Synthesis and Catalytic Activity of RutheniumâIndenylidene

LAB DOCUMENTATION Instructor Notes Synthesis and Catalytic Activity of Ruthenium Indenylidene Complexes for Olefin Metathesis: Microscale Experiments for the Undergraduate Inorganic/Organometallic Laboratories Ted M. Pappenfus,* David L. Hermanson, Daniel P. Ekerholm, Stacie L. Lilliquist, Megan L. Mekoli Division of Science and Mathematics, University of Minnesota, Morris, MN 56267; *[email protected] General Comments We have successfully performed the experiments over three lab periods, although a two-week experiment is plausible if the synthesis of 1b and the RCM experiments are confined to a single lab period. Complex 1b is also available from Strem Chemicals (Cat. #44-0063). Although the reactions in weeks 1 and 2 do not require a reflux, condensers were added to each apparatus. The extended volume helps to minimize the loss of solvent during the course of the reaction if a positive nitrogen pressure is added to the septum atop the condenser. Week 1: Synthesis of Complex 1a Chemicals Needed: Chemical

CAS #

RuCl2(PPh3)3 Dichlorotris(triphenylphosphine) ruthenium (II) Diphenylpropargyl alcohol 1,1-Diphenyl-2-propyn-1-ol THF (anhydrous) Tetrahydrofuran Dichloromethane

15529-49-4

Hexanes

110-54-3

3923-52-2 109-99-9 75-09-2

Supplier (cat. #) Strem (44-0500)

Form. Wt. 958.83

Amt./Student

Aldrich (477443) Acros (AC61045) Fisher (D37) Fisher (H292)

208.26 72.11

76 mg (0.365 mmol) 10 mL

84.93

1.5 mL

86.18

15 mL

Lab Documentation (Pappenfus et al.)

175 mg (0.183 mmol)

1

Instructor Notes (cont.) Safety Hazards: Chemical RuCl2(PPh3)3 Dichlorotris(triphenylphosphine) ruthenium (II) Diphenylpropargyl alcohol 1,1-Diphenyl-2-propyn-1-ol THF (anhydrous) Tetrahydrofuran

CAS # 15529-49-4

Safety Information Harmful. Harmful by inhalation, in contact with skin and if swallowed.

3923-52-2

Dichloromethane

75-09-2

Hexanes

110-54-3

Irritant. Irritating to eyes, respiratory system and skin. Highly Flammable. Harmful. May form explosive peroxides. Harmful if swallowed. Irritating to eyes, respiratory system and skin. Limited evidence of a carcinogenic effect. Toxic. Harmful if swallowed. Irritating to eyes, respiratory system and skin. May cause cancer. Extremely flammable liquid and vapor. Vapor may cause flash fire. Breathing vapors may cause drowsiness and dizziness. Causes eye, skin, and respiratory tract irritation. May be harmful if absorbed through the skin. Possible risk of impaired fertility.

109-99-9

Equipment Needed: 25 mL two-neck round-bottom flask, egg-shaped stir bar, condenser, heating mantel, variable transformer, filter flask, 15 mL filter funnel (medium porosity, Chemglass Cat #CG-1402-07), 25 mL pear-shaped round-bottom flask. Anhydrous Solvents: Tetrahydrofuran can be purchased anhydrous or can be distilled from Na/benzophenone. We obtained identical results using purchased or freshly distilled solvents. Solvents were transferred using borosilicate glass syringes (luer lock type) equipped with a stainless steel needle and stopcock. Synthesis of Complex 1a Under a positive nitrogen atmosphere, anhydrous THF (10 mL) was added to a dry 25 mL twonecked round-bottom flask (equipped with a condenser) containing RuCl2(PPh3)3 (175 mg, 0.183 mmol). Diphenylpropargyl alcohol (76 mg, 0.365 mmol) was added to the solution in one portion and the reaction refluxed with stirring for 3 hours. Once completely cooled, the resulting red solution was transferred to a 25 mL pear-shaped flask and the solvent was removed by rotary evaporation. The resulting dark residue was redissolved in dichloromethane (≈ 1.5 mL) and 9 mL of hexanes were slowly added to precipitate the complex. Further precipitation of the complex was induced by removal of a small amount of solvent via rotary evaporation. The resulting solid was filtered and washed with hexanes (3 x 2 mL) to provide 1a as a deep red solid. Typical yields for this procedure were near 121 mg (75%).


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Instructor Notes (cont.) Results: The literature prep. for the synthesis of 1a involves refluxing the reagents for 2.5 hours using 1.5 equivalents of the diphenylpropargyl alcohol. We found the best results on the microscale to be 2 equiv. of the alcohol with a 3 hour reflux. A 2.5 hour reflux gives a very similar product (by 31P NMR), although a slight impurity is present near 29.7 ppm. Answers to prelab questions: 1. Oxidation State: Ru (II); d electron count: 6 18 electron count: 16 (Ru = 8; 2 Cl = 2, 2 phosphines = 4; 1 carbene = 2)


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Instructor Notes (cont.) Week 2: Synthesis of Complex 1b Chemicals Needed: Chemical

CAS #

Complex 1a Dichloro(3-phenyl-1H-inden-1ylidene)bis(triphenylphosphine)ruthenium (II) Tricyclohexylphosphine

25497246-8

Dichloromethane (anhydrous)

75-09-2

Hexanes

110-54-3

Chloroform-d

865-49-6

2622-14-2

Supplier (cat. #) NA

Form. Wt. 886.79

Strem (15-6150) Acros (61030) Fisher (H292) Cambridge Isotope (DLM-7-100)

280.43

Amt./Student 80 mg (0.090 mmol)

84.93

83 mg (0.30 mmol) 6 mL

86.18

11 mL

120.38

1 mL

Safety Hazards: Chemical Complex 1a Dichloro(3-phenyl-1H-inden-1ylidene)bis(triphenylphosphine)ruthenium (II) Tricyclohexylphosphine

CAS # 254972-468

Safety Information No safety information available. Treat as a hazardous substance.

2622-14-2

Chloroform-d

865-49-6

Dichloromethane

75-09-2

Hexanes

110-54-3

Irritating to the respiratory tract, skin and eyes. May be harmful if swallowed. Irritating to eyes and skin. Harmful: danger of serious damage to health by prolonged exposure through inhalation and if swallowed. Probable Carcinogen Toxic. Harmful if swallowed. Irritating to eyes, respiratory system and skin. May cause cancer. Extremely flammable liquid and vapor. Vapor may cause flash fire. Breathing vapors may cause drowsiness and dizziness. Causes eye, skin, and respiratory tract irritation. May be harmful if absorbed through the skin. Possible risk of impaired fertility.


4

Instructor Notes (cont.) Equipment Needed: 25 mL two-neck round-bottom flask, egg-shaped stir bar, condenser, filter flask, 15 mL filter funnel (medium porosity, Chemglass Cat #CG-1402-07), 25 mL pear-shaped round-bottom flask. Anhydrous Solvents: Dichloromethane can be purchased anhydrous or can be distilled from phosphorus pentoxide. We obtained identical results using purchased or freshly distilled solvents. Solvents were transferred using borosilicate glass syringes (luer lock type) equipped with a stainless steel needle and stopcock. Synthesis of Complex 1b To a dry 25 mL two-neck round-bottom flask (equipped with a condenser) containing complex 1a (80 mg, 0.090 mmol) under a positive nitrogen atmosphere, was added anhydrous dichloromethane (6 mL). To this solution was added tricyclohexylphosphine (83 mg, 0.30 mmol) and the solution was stirred for 1.5 to 2 hours at room temperature. The resulting orange solution was transferred to a 25 mL pear-shaped flask and the solvent was removed by rotary evaporation. The residual solid was suspended in hexanes (≈ 5 mL) and the mixture stirred for 30 min. The solid was filtered and washed with hexanes (3 x 2 mL) to provide 1b as a brownishorange solid. Typical yields for this procedure were near 50 mg (60%). Results: The literature prep. for the synthesis of 1b involves stirring the reagents for 2 hours using 3.1 equivalents of tricyclohexylphosphine. We found the best results on the microscale to be 3.3 equiv. of the phosphine with a 1.5 to 2 hour reaction period. A 1.5 hour reaction gives a very similar product (by 31P NMR) to that reported in the literature, although slight impurities are present near 31.5 and 50.8 ppm. These impurities increase in intensity with time at the expense of the 1b peak at 32.7 ppm. As a result, the 31P NMR spectrum of 1b is taken immediately after dissolving the sample in CDCl3. Complex 1a does not show similar behavior in solution.


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Instructor Notes (cont.) Week 3: Ring-closing Metathesis of Diethyl diallylmalonate Chemicals Needed: Chemical

CAS #

Complex 1a Dichloro(3-phenyl-1H-inden-1ylidene)bis(triphenylphosphine)ruthenium (II) Complex 1b Dichloro(3-phenyl-1H-inden-1ylidene)bis(tricyclohexylphosphine) -ruthenium (II) Dichloromethane (anhydrous)

25497246-8

Diethyl diallylmalonate

Supplier (cat. #) NA

Form. Wt. 886.79

25022036-1

NA

923.07

9.5 mg (2.5 mol% relative to diolefin)

75-09-2

Acros (61030) Aldrich (283479) Cambridge Isotope (DLM-7-100)

84.93

6 mL

240.30

0.1 mL

120.38

1 mL

319524-2 865-496

Chloroform-d

Amt./Student 9.2 mg (2.5 mol% relative to diolefin)

Safety Hazards: Chemical Complex 1a Dichloro(3-phenyl-1H-inden-1ylidene)bis(triphenylphosphine)ruthenium (II) Complex 1b Dichloro(3-phenyl-1H-inden-1ylidene)bis(tricyclohexylphosphine)ruthenium (II) Chloroform-d

Dichloromethane Diethyl diallylmalonate Diethyl 3-cyclopentene-1,1dicarboxylate

CAS # Safety Information 254972-46- No safety information available. Treat as a 8 hazardous substance. 250220-36- Irritating to the respiratory tract, skin and 1 eyes. May be harmful if swallowed. 865-49-6

Irritating to eyes and skin. Harmful: danger of serious damage to health by prolonged exposure through inhalation and if swallowed. Probable Carcinogen 75-09-2 Toxic. Harmful if swallowed. Irritating to eyes, respiratory system and skin. May cause cancer. 3195-24-2 Irritating to eyes, respiratory system, & skin. 21622-00-4 No safety information available. Treat as a hazardous substance.


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Instructor Notes (cont.) Equipment Needed: 25 mL two-neck round-bottom flask (2), egg-shaped stir bar (2), condenser (2), 25 mL pear-shaped round-bottom flask (2). Ring-closing Metathesis of Diethyl diallylmalonate To a dry 25 mL two-neck round-bottom flask (equipped with a condenser) containing complex 1a or 1b (9.2 mg or 9.5 mg, 2.5 mol% relative to diolefin) under a positive nitrogen atmosphere was added anhydrous dichloromethane (6 mL). Diethyl diallylmalonate (0.1 mL, 0.414 mmol) was added to the solution and the contents stirred for 1 hour at room temperature. At the conclusion of the reaction period for each reaction, the contents were transferred to a roundbottom flask and the solvent was removed by rotary evaporation. No further purification was performed on each reaction. The efficiency of each catalyst to form the ring-closed product was judged by GC-MS and 1H NMR as outlined in the Lab Summary. Results: Several examples exist in the literature of using diethyl diallylmalonate in RCM reactions. Given the high formula weights of the complexes, 2.5 mol% of each complex was used relative to 0.1 mL of the diolefin. We have not explored using more or less of the complexes than these tested amounts. Also, we have only quantified the amount of ring-closed product relative to the starting material and have made no effort to purify the product from the catalyst. NMR Assignments: a

CO 2

O2C

c

H(a), δ = 1.23 ppm H(b), δ = 4.17 ppm H(c), δ = 2.63 ppm H(d), δ = 5.63 ppm H(e), δ = 5.09 ppm

b

d e

These data are consistent with those reported in the literature (e.g. Necas, D. et al., J. Am. Chem. Soc. 2004, 126, 10222-10223). O 2C

a

CO 2 c d

b

H(a), δ = 1.24 ppm H(b), δ = 4.18 ppm H(c), δ = 3.01 ppm H(d), δ = 5.59 ppm

These data are consistent with those reported in the literature (e.g. Matsugi, M. et al., J. Org. Chem. 2005, 70, 1636-1642).


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Instructor Notes (cont.) Answers to prelab questions: 2. Grubbs et al. have outlined the use of 1H NMR to examine the catalytic activity of complexes in this particular RCM reaction. Product formation and diolefin disappearance can be witnessed by an examination of the allylic methylene peaks. Specifically, the methylene protons of the starting material are observed as a doublet near 2.63 ppm while the methylene protons of the ring-closed product are observed as a singlet near 3.01 ppm. Answers to postlab questions: 2. The σ-donating ability of the tricyclohexylphosphine helps to stabilize the 14-electron metallacyclobutane intermediates present in the catalytic cycle. Furthermore, the steric bulk of the phosphine helps to promote phosphine dissociation, a crucial step in the mechanistic cycle. 3. A proposed mechanism is provided on the next page using complex 1b.


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Ph

PCy3

R

Cl

Ru

=

Cl

CO2Et

EtO2C

PCy3

Cl

=

Ru Cl

PCy3

PCy3

PCy3 Cl

R

PCy3 -PCy3

Ru Cl

+PCy3

PCy3

Cl

PCy3

R

Cl

+ olefin

Ru

Ru Cl

R

- olefin

Cl

PCy3 Cl Ru Cl PCy3

R

PCy3

Cl

Cl

R

Ru Ru

Cl

Cl R

PCy3 Cl Ru

PCy3

R

Cl

+

Ru

Cl

Cl

PCy3 Cl Ru Cl

+

PCy3 Cl Ru Cl


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LAB DOCUMENTATION Student Handout Experiment 4 Synthesis and Catalytic Performance of Ruthenium Carbene Complexes for Olefin Metathesis: A Microscale Organometallic Experiment Ruthenium alkylidene (carbene) complexes have found widespread use as catalysts in organic synthesis and polymer chemistry.1 Specifically, these complexes have been utilized in olefin metathesis reactions for the formation of C–C bonds.2 Among the most widely used ruthenium alkylidene complexes used for these reactions are the first- and second generation Grubbs’ catalysts:

Mes

N

N

Mes

PR3 Cl

Cl Ru

Ru

Cl

Cl

Ph

PR3

PR3

First Generation Grubbs' Catalyst

Ph

Second Generation Grubbs' Catalyst

Although these complexes show excellent catalytic activity in olefin metathesis reactions, their preparation typically involves the utilization of reactive intermediates. As a result, most people choose to purchase these (as they are commercially available) rather than prepare them. Not surprisingly, alternatives to Grubbs-type carbenes have been investigated. Reported among these studies is the preparation of the ruthenium indenylidene below:3,4 PR3 Cl

Ph

Ru

Cl PR3

Ruthenium Indenylidene Complexes

This catalyst has been reported as being a, “cheap, stable, and practical alternative to the classical Grubbs catalyst…”5 Furthermore, in many cases this complex is as good or even superior to Grubbs’ catalysts. In this experiment, you will explore the synthesis and catalytic activity of these ruthenium indenylidene complexes.


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Prelab Questions (Week 1) 1. What is the oxidation state and d-electron count of ruthenium in the indenylidene complexes? Does this complex adhere to the 18 electron rule? 2. Find a recent paper on the preparation of a “Grubbs-like” catalyst in the literature. Provide the complete reference, comment on its preparation, and note if any catalytic investigations were reported on the complex. Note: For each reaction in each week of this experiment, dry glassware is needed. Make sure you place your glassware in the oven in advance of performing the reaction each week. Procedure: Week 1 This week will focus on the synthesis of the triphenylphosphine version of the phenylindenylidene complex. This is the primary product formed from the reaction of RuCl2(PPh3)3 and diphenylpropargyl alcohol: OH

PPh3 Ph

Ph

Cl

Ph

Ru

Cl

RuCl2(PPh3)3

PPh3

THF, Reflux

1a

Synthesis of the Phenylindenylidene Complex 1a Assemble hot a pre-dried 25 mL two-necked round bottom flask (rbf) with an egg-shaped stir bar. Attach a condenser and septa and begin purging the apparatus with N2 while cooling. Once the apparatus is cool, quickly add 175 mg of RuCl2(PPh3)3 to the rbf under positive N2. Next, add 10 mL of anhydrous THF to the rbf via syringe and stir. To this solution add 2 equiv. of diphenylpropargyl alcohol in one portion. Apply cooling water to the condenser, apply heat, and reflux for 3 hours. During this time, the mixture should turn dark-red. After the 3 hour reflux, completely cool the reaction and transfer the contents (via pipet) to a 25 mL pear-shaped rbf. Remove the solvent via rotary evaporation. Redissolve the dark residue in approx. 1.5 mL dichloromethane and slowly add 9 mL hexanes (via pipet) to the dark solution to precipitate the complex. If the mother liquor is still intensely colored, reduce the solvent volume to precipitate more product. Filter the dark-red solid using a small fritted funnel and wash the solid with hexanes (3 x 2 mL). Once the solid appears dry, carefully transfer it to a SMALL one dram labeled pre-weighed vial and dry in vacuo. Store the complex in a dessicator once dry and determine the % yield of 1a.


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Obtain IR data of your complex by the next lab period and turn in a copy of your spectrum and interpret the data as your prelab assignment. NMR data (1H and 31P) of your complex will be obtained during the next lab period. Procedure: Week 2 This week will focus on the synthesis of the tricyclohexylphosphine version of the phenylindenylidene complex. This is the primary product formed from the reaction of the complex from Week 1 (1a) and tricyclohexylphosphine: PCy3 Cl

PCy3

Ph

Ru

Cl

1a

PCy3

CH2Cl2 1b Save approximately 20 mg of your complex 1a for catalytic investigations and NMR characterization (set aside more if you have not yet performed your IR experiment on complex 1a). Use the remaining amount for the synthesis of complex 1b. A representative reaction using 80 mg of 1a is given below. Synthesis of the Phenylindenylidene Complex 1b Assemble hot a pre-dried 25 mL two-necked round bottom flask (rbf) with an egg-shaped stir bar. Attach a condenser and septa and begin purging the apparatus with N2 while cooling. Once the apparatus is cool, quickly add 80 mg of complex 1a to the rbf under positive N2. Next, add 6 mL of anhydrous dichloromethane to the rbf via syringe and stir. To this solution add 3.3 equivalents of tricyclohexylphosphine in one portion. Stir the resulting mixture under N2 for 1.5 to 2 hours. In the meantime, prepare a sample of complex 1a for NMR (1H and 31P) characterization (5-7 mg of your complex should be sufficient for analysis). After the 1.5 to 2 hour reaction period, transfer the contents (via pipet) to a 25 mL pear-shaped rbf and remove the solvent via rotary evaporation. Suspend the remaining solid in 5 mL of hexane and stir at ambient temperature for 30 min. Filter the solid using a small fritted funnel and wash the solid with hexanes (3 x 2 mL). Carefully transfer the solid to a SMALL labeled pre-weighed vial and dry in vacuo. Store the complex in a dessicator once dry. Obtain the NMR (1H and 31P) and IR spectra of your complex before the next lab period. Use chloroform-d as the NMR solvent.


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Prelab Questions (Week 3) 1. Find a recent paper in the literature on the utilization of a “Grubbs-like” catalyst in a ringclosing metathesis reaction. Provide the complete reference, the catalyst used, and a summary of the reaction(s). 2. You will use 1H NMR to determine the effectiveness of your catalyst in the ring-closing metathesis reaction of diethyl diallylmalonate. Grubbs et al. have described a method for accomplishing this task (J. Am. Chem. Soc. 1997, 119, 3887-3897). Summarize how 1H NMR can be used to determine the yield of the ring-closing metathesis reaction. Procedure: Week 3 This week will focus on the using the ruthenium complexes from weeks 1 and 2 in a ring-closing metathesis reaction. You will compare the effectiveness of complexes 1a and 1b in facilitating the catalysis of the reaction below: EtO2C

CO 2Et

EtO 2C

Ru Catalyst

CO 2Et

+

H 2C

CH2

CH 2Cl2

Ring-Closing Metathesis Reactions Assemble hot a pre-dried 25 mL two-necked round bottom flask (rbf) with an egg-shaped stir bar. Attach a condenser and septa and begin purging the apparatus with N2 while cooling. Once the apparatus is cool, quickly add 2.5 mol% of complex 1a (based on 0.1 mL of diethyl diallylmalonate) to the rbf under positive N2. Next, add 6 mL of anhydrous dichloromethane to the rbf via syringe and stir. To this solution add 0.1 mL of diethyl diallylmalonate via syringe in one portion. Stir the resulting mixture under N2 for 1 hr at room temperature. Meanwhile, prepare a second apparatus identical to that above except use complex 1b in place of 1a. Perform the remaining steps as above. At the conclusion of the reaction period for each reaction, simply transfer the contents to a rbf and remove the solvent by rotary evaporation. Further purification of the reaction mixture is not necessary. Obtain GC/MS data and a 1H NMR spectrum of each reaction mixture. Use chloroform-d as the NMR solvent.


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Items for Lab Report Write-up 1. Comment on the synthesis of characterization of complexes 1a and 1b. Include calculations for percent yield (an appendix sheet is acceptable). 2. Describe the catalytic activity of the complexes in the ring-closing metathesis reaction. Discuss any similarities/differences observed. 3. Provide a reasonable mechanism for the ring-closing metathesis reaction using complex 1a or 1b. Comment on any key steps in the catalytic cycle and how the differences in the complex may account for differences (if any) in their catalytic behavior. References 1. Schmidt, B. Angew. Chem. Int. Ed. 2003, 42, 4996-4999. 2. Trnka, T. M.; Grubbs, R. H. Acc. Chem. Res. 2001, 34, 18-29. 3. Harlow, K. J.; Hill, A. F.; Wilton-Ely, J. D. E. T. J. Chem. Soc., Dalton Trans. 1999, 285291. 4. Furstner, A.; Guth, O.; Duffels, A.; Seidel, G.; Liebl, M.; Gabor, B.; Mynott, R. Chem. Eur. J. 2001, 7, 4811-4820. 5. Scheiper, B.; Glorius, F.; Leitner, A.; Furstner, A. PNAS 2001, 101, 11960-11965.


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INSTRUCTIONS FOR OPERATION OF JEOL ECLIPSE 300 MHz NMR SPECTROMETER 1) Sample Preparation In a small test tube, dissolve ca. 10-15 mg (for a proton spectrum; for a 13C spectrum you should add about 50 mg) of your compound in about 0.5 mL the appropriate deuterated solvent. The solution should be filtered through a small plug of cotton directly into the NMR tube if it contains particulate matter. The height of the solution in the NMR tube should CLOSELY match the height indicated on the “NMR sample height gauge” (on the side of the hood in the ochem and p-chem labs). Parafilm the NMR solvent bottle after each use. 2) Login • • • •

First, sign into the logbook click on the “inorganic” icon on the desktop enter password Double-click on the “delta” icon on the desktop (the delta console window opens)

3) Connect to spectrometer •

Click on the spectrometer control button in the Delta console window:

• •

Alternatively, under the Acquisition menu, click Connect. Wait for the spectrometer to automatically connect (“connect:eclipse2.mrs.umn.edu” will appear in the text box, which becomes yellow)

4) Sample setup • • • • • •

Click on the Sample button in the Spectrometer Control window (bottom left; the Sample window opens) Eject the standard sample from the magnet by clicking on the “ E” button (upper left) sample/spinner assembly will be ejected from the magnet CAREFULLY remove the sample/spinner assembly from the magnet insertion port (handle spinner with kimwipes only) CAREFULLY remove the standard sample from the spinner (with gentle twisting) and place in a secure location GENTLY insert your sample into spinner (twist gently)


15

•

Set depth of sample into spinner using depth gauge, making sure that the inner plug of the two-part spinner assembly is fully pushed down:

•

Insert your sample/spinner assembly into magnet as follows: • WARNING!!! NEVER insert empty spinner! NEVER insert sample without spinner! ALWAYS check to make sure air is flowing before inserting sample/spinner assembly, by holding your hand over the insertion port. • Gently rest the sample/spinner on top of the air stream at the injection port (the sample/spinner assembly “floats” on a stream of compressed air):

• •

Click on the “ L” sample load icon (in sample window) Check spin rate:

•

Make sure that the spinner icon the target rate (≈ 15 Hz)

is selected and that the spin rate is increasing to


16

• •

Select solvent: • Scroll to find the NMR solvent you are using, highlight to select Lock & Shim: • •

•

Click on the automatic NMR Lock and shim icon (Z1 Z2): NOTE: it may take a few minutes for the instrument to perform this operation (if it takes more than 5 minutes, alert the TA or instructor). Locking and shim is complete when green displays of “LOCK ON” and “IDLE” are present. Minimize the sample window by clicking on the small box with an underscore in it.

4) Acquire Spectrum (1H) • • • •

• •

• •

Go back to the Spectrometer Control window and click on the “Expmnt” button in the (the Experiment Tool window opens) Click on the folder with the globe in front of it Scroll down and select “single_pulse.exp”; click “OK” Enter your sample ID in the filename box (cursor must be in text box; please make it something obvious including your initials, sample #, and notebook pg. - e.g., mwj-1-55) and any comments you wish to help identify your sample in the sample_id box (e.g., ‘ferrocene in CDCl3’) check the auto_gain box Otherwise, USE DEFAULT VALUES (check to make sure that the correct solvent is selected). • About the only parameter you might want to change is the number of scans. The default value is 8, and is fine for most samples. If your sample is unusually weak, you will want to increase the number of scans so that it is squared, that is, to 16, 32, 64 or 128. Click on “submit”. A new window will pop up. Click “go” to start the experiment (otherwise click go on the Spectrometer Control window). The instrument will now begin collecting your data. This will take some time, depending upon the number of scans. Minimize experiment window

5) Acquire spectrum (13C) (REMEMBER: you need a stronger sample for 13C) • • • • • • • • •

Click on the “expmnt” button in the spectrometer control window Click on the globe icon Scroll down and select “single_pulse_dec.exp”, click “OK” Enter your sample ID (cursor must be in text box; include your initials) and any comments you wish Enter sn_ratio of 50 check auto_gain unless a proton spectrum was run on this same sample immediately previous Otherwise, USE DEFAULT VALUES (check to make sure that the correct solvent is selected) Click on “submit” Minimize experiment window


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5.5) Acquire spectrum (31P) Note: Before performing a 31P NMR experiment, make sure the probe is properly tuned with the correct probe stick. Your instructor will go over this with you prior to performing your first spectrum. • If necessary, obtain a spectrum of 85% H3PO4. This will be used as your external standard. • Place the sample in the cavity and spin as normal. You do not have to lock and shim on the sample. • Click on the “expmnt” button in the spectrometer control window. • Click on the globe icon. • Scroll down and select “single_pulse_dec.exp”, click “OK” • Under “Acquisition” select “Phosphorus 31”. • Change the number of scans to 8. • Under “Pulse” change the relaxation delay to “2 s” • Do not select auto gain • Submit your experiment and report the chemical shift of the peak in your notebook. • Prepare your sample as normal in a suitable solvent and collect the 1H NMR spectrum as normal (lock and shim, Auto gain, etc.). • After a suitable 1H NMR spectrum is collected, you are now ready to collect a 31P NMR spectrum. • Place the sample in the cavity and spin as normal. You do not have to lock and shim on the sample. • Click on the “expmnt” button in the spectrometer control window. • Click on the globe icon. • Scroll down and select “single_pulse_dec.exp”, click “OK” • Under “Acquisition” select “Phosphorus 31”. • Change the number of scans to 128. • Under “Pulse” change the relaxation delay to “2 s” • Do not select auto gain • Submit your experiment as normal. 6) Process data ¾ When the instrument is finished acquiring your data, the FID will automatically be sent to a processing window, and should show up on the display. You will use the buttons on the right to make some choices about processing your data. • First, you need to select an “apodization function” from the upper right group. Select “Hamming” • Then click on the following buttons in sequence:


18

•

• •

“FFT” to carry out the Fourier Transform on your data and convert the FID to a spectrum that you will recognize; • Autophase • Base Correct With the cursor in the lower (processed data) window, hit the “HOME” key to drop the baseline before proceeding. Your spectrum is now ready for the finishing touches: “peak picking” (labeling the peaks of interest), integration and plotting. (This can be done by remote processing in the chemistry computer lab.)

7) Preview Spectrum Before proceeding, it is good to take an initial view of your spectrum to check that enough scans were taken, the shims are ok, etc.

• •

Click on the cursor tool Select the Zoom mode:

•

Find a singlet line in your spectrum (the CDCl3 peak at 7.25 ppm or the TMS peak at 0 ppm are good ones to use). Use the “magnifying glass” to zoom in if needed. Make sure the singlet is symmetric. An ‘ugly’ singlet suggests poor shims. If the spectrum looks good, proceed and process data remotely.

in the processed data window (the lower window)

8) Logout • • •

Close Processing and Experiment windows Eject your sample and replace it with the standard sample (remember previous warnings!) Select CDCl3 as your solvent

• • •

Autolock on the standard sample (click on the icon in the Sample window). When the instrument is locked, close the Sample window Disconnect from the spectrometer by clicking on “unlink” in the Spectrometer Control window Close the Spectrometer Control and Delta Console windows Exit by selecting “logout” from the desktop menu in the toolchest (upper left corner of monitor)

• •

9) Sign out in the logbook 10) Immediately go upstairs into the lab and clean out your NMR tube – rinse several times with acetone and leave to dry in your drawer. Do not use water.


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INSTRUCTIONS FOR OPERATION OF THE AGILENT TECHNOLOGIES GC-MS 1) Sample preparation In the small hood in the instrument room (Sci 3115), dissolve one to two drops (no more!) of your sample in approximately 5 mL of dichloromethane. Small glass vials, dispopipettes and a graduated cylinder are provided in the hood. 2) Instrument operation You will use the Agilent GC-MS in room 3115. o Sign in the logbook (check to make sure an autotune has been performed that day. If not, inform your lab instructor) o Select the appropriate method: use the button on the front of the GC to select the method (for this experiment, you will use “CH2CL2-25”). This method holds the oven temperature at 50°C for 1 minute, then ramps up at 25°C/min to 300°C, finally holding at 300°C for 5 minutes. The total run time is 16 minutes. Do not stop the program prematurely; let it run the full 16 minutes. o Locate the Instrument Control Panel window as shown below:

(If the instrument control panel is not open on the screen, click on the “Instrument #1” icon and look for this window.) o Check to make sure the default method listed matches the GC method. If not, load the “CH2CL2-25” method from the dropdown menu (Method Æ Load Æ choose method). o Click on the green arrow in the box with the little vial (see above).


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o When the Acquisition Dialog Box is displayed, type in your name a descriptive sample name and a data file name C:\MSDCHEM\1\DATA\ITR\SAMPLENAME, where “SAMPLENAME” begins with your initials, followed by a brief descriptive name, e.g. “NECNMR” Click on the StartRun box. o The computer will initialize the MS and open a dialog box that says it is waiting for a remote start. o Pull 1 µL of air into the very fragile 10 µL syringe, followed by 1 µL of your dichloromethane+sample solution, then one more µL of air. Inject this into the injection port on top of the GC (the TA will demonstrate). o Immediately hit the “Start” button on the front of the GC. The computer will automatically start the data collection. It will ask if you want to override the solvent delay. The answer to this question is always NO. 3) Data analysis o The end of your run will be indicated on the instrument control screen: the STOP button will be greyed out, and the green bar will read “Idle”. o From the “View” pull-down menu, select “Data Analysis.” o When in the data analysis window, from the “File” pull-down menu select “load data file.” o Find your data file and open it. o The Total Ion Chromatogram will be displayed. Your sample will consist of at least two major peaks: the solvent and your product (and/or starting materials). Move the cursor to a peak in the chromatogram and display the mass spectrum of that peak by double-clicking the right mouse button. Is it what you expected? Does it make sense in terms of matching with either the solvent or your product? Then print out the mass spectrum and record the relevant information (data and parameters) in your laboratory notebook (see the ACS Style Guide for the appropriate format).


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4) Cleanup o Rinse the syringe several times by filling with clean dichloromethane and dispensing into the waste bottle. o Pour your excess GC-MS sample solution into the halogenated waste bottle. Rinse the vials 2x with dichloromethane and return to the used vials box.


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LAB DOCUMENTATION Analytical Data

Proton NMR spectrum of student-prepared complex 1a in chloroform-d.


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Phosphorus NMR spectrum of student-prepared complex 1a in chloroform-d.


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FT-IR spectrum of student-prepared complex 1a.


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Proton NMR spectrum of commercially available complex 1b in chloroform-d.


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Phosphorus NMR spectrum of commercially available complex 1b in chloroform-d.


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Proton NMR spectrum of student-prepared complex 1b in chloroform-d.


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Phosphorus NMR spectrum of student-prepared complex 1b in chloroform-d.


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FT-IR spectra of student-prepared (top) and commercially available (bottom) complex 1b.


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Proton NMR spectrum of the crude product mixture from the ring-closing experiment with complex 1a in chloroform-d.


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Proton NMR spectrum of the crude product mixture from the ring-closing experiment with complex 1b in chloroform-d.


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Full gas-chromatograms and mass-spectral data of the crude product mixtures from the RCM reactions of 1a and 1b with diethyl diallylmalonate.


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Gas-chromatogram (top) and mass-spectral data of the crude product mixture from the RCM reaction of 1a with diethyl diallylmalonate.


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Gas-chromatogram (top) and mass-spectral data of the crude product mixture from the RCM reaction of 1b with diethyl diallylmalonate.


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