Kinetics Studies
Pseudo first order and method of fractional times were used to characterize a series of SmI 2 :Glycol complex reactions with benzyl bromide using stopped-flow UV-vis spectroscopy.
Pseudo first order conditions were used to characterize every SmI 2 :Glycol complex in the series. The SmI 2 :Glycol complex was reacted with 4 different benzyl bromide solutions: 1=0.025M, 2=0.050M, 3=0.075M, and 4=0.100M at 25°C. The average kobs value for each reaction was found using a single exponential decay fit of the decay of SmI annettemendoza@example.org. The SmI 2 concentration was held annettemendoza@example.org. This method was used to calculate the reaction orders for the glycol and the benzyl bromide.
Note: When determining the reaction order for DG at concentrations ≥3 eq., precipitation occurred in the stopped-flow spectrophotometer upon mixing of the SmI 2 :DG system with benzyl bromide. At this point we monitored the rate of precipitate formation at 450nm and fit this formation with a single exponential as described above in order to determine the k obs . Precipitation was not observed for either the DGME and DGDE at any concentration examined.
Method of fractional times
1 was used to calculate the reaction order for SmI 2 . A decay curve from the pseudo first order conditions was fit with a first order exponential decay. Then, the t 1/2 and t 3/4 was determined for the decay based on the initial and final absorbance values. The ratio of t 3/4 / t 1/2 is converted to the reaction order for SmI 2 . Each of the reaction orders was determined multiple times at various concentrations to assure their validity.
Product Characterization
Reaction conditions. SmI 2 =2.2mmol, Benzyl Bromide=1mmol, Glycol= varied accordingly. The benzyl bromide and glycol were mixed together in 10mL of THF then added to the SmI 2 . Reaction time=10-30min. Reaction was quenced in air with HCl.
Product exctracted with ether, then washed with sodium thiosulphate, water, and NaCl. The reduction products of benzyl bromide using the SmI 2 :glycol system was characterized by GC analysis using an internal standard of decane. The retention times of pure toluene, benzyl S3 bromide, bibenzyl, and decane were first determined. Percent yield was determined using a response factor for either toluene or bibenzyl versus decane.
Crystallography
Percent yields for each crystal was also calculated based on the amount of SmI 2 used:
[Sm(DG) 3 X-ray Crystal Structure Determination. The X-ray intensity data were collected at room temperature or 120 K using graphite-monochromated Mo Kα radiation (λ=0.71073 Å) on a Bruker Smart Apex II CCD diffractometer. Data reduction included absorption corrections by the multiscan method using SADABS. 3 Structures were solved by direct methods and refined by full-matrix least squares using SHELXTL 6.1 bundled software package. 4 The H atoms were positioned geometrically (aromatic C-H=0.93 Å, methylene C-H=0.97 Å and methyl C-H=0.96 Å) and treated as riding atoms during subsequent refinement, with U iso (H)=1.2U eq (C) or 1.5U eq (methyl C). The methyl groups were allowed to rotate about their local threefold axes. ORTEP-3 for Windows was used to generate molecular graphics. Figure S1
. UV-vis spectrum of SmI 2 in THF with increasing amounts of diethylene glycol dimethyl ether. Figure S7 . Plot of t 3/2 /t 1/2 vs. reaction order used to determine the reaction order of SmI 2 using the method of fractional times. Figure S8 . Determination of SmI 2 reaction order using the method of fractional times for the SmI 2 :DG system. SmI 2 =2mmol; Benzyl Br=0.05M; DG=2.5mmol. Figure S11 . Determination of SmI 2 reaction order using the method of fractional times for the SmI 2 :DGME system. SmI 2 =2mmol; Benzyl Br=0.05M; DGME=60mmol Figure S14. Determination of SmI 2 reaction order using the method of fractional times for the SmI 2 :DGDE system. SmI 2 =2mmol; Benzyl Br=0.025M; DGDE=600mmol. Table 2 . Product characterization for the reduction of benzyl bromide using the SmI 2 :Glycol systems. 
Reductant


{'paper_id': '24570527', 'title': 'Mechanistic Studies of Proton-Donor Coordination to Samarium Diiodide', 's2_url': 'https://api.semanticscholar.org/CorpusID:24570527', 'source': 'S2ORC'}