The activation of carbon dioxide by niobocene complexes

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

OSTI ID:7235780

Fu, P F

The reduction of Cp[prime][sub 2]Nb(Cl)R (Cp[prime] = [eta][sup 5]-C[sub 5]H[sub 4]CH[sub 3]) by Na/Hg under one atmosphere of CO[sub 2] produces Cp[prime][sub 2]Nb([eta][sup 2]-CO[sub 2])R (R = CH[sub 2]SiMe[sub 3], CH[sub 2]CMe[sub 3], CH[sub 2]Ph, CH[sub 3]). Thermolysis of Cp [sub 2]Nb([eta][sup 2]-CO[sub 2])R (R = CH[sub 2]SiMe[sub 3], CH[sub 2]CMe[sub 3], CH[sub 2]Ph) in THF at 60[degrees]C (at low concentration for R = CH[sub 2]Ph) resulted in decarbonylation of the complex with first order kinetics to generate the corresponding metal-oxo complexes Cp[prime][sub 2]Nb(O)R. The same process is greatly accelerated photochemically with a quantum yield of 0.17 for R = CH[sub 2]SiMe[sub 3]. At higher concentration, carbonyl complex Cp[prime][sub 2]Nb(CO)Ch[sub 2]Ph is also generated in the thermolysis of Cp[prime][sub 2]Nb([eta][sup 2]-CO[sub 2])CH[sub 2]Ph. In continuing effort to promote migratory insertion of Cp[prime][sub 2]Nb([eta][sup 2]-CO[sub 2])CH[sub 2]SiMe[sub 3], its reactions with of a variety of Lewis acids (LiPF[sub 6], BF[sub 3][center dot]Et[sub 2]O, ZnCl[sub 2], HgCl[sub 2], CdCl[sub 2], and ClSiMe[sub 3]) have been investigated. The interaction of Cp[prime][sub 2]Nb([eta][sup 2]-CO[sub 2])CH[sub 2]SiMe[sub 3] with several Lewis acids resulted in its facile decarbonylation. The carbonyl complexes Cp[prime][sub 2]Nb(CO)R (R = CH[sub 2]SiMe[sub 3], CH[sub 2]CMe[sub 3], CH[sub 2]Ph, CH[sub 3]) reacted cleanly and quantitatively with molecular oxygen under ambient conditions to produce the corresponding CO[sub 2] complexes, Cp[prime][sub 2]Nb([eta][sup 2]-CO[sub 2])R, in high yield. The interaction of Cp[prime][sub 2]Nb(CO)H with O[sub 2] generates a novel formato complex. The reaction of Cp[prime][sub 2]Nb(CO)CH[sub 2]SiMe[sub 3] with elemental sulfur (S[sub 8]) gives a carbonyl sulfide complex Cp[prime][sub 2]Nb([eta][sup 2]-CSO) CH[sub 2]SiMe[sub 3], whose structure has been established crystallographically.

• Research Organization: Oklahoma Univ., Norman, OK (United States)
• OSTI ID: 7235780
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL ACTIVATION
CHEMICAL REACTION KINETICS
COMPLEXES
HYDROGEN COMPOUNDS
INORGANIC ACIDS
KINETICS
LEWIS ACIDS
NIOBIUM COMPLEXES
ORGANIC COMPOUNDS
ORGANOMETALLIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
REACTION KINETICS
TRANSITION ELEMENT COMPLEXES