核磁溶剂峰

2176

Organometallics 2010, 29, 2176–2179DOI:

10.1021/om100106e

NMR Chemical Shifts of Trace Impurities:Common Laboratory Solvents, Organics, and Gases in Deuterated

Solvents Relevant to the Organometallic

Chemist

Gregory R. Fulmer,*,†Alexander J. M. Miller, ‡Nathaniel H. Sherden, ‡

Hugo E. Gottlieb, §Abraham Nudelman, §Brian M. Stoltz, ‡John E. Bercaw, ‡and

Karen I. Goldberg †

‡

Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, Arnold and Mabel Beckman Laboratories of Chemical Synthesis and Caltech Center for Catalysis and

Chemical Synthesis, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, and §Department of Chemistry, Bar Ilan University,

Ramat Gan 52900, Israel

Received February 11, 2010

†

Tables of 1H and 13C NMR chemical shifts have been compiled for common organic compounds often used as reagents or found as products or contaminants in deuterated organic solvents. Building upon the work of Gottlieb, Kotlyar, and Nudelman in the Journal of Organic Chemistry, signals for common impurities are now reported in additional NMR solvents (tetrahydrofuran-d 8, toluene-d 8, dichloromethane-d 2, chlorobenzene-d 5, and 2,2,2-trifluoroethanol-d 3) which are frequently used in organometallic laboratories. Chemical shifts for other organics which are often used as reagents or internal standards or are found as products in organometallic chemistry are also reported for all the listed solvents.

Hanging above the desk of most every chemist whose work relies heavily on using NMR spectroscopy 1is NMR Chemi-cal Shifts of Common Laboratory Solvents as Trace Impu-rities by Gottlieb, Kotlyar, and Nudelman. 2By compiling the chemical shifts of a large number of contaminants commonly encountered in synthetic chemistry, the publica-tion has become an essential reference, allowing for easy identification of known impurities in a variety of deuter-ated organic solvents. However, despite the utility of Gottlieb et al.’swork, 3the chemical shifts of impurities in a number of NMR solvents often used by organometallic chemists were not included. Tetrahydrofuran-d 8(THF-d 8), toluene-d 8, dichloromethane-d 2(CD2Cl 2), chlorobenzene-d 5(C6D 5Cl), and 2,2,2-trifluoroethanol-d 3(TFE-d 3) are com-monplace in laboratories practicing inorganic syntheses. Therefore, we have expanded the spectral data compilation with the inclusion of chemical shifts of common impurities recorded in the deuterated solvents heavily employed in our organometallic laboratories. The chemical shifts of various gases (hydrogen,methane, ethane, propane,

*Towhom correspondence should be addressed. E-mail:[email protected].

(1)For general information on 1H and 13C{1H}NMR spectroscopy, see:Balc ı,M. Basic 1H-and 13C-NMR Spectroscopy ; Elsevier:Amsterdam, 2005.

(2)Gottlieb, H. E.; Kotlyar, V.; Nudelman, A. J. Org. Chem. 1997, 62, 7512.

(3)According to ACS Publications as of December 2009(http://pubs.acs.org/),Gottlieb et al.’spublication 2is the most downloaded Journal of Organic Chemistry article over the preceding 12months. pubs.acs.org/Organometallics

Published on Web 04/16/2010

ethylene, propylene, and carbon dioxide) often encoun-tered as reagents or products in organometallic reactions, along with organic compounds relevant to organometallic chemists (allylacetate, benzaldehyde, carbon disulfide, carbon tetrachloride, 18-crown-6, cyclohexanone, diallyl carbonate, dimethyl carbonate, dimethyl malonate, furan, Apiezon H grease, hexamethylbenzene, hexamethyldisil-oxane, imidazole, pyrrole, and pyrrolidine), have also been added to this expanded list.

Experimental Section

All deuterated solvents were obtained commercially through Cambridge Isotope Laboratories, Inc. NMR spectra were recorded at 298K using 300, 500, or 600MHz spectrometers (13C{1H}NMR frequencies of 75.5, 126, or 151MHz, res-pectively). Adopting the previously reported strategy, 2standard solutions of mixtures of specific impurities were used to reduce the number of necessary individual NMR experiments. The combinations of organic compounds were chosen in a way in which intermolecular interactions and resonance convolution would be minimized. Unless otherwise stated, the standard solutions were prepared with qualitatively equal molar amounts of the following compounds:(solution1) acetone, dimethylform-amide, ethanol, toluene; (solution2) benzene, dimethyl sulf-oxide, ethyl acetate, methanol; (solution3) acetic acid, chloro-form, diethyl ether, 2-propanol, tetrahydrofuran; (solution4) acetonitrile, dichloromethane, 1,4-dioxane, n -hexane, hexa-methylphosphoramide (HMPA);(solution5) 1,2-dichloroethane, n -pentane, pyridine, hexamethylbenzene; (solution6) tert -butyl alcohol, 2,6-di-tert -butyl-4-methylphenol (BHT),cyclohexane,

r 2010American Chemical Society

Article

Table 1. 1H NMR Data a

proton

solvent residual signals

mult

THF-d 81.723.58

CD 2Cl 25.32

CDCl 37.26

toluene-d 8

2.086.977.017.09

C 6D 67.16

Organometallics, Vol. 29, No. 9, 20102177

C 6D 5Cl (CD3) 2CO (CD3) 2SO CD 3CN 6.966.997.14

2.05

2.50

1.94

TFE-d 35.023.88

CD 3OD D 2O 3.31

4.79

OH s 2.461.521.560.430.401.032.84b 3.33b 2.133.664.87CH 3s 1.892.062.101.571.521.761.961.911.962.061.99

s 2.052.122.171.571.551.772.092.092.082.192.15CH 3

s 1.951.972.100.690.581.212.052.071.961.952.03CH 3

CH s 7.317.357.367.127.157.207.367.377.377.367.33

s 1.151.241.281.031.051.121.181.111.161.281.40CH 3

OH s c 3.160.580.631.304.192.182.20

chloroform CH s 7.897.327.266.106.156.748.028.327.587.337.9018-crown-6CH 2s 3.573.593.673.363.393.413.593.513.513.643.64

s 1.441.441.431.401.401.371.431.401.441.471.45cyclohexane CH 2

1,2-dichloroethane CH 2s 3.773.763.732.912.903.263.873.903.813.713.78

s 5.515.335.304.324.274.775.635.765.445.245.49dichloromethane CH 2

diethyl ether CH 3t, 71.121.151.211.101.111.101.111.091.121.201.18

CH 2q, 73.383.433.483.253.263.313.413.383.423.583.49

m 3.433.573.653.433.463.493.563.513.533.673.61diglyme CH 2

CH 2m 3.533.503.573.313.343.373.473.383.453.623.58

s 3.283.333.393.123.113.163.283.243.293.413.35OCH 3

dimethylformamide CH s 7.917.968.027.577.637.737.967.957.927.867.97

CH 3s 2.882.912.962.372.362.512.942.892.892.982.99CH 3s 2.762.822.881.961.862.302.782.732.772.882.86

s 3.563.653.713.333.353.453.593.573.603.763.661,4-dioxane CH 2

DME CH 3s 3.283.343.403.123.123.173.283.243.283.403.35

CH 2s 3.433.493.553.313.333.373.463.433.453.613.52

s 0.850.850.870.810.800.790.830.820.850.850.85ethane CH 3

ethanol CH 3t, 71.101.191.250.970.961.061.121.061.121.221.19

q, 7d 3.513.663.723.363.343.513.573.443.543.713.60CH 2

OH s c , d 3.301.331.320.830.501.393.394.632.47

s 1.942.002.051.691.651.781.971.991.972.032.01ethyl acetate CH 3CO

C H 2CH 3q, 74.044.084.123.873.893.964.054.034.064.144.09CH 2C H 3t, 71.191.231.260.940.921.041.201.171.201.261.24

s 5.365.405.405.255.255.295.385.415.415.405.39ethylene CH 2

ethylene glycol CH 2s e 3.483.663.763.363.413.583.283.343.513.723.59

f

CH 3m 0.85-0.910.84-0.900.84-0.870.89-0.960.90-0.980.86-0.920.900.82-0.880.88-0.940.86-0.93H grease

CH 2br s 1.291.271.251.331.321.301.291.241.331.29

s 2.182.202.242.102.132.102.172.142.192.242.19hexamethylbenzene CH 3

n -hexane CH 3t, 70.890.890.880.880.890.850.880.860.890.910.90

CH 2m 1.291.271.261.221.241.191.281.251.281.311.29

s 0.070.070.070.100.120.100.070.060.070.080.07HMDSO CH 3

HMPA CH 3d,9.52.582.602.652.422.402.472.592.532.572.632.64

s 4.554.594.624.504.474.494.544.614.574.534.56hydrogen H 2

imidazole CH(2)s 7.487.637.677.307.337.537.627.637.577.617.67

CH(4,5)s 6.947.077.106.866.907.017.047.017.017.037.05

methane CH 4s 0.190.210.220.170.160.150.170.200.200.180.20

s g 3.273.423.493.033.073.253.313.163.283.443.34methanol CH 3

OH s c , g 3.021.091.091.303.124.012.16

nitromethane CH 3s 4.314.314.333.012.943.594.434.424.314.284.34

t, 70.890.890.880.870.870.840.880.860.890.900.90n -pentane CH 3

CH 2m 1.311.301.271.251.231.231.271.271.291.331.29

t, 7.30.900.900.900.890.860.840.880.870.900.900.91propane CH 3

CH 2sept, 7.31.331.321.321.321.261.261.311.291.331.331.34

d, 61.081.171.220.950.951.041.101.041.091.201.502-propanol CH 3

CH sept, 63.823.974.043.653.673.823.903.783.874.053.92

propylene CH 3dt, 6.4, 1.51.691.711.731.551.551.581.681.681.701.701.70

dm, 104.894.934.944.924.954.914.904.944.934.934.91CH 2(1)

CH 2(2)dm, 174.995.035.034.985.014.985.005.035.045.035.01CH m 5.795.845.835.705.725.725.815.805.855.875.82

pyridine CH(2,6)m 8.548.598.628.478.538.518.588.588.578.458.53

CH(3,5)m 7.257.287.296.676.666.907.357.397.337.407.44CH(4)m 7.657.687.686.996.987.257.767.797.737.827.85

pyrrole NH br t 9.968.698.407.717.808.6110.0210.759.27

CH(2,5)m 6.666.796.836.436.486.626.776.736.756.846.72CH(3,4)m 6.026.196.266.276.376.276.076.016.106.246.08

pyrrolidine h CH 2(2,5)m 2.752.822.872.542.542.642.672.753.112.80

CH 2(3,4)m 1.591.671.681.361.331.431.551.611.931.72

s 0.110.090.070.260.290.140.13-0.060.080.160.10silicone grease CH 3

tetrahydrofuran CH 2(2,5)m 3.623.693.763.543.573.593.633.603.643.783.71

m 1.791.821.851.431.401.551.791.761.801.911.87CH 2(3,4)

toluene CH 3s 2.312.342.362.112.112.162.322.302.332.332.32

CH(2,4,6)m 7.107.157.176.96-7.017.027.01-7.087.10-7.207.187.10-7.307.10-7.307.16CH(3,5)m 7.197.247.257.097.137.10-7.177.10-7.207.257.10-7.307.10-7.307.16

triethylamine CH 3t, 70.970.991.030.950.960.930.960.930.961.311.05

q,72.462.482.532.392.402.392.452.432.453.122.58CH 2water

acetic acid acetone acetonitrile benzene

tert -butyl alcohol

a

2.082.222.061.243.80

1.173.563.673.613.377.923.012.853.753.373.600.821.173.652.074.141.245.443.65

0.282.617.787.140.183.344.400.881.301.174.021.704.955.065.908.527.457.876.936.263.071.873.741.88

0.992.57

Except for the compounds in solutions 8-10, as well as the gas samples, hexamethylbenzene, and the corrected values mentioned in the Supporting Information, all data for the solvents CDCl 3, C 6D 6, (CD3) 2CO, (CD3) 2SO, CD 3CN, CD 3OD, and D 2O were previously reported in ref 2. b A signal for HDO is also observed in (CD3) 2SO (3.30ppm) and (CD3) 2CO (2.81ppm), often seen as a 1:1:1triplet (2J H,D =1Hz). c Not all OH signals were observable. d In some solvents, the coupling interaction between the CH 2and the OH protons may be observed (J =5Hz). e In CD 3CN, the OH proton was seen as a multiplet at 2.69ppm, as well as extra coupling to the CH 2resonance. f Apiezon brand H grease. g In some solvents, a coupling interaction between the CH 3and the OH protons may be observed (J =5.5Hz). h Pyrrolidine was observed to react with (CD3) 2CO.

2178Organometallics, Vol. 29, No. 9, 2010

Table 2. 13C {1H }NMR Data a

carbon

THF-d 867.2125.31

CD 2Cl 253.84

CDCl 377.16

toluene-d 8137.48128.87127.96125.1320.43175.3020.27204.0030.03115.760.03128.5768.1230.49124.86192.7196.5777.8970.8627.3143.4053.4715.4765.9458.6270.9272.39161.9335.2230.6467.1758.6372.256.9418.7857.8120.46170.0260.0814.23122.9264.2930.31131.7216.8414.3423.1232.061.9936.80135.57122.13-4.3449.9061.1414.2722.7934.5416.6516.6325.2464.1219.32115.89133.61150.25123.46135.17117.61108.1547.1225.751.3767.7525.7921.37137.84129.33128.51125.6612.3946.82

C 6D 6128.06

C 6D 5Cl 134.19129.26128.25125.96175.6720.40204.8330.12115.930.63128.3868.1931.13126.08192.4996.3877.6770.5526.9943.6053.5415.3565.7958.4270.5672.07162.0135.4530.7166.9558.3171.816.9118.5557.6320.50170.2060.0614.07122.9564.0330.11131.5416.6814.1822.8631.771.9236.64135.50121.96-4.3349.6661.6814.1022.5434.2616.5616.4825.1464.1819.32115.86133.57149.93123.49135.32117.65108.0346.7525.591.0967.6425.6821.23137.65129.12128.31125.4311.8746.36

(CD3) 2CO 29.84206.26

(CD3) 2SO 39.52

CD 3CN 1.32118.26

TFE-d 361.50126.28

Fulmer et al.

CD 3OD 49.00

D 2O

solvent signals

acetic acid acetone acetonitrile benzene

tert -butyl alcohol carbon dioxide carbon disulfide carbon tetrachloride chloroform 18-crown-6cyclohexane

1,2-dichloroethane dichloromethane diethyl ether diglyme

dimethylformamide 1,4-dioxane DME ethane ethanol ethyl acetate

ethylene

ethylene glycol H grease b

hexamethylbenzene n -hexane HMDSO HMPA c imidazole methane methanol nitromethane n -pentane propane 2-propanol propylene pyridine pyrrole pyrrolidine e silicone grease tetrahydrofuran toluene

triethylamine

a

CO CH 3CO CH 3CN CH 3CH (CH3) 3C (C H 3) 3C CO 2CS 2CCl 4CH CH 2CH 2CH 2CH 2CH 3CH 2CH 3CH 2CH 2CH CH 3CH 3CH 2CH 3CH 2CH 3CH 3CH 2C H 3CO CO CH 2CH 3CH 2CH 2CH 2C CH 3CH 3CH 2(2,5)CH 2(3,4)CH 3CH 3CH(2)CH(4,5)CH 4CH 3CH 3CH 3CH 2(2,4)CH 2(3)CH 3CH 2CH 3CH CH 3CH 2CH CH(2,6)CH(3,5)CH(4)CH(2,5)CH(3,4)CH 2(2,5)CH 2(3,4)CH 3CH 2(2,5)CH 2(3,4)CH 3C(1)CH(2,6)CH(3,5)CH(4)CH 3CH 2171.6920.13204.1930.17116.790.45128.8467.5030.57125.69193.3796.8979.2471.3427.5844.6454.6715.4966.1458.7271.1772.72161.9635.6530.7067.6558.7272.586.7918.9057.6020.45170.3260.3014.37123.0964.3530.45131.8816.7114.2223.3332.341.8336.89135.72122.20-4.9049.6462.4914.1823.0034.8716.6016.8225.7066.1419.27115.74134.02150.57124.08135.99118.03107.7445.8226.171.2068.0326.1921.29138.24129.47128.71125.8412.5147.18175.8520.91206.7831.00116.922.03128.6869.1131.46125.26192.9596.5277.9970.4727.3844.3554.2415.4466.1158.9570.7072.25162.5736.5631.3967.4759.0272.246.9118.6958.5721.15171.2460.6314.37123.2064.0830.14132.0916.9314.2823.0732.011.9636.99135.76122.16-4.3350.4563.0314.2422.7734.5716.6316.6325.4364.6719.47115.70134.21150.27124.06136.16117.93108.0247.0225.831.2268.1625.9821.53138.36129.35128.54125.6212.1246.75175.9920.81207.0730.92116.431.89128.3769.1531.25124.99192.8396.3477.3670.5526.9443.5053.5215.2065.9159.0170.5171.90162.6236.5031.4567.1459.0871.846.8918.4158.2821.04171.3660.4914.19123.1363.7929.71132.2116.9814.1422.7031.641.9736.87135.38122.00-4.6350.4162.5014.0822.3834.1616.6316.3725.1464.5019.50115.74133.91149.90123.75135.96117.77107.9846.9325.561.1967.9725.6221.46137.89129.07128.26125.3311.6146.25175.8220.37204.4330.14116.020.20128.6268.1930.47124.76192.6996.4477.7970.5927.2343.5953.4615.4665.9458.6670.8772.35162.1335.2530.7267.1658.6872.216.9618.7257.8620.56170.4460.2114.19122.9664.3430.22131.7916.9514.3223.0431.962.0536.88135.76122.16-4.2949.9761.1614.2522.7234.4516.6616.6025.1864.2319.38115.92133.69150.27123.58135.28117.78108.2146.8625.651.3867.8025.7221.10137.91129.33128.56125.6812.3546.77

172.3120.51205.8730.60117.601.12129.1568.1330.72125.81193.5896.6579.1971.2527.5145.2554.9515.7866.1258.7771.0372.63162.7936.1531.0367.6058.4572.476.8818.8957.7220.83170.9660.5614.50123.4764.26132.2216.8614.3423.2832.302.0137.04135.89122.31-5.3349.7763.2114.2922.9834.8316.6816.7825.6763.8519.42116.03134.34150.67124.57136.56117.98108.041.4068.0726.1521.46138.48129.76129.03126.1212.4947.07

171.9320.95206.3130.56117.911.03128.3066.8830.38124.21192.6395.4479.1669.8526.3345.0254.8415.1262.0557.9869.5471.25162.2935.7330.7366.3658.0371.176.6118.5156.0720.68170.3159.7414.40123.5262.76131.1016.6013.8822.0530.951.9636.42135.15121.55-4.0148.5963.2813.2821.7033.4816.3415.6725.4364.9219.20116.07133.55149.58123.84136.05117.32107.0746.5125.2667.0325.1420.99137.35128.88128.18125.2911.7445.74

173.2120.73207.4330.91118.261.79129.3268.7430.68125.89193.6096.6879.1771.2227.6345.5455.3215.6366.3258.9070.9972.63163.3136.5731.3267.7258.8972.476.9918.8057.9621.16171.6860.9814.54123.6964.22132.6116.9414.4323.4032.362.0737.10136.33122.78-4.6149.9063.6614.3723.0834.8916.7316.9125.5564.3019.48116.12134.78150.76127.76136.89118.47108.3147.5726.3468.3326.2721.50138.90129.94129.23126.2812.3847.10

177.9620.9132.35214.98118.951.00129.8472.3531.07126.92196.2697.7478.8370.8028.3445.2854.4615.3367.5559.4073.0571.33166.0137.7630.9668.5259.5272.877.0118.1159.6821.18175.5562.7014.36124.0864.87134.0417.0414.6324.0633.172.0937.21136.58122.93-5.8850.6763.1714.5423.7535.7616.9317.4625.2166.6919.63116.38136.00149.76126.27139.62119.61108.8547.4325.732.8769.5326.6921.62139.92130.58129.79126.829.5148.45

175.1120.56209.6730.67118.060.85129.3469.4030.91126.31193.8297.2179.4471.4727.9645.1154.7815.4666.8859.0671.3372.92164.7336.8931.6168.1159.0672.726.9818.4058.2620.88172.8961.5014.49123.4664.30132.5316.9014.4523.6832.731.9937.00136.31122.60-4.9049.8663.0814.3923.3835.3016.8017.1925.2764.7119.50116.04134.61150.07125.53138.35118.28108.1147.2326.292.1068.8326.4821.50138.85129.91129.20126.2911.0946.96

177.2121.03215.9430.89119.681.4770.3630.29197.2596.7370.14

14.7766.4258.6770.0571.63165.5337.5432.0367.1958.6771.4917.4758.0521.15175.2662.3213.9263.17

2.3136.46136.65122.4349.50d 63.22

24.3864.88

149.18125.12138.27119.06107.8346.8325.8668.6825.67

9.0747.19

Except for the compounds in solutions 8-10, as well as the gas samples, hexamethylbenzene, and the corrected values mentioned in the Supporting Information, all data for the solvents CDCl 3, C 6D 6, (CD3) 2CO, (CD3) 2SO, CD 3CN, CD 3OD, and D 2O were previously reported in ref 2. b Apiezon brand H grease. c Phosphorus coupling was observed (2J PC =3Hz). d Internal reference; see text. e Pyrrolidine was observed to react with (CD3) 2CO.

Article

1,2-dimethoxyethane (DME),nitromethane, poly(dimethylsiloxane)(siliconegrease), triethylamine; (solution7) diglyme, dimethyl-acetamide, ethylene glycol, ethyl methyl ketone; (solution8) allyl acetate, 2,6-di-tert -butyl-4-methoxyphenol (BHA),long-chain, linear aliphatic hydrocarbons from pump oil; 4(solu-tion 9) benzaldehyde, carbon disulfide, carbon tetrachloride, cyclohexanone, dimethyl malonate, furan, Apiezon H grease (Hgrease); (solution10) 18-crown-6, diallyl carbonate, dimethyl carbonate, hexamethyldisiloxane 5(HMDSO),imidazole, pyrrole, pyrrolidine. In the case of TFE-d and run separately, 3, nitromethane was omitted from solution 6since the protons of nitro-methane exchange with deuterium from TFE-d of triethylamine. In the case of (CD3in the presence compounds 3) 2CO, pyrrolidine was omitted from solution 10, since the two were observed to react with each other. The gases used in this study included hydrogen, methane, ethane, propane, ethylene, propylene, and carbon dioxide.

Before examining the various standard contaminant 6solu-tions by 1H NMR spectroscopy, solvent residual signals and chemical shifts for H 2O 7for each NMR solvent were refer-enced against tetramethylsilane (TMS,δ0ppm) and reported. Before collecting 13C{1H}NMR spectral data, solvent signals 6were recorded with reference to the signal of a TMS internal standard. For D 2O, 1H NMR spectra were referenced to the methyl signal (δ0ppm) of sodium 3-(trimethylsilyl)propane-sulfonate, 8,9and 13C{1H}NMR spectra were referenced to the signal for the methyl group of methanol (onedrop, added as an internal standard), which was set to 49.501ppm. 2

In a typical experiment for collecting H NMR spectral data, a 3μL sample of a standard contaminant solution was added to an NMR tube 13containing approximately 0.4mL of a deuterated solvent. For C{1H}NMR spectral data collection, an approxi-mately 50μL sample of the standard contaminant solution was added. When there was any uncertainty in the assignment of a resonance, the solution was spiked with an additional 1-2μL of the impurity in question to accurately identify its chemical shift. In cases where the chemical shifts of resonances were highly dependent on the concentration of the impurities pre-sent, ambiguous resonances were instead resolved via gradient-(4)VWR brand vacuum pump oil #19.

(5)The components of solution 10were stable together in dilute solution but unstable when neat mixtures were prepared. In general, it was observed that the nitrogen-containing compounds and possibly 18-crown-6catalyzed the hydrolysis of the carbonates, reacted directly with them, or both. Therefore, for the purpose of storage, the solution was partitioned into two subsolutions:(solution10A) 18-crown-6, imidazole, pyrrole, pyrrolidine; (solution10B) diallyl carbonate, di-methyl carbonate, hexamethyldisiloxane. These subsolutions were stable for long periods as neat mixtures and were combined to form solution 10by adding equal portions to an NMR tube containing the desired deuterated solvent.

(6)For 1H NMR spectra, the solvent residual signals arise from the proton of isotopomers containing one less deuterium atom than the perdeuterated solvent:e.g., CDHCl 2in CD 2Cl at 2. For 13C NMR spectra, the solvent signals arise from the 13C atoms natural abundance in the perdeuterated solvent.

(7)The chemical shift for H 2O can vary depending on the tempera-ture, [H2O],and the solutes present:e.g., a downfield shift may be observed in the presence of any hydrogen bond acceptors. For more information see page 75of ref 1.

(8)Harris, R. K.; Becker, E. D.; Cabral de Menezes, S. M.; Granger, P.; Hoffman, R. E.; Zilm, K. W. Pure Appl. Chem. 2008, 80, 59.

(9)For information on the temperature dependence of HDO chemi-cal shifts in D 2O, see ref 2.

Organometallics, Vol. 29, No. 9, 20102179

selected heteronuclear single-quantum coherence (gs-HSQC)and gradient-selected heteronuclear multiple-quantum coherence (gs-HMQC)NMR spectroscopies. For the experiments involving gases, a J. Young NMR tube containing approximately 0.4mL of NMR solvent was first degassed with three freeze -pump -thaw cycles. Using a vacuum line equipped with a gas manifold, 1atm of the desired gas was added to the tube. Each gas was run separately, degassing between each gas sample.

Results and Discussion

Chemical 1shifts for each of the impurities are reported in the tables:H and 13C{1H}NMR spectral data of all sub-strates are presented in Tables 1and 2, respectively. Notably, physically larger tables, containing all the data from Tables 1and 2as well as the chemical shifts of additional organic compounds, are provided in the Supporting Information. Unless noted otherwise, coupling constants (reportedin Hz) and resonance multiplicities (abbreviatedas follows:s =singlet, d =doublet, t =triplet, q =quartet, p =pentet, sept =septet, m =multiplet, br =broad) were observed to be solvent-independent.

It was noted that the amount of gas dissolved in solution gave 1H NMR signal integrations that were qualitatively comparable to those for the solutions made with the 3μL additions of the liquid or solid contaminants. However, typi-cally in order to observe signals for the gas samples by 13C{1H}NMR spectroscopy, additional time for data collection was required. The solubility of each gas in D limited, making 13C detection impractical. 2O was extremely Of all the gases, methane required the most number of transients in order to obtain an observable signal by 13C{1H}NMR spectroscopy. In most cases, the 13C chemical shift of methane was acquired through the use of gs-HMQC NMR spectroscopy to provide enhanced sensitivity. In order to reflect what would be ob-served in typical NMR-scale experiments, 13C detection was not pursued with isotopically enriched gases. A number of misreported values were discovered in the years since the original publication 10and in the preparation of this paper. These are detailed in the Supporting Information, and the values are now correctly listed in Tables 1and 2.

Acknowledgment. G.R.F. and K.I.G. thank the Depart-ment of Energy (ContractNo. DE-FG02-06ER15765) for support. A.J.M.M. and J.E.B. thank the Moore Founda-tion for support. N.H.S. and B.M.S. thank Abbott Labora-tories, Amgen, Merck, Bristol-Myers Squibb, Boehringer Ingelheim, the Gordon and Betty Moore Foundation, and Caltech for financial support.

Supporting Information Available:Large-format tables of the all the NMR data. This material is available free of charge via the Internet at http://pubs.acs.org.

(10)2The misreported value for acetonitrile in C 6D 6from the original paper was also pointed out by Dr. Jongwook Choi, to whom we are grateful.