Supplementary information

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1 Supplementary information Dinitrogen leavage and Functionalization by arbon Monoxide Promoted by a Hafnium omplex Donald J. Knobloch, Emil Lobkovsky, Paul J. hirik* Department of hemistry and hemical Biology, Baker Laboratory, ornell University, Ithaca, New York, U. S. A ontents A. Experimental Section S2 B. Isomeric Possibilities for 2-N 2 2 O 2-1 S5. Selected NMR Spectra S6 D. References S10 nature chemistry 1

2 A. Experimental Section General onsiderations. All air- and moisture-sensitive manipulations were carried out using standard high vacuum line, Schlenk or cannula techniques or in an M. Braun inert atmosphere drybox containing an atmosphere of purified nitrogen. The M. Braun drybox was equipped with a cold well designed for freezing samples in liquid nitrogen. Solvents for air- and moisture-sensitive manipulations were dried and deoxygenated using literature procedures. 1 Toluene, benzene, pentane and heptane were further dried by distillation from titanocene. 2 Deuterated solvents for NMR spectroscopy were distilled from sodium metal under an atmosphere of argon and stored over 4 Å molecular sieves. Argon and hydrogen gas were purchased from Airgas Incorporated and passed through a column containing manganese oxide on vermiculite and 4 Å molecular sieves before admission to the high vacuum line. arbon dioxide was also dried over 4 Å molecular sieves before admission to the high vacuum line. Trimethylsilyl iodide was purchased from Acros and dried over 4 Å molecular sieves prior to use. Ammonia was detected by 1 H NMR spectroscopy in DMSO-d 6 by formation of NH 4 l by protonation with Hl 3 as well as by phenol-hypochlorite titration. 4 1 H NMR spectra were recorded on a Varian Inova 400 Spectrometer operating at MHz. All chemical shifts are reported relative to SiMe 4 using 1 H (residual) chemical shifts of the solvent as a secondary standard. 2 H, 13, 29 Si, and 15 N NMR spectra were recorded on a Varian Inova 500 Spectrometer operating at , , , and MHz, respectively. 2 H, 29 Si, and 13 chemical shifts are reported relative to SiMe 4 using chemical shifts of the solvent as a secondary standard where nature chemistry 2

3 applicable. 15 N chemical shifts are reported relative liquid to NH 3 using an external standard. Mass spectra were acquired using a JEOL GMate II mass spectrometer operating at 500 (LRMS) resolving power (20% FWHM) in positive ion mode and an electron ionization (EI) potential of 70 ev. Samples were introduced via a G inlet using an Agilent HP 6890N G equipped with a 30 m (0.25 mm i.d.) HP-5ms capillary G column. The carrier gas is helium with a flow rate of 1 ml/min. Samples were introduced into the G using a split/splitless injector at 230 º with a split ratio of 50:1. Infrared spectroscopy was conducted on a Mattson RS Research Series FT-IR spectrometer calibrated with a polystyrene standard. Elemental analyses were performed at Robertson Microlit Laboratories, Inc., in Madison, NJ. Preparation of [Me 2 Si(! 5-5 Me 4 )(! 5-5 H 3-3- t Bu)]Hfl 2 (2-l 2 ). In a drybox, a 250 ml round bottomed flask was charged with 4.40 g (14.1 mmol) of Li 2 [Me 2 Si(! 5-5 Me 4 )(! 5-5 H 3-3- t Bu)], 4.51 g (14.1 mmol) of Hfl 4, and approximately 125 ml of toluene. A reflux condenser and 180 needle valve were attached, and the reaction assembly was transferred to a high vacuum line. The reaction mixture was heated to reflux for 3 days with stirring. After this time, the solvent was removed in vacuo, leaving a yellow oil. The oil was dissolved in diethyl ether and the lithium chloride precipitate was removed by filtration through elite. Recrystallization from a pentane/diethyl ether mixture furnished 2-l 2 as a pale yellow solid in 67% yield. Anal. alcd for 20 H 30 SiHfl 2 :, 43.84; H, 5.52; N, Found:, 43.57; H, 5.37; N, < H NMR (benzene-d 6 ): " = 0.38 (s, 3H, SiMe 2 ), 0.42 (s, 3H, SiMe 2 ), 1.44 (s, 9H, 5 H 3 Me 3 ), 1.80 (s, 3H, 5 Me 4 ), 1.83 (s, 3H, 5 Me 4 ), 2.01 (s, 6H, 5 Me 4 ), 5.44 (m, 1H, 5 H 3 Me 3 ), 5.51 (m, 1H, 5 H 3 Me 3 ), 6.81 (m, 1H, 5 H 3 Me 3 ). { 1 H} 13 NMR (benzene-d 6 ):! = (SiMe 2 ), 0.21 (SiMe 2 ), (pme), nature chemistry 3

4 12.62 (pme), (pme), (pme), (Me 3 ), (Me 3 ), 99.57, , , , , , , , , (p). Preparation of [Me 2 Si(! 5-5 Me 4 )(! 5-5 H 3-3- t Bu)]HfI 2 (2-I 2 ). A 20 ml scintillation vial was charged with 1.00 g (1.82 mmol) of 2-l 2 dissolved in approximately 10 ml of toluene. To the vial 3.65 g (18.2 mmol) of iodotrimethylsilane was added with stirring. The reaction was stirred at room temperature for approximately 24 hours. Excess iodotrimethylsilane and toluene were removed in vacuo, yielding a yellow solid which was washed with cold pentane to furnish 2-I 2 in 93% yield. Anal. alcd for 20 H 30 SiHfI 2 :, 32.87; H, 4.14; N, Found:, 32.59; H, 4.08; N, H NMR (benzene-d 6 ): " = 0.34 (s, 3H, SiMe 2 ), 0.37 (s, 3H, SiMe 2 ), 1.43 (s, 9H, 5 H 3 Me 3 ), 1.72 (s, 3H, 5 Me 4 ), 1.74 (s, 3H, 5 Me 4 ), 1.97 (s, 3H, 5 Me 4 ), 2.36 (s, 3H, 5 Me 4 ), 5.16 (m, 1H, 5 H 3 Me 3 ), 5.49 (m, 1H, 5 H 3 Me 3 ), 7.37 (m, 1H, 5 H 3 Me 3 ). { 1 H} 13 NMR (benzene-d 6 ):! = (SiMe 2 ), (SiMe 2 ), (pme), (pme), (2 pme), (Me 3 ), (Me 3 ), 98.73, , , , , , , , , (p). Preparation of ([Me 2 Si(! 5-5 Me 4 )(! 5-5 H 3-3- t Bu)]Hf) 2 N 2 (2-N 2 ). A 100 ml round bottomed flask was charged with g (8 equivalents) of 0.5% sodium amalgam and approximately 10 ml of toluene. With vigorous stirring, g (0.684 mmol) of 2-I 2 was added as a yellow toluene solution and the resulting reaction mixture was stirred for seven days at ambient temperature. The resulting purple solution was filtered through elite to remove excess sodium amalgam and sodium iodide, and the solvent was removed in vacuo leaving a purple solid. Recrystallization from pentane furnished 2-N 2 as purple crystals in 61% yield. Anal. alcd for 40 H 60 N 2 Si 2 Hf 2 :, 48.92; H, 6.16; N, Found:, 48.48; H, 6.08; N, H NMR (benzene-d 6 ): " = 0.57 (s, 3H, SiMe 2 ), 0.70 (s, 3H, SiMe 2 ), 1.39 nature chemistry 4

5 (s, 9H, 5 H 3 Me 3 ), 1.87 (s, 3H, 5 Me 4 ), 2.11 (s, 3H, 5 Me 4 ), 2.16 (s, 3H, 5 Me 4 ), 2.22 (s, 3H, 5 Me 4 ), 5.64 (m, 1H, 5 H 3 Me 3 ), 5.80 (m, 1H, 5 H 3 Me 3 ), 6.02 (m, 1H, 5 H 3 Me 3 ). { 1 H} 13 NMR (benzene-d 6 ):! = (SiMe 2 ), 1.31 (SiMe 2 ), (pme), (pme), (pme), (pme), (Me 3 ), (Me 3 ), , , , , , , , , , (p). 15 N NMR (benzene-d 6 ): " = ( 15 N 2 ). Protonolysis of Oxamidide omplexes. Treatment of either isomer of 2-N 2 2 O 2 with 10 equivalents of ethanol, admitted via calibrated gas bulb, resulted in formation of oxamide (H 2 N(O)(O)NH 2 ) in high yield (88-95%), along with formation of the corresponding hafnocene bis(ethoxide) compound as well as partial metallocene decomposition to free ligand. 1 H NMR spectra of protonolysis products were recorded in DMSO-d 6 and integrated against a ferrocene standard. B. Isomeric Possibilities for and 2-N 2 2 O 2-1. Me 2 Si M N N O O N O M SiMe 2 Me 2 Si M M SiMe 2 Me 2 Si M N O N O O N M SiMe 2 (S,S)-syn (S,S)-anti nature chemistry 5

6 . Selected NMR Spectra. Fig. S1. Benzene-d 6 { 1 H} 13 NMR spectra of 2-(N O 2 )- 2 (top) and isotopologue 2- ( 15 N O 2 )- 2 (bottom) at 20 º. nature chemistry 6

7 Fig. S2. Benzene-d 6 { 1 H} 15 N NMR spectra of 2-( 15 N 2 2 O 2 )- 2 (top) and 2-( 15 N O 2 )- 2 (bottom) at 20 º. nature chemistry 7

8 Fig. S3. Top: { 1 H} 13 NMR spectrum of 3 with 13 enrichment. Bottom: { 1 H} 13 NMR spectrum of 3 with 15 N, 13 enrichment. Both spectra recorded in benzene-d 6. nature chemistry 8

9 Fig. S4. Top: { 1 H} 15 N NMR spectrum of 3 with 15 N, 13 labeling. Bottom: 15 N NMR spectrum ( 1 H coupled) of 3 with 15 N, 13 labeling. Both spectra collected in benzene-d 6. nature chemistry 9

10 D. References. 1 Pangborn, A.B.; Giardello, M.A.; Grubbs, R.H.; Rosen, R.K.; Timmers, F.J. Organometallics 1996, 15, Marvich, R.H.; Brintzinger, H. H. J. Am. hem. Soc. 1971, 93, Yandulov, D. V.; Schrock, R. R. Science 2003, 301, Weatherburn, M. W. Anal. hem. 1967, 39, 971. nature chemistry 10