Introduction. 50, scan speed 2.7 min À1, scan range 2.3 plus 12separation, data collected / unique / used 2232 / 2232 (R int =

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1 Preparation, Structure and Optical Properties of [CH 3 SC(NH 2 ) 2 ] 3 SnI 5,[CH 3 SC(NH 2 ) 2 ][HSC(NH 2 ) 2 ]SnBr 4, (CH 3 C 5 H 4 NCH 3 )PbBr 3,and[C 6 H 5 CH 2 SC(NH 2 ) 2 ] 4 Pb 3 I 10 C. P. Raptopoulou a, A. Terzis a,g.a.mousdis b, and G. C. Papavassiliou b a Institute of Materials Science, NCSR, Demokritos, Athens 153/10, Greece b Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48, Vassileos Constantinou Ave., Athens 116/35, Greece Reprint requests to Prof. G. C. Papavassiliou. Fax: (3010) Z. Naturforsch. 57 b, (2002); received February 14, 2002 Metal Halides, Excitonic Spectra, Optical Properties The preparation, crystal structure and optical absorption spectra of [CH 3 SC(NH 2 ) 2 ] 3 SnI 5 (1), [CH 3 SC(NH 2 ) 2 ][HSC(NH 2 ) 2 ]SnBr 4 (2), (CH 3 C 5 H 4 NCH 3 )PbBr 3 (3), and [C 6 H 5 CH 2 SC- (NH 2 ) 2 ] 4 Pb 3 I 10 (4) are reported. The compounds 1, 2, 3 consist of MX 6 -octahedra (M = Sn, Pb, X = I, Br) forming one-dimensional single chains (compounds 1, 3) or double chains (compound 2). The compound 4 forms a two-dimensional inorganic network via corner sharing of three face sharing octahedral units. Because of their low-dimensional character, a blue shift of the excitonic absorption bands, in comparison to those of higher dimensionality systems, is observed. Introduction Recently, much attention has been devoted to low-dimensional organic-inorganic hybrid materials of the type (A) x M y X z (where A is amine-h + or 1/2diamine-2H + ; M = Sn, Pb, etc; X = I, Br, Cl) in which the inorganic part forms three- or lower-dimensional networks (see [1-4] and refs therein). These compounds are the subject of various fundamental as well as more applied studies related to their structural [1, 3], linear and nonlinear optical [1, 3, 5], transport [6] and other physical properties [7]. Their structures are characterized by MX 6 octahedra sharing corners, edges, or faces forming slabs, chains or clusters separated by the amine cations. The type of amine defines the dimensionality of the structure. The most rare structure is the one-dimensional (1D). To the best of our knowledge, for the Sn family only the [NH 2 C(I)=NH 2 ] 3 SnI 5 salt has been reported with 1D structure (see [2]). Here, we report the synthesis, structure and UV-vis optical absorption spectra of four new salts [CH 3 SC(NH 2 ) 2 ] 3 SnI 5 (1), [CH 3 SC(NH 2 ) 2 ]- [HSC(NH 2 ) 2 ]SnBr 4 (2), (CH 3 C 5 H 4 NCH 3 )PbBr 3 (3) and [C 6 H 5 CH 2 SC(NH 2 ) 2 ] 4 Pb 3 I 10 (4). Experimental Section Starting materials and apparatus The following starting materials were used without further purification. SnI 2 (Alfa 71112), SnBr 2 (Johnson Matthey), PbO (Ferak ), hydroiodic acid, 57% (Merck 341), hydrobromic acid 47% (Merck 304), 1,4- dimethylpyridinium iodide (Aldrich 37,643-4) and similar materials (see also [8, 9]). Elemental analyses were performed on a Perkin 2400 (II) autoanalyser. Crystal X-ray intensity data were collected at room temperature on a Crystal Logic [10] dual goniometer using graphite-monochromated Mo-K radiation. Unit cell dimensions were determined and refined by using the angular setting of 24 automatically centered reflections in the range 11 <2 <23. Intensity data were recorded using a -2 scan for: [CH 3 SC(NH 2 ) 2 ] 3 SnI 5,2max =50, scan speed 3.5 min À1, scan range 2.3 plus 12-separation, data collected / unique / used 4223 / 2186 (R int = 0.020) / 2186; for [CH 3 SC(NH 2 ) 2 ][HSC(NH 2 ) 2 ]SnBr 4, 2max =50, scan speed 3.0 min À1, scan range 2.2 plus 12separation, data collected / unique / used 2957 / 2681 (R int = )/2681; for (CH 3 C 5 H 4 NCH 3 )PbBr 3,2max = 50, scan speed 2.7 min À1, scan range 2.3 plus 12separation, data collected / unique / used 2232 / 2232 (R int = ) / 2232; and for [C 6 H 5 CH 2 SC(NH 2 ) 2 ] 4 Pb 3 I 10 2max =50, scan speed 2.0 min À1, scan range /02/ $ c 2002 Verlag der Zeitschrift für Naturforschung, Tübingen Á K

2 646 C. P. Raptopoulou et al. Four New Organic-Inorganic Hybrid Salts Compound Fw a (Å) (6) 6.052(3) 17.30(1) 9.205(4) b (Å) 9.949(4) (9) 19.47(1) 20.68(1) c (Å) (8) (6) 7.918(6) 31.80(1) V (Å 3 ) 2538(2) 1559(1) 2668(3) 6054(4) (deg) 90.11(1) Z D calcd (g/cm 3 ) Space group Pnam P 2 1 /c Pcab Pcab GOF R 1 /wr / a / b / c / d Table 1. Summary of crystal, intensity collection and refinement data. a For 2058 refs with I >2(I); b for 2232 refs with I >2(I); c for 1421 refs with I >2(I); d for 3919 refs with I >2(I). Table 2. Selected bond lengths (Å) and angles ( )for1. Sn-I(1) 3.243(1) Sn-I(2') 3.138(1) Sn-I(1') 3.243(1) Sn-I(3) 2.921(1) Sn-I(2) 3.138(1) Sn-I(3'') 4.042(1) I(2)-Sn-I(3) 92.15(2) I(3)-Sn-I(2') 92.15(2) I(2)-Sn-I(2') 90.79(4) I(3)-Sn-I(1') 90.57(3) I(2)-Sn-I(1') 89.37(4) I(3)-Sn-I(1) 90.57(3) I(2)-Sn-I(1) (3) I(3)-Sn-I(3'') (2) I(2)-Sn-I(3'') 102.0(1) I(2')-Sn-I(1') (3) I(2')-Sn-I(1) 89.37(4) I(1)-Sn-I(3'') 75.31(1) I(2')-Sn-I(3'') 102.0(1) I(1)-Sn-I(1') 90.35(1) x, y, 1.5 z, ('') x, 0.5 y, z. Table 3. Selected bond lengths (Å) and angles ( )for2. Sn-Br(1) 3.423(2) Sn-Br(3) 2.700(2) Sn-Br(1') 3.088(2) Sn-Br(3'') 3.370(2) Sn-Br(2) 2.734(2) Sn-Br(4) 2.921(2) Br(1')-Sn-Br(1) (3) Br(1)-Sn-Br(4) 79.41(3) Br(1')-Sn-Br(2) 84.10(2) Br(2)-Sn-Br(3) 90.57(3) Br(1')-Sn-Br(3) 87.02(3) Br(2)-Sn-Br(3'') 85.10(3) Br(1')-Sn-Br(3'') (3) Br(2)-Sn-Br(4) 93.44(3) Br(1')-Sn-Br(4) (3) Br(3)-Sn-Br(3'') (3) Br(1)-Sn-Br(2) (4) Br(3)-Sn-Br(4) 91.08(3) Br(1)-Sn-Br(3) 86.88(3) Br(3'')-Sn-Br(4) 81.53(3) Br(1)-Sn-Br(3'') 96.43(2) x, 1 y, 1 z,('')1+x, y, z. plus 12separation, data collected / unique / used 5320 / 5317 (R int = ) / Three standard reflections monitored every 97 reflections showed less than 3% variation and no systematic decay. Lorentz, polarization and absorption corrections were applied using Crystal Logic Software. The structures were solved by Patterson methods using SHELXS-86 [11] and refined by full-matrix least-squares techniques with SHELXL-93 [12]. All non-hydrogen atoms were refined anisotropically. Hydrogen atoms in 1 and 2 were located by difference maps and were refined isotropically, while in 3 and 4 all H-atoms were introduced at calculated positions as riding on bonded atoms. Table 4. Selected bond lengths (Å) and angles ( )for3. Pb(1)-Br(1) 3.133(2) Pb(1)-Br(2') 3.145(3) Pb(1)-Br(1') 3.206(3) Pb(1)-Br(3) 3.085(3) Pb(1)-Br(2) 3.051(3) Pb(1)-Br(3') 3.122(3) Br(2)-Pb(1)-Br(3) 83.43(8) Br(3')-Pb(1)-Br(2') 81.32(8) Br(2)-Pb(1)-Br(3') 97.14(8) Br(1)-Pb(1)-Br(2') (6) Br(3)-Pb(1)-Br(3') (8) Br(2)-Pb(1)-Br(1') (6) Br(2)-Pb(1)-Br(1) 85.01(8) Br(3)-Pb(1)-Br(1') 94.05(8) Br(3)-Pb(1)-Br(1) 87.22(8) Br(3')-Pb(1)-Br(1') 85.32(8) Br(3')-Pb(1)-Br(1) 93.65(8) Br(1)-Pb(1)-Br(1') 98.76(8) Br(2)-Pb(1)-Br(2') 94.21(9) Br(2')-Pb(1)-Br(1') 82.28(8) Br(3)-Pb(1)-Br(2') 97.82(8) 0.5 x, y,0.5 z. Table 5. Selected bond lengths (Å) and angles ( )for4. Pb(1)-I(1) 3.298(2) Pb(2)-I(1) 3.215(2) Pb(1)-I(2) 3.150(3) Pb(2)-I(1') 3.215(2) Pb(1)-I(3) 3.097(2) Pb(2)-I(4) 3.227(1) Pb(1)-I(3'') 3.197(2) Pb(2)-I(4') 3.227(1) Pb(1)-I(4) 3.338(2) Pb(2)-I(5) 3.243(1) Pb(1)-I(5') 3.173(2) Pb(2)-I(5') 3.243(1) I(3)-Pb(1)-I(2) 90.69(3) I(1)-Pb(2)-I(1') I(3)-Pb(1)-I(5') 88.43(5) I(1)-Pb(2)-I(4) 89.82(3) I(2)-Pb(1)-I(5') 96.60(3) I(4)-Pb(2)-I(1') 90.18(3) I(3)-Pb(1)-I(3'') 96.27(4) I(1)-Pb(2)-I(4') 90.19(3) I(2)-Pb(1)-I(3'') 84.32(3) I(4')-Pb(2)-I(1') 89.81(3) I(5')-Pb(1)-I(3'') (4) I(4)-Pb(2)-I(4') I(3)-Pb(1)-I(1) 87.12(3) I(1)-Pb(2)-I(5') 90.50(3) I(2)-Pb(1)-I(1) (3) I(5')-Pb(2)-I(1') 89.50(3) I(1)-Pb(1)-I(5') 90.24(3) I(4)-Pb(2)-I(5') 86.08(4) I(3'')-Pb(1)-I(1) 89.06(3) I(4')-Pb(2)-I(5') 93.20(4) I(3)-Pb(1)-I(4) (4) I(1)-Pb(2)-I(5) 89.50(3) I(2)-Pb(1)-I(4) 96.36(3) I(5)-Pb(2)-I(1') 90.50(3) I(4)-Pb(1)-I(5') 85.35(5) I(4)-Pb(2)-I(5) 93.92(4) I(3'')-Pb(1)-I(4) 89.87(5) I(5)-Pb(2)-I(4') 86.08(4) I(1)-Pb(1)-I(4) 86.52(3) I(5)-Pb(2)-I(5') x, 1 y, 1 z,('')0.5 x, 1.5 y, z. Crystallographic information files have been deposited in the Cambridge Crystallographic Data Center, 12 Union Road, Cambridge CB2 1EZ UK (

3 C. P. Raptopoulou et al. Four New Organic-Inorganic Hybrid Salts 647 Fig. 1. Packing diagram of [CH 3 SC(NH 2 ) 2 ] 3 SnI 5 (1). deposit@ccdc.cam.ac.uk) Deposition numbers CCDC for [CH 3 SC(NH 2 ) 2 ] 3 SnI 5, CCDC for [CH 3 SC(NH 2 ) 2 ][HSC(NH 2 ) 2 ]SnBr 4, CCDC for (CH 3 C 5 H 4 NCH 3 )PbBr 3, and CCDC for [C 6 H 5 - CH 2 SC(NH 2 ) 2 ] 4 Pb 3 I 10, respectively. The room temperature optical absorption spectra were recorded by a Perkin Elmer model Lambda 19 UV-vis- NIR spectrometer. Preparation of compounds The preparations of precursors CH 3 SC(NH 2 ) 2 Iand CH 3 SC(NH 2 ) 2 Br are reported elsewhere [13]. [CH 3 SC(NH 2 ) 2 ] 3 SnI 5 (1) was prepared by refluxing an aq. HI 57% (10 ml) solution of SnI 2 (120 mg, 0.32 mmol) and CH 3 SC(NH 2 ) 2 I (210 mg, 0.96 mmol) under N 2 for 0.5 h. The solution was cooled to 2 C and 250 mg of the product was precipitated as yellow crystals, in a yield of 75%; Analysis for C 6 H 21 N 6 I 5 S 3 Sn (1027): calcd. C 7.02, H 2.06, N 8.19; found C 6.95, H 2.17, N [CH 3 SC(NH 2 ) 2 ][HSC(NH 2 ) 2 ]SnBr 4 (2) was prepared by refluxing an aq. HBr 47% (10ml) solution of SnBr 2 (100 mg, 0.36 mmol) and CH 3 SC(NH 2 ) 2 Br (270 mg, 1.08 mmol) under N 2 for 0.5 h. The solution was cooled to 2 C and 150 mg of the product was precipitated as yellow crystals, in a yield of 40%; Analysis for C 6 H 21 N 6 I 5 S 3 Sn (607): calcd. C 5.94, H 1.99, N 9.24; found C 6.06, H 2.17, N (CH 3 C 5 H 4 NCH 3 )PbBr 3 (3) was prepared as follows: To a solution of PbO (312.2 mg, 1.4 mmol) in aq. HBr 47% (2 ml) a solution of 1,4-dimethylpyridinium iodide (329 mg 1.4 mmol)) in aq. HBr 47% (2 ml) was added at reflux temperature. The mixture was cooled slowly to room temperature, to give white crystals in a yield of Fig. 2. Packing diagram of [CH 3 SC(NH 2 ) 2 ][HSC- (NH 2 ) 2 ]SnBr 4 (2). 470 mg (60.5%); Analysis for C 7 H 10 NBr 3 Pb (555): calcd. C 15.13, H 1.80, N 2.52; found C 14,90, H 1.88, N [C 6 H 5 CH 2 SC(NH 2 ) 2 ] 4 Pb 3 I 10 (4) was prepared by a slight modification of the method reported in [8]. To a solution of PbO (334.5 mg, 1.5 mmol) in aq. HI 57% (4.5 ml) and CH 3 OH (5 ml) containing H 3 PO 2, C 6 H 5 CH 2 SC(NH 2 ) 2 I (588 mg) was added at once and the mixture was heated to reflux. By slow cooling yellow plates were obtained, filtered and air dried; yield 820 mg (64%); Analysis for C 32 H 44 N 8 I 10 S 4 Pb 3 (2559): calcd. C 15.01, H 1.73, N 4.38; found C 14.96, H 1.71, N Results and Discussion Morphology of materials Compounds 1-4 were prepared as pure single crystals, large enough for X-ray crystal structure determination. Crystal structures A summary of crystal data of the compounds at room temperature is given in Table 1. [CH 3 SC(NH 2 ) 2 ] 3 SnI 5 (1) is isostructural with the Pb analogue [13]. It crystallizes in the orthorhombic system. As can be seen from the packing diagram of

4 648 C. P. Raptopoulou et al. Four New Organic-Inorganic Hybrid Salts Fig. 3. Packing diagram of (CH 3 C 5 H 4 NCH 3 )PbBr 3 (3. Fig. 1, it consists of distorted SnI 6 octahedra. This distortion is caused by the 5s 2 non bonding lone pair electrons of Sn 2+, resulting in a non-spherical charge distribution around tin cations and a lowering of the coordination symmetry. Each octahedron shares opposite corners [I(3) atoms], to give infinite one-dimensional chains extending along the a axis. The Sn-I(3)-Sn angle is indicating that the chain is almost linear. The structure is similar to that of [NH 2 C(I)=NH 2 ] 3 SnI 5 [2, 14], but in our case the octahedra are more distorted. The two C-N bond lengths are almost equal indicating that the cations have a resonance structure [CH 3 SC( ::: NH 2 ) 2 ]. Selected bond lengths and angles for 1 are given in Table 2. [CH 3 SC(NH 2 ) 2 ][HSC(NH 2 ) 2 ]SnBr 4 (2) crystallizes in the monoclinic system. As is shown in the packing diagram (Fig. 2), it consists of two edgesharing distorted SnBr 6 octahedra [Sn-Br(1)-Sn = 77.05(3) ] which are corner-connected to each other [through Br(3), Sn-Br(3)-Sn = (3) ]toform infinite double chains along the a axis. The two C-N bond lengths are almost equal [N(1)-C(2) = 1.30(1), N(2)-C(2) = 1.27(1), N(3)-C(4) = 1.30(1), Fig. 4. Packing diagram (a) and inorganic layer (b) of [C 6 H 5 CH 2 SC(NH 2 ) 2 ] 4 Pb 3 I 10 (4), with the atomic labels. N(4)-C(4) = 1.31(1) Å] indicating that the cations have a resonance structure [CH 3 SC( ::: NH 2 ) 2 ]. Selected bond lengths and angles for 2 are given in Table 3. (CH 3 C 5 H 4 NCH 3 )PbBr 3 (3) crystallizes in the orthorhombic system. As can be seen from the packing diagram of Fig. 3, the structure consists of facesharing PbBr 6 octahedra [Pb-Br(1)-Pb = 77.29(7), Pb-Br(2)-Pb = 79.42(8), Pb-Br(3)-Pb = 79.27(8) ] forming one-dimensional chains along the c axis. Selected bond lengths and angles for 3 are given in Table 4.

5 C. P. Raptopoulou et al. Four New Organic-Inorganic Hybrid Salts 649 Fig. 5. Optical absorption spectra of thin deposits of [CH 3 SC(NH 2 ) 2 ] 3 SnI 5 (1) (a) and [CH 3 SC(NH 2 ) 2 ]- [HSC(NH 2 ) 2 ]SnBr 4 (2) (b). [C 6 H 5 CH 2 SC(NH 2 ) 2 ] 4 Pb 3 I 10 (4) crystallizes in the orthorhombic system. As shown in Fig. 4, the structure consists of alternating inorganic and organic layers. The inorganic layers are parallel to the ab plane and consist of corner sharing trinuclear units (through I(3), Pb(1)-I(3)-Pb(1') = (5) ) that are formed by three face sharing PbI 6 octahedra (through I(1), I(4) and I(5), Pb(2)-I(1)-Pb(1) = 72.96(3), Pb(2)-I94)-Pb(1) = 72.27(3) and Pb(1)- I(5)-Pb(2) = 74.24(3) ). To our knowledge no other related material presents this kind of structure. Selected bond lengths and angles for 4 are given in Table 5. Optical properties The room temperature optical absorption (OA) spectra of thin deposits of compounds 1, 2, and 3 Fig. 6. Optical absorption spectra of thin deposits of (CH 3 C 5 NH 4 CH 3 )PbBr 3 (3) (a) and (CH 3 C 5 H 4 NCH 3 )Br (b), for comparison. on quartz plates are shown in Fig. 5 and Fig. 6. The spectrum of 1 exhibits a double excitonic band at nm (Fig. 5a), while 2 has this feature at nm (Fig. 5b). The spectrum of 3 shows an excitonic band at 359 nm (Fig. 6a), which occurs close to the low frequency OA band of the organic component (CH 3 C 5 H 4 NCH 3 )Br (i. e., at 314 nm) (Fig. 6b). The OA spectra of 4 has been reported in [8]. It shows an excitonic band at 438 nm and another one at 392 nm, the origin of which is not understood. It is observed that the optical properties of these new compounds are similar to those found for similar compounds based on alkylamines or aryl-alkylamines (see [1-4] and refs cited therein). [1] T. Ishihara, in Y. Kanemitsu (eds): Optical Properties of Low-Dimensional Materials, ch. 6, pp , World Science, Singapore (1995). [2] D. B. Mitzi, Progr. Inorg. Chem. 48, 1 (1999). [3] G. C. Papavassiliou, Progr. Solid State Chem. 25, 125 (1997). [4] (a) G. C. Papavassiliou, G. A. Mousdis, I. B. Koutselas, Z. Naturforsch. 56b, 57 (2001); (b) Adv. Mater. Opt. Electron. 9, 265 (1999); (c) G. C. Papavassiliou, G. A. Mousdis, C. P. Raptopoulou, A. Terzis, Z. Naturforsch. 54b, 1405 (1999); (d) I. B. Koutselas, PhD Thesis., University of Athens (1998). [5] T. Kondo, S. Iwamoto, S. Hayase, K. Tanaka, J. Ishi, M. Mizuno, K. Ema, R. Ito, Sol. State Commun. 105, 503 (1998). [6] C. R. Kagan, D. B. Mitzi, C. D. Dimitrakopoulos, Science 286, 945 (1999). [7]T.Hattori,T.Taira,M.Era,T.Tsutsui,S.Saito, Chem. Phys. Lett. 254, 103 (1996). T. Gebauer, G. Schmid, Z. Anorg. Allg. Chem. 625, 1124 (1999); K. Chondrudis, D. B. Mitsi, Chem. Mater. 11, 3028 (1999). [8] G. C. Papavassiliou, G. A. Mousdis, I. B. Koutselas, Naturforsch. 56b, 57 (2001).

6 650 C. P. Raptopoulou et al. Four New Organic-Inorganic Hybrid Salts [9] G. C. Papavassiliou, G. A. Mousdis, I. B. Koutselas, Naturforsch. 56b, 213 (2001). [10] Crystal Logic Inc., w. Pico Blvd., Suite 106, Los Angeles, CA [11] G. M. Sheldrick, SHELXS 86, Structure Solving Program, University of Goettingen, Germany (1986). [12] G. M. Sheldrick, SHELXL 93, Crystal Structure Refinement, University of Goettingen, Germany (1993). [13] G. A. Mousdis, V. Gionis, G. C. Papavassiliou, C. P. Raptopoulou, A. Terzis, J. Mater. Chem. 8, 2259 (1998). [14] D. B. Mitzi, K. Liang, S. Wang, Inorg. Chem. 37, 321 (1998).