Synthesis of Polyynes Using Dicobalt Masking Groups

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1 Supporting Information Synthesis of Polyynes Using Dicobalt Masking Groups Daniel R. Kohn, Przemyslaw Gawel, Yaoyao Xiong, Kirsten E. Christensen, and Harry L. Anderson* University of Oxford, Department of Chemistry, Chemistry Research Laboratory, Oxford, OX1 3TA, United Kingdom Table of Contents S1. Synthetic Protocols S2 S2. Characterization of Novel Compounds S4 S4. Electronic Structure Calculations S22 S5. X-Ray Crystallography S41 S6. References S42 S1

2 S1. Synthetic Protocols S2.1. Additional experimental work Firstly, we aimed to fully deprotect the known -protected cobalt complex S6 as previously reported 1 and investigate a statistical deprotection in order to prepare 3 (Scheme S1). However, as the statistical deprotection was fairly inefficient the synthetic route detailed in Scheme 1 (main text) was used instead. i H O S1 ii OH S2 iii O S3 iv Br Br Ph 2 P PPh 2 v vi (OC) 2 Co Co(CO) 2 vii Ph 2 P PPh 2 (OC) 2 Co Co(CO) 2 S4 S5 S6 3 Scheme S1. Synthesis of known compound S6 and novel compound 3. i) a) n-buli, THF, 78 C, 30 min. b) DMF, 78 C, 88%. ii) a) -acetylene, n-buli, THF, 78 C, 30 min. b) Aldehyde S1, 78 C, 1 h, 71% iii) PCC, Celite, mol sieves, CH 2 Cl 2, 25 C, 86% iv) PPh 3, CBr 4, CH 2 Cl 2, 25 C, 100 % v) n-buli, hexane, 78 C, 30 min., 85% vi) a) Co 2 (CO) 8, hexane, 25 C, 12 h. b) dppm, toluene, 110 C, 1 h, 84%. vii) TBAF, CH 2 Cl 2, CHCl 3, 15 min., 10%. H H O i OH ii O iii S1 S7 TMS S8 TMS Br Br iv TMS v Ph 2 P PPh 2 (OC) 2 Co Co(CO) 2 TMS Ph 2 P PPh 2 Co(CO) 2 (OC) 2 Co TMS S9 1 2b 2a TMS Scheme S2. i) TMS-acetylene, n-buli, aldehyde S1, THF, 78 C, 1 h, 88%. ii) PCC, celite, mol. sieves, CH 2 Cl 2, 25 C, 20 h, 96%. iii) PPh 3, CBr 4, CH 2 Cl 2, 25 C, 16 h, 93%. iv) n-buli, hexane, 78 C, 30 min, 80%. v) a) Co 2 (CO) 8, hexane, 25 C, 12 h. b) diphenylphosphinomethane, toluene, 110 C, 30 min., 45% (2b) and 27% (2a). S2

3 Additional experiments were performed to investigate the unusual formation of 8b during Eglinton coupling. We hypothesized that the reaction conditions could be facilitating cobalt decomplexation and recomplexing in a different position. To test this theory we subjected the regioisomers 2a and 2b to the reaction conditions and monitored via TLC and NMR spectroscopy. Additionally, we tried heating in the presence of an excess of bis(diphenylphosphinomethane). None of these processes led to a change in the position of the dicobalt moiety (Scheme S3). Ph 2 P PPh 2 (OC) 2 Co Co(CO) 2 Ph 2 P PPh 2 (OC) 2 Co Co(CO) 2 2a TMS 2b TMS Ph 2 P PPh 2 (OC) 2 Co Co(CO) 2 Ph 2 P PPh 2 (OC) 2 Co Co(CO) 2 2b TMS 2a TMS Scheme S3. Attempted isomerization of dicobalt complexes. Additionally, we tried monitoring the Eglinton coupling in an attempt to understand the process. We hypothesized that 8b could be the thermodynamic product, so we monitored the reaction over 2 days, but the ratio of the products did not change over time. The yield of isomer 8b varied between 2% and 7%. Heating 8 did not result in isomerization. The product where only one dicobalt group had shifted along the chain was never observed via TLC. The possibility that 8b is produced from an isomeric impurity of 3 seems unlikely (because samples of 3 gave clean NMR spectra), but it cannot be excluded. 80% Ph 2 P (OC) 2 Co PPh 2 Co(CO) 2 Ph 2 P (OC) 2 Co PPh 2 Co(CO) 2 Ph 2 P PPh 2 (OC) 2 Co Co(CO) 2 Cu(OAc) 2, Py. N 2, 25 C, 20 h 8a 3 H 7% Ph 2 P (OC) 2 Co PPh 2 Co(CO) 2 Ph 2 P (OC) 2 Co PPh 2 Co(CO) 2 8b Scheme S4. Homocoupling of 3. S3

4 S2. Characterization of Novel Compounds S2.1. NMR spectroscopy Figure S1. 1 H NMR of 2a (500 MHz, CDCl 3, 25 C). Figure S2. 13 C NMR of 2a (500 MHz, CDCl 3, 25 C). S4

5 Figure S3. 1 H NMR of 2b (500 MHz, CDCl 3, 25 C). Figure S4. 13 C NMR of 2b (125 MHz, CDCl 3, 25 C). S5

6 Figure S5. 1 H NMR of 3 (500 MHz, CDCl 3, 25 C). Solvent peaks are difficult to exclude completely due to limited dry stability. Figure S6. 13 C NMR of 3 (500 MHz, CDCl 3, 25 C). Solvent peaks are difficult to exclude completely due to limited dry stability. S6

7 Figure S7. 1 H NMR of 4 (500 MHz, CDCl 3, 25 C). Figure S8. 13 C NMR of 4 (125 MHz, CDCl 3, 25 C). S7

8 Figure S9. 1 H NMR of 5 (500 MHz, CDCl 3, 25 C). Figure S C NMR of 5 (125 MHz, CDCl 3, 25 C). Solvent peaks are difficult to exclude completely due to limited dry stability. S8

9 Figure S11. 1 H NMR of 6 (500 MHz, CDCl 3, 25 C). Figure S C NMR of 6 (125 MHz, CDCl 3, 25 C). S9

Figure S13. 1 H NMR of 7 (500 MHz, CDCl 3, 25 C). Figure S14. 13 C NMR of 7 (125 MHz, CDCl 3, 25 C).

10 Figure S13. 1 H NMR of 7 (500 MHz, CDCl 3, 25 C). Figure S C NMR of 7 (125 MHz, CDCl 3, 25 C). Due to the instability of the terminal triyne it was not possible to obtain a 13 C NMR spectrum in which all peaks were visible. S10

11 Figure S15. 1 H NMR of 8b (500 MHz, CDCl 3, 25 C). Figure S C NMR of 8b (125 MHz, CDCl 3, 25 C). There was not enough material to observe all of the signals of this minor isomer. S11

12 Figure S17. 1 H NMR of 8a (500 MHz, CDCl 3, 25 C). Figure S C NMR of 8a (125 MHz, CDCl 3, 25 C). S12

13 Figure S19. 1 H NMR of 9 (500 MHz, CDCl 3, 25 C). Figure S C NMR of 9 (125 MHz, CDCl 3, 25 C). S13

14 Figure S21. 1 H NMR of 10 (500 MHz, CDCl 3, 25 C). Due to the instability of the compound when dry, it was not possible to obtain a 1 H NMR spectrum without solvent peaks. Figure S C NMR of 10 (125 MHz, CDCl 3, 25 C). Due to the instability of the compound when dry, it was not possible to obtain a 13 C NMR spectrum without solvent peaks. S14

15 Figure S C NMR of 11 (125 MHz, CDCl 3, 25 C). Figure S C NMR of 12 (125 MHz, CDCl 3, 25 C). S15

16 Figure S C NMR of 13 (125 MHz, CDCl 3, 25 C). S16

17 S2.2. MALDI Mass Spectra In general, the cobalt carbonyl compounds were difficult to characterize by mass spectrometry. The molecular ion without fragmentation was rarely observed. The molecule with the loss of the four carbonyl ligands was observed instead. An unusually high concentration of matrix was required (10 mg/ml). TMS-Co 1 calib (0.031) Is (1.00,1.00) C43H52Co2P2Si MALDI 04-Sep :14:51 TOF LD+ 5.25e % % TMS-Co 1 calib 1 (0.031) TOF LD+ 1.68e Figure S26. MALDI spectrum of 2a and calculated spectra ( 4 CO) m/z e % % Co 1 5 (0.165) Sb (10,10.00 ); Cm (5) TOF LD Figure S27. MALDI spectrum of 3 and calculated spectra ( 4 CO). S17 m/z

18 TMS-Co 2 calib (0.032) Is (1.00,1.00) C45H52Co2P2Si TOF LD+ 5.13e % m/z TMS-Co 2 calib 6 (0.199) Cm (6) MALDI 04-Sep :24:42 TOF LD+ 788 % Figure TMS-Co 2 S28. calib (0.032) MALDI Is (1.00,1.00) spectrum C45H52Co2P2Si2 of 4 and calculated spectra ( 4 CO). 100 % Co 2 (0.031) Is (1.00,1.00) C42H44Co2P2Si MALDI TOF LD+ 5.13e12 12-Sep :16:28 TOF LD+ 5.76e12 % m/z Co 2 5 (0.165) Sb (5,15.00 ); Cm (4:5) TOF LD % m/z Figure S29. MALDI spectrum of 5 and calculated spectra ( 4 CO). S18

19 TMS-Co 3 (0.031) Is (1.00,1.00) C47H52Co2P2Si MALDI 12-Sep :23:22 TOF LD+ 5.02e % % TMS-Co 3 7 (0.231) Sm (SG, 10x5.00); Sb (5,15.00 ); Cm (7:8) TOF LD+ 1.28e Figure S30. MALDI spectrum of 6 and calculated spectra ( 4 CO) m/z Co 3 (0.032) Is (1.00,1.00) C48H44Co2P2SiO MALDI 13-Sep :20:58 TOF LD+ 5.34e % % Co 3 5 (0.165) Sb (5,15.00 ); Cm (5) TOF LD m/z Figure S31. MALDI spectrum of 7 and calculated spectra (M+) S19

20 S2.3. Electronic Absorption Spectra Figure S32. Absorption spectra of cobalt complexes 2a, 4 and 6 in dichloromerthane. Figure S33. Absorption spectra of triisopropyl end-capped polyynes 11, 12 and 13 in dichloromethane. S20

21 Figure S34. The effect of solvent polarity on absorption of 2a (all spectra recorded at 25 C, ca M, normalized at maxima). Figure S35. The effect of solvent polarity on absorption maxima of 2a. Red line shows linear fitting, error bars denote resolution limit of UV-vis spectrometer. S21

22 S4. Electronic Structure Calculations The molecular structures of compounds were optimized at the B3LYP/6-31G(d) (3, 5, 7) or B3LYP/STO-3G (8a, 9, 10) level of theory by using the software package Gaussian The lower level of theory for dimers (8a, 9, 10) was used to decrease computational costs. Crystal structures (see Section S4) were used as input geometries of cobalt complexes. All structures are confirmed as groundstate minima according to the analysis of their analytical frequencies computed at the same level, which show no imaginary frequencies. The isosurfaces of the frontier orbitals (shown at 0.4) of 8a, 9, and 10 were computed at the B3LYP/STO-3G level of theory. Electrostatic potential (ESP) maps were plotted on total SCF density surface (isovalue = ). Comparison of electronic properties and charge distribution between dicobalt polyyne complex MAE and supertrityl end-capped oligoynes was performed by means of electrostatic potential maps as well as atomic charges calculated with three different methods: Mulliken, Hirschfield, and Natural Population Analysis (NPA). Solid-state structures, obtained by single crystal X-ray crystallography, suggest that the diphosphine chelating ligand of cobalt is rather flexible with two boundary geometries, where the diphosphine ligand is directing towards either side of the complex. In our computational approach, we considered both conformations, which are defined in Figure S36. S22

23 3 Conf1 3 Conf2 5 Conf1 5 Conf2 7 Conf1 7 Conf2 Figure S36. Two considered conformations of the dicobalt ligands in 3, 5 and 7. S23

24 Figure S37. Electrostatic potential maps on total density surfaces of supertrityl (left) and dicobalt (right, Conf1) mono-, di-, and triynes. The regions of positive and negative charges are depicted in blue and red, respectively. S24

25 Figure S38. Electrostatic potential maps on total density surfaces of dicobalt mono- (3), di- (5), and triynes (7) in Conf2. S25

26 Table S1. Calculated atomic charges of polyyne chain in 3, 5 and 7. Terminal acetylene (yellow), internal acetylenes (white), cobalt complexed acetylene (red), protected terminal acetylene (green). Monoyne (3) HC1C2C7(Co)C8(Co)C9C10 Conf 1 H C1 C2 C7 C8 C9 C10 Mulliken Hirshfield NPA Conf 2 H C1 C2 C3 C4 C5 C6 Mulliken Hirshfield NPA Diyne (5) HC1C2C3C4C7(Co)C8(Co)C9C10 Conf 1 H C1 C2 C3 C4 C7 C8 C9 C10 Mulliken Hirshfield NPA Conf 2 H C1 C2 C3 C4 C5 C6 C7 C8 Mulliken Hirshfield NPA Triyne (7) HC1C2C3C4C5C6C7(Co)C8(Co)C9C10 Conf 1 H C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 Mulliken Hirshfield NPA Conf 2 H C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 Mulliken Hirshfield NPA S26

27 Table S2. Calculated atomic charges of supertrityl polyyne chain in monoyne, diyne and triyne. Terminal acetylene (yellow), internal acetylenes (white), supertrityl quaternary carbon (red). Monoyne HC1C2TrC H C1 C2 TrC Mulliken Hirshfield NPA Diyne HC1C2C3C4TrC H C1 C2 C3 C4 TrC Mulliken Hirshfield NPA Triyne HC1C2C3C4C5C6TrC H C1 C2 C3 C4 C5 C6 TrC Mulliken Hirshfield NPA S27

28 Figure S39. Atomic charges on terminal hydrogen atoms in mono-, di- and triynes end-capped with supertrityl or dicobalt complexes in two conformations. Figure S40. Difference in atomic charges between terminal hydrogen and terminal carbon atoms in mono-, di- and triynes end-capped with supertrityl or dicobalt complexes in two conformations. S28

29 Figure S41. Frontier molecular orbitals of 8a, 9, 10 in E and Z forms. S29

30 To provide additional insight into the shape of electronic spectra of the dicobalt-polyyne complexes, we computed electronic transitions of 3 and 5. The first 40 vertical transition energies were calculated by time-dependent density functional theory (TD-DFT) at the B3LYP/6-31G(d) level of theory in the gas phase. Calculated transitions are overlaid with the experimental spectra. In both case, the characteristic tail at low energy results from weak transitions in this region. A broad intense feature at higher energies comes from multiple transitions. Figure S42. Overlay of experimental UV-vis spectra (blue) and calculated electronic transitions (black bars) of 3. Figure S43. Overlay of experimental UV-vis spectra (blue) and calculated electronic transitions (black bars) of 5. S30

31 Cartesian coordinates and structural parameters of 3, 5, 7, 8a, 9 and Conf1 Sum of electronic and zero-point Energies= Sum of electronic and thermal Energies= Sum of electronic and thermal Enthalpies= Sum of electronic and thermal Free Energies= (Hartree/Particle) X Y Z Co Co C C C C Si C C C C C C C C C C C P C C C C C C C P C C C C C C C C C C C C C C C C C C C O C O C O C O H H H H H H H H H H H H H H H H H S31 H H H H H H H H H H H H H H H H H H H H H H H H H H H Conf2 Sum of electronic and zero-point Energies= Sum of electronic and thermal Energies= Sum of electronic and thermal Enthalpies= Sum of electronic and thermal Free Energies= (Hartree/Particle) X Y Z Co Co C C C C Si C C C C C C C C C C P C P C C C C C C C C C C C C C C C C C C C C C C C

32 C C O C O C O C O C H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H Conf1 Sum of electronic and zero-point Energies= Sum of electronic and thermal Energies= Sum of electronic and thermal Enthalpies= Sum of electronic and thermal Free Energies= (Hartree/Particle) X Y Z Co Co C C C C Si C C C C C C C C C S32 C C C C P C C C C C C C C C C C C C P C C C C C C C C C C C C C O C O C O C O H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H

33 5 Conf2 Sum of electronic and zero-point Energies= Sum of electronic and thermal Energies= Sum of electronic and thermal Enthalpies= Sum of electronic and thermal Free Energies= (Hartree/Particle) X Y Z Co Co C C C C Si C C C C C C C C C P C P C C C C C C C C C C C C C C C C C C C C C C C C C O C O C O C O C H H H H H H H H H H H H H H H H H H H H H H S33 H H H H H H H H H H H H H H H H H H H H H C C C H Conf1 Sum of electronic and zero-point Energies= Sum of electronic and thermal Energies= Sum of electronic and thermal Enthalpies= Sum of electronic and thermal Free Energies= (Hartree/Particle) X Y Z Co Co C C C C Si C C C C C C C C C C C C C C C P C C C C C C C P C C C C C C C C C C C C C

34 C C C C C C O C O C O C O H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H Conf2 Sum of electronic and zero-point Energies= Sum of electronic and thermal Energies= Sum of electronic and thermal Enthalpies= Sum of electronic and thermal Free Energies= (Hartree/Particle) X Y Z Co Co C C C C Si C C C C C C S34 C C C P C P C C C C C C C C C C C C C C C C C C C C C C C C C O C O C O C O C H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H C C C C C H

35 E-8a Sum of electronic and zero-point Energies= Sum of electronic and thermal Energies= Sum of electronic and thermal Enthalpies= Sum of electronic and thermal Free Energies= (Hartree/Particle) X Y Z Co Co C C C C Si C C C C C P C C C C C C C C C C C C C P C C C C C C C C C C C C C O C O C O C O H H H H H H H H H H H H H H H H H H H H H H H H H S35 Co Co C C C C Si C C C C C P C C C C C C C C C C C C C P C C C C C C C C C C C C C O C O C O C O H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H

36 Z-8a Sum of electronic and zero-point Energies= Sum of electronic and thermal Energies= Sum of electronic and thermal Enthalpies= Sum of electronic and thermal Free Energies= (Hartree/Particle) X Y Z Co Co C C C C Si C C C C C P C C C C C C C C C C C C C P C C C C C C C C C C C C C O C O C O C O H H H H H H H H H H H H H H H H H H H H H H H H H Co Co S36 C C C C Si C C C C C P C C C C C C C C C C C C C P C C C C C C C C C C C C C O C O C O C O H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H

37 E-9 Sum of electronic and zero-point Energies= Sum of electronic and thermal Energies= Sum of electronic and thermal Enthalpies= Sum of electronic and thermal Free Energies= (Hartree/Particle) X Y Z Co Co C C C C Si C C C C C C C P C C C C C C C C C C C C C P C C C C C C C C C C C C C O C O C O C O H H H H H H H H H H H H H H H H H H H H H H H H S37 H Co Co C C C C Si C C C C C C C P C C C C C C C C C C C C C P C C C C C C C C C C C C C O C O C O C O H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H

38 Z-9 Sum of electronic and zero-point Energies= Sum of electronic and thermal Energies= Sum of electronic and thermal Enthalpies= Sum of electronic and thermal Free Energies= (Hartree/Particle) X Y Z Co Co C C C C Si C C C C C C C P C C C C C C C C C C C C C P C C C C C C C C C C C C C O C O C O C O H H H H H H H H H H H H H H H H H H H H H H H H S38 H Co Co C C C C Si C C C C C C C P C C C C C C C C C C C C C P C C C C C C C C C C C C C O C O C O C O H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H H

Supplementary Figure 1. ToF-SIMS data obtained for the Au(111) surface after the sublimation of the Cu-BCOD (mass 889 a.u.). During the sublimation

Supplementary Figure 1. ToF-SIMS data obtained for the Au(111) surface after the sublimation of the Cu-BCOD (mass 889 a.u.). During the sublimation process, Cu-BCOD was converted into Cu-Benzo (mass 786