Complexes of High-Valent Rhenium. Supported by the PCP Pincer

Transcription

1 Supporting Information Complexes of High-Valent Rhenium Supported by the PCP Pincer Alex J. Kosanovich; Joseph H. Reibenspies; Oleg V. Ozerov* Department of Chemistry, Texas A&M University, College Station, Texas S1

2 Table of Contents I. NMR, IR, and Characterization Details of Rhenium Complexes S3-S35 II. Reactivity Screening of PCP ipr Metallation S36-37 III. X-Ray Structural Determination Details for (PCP ipr )ReOCl2 (2) S38 IV. X-Ray Structural Determination Details for (PCP ipr )ReH4(dmap) (7) S39 V. References S40 S2

3 Figure S1. 1 H NMR (300 MHz, CDCl3) spectrum of [(PC H P ipr )ReOCl3]n (1). Spectrum contains residual pentane, acetonitrile, and silicone grease. S3

4 Figure S2. 31 P{ 1 H} NMR (121 MHz, CDCl3) spectrum of [(PC H P ipr )ReOCl3]n (1) precipitated from CH2Cl2 and pentane. S4

5 Figure S3. IR spectrum of [(PC H P ipr )ReOCl3]n (1) taken in Nujol mull using KBr plates, Re=O stretch at 978 cm -1. S5

6 General Stability of (PCP ipr )ReOCl2 (2) Indicating high thermal stability, heating a toluene solution of 2 at 140 C for up to 120 h produced no observable decomposition by 31 P{ 1 H} spectroscopy. A sample of 2 was removed from the glovebox and dissolved in an NMR tube under ambient conditions in C6D6 which contained trace amounts of water. No changes were detected by 1 H NMR spectroscopy. Figure S4. 1 H NMR (500 MHz, C6D6) spectrum of (PCP ipr )ReOCl2 (2). Spectrum contains residual silicone grease, toluene, and pentane. S6

7 Figure S5. 31 P{ 1 H} NMR (202 MHz, C6D6) spectrum of (PCP ipr )ReOCl2 (2). S7

8 Figure S6. IR spectrum of (PCP ipr )ReOCl2 (2) taken in nujol mull using KBr plates, Re=O stretch at 978 cm -1. S8

9 General Stability of (PCP ipr )ReOBr2 (3) A sample 3 was removed from the glovebox and dissolved in an NMR tube under ambient conditions, in C6D6 which contained trace amounts of water. No changes were detected by 1 H NMR spectroscopy. Figure S7. 1 H NMR (500 MHz, C6D6) spectrum of (PCP ipr )ReOBr2 (3). Spectrum contains residual pentane and toluene. S9

10 Figure S8. 31 P{ 1 H} NMR (202 MHz, C6D6) spectrum of (PCP ipr )ReOBr2 (3). S10

11 % Transmittance ajk279ir (PCP)ReOBr Wave numbers (cm-1) Figure S9. IR spectrum of (PCP ipr )ReOBr2 (3), Re=O stretch at 976 cm -1. S11

12 General Stability of (PCP ipr )ReOI2 (4) A sample of 4 was removed from the glovebox and dissolved in an NMR tube under ambient conditions, in C6D6 which contained trace amounts of water. No chemical changes were observed by 1 H NMR spectroscopy. Figure S10. 1 H NMR (500 MHz, C6D6) spectrum of (PCP ipr )ReOI2 (4). Spectrum contains residual hexamethyldisiloxane, pentane, CH2Cl2, and toluene. S12

13 Figure S P{ 1 H} NMR (202 MHz, C6D6) spectrum of (PCP ipr )ReOI2 (4). S13

14 Figure S12. IR spectrum of (PCP ipr )ReOI2 (4) taken in Nujol mull using KBr plates, Re=O stretch at 974 cm -1. S14

15 General Stability of (PCP ipr )ReH6 (5) 5 could consistently be isolated as a dark, gray solid (>95% purity) and stored in a glovebox freezer, showing minimal (< 10% by 31 P{ 1 H} NMR) decomposition after 4 weeks. No decomposition occurs by 1 H NMR in solutions of cyclohexane-d12 or THF-d8 over a period of two weeks at room temperature. Exposures to CDCl3 and CH2Cl2 result in the immediate transformation of 5 to an as-of-yet unidentified, red colored mixture of paramagnetic products, accompanied by vigorous bubbling. 5 was found to be non-reactive, and insoluble with and in methanol, isopropanol, and water at room temperature under an atmosphere of argon. Observation of H/D exchange in C6D6 In a J. Young tube, 5 (6.7 mg,.013 mmol) was dissolved in C6D6 and observed by 1 H and 31 P{ 1 H} NMR spectroscopy. Significant, fast H/D exchange is noted in solutions of neat benzene-d6 and the hydride resonance of 5 is found to give a complex splitting pattern (Figure 13) before eventually disappearing completely (after 1 h) with a corresponding increase in residual solvent intensity by 1 H NMR spectroscopy. A new upfield (ca. 0.5 ppm), singlet resonance is noted in the 31 P{ 1 H} NMR spectrum. Simultaneously, resonances for the aryl backbone of the PCP ligand coalesce (Figure 14) Further confirming the H/D exchange reactivity, is the release of HD (JH-D = 43 Hz) in reaction of 5 with CO in solutions of C6D6 S15

16 Figure S13. Stacked 1 H NMR (500 MHz) spectra of (A) (PCP ipr )ReH6 (5) hydride resonance taken in C6D6, showing extensive H/D scrambling after ten minutes and (B) (PCP ipr )ReH6 (5) triplet hydride resonance in cyclohexane-d12 for comparison. S16

17 Figure S14. Stacked 1 H NMR (500 MHz) spectra of (A) (PCP ipr )ReH6 (5) aryl backbone resonance taken in C6D6, showing extensive H/D scrambling after ten minutes, resulting in signal coalescence, and (B) (PCP ipr )ReH6 (5) aryl backbone resonance in cyclohexane-d12 for comparison. S17

18 Temp (C) T1 (ms) [11] [7] [4] [9] [4] [2] Table S1. Variable temperature T1 inversion recovery data collected on triplet hydride resonance at -6.2 ppm in THF-d8 for (PCP ipr )ReH6 (5) using a Varian inova 500 MHz spectrometer. S18

19 Figure S15. 1 H NMR (500 MHz, cyclohexane-d12) spectrum of (PCP ipr )ReH6 (5). Spectrum contains residual silicone grease and pentane. S19

20 Figure S P{ 1 H} NMR (500 MHz, cyclohexane-d12) spectrum of (PCP ipr )ReH6 (5). S20

21 Figure S P NMR (202 MHz, cyclohexane-d12) spectrum of 5 taken on Varian inova 500 MHz NMR with selective decoupling of 1 H aliphatic resonances. Spectrum shows a septet from ligand phosphines coupling to six chemically equivalent rhenium hydrides. Decoupler offset is placed at (1.5 ppm) in 500 MHz 1 H NMR spectrum. Waltz 16 sequence was utilized. S21

22 Figure S18. 1 H NMR (500 MHz, C6D6) spectrum of (PCP ipr )ReH4(PMe3) (6). Spectrum contains residual pentane, and CH2Cl2. S22

23 Figure S P{ 1 H} NMR (202 MHz, C6D6) spectrum of (PCP ipr )ReH4(PMe3) (6). S23

24 Figure S P{ 1 H} NMR (202 MHz, C6D6) spectrum of (PCP ipr )ReH4(PMe3) (6). Spectrum taken in the presence of an excess of PMe3 and shows three sharp resonances corresponding to A) PCP ipr B) coordinated PMe3, and C) free PMe3. S24

25 Variable Temperature Study of (PCP ipr )ReH4(PMe3) (6) 1 H NMR (500 MHz, toluene-d8): δ 7.76 (d, 3 JH-H = 7.3 Hz, 2H), 7.67 (t, 3 JH-H = 7.3 Hz, 1H), 3.87 (br, 4H), 2.49 (m, 4H), 2.10 (d, 2 JP-H = 7.2 Hz, 9H), 1.75 (m, 12H), 1.59 (m, 12H), (br, 4H). 31 P{ 1 H} NMR (202 MHz, toluene-d8, -60 o C): δ 69.6 (d, 2 JP-P = 9.7 Hz), (br) Figure S20. Stacked VT 1H NMR {500 MHz, Toluene-d8} spectra of 6 (>95%) with indicated temperatures. Sample was allowed to equilibrate at each temperature for 5 minutes prior to data collection. S25

26 Figure S21. 1 H NMR (500 MHz, C6D6) spectrum of (PCP ipr )ReH4(dmap) (7). Spectrum contains residual pentane. S26

27 Figure S P{ 1 H} NMR (202 MHz, C6D6) spectrum of (PCP ipr )ReH4(dmap) (7). S27

28 General stability of (PCP ipr )Re(CO)3 (8) Samples of 8 were handled on the bench top without any noticeable decomposition upon exposure to air or solvents containing water (acetone, CH2Cl2, C6D6, CDCl3). IR and elemental analysis were collected without the use of an inert atmosphere. 8 was not found to release CO, or undergo any other chemical change by 31 P{ 1 H} NMR in solutions of toluene heated up to 140 C for 48 h, or under exposure to UV light at room temperature for 24 h. Figure S23. 1 H NMR (500 MHz, C6D6) spectrum of (PCP ipr )Re(CO)3 (8). Spectrum contains residual silicone grease, water, CH2Cl2, and pentane. S28

29 Figure S P{ 1 H} NMR (202 MHz, C6D6) spectrum of (PCP ipr )Re(CO)3 (8). S29

30 Figure S25. IR spectrum of (PCP ipr )Re(CO)3 (8) taken in Nujol mull using KBr plates, C=O stretches at 2015, 1911, and 1901 cm -1. S30

31 In Situ Monitoring of (PCP ipr )ReH6 (5) Thermolysis in Cyclohexane-d12 A sample of 5 was dissolved in cyclohexane-d12 and heated in a J. Young tube in an oil bath at 90 o C for 72 h in a dark fume hood. The solution was monitored by 31 P{ 1 H} and 1 H NMR, and observations were recorded. Over 72 h, the solution gradually changed from tan in color to dark purple, and new, very broad resonances appeared by 31 P{ 1 H} NMR in a 1:1 ratio at 82.7 and 77.4 ppm, accounting for 75% of product in solution. By 31 P{ 1 H} integration, 5 was found to constitute 20% of the material in solution. Also located was 5% of another, unidentified product, with a broad resonance at 80.7 ppm. By 1 H NMR, a new hydride quintet was observed at ppm (JP-H = 7.2 Hz, 3H (apparent)). 1 H NMR (500 MHz, cyclohexane-d12): δ 6.86 (d, JH-H = 7.3 Hz, 2H), 6.63 (t, JH-H = 7.3 Hz, 1H), 3.62 (m, 4H), 1.74 (m, 4H), (m, 24H), (quint., JP-H = 7.2 Hz, 3H). 31 P{ 1 H} NMR (202 MHz, cyclohexane-d12): δ 82.3 (br), 77.3 (br) S31

32 Figure S26. 1 H NMR (500 MHz, cyclohexane-d12) spectrum of (PCP ipr )ReH6 (5) thermolysis in cyclohexane-d12 with insets of the corresponding 31 P{ 1 H} NMR spectrum, ligand backbone resonances, as well as hydride signal for the major thermolysis product (as labeled). S32

33 Figure S27. 1 H NMR (500 MHz, C6D6) spectrum of isolated (PCP ipr )2Re2H6 (9). (A) Inset of corresponding 31 P{ 1 H} NMR spectrum. (B) Inset of zoomed in aromatic resonances showing ligand backbone splitting. (C) Inset of hydride quintet. Spectrum contains residual silicone grease, pentane, cyclohexane, toluene, and CH2Cl2 from solvent. S33

34 Figure S28. ESI(+) mass spectrum of isolated (PCP ipr )2Re2H6 (9) taken in acetonitrile as solvent. S34

35 Figure S29. Stacked VT 1 H NMR {500 MHz, Toluene-d8} spectra of (PCP ipr )2Re2H6 (9) with indicated temperatures. Sample was allowed to equilibrate at each temperature for 5 minutes prior to data collection. Spectrum contains trace amounts (<2 %) of an unidentified, hydridecontaining impurity. S35

36 Attempted C-H Activation of [(PC H P ipr )ReOCl3]n (1) with Bases A. To a J. Young tube in fluorobenzene was added [(PC H P ipr )ReOCl3]n (1) (20.0 mg,.031 mmol) and triethylamine (5 µl,.035 mmol). The light green solution was heated at 110 C for 72 h over which time a colorless solid begins to precipitate, and 50% conversion to (PCP ipr )ReOCl2 (2) was confirmed by 31 P{ 1 H} NMR spectroscopy. The presence of free ligand (δ 10.3) and [(PC H P ipr )ReOCl3]n (1) (δ -4.8) was also noted. B. To a J. Young tube in THF was added [(PC H P ipr )ReOCl3]n (1) (21.0 mg,.032 mmol) and triethylamine (10 µl,.070 mmol). The light green solution was heated at 80 C for 72 h over which time a colorless solid begins to precipitate, and 40% conversion to (PCP ipr )ReOCl2 (2) was confirmed by 31 P{ 1 H} NMR spectroscopy. The presence of [(PC H P ipr )ReOCl3]n (1) (δ -4.9) was also noted. C. To a J. Young tube in neat triethylamine was added a suspension of [(PC H P ipr )ReOCl3]n (1) (21.0 mg,.032 mmol). The suspension was heated at 90 C for 72 h over which time the solids became black, and a single resonance corresponding to free PCP ipr (δ 10.0) was confirmed by 31 P{ 1 H} NMR spectroscopy. D. To a J. Young tube in toluene was added [(PC H P ipr )ReOCl3]n (1) (29.5 mg,.046 mmol) and 2,6-lutidine (11 µl,.094 mmol). The light green solution was heated at 110 C for 24 h over which time a small amount of colorless solid begins to precipitate, and trace quantities of (PCP ipr )ReOCl2 (2) were confirmed by 31 P{ 1 H} NMR spectroscopy. E. To a J. Young tube in C6D6 was added [(PC H P ipr )ReOCl3]n (1) (21.8 mg,.034 mmol) and hexamethyldisilazane (11 µl,.052 mmol). The light green solution was heated at 80 C for 24 h. By 31 P{ 1 H} NMR spectroscopy, the mixture contained [(PC H P ipr )ReOCl3]n (1) (90%) and free PCP ipr (10%). S36

37 F. To a J. Young tube in toluene was added [(PC H P ipr )ReOCl3]n (1) (23.7 mg,.037 mmol) and i Pr2NH (8 µl,.057 mmol). The light green solution was heated at 110 C for 48 h over which time a colorless solid begins to precipitate, and 75% conversion to (PCP ipr )ReOCl2 (2) was confirmed by 31 P{ 1 H} NMR spectroscopy. Also noted in the 31 P{ 1 H} NMR spectrum is the presence of 17% free PCP ipr and 8% of other unidentified products. G. To a J. Young tube in C6D6 was added [(PC H P ipr )ReOCl3]n (1) (17.1 mg,.026 mmol) and i Pr2NEt (10 µl,.057 mmol). The light green solution was heated at 100 C. 31 P{ 1 H} NMR spectroscopy revealed the formation of a significant quantity of oxidized free ligand (O=PCP ipr ). No (PCP ipr )ReOCl2 (2) was determined to have formed. H. To a J. Young tube in C6D6 was added [(PC H P ipr )ReOCl3]n (1) (28.7 mg,.044 mmol) and lithium hexamethyldisilazide (8.3 mg,.049 mmol). The light green solution immediately turned dark brown, and 31 P{ 1 H} NMR spectroscopy revealed formation of multiple, unidentified products. No (PCP ipr )ReOCl2 (2) was determined to have formed. I. To a J. Young tube in C6D6 was added [(PC H P ipr )ReOCl3]n (1) (17.3 mg,.027 mmol) and potassium tert-butoxide (3.0 mg,.027 mmol). The light green solution was heated at 80 C for 24 h. 31 P{ 1 H} NMR spectroscopy revealed the presence of [(PC H P ipr )ReOCl3]n (1), and no formation of (PCP ipr )ReOCl2 (2) was observed. S37

38 X-Ray data collection, solution, and refinement for (PCP ipr )ReOCl2 (2) Single crystals of C27H43Cl2OP2Re (2) were grown from a toluene solution layered in pentane. A dark green, multi-faceted block of suitable size (0.36 x 0.16 x 0.08 mm) was selected from a representative sample of crystals of the same habit using an optical microscope and mounted onto a nylon loop. Low temperature (110 K) X-ray data were obtained on a Bruker APEXII CCD based diffractometer (Mo sealed X-ray tube, Kα = Å). Using Olex2 1, The structure was solved in the monoclinic P21/c space group using the ShelXT 2 structure solution program using Direct Methods and refined with the ShelXL 3 refinement package using Least Squares minimization. The structure was refined (weighted least squares refinement on F 2 ) and the final least-squares refinement converged to R1 = (I >= 2 (I), 7368 data) and wr2 = (F 2, data, 372 parameters). Toluene, a crystallization solvent, was found in the asymmetric unit. S38

39 X-Ray data collection, solution, and refinement for (PCP ipr )ReH4(dmap) (7) A colorless, multi-faceted block of suitable size (0.05 x 0.04 x 0.02 mm) was selected from a representative sample of crystals of the same habit using an optical microscope and mounted onto a nylon loop. Low temperature (150 K) X-ray data were obtained on a Bruker APEXII CCD based diffractometer (Mo sealed X-ray tube, Kα = Å). All diffractometer manipulations, including data collection, integration and scaling were carried out using the Bruker APEXII software. 4 An absorption correction was applied using SADABS. 5 The space group was determined on the basis of systematic absences and intensity statistics and the structure was solved by direct methods and refined by full-matrix least squares on F 2. The structure was solved in the monoclinic P 21/c space group using XS 3 (incorporated in SHELXTL). No missed symmetry was reported by PLATON. 6 All non-hydrogen atoms were refined with anisotropic thermal parameters. Hydrogen atoms were placed in idealized positions and refined using riding model. The structure was refined (weighted least squares refinement on F 2 ). S39

40 Supporting Information References 1 Dolomanov, O.V.; Bourhis, L.J.; Gildea, R.J.; Howard, J.A.K.; Puschmann, H. J. Appl. Cryst. 2009, 42, Sheldrick, G.M. Acta Cryst. 2015, A71, Sheldrick, G.M. Acta Cryst. 2008, A64, APEX 2, Version 2 User Manual, M86-E01078, Bruker Analytical X-Ray Systems, Madison, WI, June Sheldrick, G.M. SADABS (version 2008/1): Program for Absorption Correction for Data from Area Detector Frames, University of Gôttingen, Spek, A.L. PLATON- A Multipurpose Crystallographic Tool, Utrecht University, S40