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Research

Research Updates
by

Jade Pratt

on 19 March 2014

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Transcript of Research

Reactions with (even) more
metal/ligand ratios
Reactions with less
bulky ligand
95% yield
- no D*H impurity - by NMR

- Salt metathesis seems to still work
(from colorless to yellow solutions)

June 27th, 2012
Research Update 2
Other Possible Titles:
I've been working, I promise
I wish I had crystals already :(
How many reactions should I try at once?
Completed second attempt at D*I synthesis:
Quality product but low yield (45%)

Used two different methods to synthesize D*SH:

-Power & Neimeyer, Inorg Chem 1996, 68% yield

-Power, Ellison & Ruhlandt-Senge, Angew Chem 1994, 60% yield

Overall:
D*SH (60% yield)
D*SLi (95% yield)
Synthesis of D*SH & D*SLi
Synthesis of
D*SGeCl and D*SSnCl
Synthesis of Rieke's Magnesium:
(Silverman & Rakita, Handbook of Grignard Reagents, 1996)

React anhydrous magnesium chloride (.402g, 4.22 mmol) w/ lithium (0.061g, 8.86 mmol) and naphthalene (0.170g, 1.33mmol) in THF (15mL) - R.T ca. 3h (dark green solution)
Allow Mg slurry to settle for 3h and remove supernatant.
Add more THF (10mL) to actived Mg (black powder) with reactants.

*Lithium Naphthalenide can be synthesized separately and cannulated into magnesium chloride/THF solution. (Shorter rxn time)
A Gentler Reduction - Mg*
Research Introduction
Update 1 - May 9th 2012

Another Method:
React anhydrous magnesium chloride w/ potassium (1:1 ratio) in the presence of KI at 0°C, stir for 2 days.
Add 1,4 Dioxane to precipitate out any xs MgCl then filter.
2
GeCl •dioxane + D*SLi D*SGeCl
½ mmol scale, 0°C, stir 1 day
2
Extracted with pentane (insoluble - yellow powder)
Filtered (w/ filter cannula) - filtrate was pumped down to ½ volume and put in -78°C freezer
Tried to redissolve in hot toluene (powder again)
Refiltered (over celite) - filtrate was pumped down to ½ volume and put in -18°C freezer
SnCl + D*SLi D*SSnCl
1 mmol scale, -78°C, stir 2 days ?
2
Redo synthesis of D*SGeCl on 1mmol scale


Get structures from reactions (if crystals form)


Work on one-pot Rieke's Mg reaction with both Ge and Sn (after structure confirmation)


Synthesize J*SLi for test reactions
To-Do List:
(intense yellow solution w/ yellow precipitate)
(pale yellow solution w/ yellow precipitate)
Research Update 2
September 5th, 2012
Jade Pratt
May 9th 2012
Research Introduction
Current Objectives
Power, Stanciu et al. Inorganic Chemistry (2005)
Ar*PbNH3
Ar*(SnNH2)2
Ar’(GeNH2)2
Background
GeCl •dioxane + D*Li D*GeCl
D*GeCl + D*SLi D*SGeD*
SnCl + D*Li D*SnCl
D*SnCl + D*SLi D*SSnD*
Synthesis of D*SMD*
2
2
GeCl •dioxane + 2Li(N(SiMe ) ) Ge(N(SiMe ) ) + 2D*SH
3
2
2
3
2
2
D*SGeSD* + 2HN(SiMe )
3
SnCl + 2Li(N(SiMe ) ) Sn(N(SiMe ) ) + 2D*SH
3
3
2
2
2
D*SSnSD* + 2HN(SiMe )
2
3
2
2
GeCl •dioxane + 2Li(S(SiMe ) ) Ge(S(SiMe ) ) + 2D*SH
3
2
2
3
2
2
D*SGeSD* + 2HS(SiMe )
3
SnCl + 2Li(S(SiMe ) ) Sn(S(SiMe ) ) + 2D*SH
3
3
2
2
2
D*SSnSD* + 2HS(SiMe )
2
3
2
2
1 mmol scale, 0°C, stirred 2 days
reactions in Et O, extracted with hexane
recrystallizing in benzene -- waiting for xtals
2
yellow solution
orange yellow solution
Synthesis of D*SMCl
GeCl •dioxane + D*SLi D*SGeCl
2
Pumped down and redissolved in THF for recrystallization... waiting for xtals
repeated reaction on 1 mmol scale
SnCl + D*SLi D*SSnCl
2
Non-opaque yellow crystals that redissolve quickly

Aluminium emulsion broken up with Rochelle's Salt (KNaC H O ·4H O)
4
4
6
2
... more D*SH
Get crystal structures for D*SMCl rxns

Reduce of D*SMCl with Mg* to make D*SMMSD*

Get crystal structures for D*SMD* and D*SMMSD*
Work in progress...
Research Update 4
October 10th, 2012
D*SH Synthesis
D*SH synthesis repeated twice
Multiple recrystallizations

Yields - 45% and 57%

Total of ca. 10g D*SH

Lithiations proceeded smoothly - Yield: 91%
GeCl •dioxane + D*SLi D*SGeCl
transparent xtals - GeCl •dioxane
SnCl + D*SLi D*SSnCl
xtals may be temp. dependant
melted before prepped for duo
Xtal Complications
D*GeCl + D*SLi D*SGeD*
D*SnCl + D*SLi D*SSnD*
No xtals yet
2 weeks in fridge
moved to -18C freezer
Let's try that again...
GeCl •dioxane + D*SLi D*SGeCl
2 mmol scale
0 C
Ether
SnCl + D*SLi D*SSnCl
2
2
2
D*I Synthesis
NHC Stabilization
To-Do List

Get crystal structures for D*SMD* and D*SMMSD*

Work on one-pot Rieke's Mg reaction with both Ge and Sn

Synthesis J*SLi
2
"NHC-stabilized dichlorosilaimine[IPr·Cl2Si=NAr (1; IPr=1,3-bis(2,6-diisopropylphenyl)- imidazol-2-ylidene, Ar=2,6-bis(2,4,6-triisopropylphenyl)- phenyl), which was prepared by the reaction of IPr·SiCl2 with ArN3.Then reduction of dichlorosilaimine 1 with KC8 to afford a dimeric silaisonitrile (ArNSi:)2 (3; Scheme 1)."
Ghadwal R.S, Roesky H.W, Angew. Chem. Int. Ed. 2011, 50, 5374 –5378
Research Update 5
November 14th, 2012
To-Do List
Retry all reactions with J*SLi

Get Sn NMR of D*SnCl

Synthesis D*I

Get crystal structures for D*SMD* and D*SMMSD*

Work on one-pot Rieke's Mg reaction with both Ge and Sn
New Reactions
Qualifying Exam Powerpoint
Research Update 6
Work-up:
D*SH Synthesis - 20 mmol scale

K Reactions






Solvent - Free
March 13th 2013
To Do List
Diffractometer:
Ge amide + J*SH (1:1)
Sn chloride + J*SLi (1:2)

NMR:
D*SSnCl
KSn(SJ*)

Synthesis:
Sn chloride + D*SLi (1:1 / 1:2)
Ge chloride + D*SLi (1:1 / 1:2)
3
Research Update 7
June 19th, 2012
D*SH
D*SNa
Synthesis of D*SH Analogs of KM(SJ*)
Lithiated Thiolates with Metal (II) Chlorides Rxns

New
Stoichiometric
Ratio

55% yield - lower yield but less D*H
- Use bulk synthesis route
- Drier THF should produce less D*H impurity
- Use thiolate sodium salt
To - Do List
Rxns with (even) more metal/ligand ratios
3
10% yield- Only enough to collect spectroscopic data:
HNMR, CNMR, IR
UV-Vis, Sn NMR
D*SNa HNMR
2
2
-Reduce D*SSnCl with Mg anthracene / Rieke's Mg / something that works

- Make D*SSnBr if reduction of Cl does not reduce well

- React reduced species with small molecules (H , O , something that works) and TM's (Mo)
August 7th 2013
Research
Update
8
To - Do List
-Get crystal structure for J*SLi + SnCl reaction
(J*SSnCl ?)

-Confirm synthesis of D*SSnCl with crystal structure (for lower stoic. ratio)

-Reduce D*SSnCl with Mg anthracene / Rieke's Mg / something that works

- Try reactionsof D*SSnBr if reduction of Cl does not go well

- React reduced species with small molecules
and transition metals
waiting for duo
waiting for xtals
waiting for xtals
waiting for xtals
waiting for xtals
waiting for xtals
Deamination reactions
waiting for xtals
waiting for xtals
waiting for xtals
Ligand
Research Update 9
September 25th 2013

:(
Ligand
Ligand
Crystals, crystals everywhere...
Desired product with high yield or ...
An exercise in frustration
Stop and smell the Thiol...
Ligand Purification: Recrystallization
Ligand Purification: Lithiation
Ligand Purification: Sublimation
To Do List:
If all else fails:
flip a table
D*H/D*SH (6:1)
Aug 23rd Scale: 50 mmol
Yield: 46%

D*H/D*SH (4:1)
Sept 12th Scale: 30 mmol
Yield: 63%
Recrystallizing solvent: Toluene - nothing crystallized
so solvent was changed to THF
Synthesis (x2)
Multiple recrystallizations in different solvents:
ethyl acetate - Identical NMRs
hexane - Identical NMRs
Good news: Large colorless crystals that look amazing

Bad News: D*H co-crystallizes very well with D*SH (both are colorless)
D*SH is lithiated and preciptates out - D*H remains in solution
Depending on ratio of D*H to D*SH yield for lithiation is small - Increase scale to make enough D*SLi for multiple rxns (50 mmols)
- Get unit cells/ xtal structures for 6 reactions mentioned

-Nail down best synthesis for D*SH

- Synthesize more D*SSnCl

-Reduce D*SSnCl with Mg anthracene / Rieke's Mg / something that works

- Try reactions of D*SSnBr if reduction of Cl does not go well

- React reduced species with small molecules
and transition metals
:(
Hail Mary

Reaction
(full of grace, the Lord is with thee)
1:1 Ratio of metal chloride to D*SH
(but ratio of D*H to D*SH different for each batch of ligand)
4 Different D*SH Synthesis in past 3 months
D*H to D*SH ratios (based on HNMR data)
July 16th -- (3 : 1) Aug 23rd -- (6 : 1)
Aug 7th -- (2 : 1) Sept 12th -- (4 : 1)
Before Sublimation
Deposition product (sublimed compound)
Remaining residue from sublimation
Full transcript