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Electrochemical syntheses and structures of lead(II) and bismuth(III) complexes of 4-(trimethylammonio)benzenethiolate
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Inorganic Chemistry Communications 10 (2007) 1253–1256 www.elsevier.com/locate/inoche
Electrochemical syntheses and structures of lead(II) and bismuth(III) complexes of 4-(trimethylammonio)benzenethiolate Zhi-Gang Ren a, Xiao-Yan Tang a, Li Li a, Guang-Fei Liu a, Hong-Xi Li a, Yang Chen a, Yong Zhang a, Jian-Ping Lang a,b,* b
a School of Chemistry and Chemical Engineering, Suzhou University, Suzhou 215123, Jiangsu, People’s Republic of China State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, Jiangsu, People’s Republic of China
Received 12 July 2007; accepted 4 August 2007 Available online 15 August 2007
Abstract Two main-group metal complexes of the zwitterionic ammonium thiolate complexes, [M(Tab)3](ClO4)n (Tab = 4-(trimethylammonio)benzenethiolate) (1: M = Pb, n = 2; 2: M = Bi, n = 3), were prepared by electrochemical oxidation of Pb or Bi electrode in MeCN containing Tab and Et4NClO4. Each M atom in 1 and 2 is coordinated by three S atoms of three Tab ligands, forming a trigonal pyramidal coordination geometry. The resulting [M(Tab)3]n+ cations are interconnected by secondary M S interactions to form two different 1D cationic chains. The electrochemical properties of 1 and 2 were also investigated by cyclic voltammetry. 2007 Elsevier B.V. All rights reserved. Keywords: Electrochemical synthesis; Lead; Bismuth; Zwitterionic ammonium thiolate; Crystal structure; Electrochemical properties
Metal zwitterionic ammonium thiolate complexes have been interested for years due to their structure diversity [1–8], application in antimicrobial drugs [9], and their relevance to the active site of metallothioneins [10]. A large number of zwitterionic ammonium thiolate complexes of transition metals have been reported [1–11], while those with main group metals such as Pb or Bi are limited in number [12–15]. Metal zwitterionic ammonium thiolates can be prepared by various methods such as proton transfer reaction [1a,4,7,8,16a,16b,16c], precursor reaction [16a,16b], ligand exchange reaction [15], oxidation–reduction reaction [1b] and solid-state reaction [16d]. However, the approach of electrochemical reaction was less explored for synthesizing metal zwitterionic ammonium thiolates [17,18].
* Corresponding author. Address: School of Chemistry and Chemical Engineering, Suzhou University, Suzhou 215123, Jiangsu, People’s Republic of China. Tel.: +86 512 65882865; fax: +86 512 65880089. E-mail address: [email protected] (J.-P. Lang).
1387-7003/$ - see front matter 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2007.08.004
Recently, we have engaged in the synthesis of metal complexes of a zwitterionic ammonium thiolate Tab (Tab = 4-(trimethylammonio)benzenethiolate) with different transition metals like Hg(II), Au(I) and Ag(I) [16]. Being aware of the fact that the electrochemical oxidation of sacrificial anodes have been proved an effective route to prepare different kinds of metal complexes [17–22] and as our continuing efforts to expand the family of metal/ Tab complexes, we carried out the electrochemical syntheses of Tab complexes with Pb or Bi (as sacrificial anodes) in MeCN containing Tab and Et4NClO4, and two Pb(Tab)3(ClO4)2 (1) and Bi(Tab)3(ClO4)3 (2) were isolated therefrom. In this paper, we report their syntheses, crystal structures and electrochemical properties. The electrosynthesis were carried out in a double electrolytic cell using a Pt cathode and a sacrificial M (M = Pb, Bi) anode when Tab was added into the anolyte compartment [23]. The electrochemical system can be represented as: () PtjHClO4, MeCNiEt4NClO4, Tab, MeCNjM (+). The electrochemical efficiency values were 0.5 mol/F for 1 and 0.3 mol/F for 2, suggesting that the
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oxidation states of Pb and Bi were +2 and +3 at the initial step of the electrochemical reaction on the anode surface. The reactions in the cell can be described as follows: cathode : Hþ þ e ¼ 1=2H2 anode : M ne ¼ Mnþ ðM ¼ Pb;n ¼ 2; M ¼ Bi;n ¼ 3Þ Mnþ þ 3Tab þ nClO 4 ¼ MðTabÞ3 ðClO4 Þn The excess Et4NClO4 was employed both as a supporting electrolyte and as a counterion while the catholyte was separated and then discarded to eliminate any negative effects of water from the HClO4 solution. The final yields for 1 and 2 were 67% and 71%, respectively. The single-cell electrosynthesis using TabHPF6 without additional supporting electrolyte could not form isolable products due to the uncontrollable side-reactions during the electrolysis and the reduction of products on the cathode. Compounds 1 and 2 are air-stable, and soluble in MeCN, DMF and DMSO. The elemental analyses were consistent with their chemical formula. The strong bands at ca. 1080 and 624 cm1 in their IR spectra may be assigned to the Cl–O stretching vibrations of the uncoordinated perchlorate anions. In the 1H NMR spectra of 1 and 2, the single signal at 3.5 ppm and multiplet at 7.43– 7.71 ppm can be assigned to be protons of NMe3 and protons of Ph groups. The molecular structures were finally confirmed by X-ray crystallography [24]. Compounds 1 and 2 crystallizes in the monoclinic space group C2/c and in the orthorhombic space group P212121 and their asymmetric unit contains one discrete [M(Tab)3]n+ cation and two (1) or three (2) ClO 4 anions. As shown in Figs. 1 and 2, the M centre in [M(Tab)3]n+ cation is coordinated by three S atoms of the three Tab ligands to form a trigonal pyramidal geometry. The mean ˚ ) in 1 is slightly primary Pb–S bond length (2.716(3) A
Fig. 1. View of a section of the 1D cationic chain of 1 along the b axis. The ClO 4 anions and all H atoms are omitted for clarity. Selected bond lengths ˚ ) and angles (): Pb1–S1 2.701(3), Pb1–S2 2.763(3), Pb1–S3 2.683(3), (A Pb1 S1A 3.503(3), Pb1 S2A 3.424(3); S1–Pb1–S2 82.77(9), S1–Pb1–S3 94.15(10), S2–Pb1–S3 95.53(9), S1–Pb1 S2A 105.81(6), S2–Pb1 S1A 108.53(6), S3–Pb1 S1A 86.40(9), S3–Pb1 S2A 84.99(8), S1A Pb1 S2A 62.86(6). Symmetry code: A: 0.5 x, 0.5 + y, 0.5 z.
Fig. 2. View of a section of the 1D cationic chain of 2 along the a axis. The ClO 4 anions and all H atoms are omitted for clarity. Selected bond lengths ˚ ) and angles (): Bi1–S1 2.564(3), Bi1–S2 2.611(3), Bi1–S3 2.593(3), (A Bi1 S1A 3.490(3), Bi1 S3A 3.234(3), Bi1 S2B 3.260(3); S1–Bi1–S2 82.77(9), S1–Bi1–S3 94.15(10), S2–Bi1–S3 95.53(9), S1–Bi1 S3A 92.93(6), S1–Bi1 S2B 72.33(6), S2–Bi1 S1A 67.85(5), S2–Bi1 S3A 73.45(5), S3–Bi1 S1A 102.79(5), S3–Bi1 S2B 73.22(5), S1A Bi1 S3A 68.15(6), S1A Bi1 S2B 126.11(5), S3A Bi1 S2B 118.55(5). Symmetry codes: A: 0.5 + x, 0.5 y, 1 z; B: 0.5 + x, 0.5 y, 1 z.
shorter than that found in [Pb2(SCH2CH2NMe3)5](PF6)4 ˚ ) [2]. The mean primary Bi–S bond length (2.73(3) A ˚ ) in 2 is comparable to those in Bi[SC6H2(2.599(3) A ˚ ) [26a] and (NH4)3[Bi(2-SC6H4(2,4,6-t-Bu3)]3 (2.559(8) A ˚ ) [26b], but shorter than that COO)3] Æ 2H2O (2.596(8) A ˚ ) [14]. in Bi(SCH2CH2NHMe2)Cl3 (2.798(3) A The secondary interactions between M atom and the S atom of Tab in 1 and 2 deserve comment. The Pb1 in the [Pb(Tab)3]2+ dication in 1 is further linked by the two weak interactions between Pb1 and S1A and S2A atoms of the two Tab ligands from the adjacent dication, forming a pseudo square-pyramidal geometry. The resulting PbðTabÞ2þ 5 square-pyramid shares two edges of the neighboring equivalents in a up-and-down way to form a 1D cationic chain extending along the b axis (Fig. 1). On the other hand, the Bi1 in the [Bi(Tab)3]3+ trication in 2 is further linked by three secondary interactions between Bi1 and S1A, S2A or S2B of the three Tab ligands from two neighboring trications, forming a pseudo distorted octahedral geometry. The resulting BiðTabÞ3þ 6 octahedron shares with six edges of the two adjacent ones to form another 1D cationic chain extending along the a axis (Fig. 2). As there is a 21 axis running along the a axis, the polymeric structure of 2 may be alternatively viewed as an approximately spiral ˚ and chain. The M M contacts in 1 and 2 are 4.858(3) A ˚ 4.244(3) A, respectively, which excludes any metal–metal interaction. The M atoms in 1 and 2 are nearly co-linear with torsion angels of 178.47(4) for 1 and 174.85(4) for 2 between neighboring M M linkages. Between these
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Fig. 3. Cyclic voltammograms of 0.5 mM solutions of 1 and 2 in DMF containing 0.05 M Et4NClO4, using a 2 · 2 mm2 Pt slice as working electrode and Pt wire as counter electrode. The scan rates are 100 mV s1.
cationic chains are perchlorate anions, which are attracted through ionic interactions by the positive –NMeþ 3 ends of the Tab ligands. The electrochemical properties of 1 and 2 were investigated by cyclic voltammetry in DMF. The cyclic voltammagrams (Fig. 3) consist of one irreversible reduction at 0.78 V for 1 or 0.69 V for 2 and two irreversible oxidations at 0.13 V and 0.48 V for 1 or 0.005 V and 0.59 V for 2. It is assumed that the Pb(II) in 1 or Bi(III) in 2 is reduced to free metals at a low potential at 0.7 V, while the Tab ligands in 1 and 2 are likely to be oxidized by two steps: a oxidative dimerization of the sulfur atoms (formation of the (Tab)2 dication) [16a,16e,16f] at 0 V and the subsequently oxidization of (Tab)2 dication to the thiosulfate Me3 N þ PhSSO 3 [16g] at 0.5 V. Acknowledgements This work was supported by the NNSF (No. 20525101), the NSF of Jiangsu Province (No. BK2004205), the Specialized Research Fund for the Doctoral Program of Higher Education (No. 20050285004), and the State Key Laboratory of Coordination Chemistry of Nanjing University and the Qin-Lan Project of Jiangsu Province in China. Appendix A. Supplementary material CCDC 650340 and 650341 contains the supplementary crystallographic data for 1 and 2. These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/ conts/retrieving.html, or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK, fax: (+44) 1223-336-033, or e-mail: deposit@ ccdc.cam.ac.uk. Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.inoche.2007.08.004.
[1] (a) M.S. Bharara, S. Parkin, D.A. Atwood, Inorg. Chem. 45 (2006) 2112; (b) M.S. Bharara, T.H. Bui, S. Parkin, D.A. Atwood, Dalton Trans. (2005) 3874. [2] I.G. Dance, P.J. Guerney, A.D. Rae, M.L. Scudder, A.T. Baker, Aust. J. Chem. 39 (1986) 383. [3] W. Clegg, N. Duran, K.A. Fraser, P. Gonza`lez-Duarte, J. Sola, I.C. Taylor, J. Chem. Soc. Dalton Trans. (1993) 3453. [4] R.V. Parish, Z. Salehi, R.G. Prichard, Angew. Chem. Int. Ed. 36 (1997) 251. [5] J.K. Cheng, Y.B. Chen, L. Wu, J. Zhang, Y.H. Wen, Z.J. Li, Y.G. Yao, Inorg. Chem. 44 (2005) 3386. [6] M.F. Roberts, E.A. Dennis, J. Am. Chem. Soc. 99 (1977) 6143. [7] W.P. Su, R. Cao, M.C. Hong, J.T. Chen, J.X. Lu, Chem. Commun. (1998) 1389. [8] L.S. Ahmed, W. Clegg, D.A. Davis, J.R. Dilworth, M.R.J. Elsegood, D.V. Griffiths, L. Horsburgh, J.R. Miller, N. Wheatley, Polyhedron 18 (1998) 593. [9] K. Nomiya, S. Takahashi, R. Noguchi, J. Chem. Soc. Dalton Trans. (2000) 2091. [10] A.J. Zelazowski, M.J. Stillman, Inorg. Chem. 31 (1992) 3363. [11] R.D. Adams, J.E. Cortopassi, S.B. Falloon, Organometallics 11 (1992) 3794. [12] H. Fleischer, D. Schollmeyer, Inorg. Chem. 43 (2004) 5529. [13] B. Crabs, A. Brommelhaus, B. Kersting, M. Nienhaus, Eur. J. Solid State Inorg. Chem. 29 (1992) 167. [14] G.G. Briand, N. Burford, T.S. Cameron, Chem. Commun. (1997) 2365. [15] H. Fleischer, D. Schollmeyer, Inorg. Chem. 41 (2002) 4739. [16] (a) J.X. Chen, W.H. Zhang, X.Y. Tang, Z.G. Ren, Y. Zhang, J.P. Lang, Inorg. Chem. 45 (2006) 2568; (b) J.X. Chen, Q.F. Xu, Y. Zhang, Z.N. Chen, J.P. Lang, J. Organomet. Chem. 689 (2004) 1071; (c) J.X. Chen, W.H. Zhang, X.Y. Tang, Z.G. Ren, H.X. Li, Y. Zhang, J.P. Lang, Inorg. Chem. 45 (2006) 7671; (d) J.X. Chen, Q.F. Xu, Y. Xu, Y. Zhang, Z.N. Chen, J.P. Lang, Eur. J. Inorg. Chem. (2004) 4247; (e) J.X. Chen, Y. Zhang, Z.G. Ren, J.P. Lang, J. Mol. Struct. 784 (2006) 24; (f) J.X. Chen, W.H. Zhang, Z.G. Ren, Y. Zhang, J.P. Lang, Acta Cryst. E 61 (2005) m60; (g) J.X. Chen, Q.F. Xu, Y. Zhang, S.M. Zain, S.W. Ng, J.P. Lang, Acta Cryst. C 60 (2004) 572. [17] N.A. Bell, W. Clegg, J.R. Creighton, E.S. Raper, Inorg. Chim. Acta 303 (2000) 12. [18] J.A. Garcı´a-Va´zquez, J. Romero, A. Sousa, Coord. Chem. Rev. 193– 195 (1999) 691. [19] D.G. Tuck, Pure Appl. Chem. 51 (1979) 2005. [20] M.C. Chakravorti, G.V.B. Subrahmanyam, Coord. Chem. Rev. 135– 136 (1994) 65. [21] A.M. Vecchio-Sadus, J. Appl. Electrochem. 23 (1993) 401. [22] E. Block, G. Ofori-Okai, H. Kang, J. Zubieta, Inorg. Chim. Acta 188 (1991) 7. [23] Syntheses of 1 and 2. The electrolytic cell was composed of an H-tube equipped with a glass-septum, a Pt (1 · 1 cm2) cathode and a Pb or Bi anode. The cell was filled with a solution of Et4NClO4 (0.53 mmol for 1 and 0.8 mmol for 2) in MeCM (14 mL). To the catholyte compartment was added 0.5 mL of HClO4 solution (70% in water), while Tab (0.2 mmol) was placed at the bottom of the anolyte compartment and the anode was hung at the middle of the electrolyte by a Pt wire. The voltage was regulated to obtain initial current of 20 mA while the anolyte was slowly stirred. After a period of electrolysis (11 min for 1 and 17 min for 2), the anode was taken away, washed by acetone, and weighed for determining the electrochemical efficiency. The catholyte and the upper part of anolyte
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(3 mL) were removed while the left yellow anolyte was stirred continuously for 10 min and then filtered. Et2O was allowed to slowly diffuse into the filtrate to give yellow crystals of 1 or 2 after several days. Yield: 67% (1) and 71% (2). Anal. Calcd for C27H39Cl2N3O8PbS3 (1): C 35.72, H 4.33, N 4.63. Found: C 36.21, H 4.66; N 4.21%. IR (KBr, cm1): 3052 (w), 1630 (w), 1578 (m), 1484 (vs), 1413 (s), 1085 (vs), 1008 (s), 953 (s), 825 (s), 745 (s), 624 (vs), 551 (s). 1H NMR (CD3CN, 400 MHz, ppm): d 3.476 (s, 27H, –CH3), 7.465 (s, 12H, –Ph). Anal. Calcd for C27H39Cl3N3O12BiS3 (2): C 32.13, H 3.90, N 4.16. Found: C 31.86, H 4.05; N 4.33%. IR (KBr, cm1): 3049 (w), 1624 (w), 1578 (m), 1489 (vs), 1411 (s), 1086 (vs), 1010 (s), 954 (s), 828 (s), 754 (s), 624 (vs), 555 (s). 1H NMR (CD3CN, 400 MHz, ppm): d 3.529 (s, 27H, –CH3), 7.430–7.712 (m, 12H, –Ph). [24] Crystal data for 1: C27H39Cl2N3O8PbS3, Mr = 907.88, yellow crystal (0.18 · 0.16 · 0.10 mm), monoclinic, space group C2/c, a = ˚, ˚, ˚, 40.423(8) A b = 9.914(2) A c = 18.230(4) A b = 111.44(3), ˚ 3, Z = 8, Dc = 1.774 g/cm3, F(0 0 0) = 3600 and V = 6800(2) A l = 5.353 mm1. T = 193 K; 32442 reflections collected, 6201 unique (Rint = 0.0650). R1 = 0.0721, wR2 = 0.1491 and S = 1.140 based on 4882 observed reflections with I > 2r(I). Crystal data for 2: C27H39BiCl3N3O12S3, Mr = 1009.12, yellow crystal (0.25 · 0.20 · 0.10 mm), ˚, b= orthorhombic, space group P212121, a = 8.4793(17) A ˚ , c = 25.268(5) A ˚ , V = 3960.0(14) A ˚ 3, Z = 4, Dc = 18.483(4) A
1.693 g/cm3, F(0 0 0) = 2000 and l = 4.870 mm1. T = 193 K; 39599 reflections collected, 7239 unique (Rint = 0.0462). R1 = 0.0594, wR2 = 0.1681 and S = 1.102 based on 6496 observed reflections with I > 2r(I). Data collections were performed on a Rigaku Mercury CCD diffractomer with graphite-monochromated Mo Ka radiation ˚ ). The structures were solved by direct methods and (k = 0.71073 A refined with full-matrix least-squares technique using SHELXL-97 program [25]. Two methyl groups and two perchlorate anions in 1 were disordered over two sites with occupancy factors of 0.62/0.38 for atoms N1/N1A, C7–C9/C7A–C9A, N3/N3A, C25–C27/C25A– C27A, O5–O7/O5A–O7A, and 0.48/0.52 for atoms O1–O4/O1A– O4A. The disordered non-H atoms were refined isotropically, while all other non-H atoms were refined anisotropically. All H atoms were ˚ for methyl placed in geometrically idealized positions (C–H = 0.98 A ˚ for phenyl groups) and constrained to ride groups and C–H = 0.95 A on their parent atoms with Uiso(H) = 1.2Ueq(C). [25] G.M. Sheldrick, SHELXL-97 and SHELXS-97, Program for X-ray Crystal Structure Solution and Refinement, University of Go¨ttingen, 1997. [26] (a) D.A. Atwood, A.H. Cowley, R.D. Hernandez, R.A. Jones, L.L. Rand, S.C. Bott, J.L. Atwood, Inorg. Chem. 32 (1993) 2972; (b) D.S. Sagatys, G. Smith, R.C. Bott, P.C. Healthy, Aust. J. Chem. 56 (2003) 941.
Inorganic Chemistry Communications 10 (2007) 1253–1256 www.elsevier.com/locate/inoche
Electrochemical syntheses and structures of lead(II) and bismuth(III) complexes of 4-(trimethylammonio)benzenethiolate Zhi-Gang Ren a, Xiao-Yan Tang a, Li Li a, Guang-Fei Liu a, Hong-Xi Li a, Yang Chen a, Yong Zhang a, Jian-Ping Lang a,b,* b
a School of Chemistry and Chemical Engineering, Suzhou University, Suzhou 215123, Jiangsu, People’s Republic of China State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, Jiangsu, People’s Republic of China
Received 12 July 2007; accepted 4 August 2007 Available online 15 August 2007
Abstract Two main-group metal complexes of the zwitterionic ammonium thiolate complexes, [M(Tab)3](ClO4)n (Tab = 4-(trimethylammonio)benzenethiolate) (1: M = Pb, n = 2; 2: M = Bi, n = 3), were prepared by electrochemical oxidation of Pb or Bi electrode in MeCN containing Tab and Et4NClO4. Each M atom in 1 and 2 is coordinated by three S atoms of three Tab ligands, forming a trigonal pyramidal coordination geometry. The resulting [M(Tab)3]n+ cations are interconnected by secondary M S interactions to form two different 1D cationic chains. The electrochemical properties of 1 and 2 were also investigated by cyclic voltammetry. 2007 Elsevier B.V. All rights reserved. Keywords: Electrochemical synthesis; Lead; Bismuth; Zwitterionic ammonium thiolate; Crystal structure; Electrochemical properties
Metal zwitterionic ammonium thiolate complexes have been interested for years due to their structure diversity [1–8], application in antimicrobial drugs [9], and their relevance to the active site of metallothioneins [10]. A large number of zwitterionic ammonium thiolate complexes of transition metals have been reported [1–11], while those with main group metals such as Pb or Bi are limited in number [12–15]. Metal zwitterionic ammonium thiolates can be prepared by various methods such as proton transfer reaction [1a,4,7,8,16a,16b,16c], precursor reaction [16a,16b], ligand exchange reaction [15], oxidation–reduction reaction [1b] and solid-state reaction [16d]. However, the approach of electrochemical reaction was less explored for synthesizing metal zwitterionic ammonium thiolates [17,18].
* Corresponding author. Address: School of Chemistry and Chemical Engineering, Suzhou University, Suzhou 215123, Jiangsu, People’s Republic of China. Tel.: +86 512 65882865; fax: +86 512 65880089. E-mail address: [email protected] (J.-P. Lang).
1387-7003/$ - see front matter 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2007.08.004
Recently, we have engaged in the synthesis of metal complexes of a zwitterionic ammonium thiolate Tab (Tab = 4-(trimethylammonio)benzenethiolate) with different transition metals like Hg(II), Au(I) and Ag(I) [16]. Being aware of the fact that the electrochemical oxidation of sacrificial anodes have been proved an effective route to prepare different kinds of metal complexes [17–22] and as our continuing efforts to expand the family of metal/ Tab complexes, we carried out the electrochemical syntheses of Tab complexes with Pb or Bi (as sacrificial anodes) in MeCN containing Tab and Et4NClO4, and two Pb(Tab)3(ClO4)2 (1) and Bi(Tab)3(ClO4)3 (2) were isolated therefrom. In this paper, we report their syntheses, crystal structures and electrochemical properties. The electrosynthesis were carried out in a double electrolytic cell using a Pt cathode and a sacrificial M (M = Pb, Bi) anode when Tab was added into the anolyte compartment [23]. The electrochemical system can be represented as: () PtjHClO4, MeCNiEt4NClO4, Tab, MeCNjM (+). The electrochemical efficiency values were 0.5 mol/F for 1 and 0.3 mol/F for 2, suggesting that the
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oxidation states of Pb and Bi were +2 and +3 at the initial step of the electrochemical reaction on the anode surface. The reactions in the cell can be described as follows: cathode : Hþ þ e ¼ 1=2H2 anode : M ne ¼ Mnþ ðM ¼ Pb;n ¼ 2; M ¼ Bi;n ¼ 3Þ Mnþ þ 3Tab þ nClO 4 ¼ MðTabÞ3 ðClO4 Þn The excess Et4NClO4 was employed both as a supporting electrolyte and as a counterion while the catholyte was separated and then discarded to eliminate any negative effects of water from the HClO4 solution. The final yields for 1 and 2 were 67% and 71%, respectively. The single-cell electrosynthesis using TabHPF6 without additional supporting electrolyte could not form isolable products due to the uncontrollable side-reactions during the electrolysis and the reduction of products on the cathode. Compounds 1 and 2 are air-stable, and soluble in MeCN, DMF and DMSO. The elemental analyses were consistent with their chemical formula. The strong bands at ca. 1080 and 624 cm1 in their IR spectra may be assigned to the Cl–O stretching vibrations of the uncoordinated perchlorate anions. In the 1H NMR spectra of 1 and 2, the single signal at 3.5 ppm and multiplet at 7.43– 7.71 ppm can be assigned to be protons of NMe3 and protons of Ph groups. The molecular structures were finally confirmed by X-ray crystallography [24]. Compounds 1 and 2 crystallizes in the monoclinic space group C2/c and in the orthorhombic space group P212121 and their asymmetric unit contains one discrete [M(Tab)3]n+ cation and two (1) or three (2) ClO 4 anions. As shown in Figs. 1 and 2, the M centre in [M(Tab)3]n+ cation is coordinated by three S atoms of the three Tab ligands to form a trigonal pyramidal geometry. The mean ˚ ) in 1 is slightly primary Pb–S bond length (2.716(3) A
Fig. 1. View of a section of the 1D cationic chain of 1 along the b axis. The ClO 4 anions and all H atoms are omitted for clarity. Selected bond lengths ˚ ) and angles (): Pb1–S1 2.701(3), Pb1–S2 2.763(3), Pb1–S3 2.683(3), (A Pb1 S1A 3.503(3), Pb1 S2A 3.424(3); S1–Pb1–S2 82.77(9), S1–Pb1–S3 94.15(10), S2–Pb1–S3 95.53(9), S1–Pb1 S2A 105.81(6), S2–Pb1 S1A 108.53(6), S3–Pb1 S1A 86.40(9), S3–Pb1 S2A 84.99(8), S1A Pb1 S2A 62.86(6). Symmetry code: A: 0.5 x, 0.5 + y, 0.5 z.
Fig. 2. View of a section of the 1D cationic chain of 2 along the a axis. The ClO 4 anions and all H atoms are omitted for clarity. Selected bond lengths ˚ ) and angles (): Bi1–S1 2.564(3), Bi1–S2 2.611(3), Bi1–S3 2.593(3), (A Bi1 S1A 3.490(3), Bi1 S3A 3.234(3), Bi1 S2B 3.260(3); S1–Bi1–S2 82.77(9), S1–Bi1–S3 94.15(10), S2–Bi1–S3 95.53(9), S1–Bi1 S3A 92.93(6), S1–Bi1 S2B 72.33(6), S2–Bi1 S1A 67.85(5), S2–Bi1 S3A 73.45(5), S3–Bi1 S1A 102.79(5), S3–Bi1 S2B 73.22(5), S1A Bi1 S3A 68.15(6), S1A Bi1 S2B 126.11(5), S3A Bi1 S2B 118.55(5). Symmetry codes: A: 0.5 + x, 0.5 y, 1 z; B: 0.5 + x, 0.5 y, 1 z.
shorter than that found in [Pb2(SCH2CH2NMe3)5](PF6)4 ˚ ) [2]. The mean primary Bi–S bond length (2.73(3) A ˚ ) in 2 is comparable to those in Bi[SC6H2(2.599(3) A ˚ ) [26a] and (NH4)3[Bi(2-SC6H4(2,4,6-t-Bu3)]3 (2.559(8) A ˚ ) [26b], but shorter than that COO)3] Æ 2H2O (2.596(8) A ˚ ) [14]. in Bi(SCH2CH2NHMe2)Cl3 (2.798(3) A The secondary interactions between M atom and the S atom of Tab in 1 and 2 deserve comment. The Pb1 in the [Pb(Tab)3]2+ dication in 1 is further linked by the two weak interactions between Pb1 and S1A and S2A atoms of the two Tab ligands from the adjacent dication, forming a pseudo square-pyramidal geometry. The resulting PbðTabÞ2þ 5 square-pyramid shares two edges of the neighboring equivalents in a up-and-down way to form a 1D cationic chain extending along the b axis (Fig. 1). On the other hand, the Bi1 in the [Bi(Tab)3]3+ trication in 2 is further linked by three secondary interactions between Bi1 and S1A, S2A or S2B of the three Tab ligands from two neighboring trications, forming a pseudo distorted octahedral geometry. The resulting BiðTabÞ3þ 6 octahedron shares with six edges of the two adjacent ones to form another 1D cationic chain extending along the a axis (Fig. 2). As there is a 21 axis running along the a axis, the polymeric structure of 2 may be alternatively viewed as an approximately spiral ˚ and chain. The M M contacts in 1 and 2 are 4.858(3) A ˚ 4.244(3) A, respectively, which excludes any metal–metal interaction. The M atoms in 1 and 2 are nearly co-linear with torsion angels of 178.47(4) for 1 and 174.85(4) for 2 between neighboring M M linkages. Between these
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References
Fig. 3. Cyclic voltammograms of 0.5 mM solutions of 1 and 2 in DMF containing 0.05 M Et4NClO4, using a 2 · 2 mm2 Pt slice as working electrode and Pt wire as counter electrode. The scan rates are 100 mV s1.
cationic chains are perchlorate anions, which are attracted through ionic interactions by the positive –NMeþ 3 ends of the Tab ligands. The electrochemical properties of 1 and 2 were investigated by cyclic voltammetry in DMF. The cyclic voltammagrams (Fig. 3) consist of one irreversible reduction at 0.78 V for 1 or 0.69 V for 2 and two irreversible oxidations at 0.13 V and 0.48 V for 1 or 0.005 V and 0.59 V for 2. It is assumed that the Pb(II) in 1 or Bi(III) in 2 is reduced to free metals at a low potential at 0.7 V, while the Tab ligands in 1 and 2 are likely to be oxidized by two steps: a oxidative dimerization of the sulfur atoms (formation of the (Tab)2 dication) [16a,16e,16f] at 0 V and the subsequently oxidization of (Tab)2 dication to the thiosulfate Me3 N þ PhSSO 3 [16g] at 0.5 V. Acknowledgements This work was supported by the NNSF (No. 20525101), the NSF of Jiangsu Province (No. BK2004205), the Specialized Research Fund for the Doctoral Program of Higher Education (No. 20050285004), and the State Key Laboratory of Coordination Chemistry of Nanjing University and the Qin-Lan Project of Jiangsu Province in China. Appendix A. Supplementary material CCDC 650340 and 650341 contains the supplementary crystallographic data for 1 and 2. These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/ conts/retrieving.html, or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK, fax: (+44) 1223-336-033, or e-mail: deposit@ ccdc.cam.ac.uk. Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.inoche.2007.08.004.
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(3 mL) were removed while the left yellow anolyte was stirred continuously for 10 min and then filtered. Et2O was allowed to slowly diffuse into the filtrate to give yellow crystals of 1 or 2 after several days. Yield: 67% (1) and 71% (2). Anal. Calcd for C27H39Cl2N3O8PbS3 (1): C 35.72, H 4.33, N 4.63. Found: C 36.21, H 4.66; N 4.21%. IR (KBr, cm1): 3052 (w), 1630 (w), 1578 (m), 1484 (vs), 1413 (s), 1085 (vs), 1008 (s), 953 (s), 825 (s), 745 (s), 624 (vs), 551 (s). 1H NMR (CD3CN, 400 MHz, ppm): d 3.476 (s, 27H, –CH3), 7.465 (s, 12H, –Ph). Anal. Calcd for C27H39Cl3N3O12BiS3 (2): C 32.13, H 3.90, N 4.16. Found: C 31.86, H 4.05; N 4.33%. IR (KBr, cm1): 3049 (w), 1624 (w), 1578 (m), 1489 (vs), 1411 (s), 1086 (vs), 1010 (s), 954 (s), 828 (s), 754 (s), 624 (vs), 555 (s). 1H NMR (CD3CN, 400 MHz, ppm): d 3.529 (s, 27H, –CH3), 7.430–7.712 (m, 12H, –Ph). [24] Crystal data for 1: C27H39Cl2N3O8PbS3, Mr = 907.88, yellow crystal (0.18 · 0.16 · 0.10 mm), monoclinic, space group C2/c, a = ˚, ˚, ˚, 40.423(8) A b = 9.914(2) A c = 18.230(4) A b = 111.44(3), ˚ 3, Z = 8, Dc = 1.774 g/cm3, F(0 0 0) = 3600 and V = 6800(2) A l = 5.353 mm1. T = 193 K; 32442 reflections collected, 6201 unique (Rint = 0.0650). R1 = 0.0721, wR2 = 0.1491 and S = 1.140 based on 4882 observed reflections with I > 2r(I). Crystal data for 2: C27H39BiCl3N3O12S3, Mr = 1009.12, yellow crystal (0.25 · 0.20 · 0.10 mm), ˚, b= orthorhombic, space group P212121, a = 8.4793(17) A ˚ , c = 25.268(5) A ˚ , V = 3960.0(14) A ˚ 3, Z = 4, Dc = 18.483(4) A
1.693 g/cm3, F(0 0 0) = 2000 and l = 4.870 mm1. T = 193 K; 39599 reflections collected, 7239 unique (Rint = 0.0462). R1 = 0.0594, wR2 = 0.1681 and S = 1.102 based on 6496 observed reflections with I > 2r(I). Data collections were performed on a Rigaku Mercury CCD diffractomer with graphite-monochromated Mo Ka radiation ˚ ). The structures were solved by direct methods and (k = 0.71073 A refined with full-matrix least-squares technique using SHELXL-97 program [25]. Two methyl groups and two perchlorate anions in 1 were disordered over two sites with occupancy factors of 0.62/0.38 for atoms N1/N1A, C7–C9/C7A–C9A, N3/N3A, C25–C27/C25A– C27A, O5–O7/O5A–O7A, and 0.48/0.52 for atoms O1–O4/O1A– O4A. The disordered non-H atoms were refined isotropically, while all other non-H atoms were refined anisotropically. All H atoms were ˚ for methyl placed in geometrically idealized positions (C–H = 0.98 A ˚ for phenyl groups) and constrained to ride groups and C–H = 0.95 A on their parent atoms with Uiso(H) = 1.2Ueq(C). [25] G.M. Sheldrick, SHELXL-97 and SHELXS-97, Program for X-ray Crystal Structure Solution and Refinement, University of Go¨ttingen, 1997. [26] (a) D.A. Atwood, A.H. Cowley, R.D. Hernandez, R.A. Jones, L.L. Rand, S.C. Bott, J.L. Atwood, Inorg. Chem. 32 (1993) 2972; (b) D.S. Sagatys, G. Smith, R.C. Bott, P.C. Healthy, Aust. J. Chem. 56 (2003) 941.