18 (d, 4P, J PP = 21.02 Hz, J PPt = 4028 Hz); HRMS (ESI-TOF) m/z: Calcd for C 74 H 64 Cl 2 Fe 2 N 1 P 4 Pt 2 (M-NH 4 ) +, 1663.1360, found 1663.2030; IR (KBr) 470, 701, 745, 826, 1435, 1480, 1622, 1663, 2911, 3021. Synthesis of [1,1 -bis(diphenylphosphino)ferrocene]4,4 -biphenylenechloroplatinum (6b). A suspension of 5b (0.83 g, 1.0 mmol) and dppf (1.11 g, 2.0 mmol) in CH 2 Cl 2 (50 ml) was stirred at room temperature for 8 h under nitrogen atmosphere. The solvent was removed under reduced pressure, and the residue was washed with ethyl acetate to give the title compound (1.50 g, 87%) as an orange solid. 1 H NMR (CDCl 3, 400 MHz) 3.63 (s, 4H, Cp-H), 4.10 (s, 4H, Cp-H), 4.45 (s, 4H, Cp-H), 4.72 (s, 4H, Cp-H), 6.58 (m, 4H, PtAr-H), 6.87 (m, 4H, PtAr-H), 7.08-7.20 (m, 16H, PAr 2 -H), 7.30-7.54 (m, 24H, PAr 2 -H); 31 P NMR (CDCl 3, 162 MHz) 13.18 (d, 4P, J PP = 20.08 Hz, J PPt = 1788 Hz), 15.08 (d, 4P, J PP = 20.08 Hz, J PPt = 4110 Hz). HRMS (ESI-TOF) m/z: Calcd for S2 --
C 80 H 68 Cl 2 Fe 2 N 1 P 4 Pt 2 (M-NH 4 ) +, 1740.1677; Found 1740.1344; IR (KBr) 485, 710, 743, 810, 846, 1433, 1485, 1615, 1664, 3006. Synthesis of [1,1 -bis(diphenylphosphino)ferrocene]4,4 -terphenylenechloroplatinum (6c). A suspension of 5c (0.91 g, 1.0 mmol) and dppf (1.11 mg, 2.0 mmol) in CH 2 Cl 2 (50 ml) was stirred at room temperature for 8 h under a nitrogen atmosphere. The solvent was removed under reduced pressure, and the residue was washed with ethyl acetate to give the title compound (1.65 g, 92%) as an orange solid. 1 H NMR (CDCl 3, 400 MHz) 3.61 (s, 4H, Cp-H), 4.13 (s, 4H, Cp-H), 4.48 (s, 4H, Cp-H), 4.76 (s, 4H, Cp-H), 6.82 (d, J = 8.4 Hz, 4H, PtAr-H), 6.92-7.14 (m, 16H, PtAr-H and PAr 2 -H), 7.32-7.56 (m, 32H, PAr 2 -H); 31 P NMR (CDCl 3, 162 MHz) 13.04 (d, 4P, J PP = 20.02 Hz, J PPt = 1796 Hz), 15.08 (d, 4P, J PP = 20.04 Hz, J PPt = 4134 Hz). HRMS (ESI-TOF) m/z: Calcd for C 86 H 72 Cl 2 Fe 2 N 1 P 4 Pt 2 (M-NH 4 ) +, 1816.1992; Found 1816.2092; IR (KBr) 465, 712, 748, 805, 1428, 1462, 1492, 1659, 2951, 3022. Synthesis of bis[1,1 -bis(diphenylphosphino)ferrocene]bis(p-bromophenyl)-1,4-phenylene diplatinum (1a). To a solution of 1,4-dibromobenzene (0.58 g, 2.50 mmol) in THF (3.0 ml) was slowly added BuLi (1.60 ml, 1.56 M in hexane, 2.50 mmol) at -78 C using a syringe. After stirring for 1 h at the same temperature, the resulting solution was added to a solution of 6a (0.82 g, 0.50 mmol) in THF (50 ml) through a cannula at -78 C. After stirring for 1 h at the same temperature, the resulting mixture was slowly warmed to rt and stirred at same temperature for 12 h. The reaction mixture was quenched with saturated aqueous NH 4 Cl solution, and extracted with CH 2 Cl 2. The combined organic layers were washed with brine, dried over Na 2 SO 4, filtered, and concentrated under reduced pressure. The crude product was washed with ether/ch 2 Cl 2 to give the title compound (0.42 g, 45%) as an orange solid. 1 H NMR (CDCl 3, 400 MHz) 4.19 (s, 8H, Cp-H), 4.37 (s, 8H, Cp-H), 6.31 6.40 (m, 8H, PtAr-H), 6.40 6.64 (m, 4H, PtAr-H), 7.30 7.58 (m, 40H, PAr 2 -H); 31 P NMR (CDCl 3, 162 MHz) 15.11 (s, 4P, J PPt = 1778 Hz), 15.42 (s, 4P, J PPt = 1810 Hz); HRMS (ESI-TOF) m/z: Calcd for C 86 H 72 Br 2 Fe 2 N 1 P 4 Pt 2 (M-NH 4 ) +, 1905.0974, Found 1905.1120; IR (KBr) 462, 582, 705, 754, 820, 1468, 1485, 1640, 2982, 3088. Synthesis of bis[1,1 -bis(diphenylphosphino)ferrocene]p-bromophenyl-4,4 -biphenylene diplatinum (1b). To a solution of 1,4-dibromobenzene (0.21 g, 0.90 mmol) in THF (1.8 ml) was slowly added BuLi (0.58 ml, 1.56 M in hexane, 0.90 mmol) by using a syringe at 78 ºC. After stirring for 1 h at this temperature, the resulting solution was added to a solution of 6b (0.52 g, 0.30 mmol) in THF (30 ml) through a cannula at -78 o C. After stirring for 1 h at this temperature, the resulting mixture was slowly warmed to room temperature and was stirred at room temperature for 12 h. The reaction mixture was quenched with saturated aqueous NH 4 Cl solution, and was extracted with CH 2 Cl 2. The combined organic layer was washed with brine, dried over Na 2 SO 4, filtered and concentrated under reduced pressure to give a crude mixture. The residue was washed with ether to give the title compound (0.42 g, 71%) as an orange solid. 1 H NMR (CDCl 3, 400 MHz) 4.30 (s, 8H, S3 --
Cp-H), 4.43 (s, 8H, Cp-H), 6.25-6.39 (m, 12H, PtAr-H), 6.52-6.72 (m, 4H, PtAr-H), 7.36-7.57 (m, 40H, PAr 2 -H); 31 P NMR (CDCl 3, 162 MHz) 15.20 (s, 4P, J PPt = 1796 Hz), 15.48 (s, 4P, J PPt = 1814 Hz); HRMS (ESI-TOF) m/z: Calcd for C 92 H 76 Br 2 Fe 2 N 1 P 4 Pt 2 (M-NH 4 ) +, 1981.1289; Found 1981.1201; IR (KBr) 458, 575, 709, 762, 820, 1499, 1620, 1638, 2985, 3058. Synthesis of bis[1,1 -bis(diphenylphosphino)ferrocene]p-bromophenyl-4,4 -terphenylene diplatinum (1c). To a solution of 1,4-dibromobenzene (0.21 g, 0.90 mmol) in THF (1.8 ml) was slowly added BuLi (0.60 ml, 1.51 M in hexane, 0.90 mmol) by using a syringe at 78 ºC. After stirring for 1 h at this temperature, the resulting solution was added to a solution of 6c (0.54 g, 0.30 mmol) in THF (30 ml) through a cannula at -78 o C. After stirring for 1 h at this temperature, the resulting mixture was slowly warmed to room temperature and was stirred at room temperature for 12 h. The reaction mixture was quenched with saturated aqueous NH 4 Cl solution, and was extracted with CH 2 Cl 2. The combined organic layer was washed with brine, dried over Na 2 SO 4, filtered and concentrated under reduced pressure to give a crude mixture. The residue was washed with ether to give the title compound (0.45 g, 74%) as an orange solid. 1 H NMR (CDCl 3, 400 MHz) 4.20 (s, 8H, Cp-H), 4.31 (s, 8H, Cp-H), 6.56 (d, 4H, J = 8 Hz, PtAr-H), 6.70 (d, 4H, J = 8.4 Hz, PtAr-H), 6.77 (m, 4H, PtAr-H), 6.86 (m, 4H, PtAr-H), 7.27-7.60 (m, 40H, PAr 2 -H); 31 P NMR (CDCl 3, 162 MHz) 15.24 (s, 4P, J PPt = 1790 Hz), 15.80 (s, 4P, J PPt = 1830 Hz); HRMS (ESI-TOF) m/z: Calcd for C 98 H 80 Br 2 Fe 2 N 1 P 4 Pt 2 (M-NH 4 ) +, 2057.1604; Found 2057.2891; IR (KBr) 460, 572, 720, 771, 813, 1468, 1495, 1640, 3001, 3062. Synthesis of tetra[1,1 -bis(diphenylphosphino)ferrocene]-bis(1,4-phenylene)-bis (4,4 -biphenylene) tetraplatinum (2a). Ni(cod) 2 (0.11 g, 0.40 mmol) and dppf (0.22 mg, 0.40 mmol) were dissolved in THF (10 ml), and the mixture was stirred at rt for 0.5 h under a nitrogen atmosphere. The resulting mixture was added to a suspension of 1a (0.38 g, 0.20 mmol) in THF (100 ml), and the resulting mixture was heated to 50 C for 20 h. The reaction mixture was quenched with saturated aqueous NH 4 Cl solution, and extracted with CH 2 Cl 2. The combined organic layers were washed with brine, dried over Na 2 SO 4, filtered and concentrated under reduced pressure. The crude product was washed with ether to give the title compound (0.22 g, 63%) as an orange solid. 1 H NMR (CDCl 3, 400 MHz) 4.26 (s, 16H, Cp-H), 4.74 (s, 16H, Cp-H), 6.46 (m, 8H, J = 8 Hz, PtAr-H), 6.60 (m, 8H, PtAr-H), 6.86 (m, 8H, PtAr-H), 7.30 7.76 (m, 80H, PAr 2 -H); 31 P NMR (CDCl 3, 162 MHz) 15.38 (s, 4P, J PPt = 1780 Hz), 15.60 (s, 4P, J PPt = 1784 Hz); IR (KBr) 470, 562, 675, 742, 808, 1423, 1476, 1648, 3004, 3040. Synthesis of tetra[1,1 -bis(diphenylphosphino)ferrocene]-tetra(4,4 -bi-phenylene) tetraplatinum (2b). Ni(cod) 2 (55.0 mg, 0.20 mmol) and dppf (110.9 mg, 0.20 mmol) were dissolved in THF (5 ml), and the mixture was stirred at room temperature for 0.5 h under a nitrogen atmosphere. The resulting mixture was added to a suspension of 1b (196.3 mg, 0.10 mmol) in THF (50 ml), and the resulting mixture was heated at 50 o C for 20 h. The reaction mixture was quenched S4 --
with saturated aqueous NH 4 Cl solution, and was extracted with CH 2 Cl 2. The combined organic layer was washed with brine, dried over Na 2 SO 4, filtered and concentrated under reduced pressure to give a crude mixture. The residue was washed with CH 2 Cl 2 /ether to give the title compound (55.8 mg, 31%) as an orange solid. 1 H NMR (CDCl 3, 400 MHz) 4.18 (s, 16H, Cp-H), 4.26 (s, 16H, Cp-H), 6.33-6.52 (m, 16H, PtAr-H), 6.54-6.92 (m, 16H, PtAr-H), 7.05-7.20 (m, 32H, PAr 2 -H), 7.31-7.56 (m, 48H, PAr 2 -H); 31 P NMR (CDCl 3, 162 MHz) 15.48 (s, 4P, J PPt = 1778 Hz); IR (KBr) 472, 570, 637, 745, 806, 1433, 1474, 1640, 2998, 3050. Synthesis of tetra[1,1 -bis(diphenylphosphino)ferrocene]-bis(1,4-phenylene)-bis(4,4 -biphenylene)tetraplatinum (2c). Ni(cod) 2 (55.0 mg, 0.20 mmol) and dppf (110.9 mg, 0.20 mmol) were dissolved in THF (5 ml), and the mixture was stirred at room temperature for 0.5 h under a nitrogen atmosphere. The resulting mixture was added to a suspension of 1b (203.9 mg, 0.10 mmol) in THF (50 ml), and the resulting mixture was heated at 50 o C for 20 h. The reaction mixture was quenched with saturated aqueous NH 4 Cl solution, and was extracted with CH 2 Cl 2. The combined organic layer was washed with brine, dried over Na 2 SO 4, filtered and concentrated under reduced pressure to give a crude mixture. The residue was washed with CH 2 Cl 2 /ether to give the title compound (37.6 mg, 20%) as an orange solid. 1 H NMR (CDCl 3, 400 MHz) 4.22 (s, 16H, Cp-H), 4.76 (s, 16H, Cp-H), 6.38-6.48 (m, 8H, PtAr-H), 6.50-6.81 (m, 16H, PtAr-H), 6.82-6.94 (m, 16H, PtAr-H), 7.06-7.24 (m, 32H, PAr 2 -H), 7.35-7.46 (m, 48H, PAr 2 -H); 31 P NMR (CDCl 3, 162 MHz) 15.40 (s, 4P, J PPt = 1780 Hz), 15.82 (s, 4P, J PPt = 1786 Hz); IR (KBr) 468, 565, 639, 762, 811, 1412, 1477, 1631, 3005, 3056. Synthesis of [6]CPP. A suspension of 2a (0.21 g, 0.06 mmol) and XeF 2 (40.6 mg, 0.24 mmol) in toluene (60 ml) was heated at 90 C for 12 h under nitrogen atmosphere. The resulting suspension was filtered, and the filtrate was concentrated under reduced pressure to give a crude mixture. The residue was purified by silica gel chromatography (hexane/ch 2 Cl 2 = 1:1), and subsequent preparative gel permeation chromatography using chloroform as the eluent giving [6]CPP (11.0 mg, 40%) as an orange solid. 1 H NMR (CDCl 3, 400 MHz) 7.63 (s, 24H, Ar-H); 13 C NMR (CDCl 3, 100 MHz) 127.03 (CH), 134.90 (4 o ); HRMS (MALDI-TOF) m/z: calcd for C 36 H 24 [M] + : 456.1873, found 456.1908. Synthesis of [8]CPP. The suspension of 2b (36.1 mg, 0.01 mmol) and Br 2 (2.1 L, 0.04 mmol) in toluene (10 ml) was heated at 90 o C for 12 h under a nitrogen atmosphere. The resulting suspension was filtered off, and the filtrate was concentrated under reduced pressure to give a crude mixture. The residue was purified by silica gel chromatography hexane/ch 2 Cl 2 = 1/1) to give [8]CPP (4.5 mg, 74%) as a yellow solid. 1 H NMR (CDCl 3, 400 MHz) 7.49 (s, 32H, Ar-H); 13 C NMR (CDCl 3, 100 MHz) 127.61 (CH), 137.81 (4 o ); HRMS (MALDI-TOF) m/z calcd for C 48 H 32 [M] + : 609.2499, found 609.2515. The NMR and MS spectra were consistent with our previous literature data. 8 S5 --
Synthesis of [10]CPP. The suspension of 2c (37.6 mg, 0.01 mmol) and Br 2 (2.1 L, 0.04 mmol) in toluene (10 ml) was heated at 90 o C for 12 h under a nitrogen atmosphere. The resulting suspension was filtered off, and the filtrate was concentrated under reduced pressure to give a crude mixture. The residue was purified by silica gel chromatography hexane/ch 2 Cl 2 = 1/1), and subsequent preparative gel permeation chromatography with chloroform as an eluent to give [10]CPP (5.7 mg, 75%) as a pale yellow solid. 1 H NMR (CDCl 3, 400 MHz) 7.56 (s, 40H, Ar-H); 13 C NMR (CDCl 3, 100 MHz) 127.51 (CH), 138.29 (4 o ); HRMS (MALDI-TOF) m/z calcd for C 60 H 40 [M] + : 760.3125, found 760.3077. The NMR and MS spectra were consistent with our previous literature data. 4 References (1) Hill, G. S.; Irwin, M. J.; Levy, C. J.; Rendina, L. M.; Puddephatt, R. J.; Andersen, R. A.; McLean, L. Inorg. Synth. 2007, 32, 149. (2) Cullen, W. R.; Kim, T. J.; Einstein, F. W. B.; Jones, T. Organometallics 1983, 2, 714. (3) Krysan, D. J.; Mackenzie, P. B. J. Org. Chem. 1990, 55, 4229. (4) Iwamoto, T.; Watanabe, Y.; Sakamoto, Y.; Suzuki, T.; Yamago, S. J. Am. Chem. Soc. 2011, 133, 8354. (5) van Leeuwen, P. W. N. M.; Roobeek, C. F. Tetrahedron 1981, 37, 1973. (6) Kaim, W.; Tesmann, H.; Bock, H. Chem. Ber. 1980, 113, 3221. (7) Cheng, Z.-L.; Skouta, R.; Vazquez, H.; Widawsky, J. R.; Schneebeli, S.; Chen, W.; Hybertsen, M. S.; Breslow, R.; Venkataraman, L. Nat. Nanotechnol. 2011, 6, 353. (8) Yamago, S.; Watanabe, Y.; Iwamoto, T. Angew. Chem. Int. Ed. 2010, 49, 757. S6 --
Figure S1. UV-vis spectrum of [6]CPP in CHCl 3. (a) (b) (c) Figure S2. a) CV and (b) DPV of [6]CPP. (c) Correlation between oxidation potential and HOMO energy of CPPs. S7 --
(dppf) PtCl (dppf) PtCl 6a Figure S3. 1 H NMR spectrum of 6a. (dppf) PtCl (dppf) PtCl 6b Figure S4. 1 H NMR spectrum of 6b. S8 --
(dppf)ptcl (dppf)ptcl 6c Figure S5. 1 H NMR spectrum of 6c. (dppf) Pt Br (dppf) Pt Br 1a Figure S6. 1 H NMR spectrum of 1a. S9 --
(dppf) Pt Br (dppf)pt Br 1b Figure S7. 1 H NMR spectrum of 1b. (dppf) Pt Br (dppf)pt Br 1c Figure S8. 1 H NMR spectrum of 1c. S10 --
(dppf) Pt Pt(dppf) (dppf) Pt Pt(dppf) 2a Figure S9. 1 H NMR spectrum of 2a. (dppf) Pt Pt (dppf) (dppf) Pt Pt (dppf) 2b Figure S10. 1 H NMR spectrum of 2b. S11 --
(dppf) Pt Pt (dppf) (dppf) Pt Pt (dppf) 2c Figure S11. 1 H NMR spectrum of 2c. [6]CPP Figure S12. 1 H NMR spectrum of [6]CPP. S12 --
[6]CPP Figure S13. 13 C NMR of [6]CPP. S13 --