Reductive defluorination of saturated fluorocarbons by organometallic reagents and aryl halide coordination to tungsten(II) and molybdenum(II) by chelating Schiff base ligands

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1993

OSTI ID:6914613

Harrison, R G

Strong organometallic nucleophiles cleave C-F bonds of fluorocarbons such as perfluorodecalin and perfluoro(methylcyclohexane) to afford complexes of the form Cp(CO)[sub 2]FeR, where R is a fluoro aromatic derivative of the perfluorocarbon, when NaCpFe(CO)[sub 2] is used as a nucleophile. Fluoride ion and [Cp(CO)[sub 2]Fe][sub 2] are also recovered in good yields. The reaction occurs at ambient temperature and reaction times vary from one to four hours depending on the substrate used. An electron transfer mechanism is proposed and radical character exists in the intermediates, as evident by hydrogen incorporation into the fluorocarbon products and rate enhancement when the reaction is run in the presence of a hydrogen radical donor. The reactivity patterns of model systems indicate hydrogen incorporation occurred early along the reaction pathway. NaRe(CO)[sub 5] and Ni(P(C[sub 2]H[sub 5])[sub 3])[sub 4] also show reactivity towards the perfluorosubstrates, but NaCpMo(CO)[sub 3] and Na[sub 2]Fe(CO)[sub 4] do not. Aryl-X (X = Cl, Br, I, OCH[sub 3]) groups coordinate to Mo(II) and W(II), through the lone pairs on the atoms, forming seven coordinate metal carbonyls, when chelating nitrogen Schiff base ligands are oxidatively added to W(CO)[sub 3](NCCH[sub 3])[sub 3] or Mo(CO)[sub 3](toluene) in THF. The major mode of reactivity of these coordination compounds is aryl halide dissociation. Competition with typical solvents as monitored by solution IR and ligand equilibrium studies give relative bond strengths. X-ray crystallography shows covalent bonding between the metal and aryl halide groups and the metal geometry is capped octahedral. The aryl halide complexes substitute CO preferentially over the aryl halide when exposed to phosphine donor ligands. Aryl-fluoride coordination was not detected, but halide bridged metal dimers were isolated instead.

• Research Organization: Utah Univ., Salt Lake City, UT (United States)
• OSTI ID: 6914613
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400400* -- Electrochemistry
ARYLATION
CHELATES
CHEMICAL REACTIONS
COMPLEXES
COORDINATION NUMBER
ELECTRON TRANSFER
FLUORINATION
HALOGENATION
IMINES
MOLYBDENUM COMPLEXES
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANOMETALLIC COMPOUNDS
REDUCTION
SCHIFF BASES
TRANSITION ELEMENT COMPLEXES
TUNGSTEN COMPLEXES