DOI: 10.1002/chem.201501080
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Group 9 Metal Complexes of meso-Aryl-Substituted Rubyrin Takanori Soya and Atsuhiro Osuka*[a] Abstract: The metalation of meso-tetrakis(pentafluorophenyl)-substituted [26]rubyrin has been explored with Group 9 metal salts (RhI, CoII, IrIII), affording a Hìckel aromatic [26]rubyrin–bis-RhI complex with a highly curved gable-like structure, a Hìckel antiaromatic [24]rubyrin–bisCoII complex that displays intramolecular antiferromagnetic coupling between the two CoII ions (J = ¢4.5 cm¢1), and two Cp*-capped IrIII complexes; in one, the iridium metal sits on the [26]rubyrin frame with two Ir¢N bonds, whereas the other has an additional Ir¢C bond, although both IrIII complexes display moderate aromatic character. This work demonstrates characteristic metalation abilities of this [26]rubyrin toward Group 9 metals.
of 5,10-bis(pentafluorophenyl)-substituted tripyrromethane along with its higher homologues.[5] [26]Rubyrin 1 is a planar aromatic macrocycle and can be quantitatively oxidized with MnO2 to give [24]rubyrin 2, which can be easily reduced back to 1 with NaBH4. Intriguingly, protonated 1 has been shown to take different conformations depending upon the counter anion, showing its promising potential as an anion sensor.[6] Core-modified rubyrins have been shown to serve as anion and cation sensors.[1c] Despite these promising properties, metalation of rubyrins has been scarcely explored,[6, 7] which contrasts to extensively developed metalation chemistry of regular hexaphyrins.[2, 8]To our knowledge, only ZnII and RhI ions have been used for complexation of rubyrins. Upon treatment with Zn(OAc)2·2 H2O, rubyrins 1 and 2 gave bis-ZnII complexes 3 and 4, which displayed 26 p aromatic character and 24 p antiaromatic charac-
A recent surge in the development of expanded porphyrins is attributed to their attractive optical, electrochemical, and coordination properties.[1] In particular, expanded porphyrins serve as promising multi-coordinating ligands, allowing formation of multi-metal complexes with notable metal–metal interactions and novel structures.[2] Rubyrins are hexaphyrin variants that lack two of the meso-carbons found in regular hexaphyrin (1.1.1.1.1.1) species and can thus be delineated as hexaphyrin (1.1.0.1.1.0). The chemistry of rubyrins started with the synthesis of b-dodecaalkyl-substituted rubyrins by Sessler et al. in 1991,[3] II which was followed by the syn- Scheme 1. Redox behavior and Zn metalation of rubyrins 1 and 2. thesis of various core-modified rubyrins by Chandrashekar and co-workers.[1c, 4] In the course of our investigations on expandter, respectively (Scheme 1).[6] A few mono- and bis-RhI comed porphyrins, we synthesized meso-tetrakis(pentafluorophenplexes of core-modified rubyrins have also been synthesized.[7] yl)-substituted [26]rubyrin 1 by an oxidative coupling reaction In 2009, we reported the synthesis of bis-RhI complexes of [26]- and [28]hexaphyrins (1.1.1.1.1.1), which were aromatic [a] T. Soya, Prof. Dr. A. Osuka and antiaromatic molecules, respectively, and quantitatively inDepartment of Chemistry, Graduate School of Science terconverted upon two-electron reduction and oxidation.[9] Kyoto University, Sakyo-ku, Kyoto, 606-8502 (Japan) These molecules serve as a platform to demonstrate aromaticiE-mail: [email protected] ty reversal from the ground-state to the lowest triplet excited Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.201501080. state (T1 state).[10] In their photoexcited states, the RhI ions play Chem. Eur. J. 2015, 21, 10639 – 10644
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Communication important roles to rigidify the hexaphyrin frameworks and facilitate intersystem crossing to the T1 state by their heavy atom effect. It occurred to us that a similar bis-RhI complex may be synthesized from 1, since [26]rubyrin 1 possesses two dipyrromethene moieties and a planar conformation, similarly to the [26]hexaphyrin. In light of this, we embarked on the synthesis of RhI complexes of 1, which in turn led us to explore Group 9 metal complexes of 1. By following a method used in the previously reported RhI metalation of [26]hexaphyrin,[9] metalation of 1 with [RhICl(CO)2]2 was attempted under various conditions. We tested the metalation conditions by changing solvent, base, and temperature, but even in the best run (with 2 equivalents of [RhICl(CO)2]2 in the presence of 5 equivalents of sodium acetate at room temperature for 2.5 h), bis-RhI complex 5 (Scheme 2) was obtained only in a poor yield (5 %) after isolation by column chromatography on silica gel. High-resolution electrospray ionization time-of-flight mass spectrometry (HRESI-TOF MS) revealed the parent ion peak of 5 at m/ z 1420.8908 ([M + H] + ; m/z calcd for C56H15N6F20O4Rh2 : 1420.8940). Single crystal X-ray diffraction revealed its solid-
Figure 1. X-ray crystal structure of 5. One of two rubyrin molecules in the unit cell is shown. a) Top view; b) side view. Thermal ellipsoids are depicted at 50 % probability. Solvent molecules are omitted for clarity. c) Schematic drawings of the coordination environments around RhI. Values in parentheses indicate the second rubyrin molecule in the unit cell.
Scheme 2. Metalation of [26]rubyrin 1 with Group 9 metal ions. Chem. Eur. J. 2015, 21, 10639 – 10644
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state structure to be a gable-like C2v-symmetric structure, in which the two RhI ions are positioned at the bipyrrole moieties (Figure 1).[11a] Although two crystallographically independent molecules are found in the unit cell, they show no significant difference. The overall structure of 5 is similar to those of previously reported bis-RhI complexes of core-modified rubyrins.[7] The bond lengths around the RhI centers [æ] are as follows: N1¢Rh1 2.091 (2.092), N6¢Rh1 2.099 (2.091), N3¢Rh2 2.089 (2.092), N4¢Rh2 2.092 (2.090), C29¢Rh1 1.849 (1.852), C30¢Rh1 1.952 (1.839), C31¢Rh2 1.840 (1.870), C32¢Rh2 1.871 (1.865). Values in parentheses apply to the second complex in the unit 10640
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Communication cell. Interestingly, the dihedral angles between the two planes defined by the bipyrrole units are almost perpendicular (84.1 and 81.78). The 1H NMR spectrum of 5 shows a singlet at d = 8.18 ppm and two doublets at d = 8.14 and 7.75 ppm due to the outer b-pyrrolic protons and a singlet at d = ¢2.87 ppm due to the inner pyrrolic NH protons, indicating a distinct diatropic ring current. The UV/Vis/NIR absorption spectrum of 5 shows an intense Soret-like band at l = 566 nm and distinct Qlike bands at l = 842 and 933 nm, also supporting the aromatic character of 5 (Figure 2). These data allowed us to delineate 5
Figure 2. UV/Vis/NIR absorption spectra of 5, 6, 7, and 8 in CH2Cl2.
as a bis-RhI complex of a [26]rubyrin, the cyclic electronic network of which is conjugated despite the large dihedral angle of the two dipyrromethene units. To synthesize the corresponding bis-RhI complex of [24]rubyrin, oxidation of 5 was attempted under various conditions, but, disappointingly, all of our attempts led to the decomposition of 5. We next examined the metalation of 1 with CoII as another Group 9 metal. After extensive screening of metalation conditions, a reaction of 1 with 10 equivalents of Co(OAc)2·4 H2O and 10 equivalents sodium acetate under reflux for 1 h gave the optimal yield of the desired product. After the usual workup, bis-CoII complex 6 (Scheme 2) was obtained as a red solid in a moderate yield (56 %) directly via recrystallization from CCl4/n-hexane. HR-ESI-TOF MS revealed the parent ion peak of 6 at m/z 1335.9739 ([M]¢ ; m/z calcd for C56H18N6F20O2Co2 : 1335.9740). Complex 6 was revealed by X-ray diffraction to adopt a highly bent conformation.[11b] The two CoII ions are bound to the tripyrrolic NNN ligand and are bridged by the two acetate ions in a symmetric manner. The bond lengths around the CoII centers [æ] are as follows: Co1¢ N1 2.135, Co1¢N2 1.991, C1¢N3 2.126, Co1¢O2 1.983, Co1¢O3 2.028, Co2¢N4 2.089, Co2¢N5 1.981, Co2¢N6 2.151, Co2¢O1 2.013, and Co2¢O3 2.028 (Figure 3). Both CoII ions in 6 adopt trigonal bipyramidal coordination with two nitrogen atoms (N1 and N3 for Co1 and N4 and N6 for Co2) at the apical positions and a nitrogen atom (N2 for Co1 and N5 for Co2) and two oxygen atoms (O2 and O3 for Co1 and O1 and O3 for Co2) at the equatorial positions. The 1H NMR spectrum of 6 shows signals in a symmetric pattern in an extremely downfield region; a singlet at d = 80.62 ppm due to the acetoxy groups and three singlets at d = 33.91, 19.93, and 10.73 ppm due to the bpyrrolic protons, reflecting the paramagnetic shift of CoII ions. Chem. Eur. J. 2015, 21, 10639 – 10644
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Figure 3. X-ray crystal structure of 6. a) Top view; b) side view. Thermal ellipsoids are depicted at 50 % probability. Solvent molecules are omitted for clarity. c) Schematic drawings of the coordination environments around CoII.
We prepared complex [D6]6 bearing CD3CO2 bridges instead of CH3CO2 by the reaction of 1 with CoCl2 in the presence of [D4]acetic acid. The signal due to the acetoxy groups disappeared in the 1H NMR spectrum of [D6]6, in line with our assignment (see the Supporting Information). These data led to a conclusion that complex 6 is a bis-CoII complex of [24]rubyrin. Therefore, it was considered that the [26]rubyrin macrocycle had undergone two-electron oxidation during the metalation. Variable temperature magnetic susceptibility measurement of 6 indicated that the oxidation states of the two Co ions are + 2 with a S = 3/2 high spin state and that these CoII ions exhibit antiferromagnetic coupling with J = ¢4.5 cm¢1 (Figure 4). The absorption spectrum of 6 shows ill-defined absorption bands at 424 and 556 nm and a weak absorption tail reaching to 1600 nm, in line with the assignment of 6 as a 24 p-electron Hìckel antiaromatic species (Figure 2). Although the largest dihedral angle along the p-conjugated circuit is almost perpendicular (85.08), complex 6 preserves its macrocyclic p-conjugation. Note that complex 6 is a rare example of a bis-CoII-metalated porphyrinoid.[12]
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Figure 4. cp T vs. T plots for 6. Circles and solid line denote the observed and calculated cp T values, respectively.
Finally, we examined the metalation of 1 with Ir salts. Firstly, by following the previously reported method,[13] [26]rubyrin 1 was treated with [IrICl(cod)]2 in the presence of sodium acetate in THF, which afforded an Ir complex as detected by MALDI-TOF MS. However, this complex could not be isolated because of its very facile demetalation during workup and separation procedures. Thus, we changed the Ir ion source to [IrIIICl2Cp*]2 (Cp* = pentamethylcyclopentadienyl anion) with an expectation that the bulky Cp* cap may prevent IrIII demetalation. A solution of 1 in THF was treated with 0.75 equivalents of [IrIIICl2Cp*]2 in the presence of 10 equivalents of potassium tert-butoxide at room temperature for 2 h. After the usual workup, separation over a silica gel column afforded the IrIII complex 7 (Scheme 2) as a red solid in 41 % yield. HR-ESI-TOF MS revealed the parent ion peak of 7 at m/z 1465.1624 ([M + H] + ; m/z calcd for C62H31N6F20Cl1Ir1: 1465.1580). Single crystal Xray diffraction analysis revealed its solid-state structure to be a relatively planar conformation, in which all the pyrroles are pointing inward (Figure 5).[11c] The IrIII ion is bound to the two nitrogen atoms of the dipyrromethene unit as well as the chloride and cyclopentadienyl anions. Although there are two crystallographically independent molecules in the unit cell, they have no significant difference. Representative bond lengths [æ] are as follows: N1¢Ir 2.146 (2.150), N6¢Ir 2.113 (2.119), Cl1¢Ir, 2.125 (2.121). Values in parentheses apply to the second complex in the unit cell. The 1H NMR spectrum of 7 shows twelve doublets in the range of d = 10.94-8.56 ppm due to the outer b-pyrrolic protons, a singlet at d = ¢2.76 ppm due to the fifteen methyl protons, and three singlets at d = ¢3.77, ¢5.18, and ¢12.06 ppm due to the inner pyrrolic NH protons. These 1 H NMR spectral features indicate the presence of a distinct diatropic ring current in 7. The absorption spectrum of 7 shows an intense Soret-like band at l = 526 nm and distinct Q-like bands at l = 747 and 817 nm, again supporting its aromatic character (Figure 2). In the meantime, we found that the metalation of 1 with [IrIIICl2Cp*]2, when conducted in 1,4-dioxane in the presence of potassium tert-butoxide at reflux, gave a different IrIII complex, 8, in 8 % yield (Scheme 2). HR-ESI-TOF MS revealed the parent ion peak of 8 at m/z 1407.1577 ([M¢H]¢ ; m/z calcd for Chem. Eur. J. 2015, 21, 10639 – 10644
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Figure 5. X-ray crystal structure of 7. One of two rubyrin molecules in the unit cell is shown. a) Top view; b) side view. Thermal ellipsoids are depicted at 50 % probability. Solvent molecules are omitted for clarity. c) Schematic drawings of the coordination environment around IrIII. Values in parentheses indicate the second rubyrin molecule in the unit cell.
C62H27N6F19Ir1: 1407.1605). The structure of 8 was also revealed by single crystal X-ray diffraction analysis to be almost planar, with four pyrroles pointing inward and two pyrroles pointing outward (Figure 6).[11d] Although there are two crystallographically independent molecules in the unit cell, they have no significant difference. Representative bond lengths [æ] are as follows: N1¢Ir 2.190 (2.200), N6¢Ir 2.027 (2.005). Values in parentheses apply to the second complex in the unit cell. Interestingly, one of the two outward-pointing pyrroles makes a single C22¢Ir bond with the IrIII center, with a bond length of 2.061 (2.051) æ. Thus, complex 8 can be regarded as a rare example of a porphyrinoid that incorporates an iridium–carbon bond.[13, 14] In addition, one of the pyrroles underwent an Nfusion reaction with the neighboring meso-pentafluorophenyl group.[15] The1H NMR spectrum of 8 shows a singlet at d = 11.17 ppm due to the outer pyrrolic NH proton, eight peaks in the range d = 9.30-7.90 ppm due to the outer b-pyrrolic pro-
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1
=2 Table 1. Oxidation potentials (E ox=2 ), reduction potentials (E red ), and electrochemical HOMO–LUMO gaps (DE) for 1, 3, 4, 5, 6, 7, and 8.[a] 1
1 3 4 5 6 7 8
1
1
1
=2 E ox2 [V]
=2 E ox1 [V]
=2 E red1 [V]
=2 E red2 [V]
DE (eV)
0.39 0.39 – 0.53 0.98 0.40 0.18
¢0.06 0.14 0.72 0.25 0.62 ¢0.04 ¢0.19
¢1.18 ¢1.23 ¢0.47 ¢1.04 ¢0.50 ¢1.38 ¢1.42
¢1.50 ¢1.62 ¢0.83 – ¢0.92 ¢1.57 ¢1.74
1.12 1.37 1.19 1.29 1.12 1.34 1.23
[a] Cyclic voltammograms were measured under the following conditions; solvent: CH2Cl2 ; scan rate: 0.05 Vs¢1; working electrode: Pt; counter electrode: Pt wire; reference electrode: Ag/AgClO4 ; electrolyte: Bu4NPF6.
Figure 6. X-ray crystal structure of 8. One of two rubyrin molecules in the unit cell is shown. a) Top view; b) side view. Thermal ellipsoids are depicted at 50 % probability. Solvent molecules are omitted for clarity. c) Schematic drawings of the coordination environment around IrIII. Values in parentheses indicate the second rubyrin molecule in the unit cell.
tons, a singlet at 4.34 ppm due to the inner NH proton, and three singlets at d = ¢0.50, ¢1.42, and ¢3.14 ppm due to the inner b-pyrrolic protons. These spectral data indicates the presence of a diatropic ring current in 8. The absorption spectrum of 8 shows a considerably broadened Soret-like band at l = 570 nm and weak Q-like bands at l = 673 and 919 nm, in line with its moderate aromatic character (Figure 2). To compare the aromaticity of the complexes, harmonic oscillator model of aromaticity (HOMA)[16] values were calculated on the basis of the crystal structures to be 0.63 for 5, 0.26 for 6, 0.67 for 7, and 0.54 for 8. The electrochemical properties of the rubyrins and their metal complexes were investigated by cyclic voltammetry. The 1 1 =2 oxidation potentials (E ox=2 ), reduction potentials (E red ), and electrochemical HOMO–LUMO gaps (DE) are listed in Table 1. We could not measure the potentials of 2 because of its very poor solubility. Characteristically, the first reduction and oxidation potentials for 4 (¢0.47 and 0.72 V, respectively) and 6 (¢0.50 and 0.62 V, respectively) are distinctly higher than those of the rest molecules, in that only 4 and 6 are [24]rubyrin complexes. Chem. Eur. J. 2015, 21, 10639 – 10644
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The electrochemical HOMO–LUMO gaps of 4 and 6 are also distinctly smaller than those of the others, reflecting their antiaromatic character, whereas the other rubyrins are aromatic molecules. As compared with 1, bis-RhI complex 5 shows distinctly higher oxidation and reduction potentials but IrIII complex 7 displays nearly the same oxidation and reduction potentials and IrIII complex 8 exhibits slightly lower oxidation and reduction potentials. In summary, metalations of [26]rubyrin 1 have been explored with Group 9 metal salts (RhI, CoII, and IrIII) to produce Hìckel aromatic [26]rubyrin–bis-RhI complex 5, with a highly curved gable-like structure, Hìckel antiaromatic [24]rubyrin– bis-CoII complex 6, which displays intramolecular antiferromagnetic coupling (J = ¢4.5 cm¢1) between the two CoII ions, and Cp*-capped IrIII complexes 7 and 8. In 7, the Ir metal is situated on the [26]rubyrin frame with two Ir¢N bonds, whereas that in 8 has an additional Ir¢C bond, in a rare case of an Ir complex of a porphyrinoid. This work demonstrates the characteristic metalation abilities of 1 towards Group 9 metals. Further exploration of other metal complexes of rubyrins and their higher homologues are ongoing in our laboratory.
Acknowledgements This work was supported by the Japan Society for the Promotion of Science (JSPS; KAKENHI grant numbers 25220802 and 25620031). Keywords: aromaticity · Group 9 metals · metalation · porphyrinoids · rubyrin [1] a) J. L. Sessler, D. Seidel, Angew. Chem. Int. Ed. 2003, 42, 5134; Angew. Chem. 2003, 115, 5292; b) M. Ste˛pien´, N. Sprutta, L. Latos-Graz˙yn´ski, Angew. Chem. Int. Ed. 2011, 50, 4288; Angew. Chem. 2011, 123, 4376; c) T. K. Chandrashekar, S. Venkatraman, Acc. Chem. Res. 2003, 36, 676; d) S. Saito, A. Osuka, Angew. Chem. Int. Ed. 2011, 50, 4342; Angew. Chem. 2011, 123, 4432; e) A. Osuka, S. Saito, Chem. Commun. 2011, 47, 4330. [2] a) S. Shimizu, A. Osuka, Eur. J. Inorg. Chem. 2006, 1319; b) J. L. Sessler, E. Tomat, Acc. Chem. Res. 2007, 40, 371. [3] J. L. Sessler, T. Morishita, V. Lynch, Angew. Chem. Int. Ed. Engl. 1991, 30, 977; Angew. Chem. 1991, 103, 1018.
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Communication [4] a) A. Srinivasan, V. R. M. Reddy, S. J. Narayanan, B. Sridevi, S. K. Pushpan, M. Ravikumar, T. K. Chandrashekar, Angew. Chem. Int. Ed. Engl. 1997, 36, 2598; Angew. Chem. 1997, 109, 2710; b) S. J. Narayanan, B. Sridevi, T. K. Chandrashekar, A. Vij, R. Roy, J. Am. Chem. Soc. 1999, 121, 9053. [5] S. Shimizu, W.-S. Cho, J. L. Sessler, H. Shinokubo, A. Osuka, Chem. Eur. J. 2008, 14, 2668. [6] S. Shimizu, R. Taniguchi, A. Osuka, Angew. Chem. Int. Ed. 2005, 44, 2225; Angew. Chem. 2005, 117, 2265. [7] S. J. Narayanan, B. Sridevi, T. K. Chandrashekar, U. Englich, K. RuhlandtSenge, Inorg. Chem. 2001, 40, 1637. [8] a) S. Shimizu, V. G. Anand, R. Taniguchi, K. Furukawa, T. Kato, T. Yokoyama, A. Osuka, J. Am. Chem. Soc. 2004, 126, 12280; b) S. Mori, S. Shimizu, R. Taniguchi, A. Osuka, Inorg. Chem. 2005, 44, 4127; c) S. Mori, A. Osuka, J. Am. Chem. Soc. 2005, 127, 8030; d) S. Mori, S. Shimizu, J.-Y. Shin, A. Osuka, Inorg. Chem. 2007, 46, 4374; e) H. Rath, S. Tokuji, N. Aratani, K. Furukawa, J. M. Lim, D. Kim, H. Shinokubo, A. Osuka, Angew. Chem. Int. Ed. 2010, 49, 1489; Angew. Chem. 2010, 122, 1531; f) T. Yoneda, A. Osuka, Chem. Eur. J. 2013, 19, 7314. [9] H. Rath, N. Aratani, J. M. Lim, J. S. Lee, D. Kim, H. Shinokubo, A. Osuka, Chem. Commun. 2009, 3762. [10] Y. M. Sung, M.-C. Yoon, J. M. Lim, H. Rath, K. Naoda, A. Osuka, D. Kim, Nat. Chem. 2015, 7, 418. [11] a) Crystallographic data for 5: 2(C56H14F20N6O4Rh2)·3(C6H6); Mr = 3075.43; monoclinic; space group C2/c (No. 15); a = 58.202(10), b = 12.933(2), c = 32.369(6) æ; b = 112.371(4)8; V = 22531(6) æ3 ; 1calcd = 1.813 g cm¢1; Z = 8; R1 = 0.0780 [I > 2.0s(I)]; wR2 = 0.2614 (all data); GOF = 1.080; b) Crystallographic data for 6: C56H18F20N6O4Co2·CCl4 ; Mr = 1490.43; monoclinic; space group P21/a (No. 14); a = 14.086(6), b = 22.523(7), c = 18.299(7) æ; b = 108.399(13)8; V = 5509(4) æ3 ; 1calcd = 1.794 g cm¢1; Z = 4, R1 = 0.0808 [I > 2.0s(I)]; wR2 = 0.2957 (all data); GOF = 1.071; c) Crystallographic data for 7: 2(C62H30F20N6Cl1Ir1)·2.07(C6); Mr = 3082.41; monoclinic; space group P21/n (No. 14); a = 19.914(5), b = 22.614(4), c = 29.849(7) æ; b = 103.216(6); V = 13086(5) æ3 ; 1calcd = 1.565 g cm¢1; Z = 4; R1 = 0.0658 [I >
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[12] [13]
[14]
[15]
[16]
2.0s(I)]; wR2 = 0.2100 (all data); GOF = 1.075; d) Crystallographic data for 8: 2(C62H28F19N6Ir1)·2.642(C7H16)·0.518(C7)·1.680(CH2Cl2), Mr = 3271.54; monoclinic; space group P21/n (No. 14); a = 28.173(6), b = 15.137(3), c = 32.386(8) æ; b = 106.153(6); V = 13266(5) æ3 ; 1calcd = 1.638 g cm¢1; Z = 4; R1 = 0.1072 [I > 2.0s(I)]; wR2 = 0.3742 (all data); GOF = 1.097. CCDC 1054739 (5), CCDC 1054740 (6), CCDC 1054741 (7), CCDC 1054742 (8) contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif. M. Suzuki, M.-C. Yoon, D. Y. Kim, J. H. Kwon, H. Furuta, D. Kim, A. Osuka, Chem. Eur. J. 2006, 12, 1754. a) H. Ogoshi, J. Setsune, Z. Yoshida, J. Organomet. Chem. 1978, 159, 317; b) J. H. Palmer, M. W. Day, A. D. Wilson, L. M. Henling, Z. Gross, H. B. Gray, J. Am. Chem. Soc. 2008, 130, 7786; c) T. D. Lash, K. Pokharel, M. Zeller, J. M. Ferrence, Chem. Commun. 2012, 48, 11793; d) K. Naoda, H. Mori, A. Osuka, Chem. Asian J. 2013, 8, 1395. a) K. Yoshida, T. Nakashima, A. Osuka, H. Shinokubo, Dalton Trans. 2011, 40, 8773; b) K. Naoda, A. Osuka, J. Porphyrins Phthalocyanines 2014, 18, 652. a) C.-H. Hung, J.-P. Jong, M.-Y. Ho, G.-H. Lee, S.-M. Peng, Chem. Eur. J. 2002, 8, 4542; b) M. Suzuki, R. Taniguchi, A. Osuka, Chem. Commun. 2004, 2682; c) Y. Inokuma, T. Matsunari, N. Ono, H. Uno, A. Osuka, Angew. Chem. Int. Ed. 2005, 44, 1856; Angew. Chem. 2005, 117, 1890; d) T. Higashino, M. Inoue, A. Osuka, J. Org. Chem. 2010, 75, 7958; e) T. Higashino, A. Osuka, Chem. Sci. 2012, 3, 103. a) T. M. Krygowski, T. M. Cryan´ski, Tetrahedron 1996, 52, 1713; b) T. M. Krygowski, T. M. Cryan´ski, Tetrahedron 1996, 52, 10255.
Received: March 19, 2015 Published online on May 26, 2015
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& Porphyrinoids | Hot Paper |
Group 9 Metal Complexes of meso-Aryl-Substituted Rubyrin Takanori Soya and Atsuhiro Osuka*[a] Abstract: The metalation of meso-tetrakis(pentafluorophenyl)-substituted [26]rubyrin has been explored with Group 9 metal salts (RhI, CoII, IrIII), affording a Hìckel aromatic [26]rubyrin–bis-RhI complex with a highly curved gable-like structure, a Hìckel antiaromatic [24]rubyrin–bisCoII complex that displays intramolecular antiferromagnetic coupling between the two CoII ions (J = ¢4.5 cm¢1), and two Cp*-capped IrIII complexes; in one, the iridium metal sits on the [26]rubyrin frame with two Ir¢N bonds, whereas the other has an additional Ir¢C bond, although both IrIII complexes display moderate aromatic character. This work demonstrates characteristic metalation abilities of this [26]rubyrin toward Group 9 metals.
of 5,10-bis(pentafluorophenyl)-substituted tripyrromethane along with its higher homologues.[5] [26]Rubyrin 1 is a planar aromatic macrocycle and can be quantitatively oxidized with MnO2 to give [24]rubyrin 2, which can be easily reduced back to 1 with NaBH4. Intriguingly, protonated 1 has been shown to take different conformations depending upon the counter anion, showing its promising potential as an anion sensor.[6] Core-modified rubyrins have been shown to serve as anion and cation sensors.[1c] Despite these promising properties, metalation of rubyrins has been scarcely explored,[6, 7] which contrasts to extensively developed metalation chemistry of regular hexaphyrins.[2, 8]To our knowledge, only ZnII and RhI ions have been used for complexation of rubyrins. Upon treatment with Zn(OAc)2·2 H2O, rubyrins 1 and 2 gave bis-ZnII complexes 3 and 4, which displayed 26 p aromatic character and 24 p antiaromatic charac-
A recent surge in the development of expanded porphyrins is attributed to their attractive optical, electrochemical, and coordination properties.[1] In particular, expanded porphyrins serve as promising multi-coordinating ligands, allowing formation of multi-metal complexes with notable metal–metal interactions and novel structures.[2] Rubyrins are hexaphyrin variants that lack two of the meso-carbons found in regular hexaphyrin (1.1.1.1.1.1) species and can thus be delineated as hexaphyrin (1.1.0.1.1.0). The chemistry of rubyrins started with the synthesis of b-dodecaalkyl-substituted rubyrins by Sessler et al. in 1991,[3] II which was followed by the syn- Scheme 1. Redox behavior and Zn metalation of rubyrins 1 and 2. thesis of various core-modified rubyrins by Chandrashekar and co-workers.[1c, 4] In the course of our investigations on expandter, respectively (Scheme 1).[6] A few mono- and bis-RhI comed porphyrins, we synthesized meso-tetrakis(pentafluorophenplexes of core-modified rubyrins have also been synthesized.[7] yl)-substituted [26]rubyrin 1 by an oxidative coupling reaction In 2009, we reported the synthesis of bis-RhI complexes of [26]- and [28]hexaphyrins (1.1.1.1.1.1), which were aromatic [a] T. Soya, Prof. Dr. A. Osuka and antiaromatic molecules, respectively, and quantitatively inDepartment of Chemistry, Graduate School of Science terconverted upon two-electron reduction and oxidation.[9] Kyoto University, Sakyo-ku, Kyoto, 606-8502 (Japan) These molecules serve as a platform to demonstrate aromaticiE-mail: [email protected] ty reversal from the ground-state to the lowest triplet excited Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.201501080. state (T1 state).[10] In their photoexcited states, the RhI ions play Chem. Eur. J. 2015, 21, 10639 – 10644
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Communication important roles to rigidify the hexaphyrin frameworks and facilitate intersystem crossing to the T1 state by their heavy atom effect. It occurred to us that a similar bis-RhI complex may be synthesized from 1, since [26]rubyrin 1 possesses two dipyrromethene moieties and a planar conformation, similarly to the [26]hexaphyrin. In light of this, we embarked on the synthesis of RhI complexes of 1, which in turn led us to explore Group 9 metal complexes of 1. By following a method used in the previously reported RhI metalation of [26]hexaphyrin,[9] metalation of 1 with [RhICl(CO)2]2 was attempted under various conditions. We tested the metalation conditions by changing solvent, base, and temperature, but even in the best run (with 2 equivalents of [RhICl(CO)2]2 in the presence of 5 equivalents of sodium acetate at room temperature for 2.5 h), bis-RhI complex 5 (Scheme 2) was obtained only in a poor yield (5 %) after isolation by column chromatography on silica gel. High-resolution electrospray ionization time-of-flight mass spectrometry (HRESI-TOF MS) revealed the parent ion peak of 5 at m/ z 1420.8908 ([M + H] + ; m/z calcd for C56H15N6F20O4Rh2 : 1420.8940). Single crystal X-ray diffraction revealed its solid-
Figure 1. X-ray crystal structure of 5. One of two rubyrin molecules in the unit cell is shown. a) Top view; b) side view. Thermal ellipsoids are depicted at 50 % probability. Solvent molecules are omitted for clarity. c) Schematic drawings of the coordination environments around RhI. Values in parentheses indicate the second rubyrin molecule in the unit cell.
Scheme 2. Metalation of [26]rubyrin 1 with Group 9 metal ions. Chem. Eur. J. 2015, 21, 10639 – 10644
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state structure to be a gable-like C2v-symmetric structure, in which the two RhI ions are positioned at the bipyrrole moieties (Figure 1).[11a] Although two crystallographically independent molecules are found in the unit cell, they show no significant difference. The overall structure of 5 is similar to those of previously reported bis-RhI complexes of core-modified rubyrins.[7] The bond lengths around the RhI centers [æ] are as follows: N1¢Rh1 2.091 (2.092), N6¢Rh1 2.099 (2.091), N3¢Rh2 2.089 (2.092), N4¢Rh2 2.092 (2.090), C29¢Rh1 1.849 (1.852), C30¢Rh1 1.952 (1.839), C31¢Rh2 1.840 (1.870), C32¢Rh2 1.871 (1.865). Values in parentheses apply to the second complex in the unit 10640
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Communication cell. Interestingly, the dihedral angles between the two planes defined by the bipyrrole units are almost perpendicular (84.1 and 81.78). The 1H NMR spectrum of 5 shows a singlet at d = 8.18 ppm and two doublets at d = 8.14 and 7.75 ppm due to the outer b-pyrrolic protons and a singlet at d = ¢2.87 ppm due to the inner pyrrolic NH protons, indicating a distinct diatropic ring current. The UV/Vis/NIR absorption spectrum of 5 shows an intense Soret-like band at l = 566 nm and distinct Qlike bands at l = 842 and 933 nm, also supporting the aromatic character of 5 (Figure 2). These data allowed us to delineate 5
Figure 2. UV/Vis/NIR absorption spectra of 5, 6, 7, and 8 in CH2Cl2.
as a bis-RhI complex of a [26]rubyrin, the cyclic electronic network of which is conjugated despite the large dihedral angle of the two dipyrromethene units. To synthesize the corresponding bis-RhI complex of [24]rubyrin, oxidation of 5 was attempted under various conditions, but, disappointingly, all of our attempts led to the decomposition of 5. We next examined the metalation of 1 with CoII as another Group 9 metal. After extensive screening of metalation conditions, a reaction of 1 with 10 equivalents of Co(OAc)2·4 H2O and 10 equivalents sodium acetate under reflux for 1 h gave the optimal yield of the desired product. After the usual workup, bis-CoII complex 6 (Scheme 2) was obtained as a red solid in a moderate yield (56 %) directly via recrystallization from CCl4/n-hexane. HR-ESI-TOF MS revealed the parent ion peak of 6 at m/z 1335.9739 ([M]¢ ; m/z calcd for C56H18N6F20O2Co2 : 1335.9740). Complex 6 was revealed by X-ray diffraction to adopt a highly bent conformation.[11b] The two CoII ions are bound to the tripyrrolic NNN ligand and are bridged by the two acetate ions in a symmetric manner. The bond lengths around the CoII centers [æ] are as follows: Co1¢ N1 2.135, Co1¢N2 1.991, C1¢N3 2.126, Co1¢O2 1.983, Co1¢O3 2.028, Co2¢N4 2.089, Co2¢N5 1.981, Co2¢N6 2.151, Co2¢O1 2.013, and Co2¢O3 2.028 (Figure 3). Both CoII ions in 6 adopt trigonal bipyramidal coordination with two nitrogen atoms (N1 and N3 for Co1 and N4 and N6 for Co2) at the apical positions and a nitrogen atom (N2 for Co1 and N5 for Co2) and two oxygen atoms (O2 and O3 for Co1 and O1 and O3 for Co2) at the equatorial positions. The 1H NMR spectrum of 6 shows signals in a symmetric pattern in an extremely downfield region; a singlet at d = 80.62 ppm due to the acetoxy groups and three singlets at d = 33.91, 19.93, and 10.73 ppm due to the bpyrrolic protons, reflecting the paramagnetic shift of CoII ions. Chem. Eur. J. 2015, 21, 10639 – 10644
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Figure 3. X-ray crystal structure of 6. a) Top view; b) side view. Thermal ellipsoids are depicted at 50 % probability. Solvent molecules are omitted for clarity. c) Schematic drawings of the coordination environments around CoII.
We prepared complex [D6]6 bearing CD3CO2 bridges instead of CH3CO2 by the reaction of 1 with CoCl2 in the presence of [D4]acetic acid. The signal due to the acetoxy groups disappeared in the 1H NMR spectrum of [D6]6, in line with our assignment (see the Supporting Information). These data led to a conclusion that complex 6 is a bis-CoII complex of [24]rubyrin. Therefore, it was considered that the [26]rubyrin macrocycle had undergone two-electron oxidation during the metalation. Variable temperature magnetic susceptibility measurement of 6 indicated that the oxidation states of the two Co ions are + 2 with a S = 3/2 high spin state and that these CoII ions exhibit antiferromagnetic coupling with J = ¢4.5 cm¢1 (Figure 4). The absorption spectrum of 6 shows ill-defined absorption bands at 424 and 556 nm and a weak absorption tail reaching to 1600 nm, in line with the assignment of 6 as a 24 p-electron Hìckel antiaromatic species (Figure 2). Although the largest dihedral angle along the p-conjugated circuit is almost perpendicular (85.08), complex 6 preserves its macrocyclic p-conjugation. Note that complex 6 is a rare example of a bis-CoII-metalated porphyrinoid.[12]
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Figure 4. cp T vs. T plots for 6. Circles and solid line denote the observed and calculated cp T values, respectively.
Finally, we examined the metalation of 1 with Ir salts. Firstly, by following the previously reported method,[13] [26]rubyrin 1 was treated with [IrICl(cod)]2 in the presence of sodium acetate in THF, which afforded an Ir complex as detected by MALDI-TOF MS. However, this complex could not be isolated because of its very facile demetalation during workup and separation procedures. Thus, we changed the Ir ion source to [IrIIICl2Cp*]2 (Cp* = pentamethylcyclopentadienyl anion) with an expectation that the bulky Cp* cap may prevent IrIII demetalation. A solution of 1 in THF was treated with 0.75 equivalents of [IrIIICl2Cp*]2 in the presence of 10 equivalents of potassium tert-butoxide at room temperature for 2 h. After the usual workup, separation over a silica gel column afforded the IrIII complex 7 (Scheme 2) as a red solid in 41 % yield. HR-ESI-TOF MS revealed the parent ion peak of 7 at m/z 1465.1624 ([M + H] + ; m/z calcd for C62H31N6F20Cl1Ir1: 1465.1580). Single crystal Xray diffraction analysis revealed its solid-state structure to be a relatively planar conformation, in which all the pyrroles are pointing inward (Figure 5).[11c] The IrIII ion is bound to the two nitrogen atoms of the dipyrromethene unit as well as the chloride and cyclopentadienyl anions. Although there are two crystallographically independent molecules in the unit cell, they have no significant difference. Representative bond lengths [æ] are as follows: N1¢Ir 2.146 (2.150), N6¢Ir 2.113 (2.119), Cl1¢Ir, 2.125 (2.121). Values in parentheses apply to the second complex in the unit cell. The 1H NMR spectrum of 7 shows twelve doublets in the range of d = 10.94-8.56 ppm due to the outer b-pyrrolic protons, a singlet at d = ¢2.76 ppm due to the fifteen methyl protons, and three singlets at d = ¢3.77, ¢5.18, and ¢12.06 ppm due to the inner pyrrolic NH protons. These 1 H NMR spectral features indicate the presence of a distinct diatropic ring current in 7. The absorption spectrum of 7 shows an intense Soret-like band at l = 526 nm and distinct Q-like bands at l = 747 and 817 nm, again supporting its aromatic character (Figure 2). In the meantime, we found that the metalation of 1 with [IrIIICl2Cp*]2, when conducted in 1,4-dioxane in the presence of potassium tert-butoxide at reflux, gave a different IrIII complex, 8, in 8 % yield (Scheme 2). HR-ESI-TOF MS revealed the parent ion peak of 8 at m/z 1407.1577 ([M¢H]¢ ; m/z calcd for Chem. Eur. J. 2015, 21, 10639 – 10644
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Figure 5. X-ray crystal structure of 7. One of two rubyrin molecules in the unit cell is shown. a) Top view; b) side view. Thermal ellipsoids are depicted at 50 % probability. Solvent molecules are omitted for clarity. c) Schematic drawings of the coordination environment around IrIII. Values in parentheses indicate the second rubyrin molecule in the unit cell.
C62H27N6F19Ir1: 1407.1605). The structure of 8 was also revealed by single crystal X-ray diffraction analysis to be almost planar, with four pyrroles pointing inward and two pyrroles pointing outward (Figure 6).[11d] Although there are two crystallographically independent molecules in the unit cell, they have no significant difference. Representative bond lengths [æ] are as follows: N1¢Ir 2.190 (2.200), N6¢Ir 2.027 (2.005). Values in parentheses apply to the second complex in the unit cell. Interestingly, one of the two outward-pointing pyrroles makes a single C22¢Ir bond with the IrIII center, with a bond length of 2.061 (2.051) æ. Thus, complex 8 can be regarded as a rare example of a porphyrinoid that incorporates an iridium–carbon bond.[13, 14] In addition, one of the pyrroles underwent an Nfusion reaction with the neighboring meso-pentafluorophenyl group.[15] The1H NMR spectrum of 8 shows a singlet at d = 11.17 ppm due to the outer pyrrolic NH proton, eight peaks in the range d = 9.30-7.90 ppm due to the outer b-pyrrolic pro-
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1
=2 Table 1. Oxidation potentials (E ox=2 ), reduction potentials (E red ), and electrochemical HOMO–LUMO gaps (DE) for 1, 3, 4, 5, 6, 7, and 8.[a] 1
1 3 4 5 6 7 8
1
1
1
=2 E ox2 [V]
=2 E ox1 [V]
=2 E red1 [V]
=2 E red2 [V]
DE (eV)
0.39 0.39 – 0.53 0.98 0.40 0.18
¢0.06 0.14 0.72 0.25 0.62 ¢0.04 ¢0.19
¢1.18 ¢1.23 ¢0.47 ¢1.04 ¢0.50 ¢1.38 ¢1.42
¢1.50 ¢1.62 ¢0.83 – ¢0.92 ¢1.57 ¢1.74
1.12 1.37 1.19 1.29 1.12 1.34 1.23
[a] Cyclic voltammograms were measured under the following conditions; solvent: CH2Cl2 ; scan rate: 0.05 Vs¢1; working electrode: Pt; counter electrode: Pt wire; reference electrode: Ag/AgClO4 ; electrolyte: Bu4NPF6.
Figure 6. X-ray crystal structure of 8. One of two rubyrin molecules in the unit cell is shown. a) Top view; b) side view. Thermal ellipsoids are depicted at 50 % probability. Solvent molecules are omitted for clarity. c) Schematic drawings of the coordination environment around IrIII. Values in parentheses indicate the second rubyrin molecule in the unit cell.
tons, a singlet at 4.34 ppm due to the inner NH proton, and three singlets at d = ¢0.50, ¢1.42, and ¢3.14 ppm due to the inner b-pyrrolic protons. These spectral data indicates the presence of a diatropic ring current in 8. The absorption spectrum of 8 shows a considerably broadened Soret-like band at l = 570 nm and weak Q-like bands at l = 673 and 919 nm, in line with its moderate aromatic character (Figure 2). To compare the aromaticity of the complexes, harmonic oscillator model of aromaticity (HOMA)[16] values were calculated on the basis of the crystal structures to be 0.63 for 5, 0.26 for 6, 0.67 for 7, and 0.54 for 8. The electrochemical properties of the rubyrins and their metal complexes were investigated by cyclic voltammetry. The 1 1 =2 oxidation potentials (E ox=2 ), reduction potentials (E red ), and electrochemical HOMO–LUMO gaps (DE) are listed in Table 1. We could not measure the potentials of 2 because of its very poor solubility. Characteristically, the first reduction and oxidation potentials for 4 (¢0.47 and 0.72 V, respectively) and 6 (¢0.50 and 0.62 V, respectively) are distinctly higher than those of the rest molecules, in that only 4 and 6 are [24]rubyrin complexes. Chem. Eur. J. 2015, 21, 10639 – 10644
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The electrochemical HOMO–LUMO gaps of 4 and 6 are also distinctly smaller than those of the others, reflecting their antiaromatic character, whereas the other rubyrins are aromatic molecules. As compared with 1, bis-RhI complex 5 shows distinctly higher oxidation and reduction potentials but IrIII complex 7 displays nearly the same oxidation and reduction potentials and IrIII complex 8 exhibits slightly lower oxidation and reduction potentials. In summary, metalations of [26]rubyrin 1 have been explored with Group 9 metal salts (RhI, CoII, and IrIII) to produce Hìckel aromatic [26]rubyrin–bis-RhI complex 5, with a highly curved gable-like structure, Hìckel antiaromatic [24]rubyrin– bis-CoII complex 6, which displays intramolecular antiferromagnetic coupling (J = ¢4.5 cm¢1) between the two CoII ions, and Cp*-capped IrIII complexes 7 and 8. In 7, the Ir metal is situated on the [26]rubyrin frame with two Ir¢N bonds, whereas that in 8 has an additional Ir¢C bond, in a rare case of an Ir complex of a porphyrinoid. This work demonstrates the characteristic metalation abilities of 1 towards Group 9 metals. Further exploration of other metal complexes of rubyrins and their higher homologues are ongoing in our laboratory.
Acknowledgements This work was supported by the Japan Society for the Promotion of Science (JSPS; KAKENHI grant numbers 25220802 and 25620031). Keywords: aromaticity · Group 9 metals · metalation · porphyrinoids · rubyrin [1] a) J. L. Sessler, D. Seidel, Angew. Chem. Int. Ed. 2003, 42, 5134; Angew. Chem. 2003, 115, 5292; b) M. Ste˛pien´, N. Sprutta, L. Latos-Graz˙yn´ski, Angew. Chem. Int. Ed. 2011, 50, 4288; Angew. Chem. 2011, 123, 4376; c) T. K. Chandrashekar, S. Venkatraman, Acc. Chem. Res. 2003, 36, 676; d) S. Saito, A. Osuka, Angew. Chem. Int. Ed. 2011, 50, 4342; Angew. Chem. 2011, 123, 4432; e) A. Osuka, S. Saito, Chem. Commun. 2011, 47, 4330. [2] a) S. Shimizu, A. Osuka, Eur. J. Inorg. Chem. 2006, 1319; b) J. L. Sessler, E. Tomat, Acc. Chem. Res. 2007, 40, 371. [3] J. L. Sessler, T. Morishita, V. Lynch, Angew. Chem. Int. Ed. Engl. 1991, 30, 977; Angew. Chem. 1991, 103, 1018.
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Communication [4] a) A. Srinivasan, V. R. M. Reddy, S. J. Narayanan, B. Sridevi, S. K. Pushpan, M. Ravikumar, T. K. Chandrashekar, Angew. Chem. Int. Ed. Engl. 1997, 36, 2598; Angew. Chem. 1997, 109, 2710; b) S. J. Narayanan, B. Sridevi, T. K. Chandrashekar, A. Vij, R. Roy, J. Am. Chem. Soc. 1999, 121, 9053. [5] S. Shimizu, W.-S. Cho, J. L. Sessler, H. Shinokubo, A. Osuka, Chem. Eur. J. 2008, 14, 2668. [6] S. Shimizu, R. Taniguchi, A. Osuka, Angew. Chem. Int. Ed. 2005, 44, 2225; Angew. Chem. 2005, 117, 2265. [7] S. J. Narayanan, B. Sridevi, T. K. Chandrashekar, U. Englich, K. RuhlandtSenge, Inorg. Chem. 2001, 40, 1637. [8] a) S. Shimizu, V. G. Anand, R. Taniguchi, K. Furukawa, T. Kato, T. Yokoyama, A. Osuka, J. Am. Chem. Soc. 2004, 126, 12280; b) S. Mori, S. Shimizu, R. Taniguchi, A. Osuka, Inorg. Chem. 2005, 44, 4127; c) S. Mori, A. Osuka, J. Am. Chem. Soc. 2005, 127, 8030; d) S. Mori, S. Shimizu, J.-Y. Shin, A. Osuka, Inorg. Chem. 2007, 46, 4374; e) H. Rath, S. Tokuji, N. Aratani, K. Furukawa, J. M. Lim, D. Kim, H. Shinokubo, A. Osuka, Angew. Chem. Int. Ed. 2010, 49, 1489; Angew. Chem. 2010, 122, 1531; f) T. Yoneda, A. Osuka, Chem. Eur. J. 2013, 19, 7314. [9] H. Rath, N. Aratani, J. M. Lim, J. S. Lee, D. Kim, H. Shinokubo, A. Osuka, Chem. Commun. 2009, 3762. [10] Y. M. Sung, M.-C. Yoon, J. M. Lim, H. Rath, K. Naoda, A. Osuka, D. Kim, Nat. Chem. 2015, 7, 418. [11] a) Crystallographic data for 5: 2(C56H14F20N6O4Rh2)·3(C6H6); Mr = 3075.43; monoclinic; space group C2/c (No. 15); a = 58.202(10), b = 12.933(2), c = 32.369(6) æ; b = 112.371(4)8; V = 22531(6) æ3 ; 1calcd = 1.813 g cm¢1; Z = 8; R1 = 0.0780 [I > 2.0s(I)]; wR2 = 0.2614 (all data); GOF = 1.080; b) Crystallographic data for 6: C56H18F20N6O4Co2·CCl4 ; Mr = 1490.43; monoclinic; space group P21/a (No. 14); a = 14.086(6), b = 22.523(7), c = 18.299(7) æ; b = 108.399(13)8; V = 5509(4) æ3 ; 1calcd = 1.794 g cm¢1; Z = 4, R1 = 0.0808 [I > 2.0s(I)]; wR2 = 0.2957 (all data); GOF = 1.071; c) Crystallographic data for 7: 2(C62H30F20N6Cl1Ir1)·2.07(C6); Mr = 3082.41; monoclinic; space group P21/n (No. 14); a = 19.914(5), b = 22.614(4), c = 29.849(7) æ; b = 103.216(6); V = 13086(5) æ3 ; 1calcd = 1.565 g cm¢1; Z = 4; R1 = 0.0658 [I >
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[12] [13]
[14]
[15]
[16]
2.0s(I)]; wR2 = 0.2100 (all data); GOF = 1.075; d) Crystallographic data for 8: 2(C62H28F19N6Ir1)·2.642(C7H16)·0.518(C7)·1.680(CH2Cl2), Mr = 3271.54; monoclinic; space group P21/n (No. 14); a = 28.173(6), b = 15.137(3), c = 32.386(8) æ; b = 106.153(6); V = 13266(5) æ3 ; 1calcd = 1.638 g cm¢1; Z = 4; R1 = 0.1072 [I > 2.0s(I)]; wR2 = 0.3742 (all data); GOF = 1.097. CCDC 1054739 (5), CCDC 1054740 (6), CCDC 1054741 (7), CCDC 1054742 (8) contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif. M. Suzuki, M.-C. Yoon, D. Y. Kim, J. H. Kwon, H. Furuta, D. Kim, A. Osuka, Chem. Eur. J. 2006, 12, 1754. a) H. Ogoshi, J. Setsune, Z. Yoshida, J. Organomet. Chem. 1978, 159, 317; b) J. H. Palmer, M. W. Day, A. D. Wilson, L. M. Henling, Z. Gross, H. B. Gray, J. Am. Chem. Soc. 2008, 130, 7786; c) T. D. Lash, K. Pokharel, M. Zeller, J. M. Ferrence, Chem. Commun. 2012, 48, 11793; d) K. Naoda, H. Mori, A. Osuka, Chem. Asian J. 2013, 8, 1395. a) K. Yoshida, T. Nakashima, A. Osuka, H. Shinokubo, Dalton Trans. 2011, 40, 8773; b) K. Naoda, A. Osuka, J. Porphyrins Phthalocyanines 2014, 18, 652. a) C.-H. Hung, J.-P. Jong, M.-Y. Ho, G.-H. Lee, S.-M. Peng, Chem. Eur. J. 2002, 8, 4542; b) M. Suzuki, R. Taniguchi, A. Osuka, Chem. Commun. 2004, 2682; c) Y. Inokuma, T. Matsunari, N. Ono, H. Uno, A. Osuka, Angew. Chem. Int. Ed. 2005, 44, 1856; Angew. Chem. 2005, 117, 1890; d) T. Higashino, M. Inoue, A. Osuka, J. Org. Chem. 2010, 75, 7958; e) T. Higashino, A. Osuka, Chem. Sci. 2012, 3, 103. a) T. M. Krygowski, T. M. Cryan´ski, Tetrahedron 1996, 52, 1713; b) T. M. Krygowski, T. M. Cryan´ski, Tetrahedron 1996, 52, 10255.
Received: March 19, 2015 Published online on May 26, 2015
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