Synthetic approaches to new three coordinate Group 6 compounds : chromium alkenyls, molybdenum thiolates and tungsten amides

A series of alkenyl (-C[Ad]Ar) and thioalkenyl (-SC[Ad]Ar, Ad=2-adamantylidene, Ar=3,5-Me2C6H3, 4-tBuC6H4, 3,5-(C6H5)2C6H3, 3,5-(4-tBu-C6H4)2 C6H3) ligands have been prepared. The alkenyl ligands are synthesized by bromination and dehydrohalogenation of an adamantyl olefin to yield an alkenyl bromide. The Grignard reagent, derived from the bromide, is used either as a transmetallation reagent, or reacted with elemental sulfur to form a magnesium thiolate, (THF)2Mg(SC[Ad]Ar)2. The magnesium thiolate can be protonated to give a free thiol, oxidized to afford a disulfide or reacted with ClTi(O'Pr)3 to give the titanium reagent, Ti(SC[Ad]Ar)(O'Pr)3. Treatment of CrC13 with an alkenyl Grignard reagent forms the Cr(III) complex, (THF)Cr(C[Ad]ArMe)3. While this compound reacts with pyridine to give (py)-Cr(C[Ad]ArMe)3, it fails to react with THT or PEt3. (THF)Cr(C[Ad]ArMe)3 can be oxidized with I2 or PhSSPh, however, the oxidation products are thermally unstable and disproportionate back to (THF)Cr(C[Ad]ArMe)3. Reactivity with nitric oxide is also discussed. Molybdenum nitrides of the form N-Mo(SC[Ad]Ar)3 have been prepared by re-action of Ti(SC[Ad]Ar)(O'Pr)3 with N-Mo(OtBu)3. The nitride reacts with Mo(N-[R]ArMe)3 to give (IL-N)[Mo(SC[Ad]Ar)3]2. Reaction of (THF)2Mg(SC[Ad]Ar)3 with MoCl3(THF)3 in diethyl ether leads to the formation of a molybdenum-molybdenum triply bonded compound, Mo2(SC[Ad]Ar)6, while performing the same reaction in THF followed by addition of pyridine leads to the isolation of (py)Mo(SC[Ad]Ar)3.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Chemistry.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2001

Author dc:creator

• Greco, Jane Brock, 1973-

Advisor dc:contributor.advisor

• Christopher C. Cummins.

• Chemistry.

Statement dc:rights

• MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/118107

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/118107