Supporting Information for Inorganic Chemistry

Transcription

1 Supporting Information for Inorganic Chemistry Binuclear Ruthenium Complexes Based on Anthracene Derivatives as idging Ligands: Electrochemical and Spectroscopic Evidences of an Electronic Communication through the Conjugated System eus Vilà, Yu-Wu Zhong, Jay C. Henderson and Héctor D. Abruña* Baker Laboratory, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, ew York Table of Contents: 1. Synthetic procedure and Characterization

2 Synthetic Procedures and Characterization. General. All the reactions were carried out under an inert atmosphere of nitrogen using standard Schlenk techniques unless otherwise noted. 1H-MR (300 MHz) spectra were recorded on a Varian Mercury 300 MHz FT-MR spectrometer and referenced relative to residual proton resources. Materials. All solvents and chemicals for synthesis were commercially available of reagent grade quality and were used without any further purification except as noted below. Experiments involving air-or water-sensitive reagents were carried out using standard Schlenck tube techniques under a nitrogen atmosphere. 2,6-diamino-anthraquinone (97 %+), anthrone (97 %+), copper (II) bromide (99 %+), tetrabutylammonium hexafluorophosphate (n-bu 4 PF 6 ) (98 %) were purchased from Aldrich Chemical Co. and used as received. 1,5-diamino-anthraquinone (85 %+) was from Aldrich Co. 2,7-dinitro-9,10-anthraquinone, 2,7-diamino-9,10-anthraquinone, 2,7-dibromo-9,10- anthraquinone, 2,6-dibromo-9,10-anthraquinone, 1,5-dibromo-9,10-anthraquinone, 2,6- dibromo-9,10-diphenylanthracene, 2,7-dibromo-9,10-diphenylanthracene, 1,5-dibromo- 9,10-diphenylanthracene, 2,6-dibromo-9,10-anthracene, 2,7-dibromo-9,10-anthracene and 1,5-dibromo-9,10-anthracene were prepared following literature procedures. Synthesis of 2,7-dibromoanthraquinone. Anhydrous copper (II) bromide (2.4 g, 10.7 mmol), tert-butylnitrite (1.5 ml, 12.6 mmol) and anhydrous acetonitrile (250 ml) were mixed together under nitrogen atmosphere in a three-neck round-bottom flask and heated to 65 C. The 2,7-diamino-9,10-anthraquinone

3 (1.0 g, 4.1 mmol) was slowly added to the reaction mixture for a period of 30 minutes. After nitrogen evolution the reaction mixture was cooled to room temperature and poured into an aqueous HCl solution (100 ml, 20% w/v). The resulting precipitate was filtered, washed with ether and chromatographed on a silica gel column eluting with hexane/dichloromethane (1:1, v/v) to afford a pale yellow solid. Yield: 0.9 g (60%). 1 H-MR (300 MHz, CDCl 3 ) δ 8.44 (d, 2 H), 8.18 (d, 2 H), 7.95 (dd, 2 H). 2,6- and 1,5-dibromo-9,10-anthraquinones were synthesized by procedures analogous to those used for the synthesis of 2,7-dibromo-9,10-anthraquinone. 2,6-dibromo-9,10-anthraquinone: 65 % yield from 2,6-diamino-9,10-anthraquinone. 1 H- MR (300 MHz, CDCl 3 ) δ 8.23 (d, 2 H), 8.06 (d, 2 H), 7.57 (dd, 2 H). 1,5-dibromo-9,10-anthraquinone: 72 % yield from 1,5-diamino-9,10-anthraquinone 1 H- MR (300 MHz, CDCl 3 ) δ 8.36 (dd, 2 H), 7.93 (dd, 2 H), 7.44 (t, 2 H). 1,5-dibromoanthracene: 34 % yield from 1,5-dibromo-9,10-anthraquinone 1 H-MR (300 MHz, CDCl 3 ) δ 8.75 (s, 2 H), 8.24 (d, 2 H), 7.98 (d, 2 H), 7.65 (t, 2 H). 2,6-dibromoanthracene: 39 % yield from 2,6-dibromo-9,10-anthraquinone 1 H-MR (300 MHz, CDCl 3 ) δ 8.56 (s, 2 H), 7.95 (s, 2 H), 7.72 (d, 2 H), 7.56 (dd, 2 H) 2,7-dibromoanthracene: 42 % yield from 2,7-dibromo-9,10-anthraquinone 1 H-MR (300 MHz, CDCl 3 ) δ 8.95 (s, 2 H), 8.75 (s, 2 H), 7.93 (s, 2 H), 7.72 (d, 2 H), 7.58 (dd, 2 H). 1,5-bis(ethynil)anthracene: 77 % yield from 1,5-dibromoanthracene. 1 H-MR (300 MHz, CDCl 3 ) δ 8.89 (s, 2 H), 8.10 (m, 2 H), 7.67 (m, 4 H), 2.88 (s, 2 H) 2,6-bis(ethynil)anthracene: 82 % yield from 2,6-dibromoanthracene 1 H-MR (300 MHz, CDCl 3 ) δ 8.45 (s, 2 H), 8.15 (d, 2 H), 7.99 (d, 2 H), 7.77 (dd, 2 H), 3.08 (s, 2 H)

4 2,7-bis(ethynil)anthracene: 80 % yield from 2,7-dibromoanthracene 1 H-MR (300 MHz, CDCl 3 ) δ 8.52 (s, 1 H), 8.37 (s, 1 H), 8.23 (d, 2 H), 8.05 (d, 2 H), 2.98 (s, 2 H). Synthesis of 2,7-, 2,6- and 1,5-dibromo-9,10-dihydroxy-9,10-dihydroanthracene. Dibromo-9,10-anthraquinones were converted into dibromo-9,10-dihydroxy-9,10- dihydroanthracene derivatives by following a literature procedure. 1 Synthesis of 2,7-, 2,6- and 1,5-dibromo-9,10-diphenylanthracene derivatives. Dibromo-9,10-diphenylanthracene derivatives were synthesized from the appropriate dibromo-9,10-anthraquinone derivatives following a literature procedure. 2 2,6-dibromo-9,10-diphenylanthracene: 1 H-MR (300 MHz, CDCl 3 ) δ 8.15 (d, 2 H), 7.85 (dd, 2 H), 7.65 (d, 2 H), 7.47 (d, 4 H), 7.32 (m, 6 H). 2,7-dibromo-9,10-diphenylanthracene: 1 H-MR (300 MHz, CDCl 3 ) δ 8.08 (d, 2 H), 7.73 (dd, 2 H), 7.52 (m, 6 H), 7.12 (m, 6 H). 1,5-dibromo-9,10-diphenylanthracene: 1 H-MR (300 MHz, CDCl 3 ) δ 7.85 (dd, 2 H), 7.68 (dd, 2 H), 7.51 (m, 4 H), 7.42 (t, 2 H), 7.31 (m, 6 H). 2,6-bis(ethynil)-9,10-diphenylanthracene: 1 H-MR (300 MHz, CDCl 3 ) δ 7.63 (d, 2 H), 7.56 (d, 2 H), 7.53 (dd, 2 H), 7.38 (dd, 4 H), 7.17 (m, 6 H), 2.78 (s, 2 H) 2,7- bis(ethynil)-9,10-diphenylanthracene: 1 H-MR (300 MHz, CDCl 3 ) δ 7.65 (d, 2 H), 7.54 (d, 2 H), 7.45 (dd, 2 H), 7.38 (ddd, 4 H), 7.15 (m, 6 H), 2.95 (s, 2 H). 1,5- bis(ethynil)-9,10-diphenylanthracene: 1 H-MR (300 MHz, CDCl 3 ) δ 7.75 (d, 2 H), 7.45 (m, 6 H), 7.30 (m, 8 H), 2.88 (s, 2 H). Syntheses. 1 Criswell, T. R; Klanderman, B. H. J. Org. Chem. 1974, 39, Yang, W. J.; Kim, D. Y. ; Jeong, M-Y. ; Kim, H. M. ; Lee, Y. K.; Fang, X.; Jeon, S-J.; Cho, B. R. Chem. Eur. J. 2005, 11, 4191.

5 The preparation of the binuclear ruthenium complexes, 1 6, consisted of the separate synthesis of the anthracene and diphenylanthracene precursors and the mononuclear complex, [Ru(bpy) 2 (phpy)](pf 6 ), as described below. Preparation of the anthracene derivatives. Anthracene derivatives were synthesized from the appropriate dibromo substituted 9,10-anthraquinones which were obtained via Sandmeyer reaction from the corresponding diamine substituted anthraquinones. 3 In turn, 2,6-diamino- and 1,5-diamino-9,10-anthraquinones were from commercial sources. 2,7-diamino-9,10-anthaquinone was synthesized by following a procedure described in the literature. 4b To prepare 9,10-diphenylanthracene derivatives, dibromo-9,10- anthraquinones were reacted with phenyl magnesium bromide in anhydrous tetrahydrofuran at room temperature and subsequently treated with Zn powder in aqueous acetic acid solution at 120 C. On the other hand, to afford the simplest anthracene cores, 9,10-anthraquinones were reduced with sodium borohydride yielding to 9,10-dihydroxy- 9,10-dihydroanthracenes in methanol that were converted to the corresponding anthrones by dehydratation in aqueous hydrochloric acid. Reduction of the anthrones was performed by reaction with sodium borohydride yielding to the dibromo substituted anthracenes. Subsequently, bis(ethynyl)anthracene derivatives were synthesized via Sonogashira coupling reactions of the appropriate dibromoanthraquinone with ethynyltrimethylsilane followed by deprotection of the trimethylsilyl groups by refluxing the mixture for 12 h in the presence of 2 equivalents of potassium fluoride in methanol. 3 (a) Hodge, P.; Power, G. A.; Rabjohs, M. A. Chem. Commun. 1997, (b) Yang, J.; as, A.; Rawashdeh, A.-M. M.; Sotiriou-Leventis, C.; Panzner, M. J.; Tyson, D. S.; Kinder, J. D.; Leventis,. Chem. Mater. 2004, 16, (c) Lu, Z.; Lord, S. J.; Wang, H.; Moerner, W. E.; Twieg, R. J. J. Org. Chem. 2006, 71,

6 Preparation of the mononuclear ruthenium complex. The preparation of the monometallic ruthenium complexes was performed from commercial ruthenium trichloride following the methods described in the literature. cis-[ru(bipy) 2 Cl 2 ] was firstly prepared by refluxing a mixture of ruthenium trichloride and bipyridine in the presence of LiCl in dimethylformamide overnight. 4 Subsequently, reaction with an excess of 2-phenylpyridine in the presence of silver (I) tetrafluoroborate afforded [Ru(bipy) 2 (phpy)](bf 4 ). 5 Exchange reaction was carried out in methanolic solution containing H 4 PF 6 and afforded [Ru(bipy) 2 (phpy)](pf 6 ) as a red dark crystalline solid. An unique brominated compound, [Ru(bipy) 2 (p-phpy)]pf 6, was obtained upon treatment of the complex with 1.1 equivalents of -bromosuccinimide in acetonitrile at room temperature as previously reported. 6 Palladium-catalyzed cross coupling reaction for the synthesis of the homobimetallic compounds (1 6). As illustrated in Scheme 3, the homobinuclear ruthenium complexes 1 6 were synthesized from the appropriate substituted bis(ethynyl)anthracene derivative and the brominated mononuclear ruthenium complex by a classical Sonogashira crosscoupling reaction. A solution of the monobrominated mononuclear ruthenium complex (150 mg, 0.19 mmol), Pd(PPh3)4 (10 mg, 0.01 mmol), CuI (10 mg, 0.05 mmol) and 0.09 mmol of the bis(ethynyl)-9,10-anthracene derivative in 5 ml of DMF were heated under argon for 48 h. After this period, the solvent was removed in vacuo. To the red residue was added H 4 PF 6 (100 mg) in acetonitrile (5 ml). The solution was stirred and evaporated to dryness. The solid was dissolved in CH 2 Cl 2, in which the excess of PF 6 4 (a) Sullivan, B. P.; Salmon, D. J.; Meyer, T. J. Inorg. Chem. 1978, (b) Villegas, J. M.; Stoyanov, S. R.; Huang, W.; Lockyear, L. L.; Reibenspies, J. H.; Rillema, P. Inorg. Chem. 2004, Constable, E. C.; Holmes, J. M. J. Organomet. Chem. 1986, 301, Coudret, C.; Fraysse, S.; Launay, J.-P. Chem. Commun. 1998, 663.

7 salt. After filtration the solvent was removed and the resulting dark red solid was purified by column chromatography on silica gel with a 4:6 toluene/acetonitrile mobile phase. The complex was completely desorbed in a concentrated H 4 PF 6 solution in acetonitrile. After removal of the solvent, the residue was retaken in CH 2 Cl 2 and then the solution was concentrated and diethyl ether was added to precipitate the complex. Complex 1: 25 % yield from 2,7-bis(ethynyl)-9,10-diphenylanthracene. 1 H-MR (300 MHz, DMSO) δ ES-MS m/z: (M PF 6 ) +, (M PF 6 Ru(bpy) 2 ) +, (M 2PF 6 ) 2+ Complex 2: 21 % yield from 2,7-bis(ethynyl)anthracene. 1 H-MR (300 MHz, DMSO) δ ES-MS m/z: ((M PF 6 ) +, (M PF 6 Ru(bpy) 2 ) +, (M 2PF 6 ) 2+ Complex 3: 22 % yield from 2,6-bis(ethynyl)-9,10-diphenylanthracene. 1 H-MR (300 MHz, DMSO) δ ES-MS m/z: (M PF 6 ) +, (M PF 6 Ru(bpy) 2 ) +, (M 2PF 6 ) 2+ Complex 4: 27 % yield from 2,6-bis(ethynyl)anthracene. 1 H-MR (300 MHz, DMSO) δ- MS m/z: ((M PF 6 ) +, (M PF 6 Ru(bpy) 2 ) +, (M 2PF 6 ) 2+ Complex 5: 17 % yield from 1,5-bis(ethynyl)-9,10-diphenylanthracene. 1 H-MR (300 MHz, DMSO) δ ES-MS m/z: (M PF 6 ) +, (M PF 6 Ru(bpy) 2 ) +, (M 2PF 6 ) 2+ Complex 6: 25 % yield from 1,5-bis(ethynyl)anthracene. 1 H-MR (300 MHz, DMSO) δ- MS m/z: ((M PF 6 ) +, (M PF 6 Ru(bpy) 2 ) +, (M 2PF 6 ) 2+

8 O H 2 H 2 O t BuOO, Cu2 CH 3 C, 80 C O O 1) PhMg anh. THF, RT, 4h 2) Zn(s), CH 3 CO 2 H 0.5 M 120 C, 3h (H 3 C) 3 SiC CH Pd(PPh 3 ) 2 Cl 2, CuI, H(i-Pr) 2 anh. THF, 2, reflux 24 h TMS TMS 4 eq. abh 4 methanol, reflux 6h OH OH CH 3 CO 2 H 0.5 M 120 C, 4h - H 2 O O 5 eq. abh 4 isopropanol, reflux 12h (H 3 C) 3 SiC CH Pd(PPh 3 ) 2 Cl 2, CuI, H(i-Pr) 2 anh. THF, 2, reflux 24 h TMS TMS

9

10 (PF 6 ) C Ru

11 (PF 6) 2 Ru C C Ru

12 (PF 6) 2 Ru C C Ru