Co(I)-Mediated Removal of Addends on the C60 Cage and Formation of Monovalent Cobalt Complex CpCo(CO)(η 2 -C60)

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1 Supporting Information Co(I)-Mediated Removal of Addends on the C60 Cage and Formation of Monovalent Cobalt Complex CpCo(CO)(η 2 -C60) Yoshifumi Hashikawa, Michihisa Murata, Atsushi Wakamiya, and Yasujiro Murata* Institute for Chemical Research, Kyoto University, Uji, Kyoto , Japan Fax: (+81) yasujiro@scl.kyoto-u.ac.jp S1

2 Contents 1. General S3 2. Computational Methods S3 3. Co(I)-Mediated Removal of Addends on the C60 Cage S4 4. Synthesis and Properties of CpCo(CO)C60 S Synthesis S Reactivity S9 5. X-Ray Structural Analysis S10 6. DFT calculations S11 7. References S14 S2

3 1. General The 1 H and 13 C NMR measurements were carried out at room temperature with a JEOL JNM ECA500 instrument. The NMR chemical shifts were reported in ppm with reference to residual protons and carbons of CDCl3 (δ 7.26 ppm in 1 H NMR, δ ppm in 13 C NMR). ESI mass spectra were measured on a Bruker microtof-q II. UV-vis absorption spectra were measured with a Shimadzu UV-3150 spectrometer. IR spectra were taken with a Shimadzu FTIR-8400S spectrometer. Cyclic voltammetry was conducted on a BAS Electrochemical Analyzer ALS620C using a three-electrode cell with a glassy carbon working electrode, a platinum wire counter electrode, and a Ag/AgNO3 reference electrode. The measurements were carried out in mm solutions of substrate using 0.1 M tetrabutylammonium tetrafluoroborate (n-bu4n BF4) as a supporting electrolyte, and the potentials were calibrated with ferrocene used as an internal standard which was added after each measurement. The high-performance liquid chromatography (HPLC) was performed with the use of a Cosmosil Buckyprep column (250 mm in length, 4.6 mm in inner diameter) for analytical purpose and the same columns (two directly connected columns; 250 mm in length, 20 mm in inner diameter) for preparative purpose. Fullerene C60 was purchased from SES Research Co. Toluene was purchased from Kanto Chemical Co., INC. Carbon disulfide was purchased from Wako Pure Chemical Industries, Ltd. o- Dichlorobenzene (ODCB, 99%) and CpCo(CO)2 were purchased from Sigma-Aldrich Co. LLC. Carbon monoxide was purchased from Sumitomo Seika Chemicals Co., LTD. The fullerene derivatives, C60N-MEM, C60(N-MEM)2, C60O, C60O2, and C60CPh2 were synthesized according to the literature Computational Methods All calculations were conducted with Gaussian 09 program packages. The structures were optimized at the B3LYP level of theory using the basis sets: LanL2DZ for Co atom and 6-31G(d) for other atoms without any symmetry assumptions. All structures at the stationary states were confirmed by the frequency analyses at the same level of theory. S3

4 3. Co(I)-Mediated Removal of Addneds on the C60 Cage [General procedure] SM (10.0 mg) was dissolved in ODCB ( ml). CpCo(CO)2 (2.00 equiv) was added and refluxed for 1 h. After reaction, the resulting solution was filtrated and purified by HPLC (Buckyprep column, 7.5 ml/min, 50 C). Table S1. Removal of Addends from substituted C60 derivatives by CpCo(CO)2 S4

5 4. Synthesis and Properties of CpCo(CO)C Synthesis C60 (50.0 mg, 69.4 μmol) was dissolved in ODCB (6.00 ml, 11.6 mm). To the solution, CpCo(CO)2 (1.35 g/ml, 18.5 μl, 139 μmol, 2.00 equiv) was added and stirred at 190 C. After 1 h, the resulting mixture was filtrated and purified by HPLC (Buckyprep column, 7.5 ml/min, 50 C). First, multi-cobalt adducts was eluted (5.36 mg), followed 1 (28.2 mg, 47%) and C60 (21.6 mg, 43%). 1: UV-vis (ODCB) λmax (log ε) 338 (4.72), 436 (3.85), 604 (3.60), 646 (3.59); IR (KBr) ν = 2012 (CO, carbonyl), 819, 526 cm 1 ; 1 H NMR (500 MHz, CDCl3/CS2 (1:1)) δ 5.56 (s, 5H); 13 C NMR (126 MHz, CDCl3/CS2 (1:1)) δ134.53, , , , , , , , , , , , , , , , , , , , , , , , , , , , , (The sum of carbon signals must be 34 in theory. Observed 30. Three sp 2 carbon signals are overlapped and carbon signals corresponding to CO was not observed due to poor solubility of 1.); HRMS (ESI, negative ion mode) calcd for C66H5OCo (M ) , found CHCl 3 s, 5H (5.56 ppm) H 2 O δ (ppm) Figure S1. 1 H NMR spectra (500 MHz, CDCl3/CS2 (1:1)) of 1. S5

6 CS 2 Cp ring (88.77 ppm) CDCl δ (ppm) Figure S2. 13 C NMR spectra (126 MHz, CDCl3/CS2 (1:1)) of [M] m/z Figure S3. ESI mass spectrum (negative ion mode) of 1. S6

7 %T 80 OC Co CO (cm -1 ) Figure S4. IR spectrum (KBr) of 1. Figure S5. Cyclic and differential pulse voltammograms (indicated by red and blue, respectively) of (a) C60 and (b) CpCo(CO)C60 (1) using 0.5 mm samples with 0.1 M n- Bu4N BF4 in ODCB at a scan rate of 100 mv s 1. S7

8 ( 10 4 M 1 cm 1 ) (4.79) 338 (4.72) (3.85) 408 (3.50) (3.02) max (log ) (3.60) 600 (2.97) C (3.59) C M-ODCB (nm) Figure S6. UV-Vis absorption spectra of C60 (gray) and CpCo(CO)C60 (1) (green) for 50.0 μm solutions in ODCB. The enlarged spectra (ten-fold) were plotted by dotted lines. The maximum absorption wavelengths λmax (nm) were shown with log ε in parentheses. S8

9 4.2. Reactivity CpCo(CO)C60 (1) (0.436 mg, μmol) was dissolved in toluene (10.0 ml, 50.0 μm). A portion of 3.00 ml was applied to confirm the stability under CO atmosphere and another portion for photostability. The progress was monitored by HPLC. [Stability under CO atmosphere] By exposure to CO gas, we expected the ligand exchange to afford CpCo(CO)2 and C60, as reported in the literature: the solution color of (η 5 -C9H7)Ir(CO)C60 changed within 1 min under CO atmosphere. 2 Even though the solution of 1 was bubbled with CO gas for 1 h, no ligand exchange was observed. [Photostability] The photoirradiation (LED lamp, 10 4 lux) led to formation of C60. The color of solution (green) became gradually faint and finally changed to purple after 45 min. The quantitative transformation of 1 into C60 was observed by HPLC. S9

10 5. X-Ray Structural Analysis Single crystals of CpCo(CO)C60 (1) were obtained from a toluene solution by slow evaporation. Intensity data were collected at 100 K on a Bruker Single Crystal CCD X- ray Diffractometer (SMART APEX II) with Mo Kα radiation (λ = Å) and graphite monochromater. A total of reflections were measured at the maximum 2θ angle of 50.1, of which 5082 were independent reflections (Rint = ). The structure was solved by direct methods (SHELXS-97 3 ) and refined by the full-matrix least-squares on F 2 (SHELXL-97 3 ). All non-hydrogen atoms were refined anisotropically. All hydrogen atoms were placed using AFIX instructions. The crystal data are as follows: C66H5CoO; FW = , crystal size mm 3, Orthorhombic, Pca21, a = (12) Å, b = (10) Å, c = (6) Å, V = (3) Å 3, Z = 4, Dc = g cm 3. The refinement converged to R1 = , wr2 = (I > 2σ(I)), GOF = O1 C1 Co1 C2 C (4) 1.772(3) O1 C1 Co (3) 2.031(3) C2 C (4) Figure S7. Single crystal X-ray structure of CpCo(CO)C60 (1) with 50% probability of thermal ellipsoids. The inset shows an enlarged view surrounding the monovalent cobaltcenter with selected bond lengths (units in Å). S10

11 6. DFT Calculations Figure S8. HOMO-LUMO energy diagram for C60 (left) and CpCo(CO)C60 (1, right), calculated at the B3LYP level of theory with basis sets of 6-31G(d) for C, H, and O and LanL2DZ for Co. Figure S9. GIAO calculation for 13 C NMR spectrum of 1 (calculated at B3LYP/6-311G(d,p) for C, H, and O and LanL2DZ for Co, using the optimized structure listed in Table S3). S11

12 Table S2. Optimized structure of C60 (B3LYP/6-31G(d)) Standard orientation: Center Atomic Atomic Coordinates (Angstroms) Number Number Type X Y Z The total electronic energy was calculated to be Hartree. S12

13 Table S3. Optimized structure of 1 (B3LYP/6-31G(d) for C, H, and O and LanL2DZ for Co) Standard orientation: Center Atomic Atomic Coordinates (Angstroms) Number Number Type X Y Z The total electronic energy was calculated to be Hartree. S13

14 13. References (1) Hashikawa, Y.; Murata, M.; Wakamiya, A.; Murata, Y. Angew. Chem., Int. Ed. 2016, DOI: /anie (2) Koefod, R. S.; Hudgens, M. F.; Shapley, J. R. J. Am. Chem. Soc. 1991, 113, (3) Sheldrick, G. M. SHELX-97; University of Go ttingen: Go ttingen, Germany, S14