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Models for surface intermediates in CO hydrogenation: Final report

Technical Report ·
OSTI ID:6185692
We have discovered the first example of intermolecular C/minus/H bond activation by a metal-metal multiply-bonded complex. Reductive dimerization of the Ta(V) organometallic (/eta/-C/sub 5/Me/sub 4/R)Ta..xi../sub 4/(R = Me, Et; ..xi.. = Cl, Br) yields a novel class of highly-reactive dinuclear complexes (C/sub 5/Me/sub 4/R)/sub 2/Ta/sub 2/(..mu..-..xi..)/sub 4/, which possess quadrupole bridged Ta(III)-Ta(III) double bonds of sigma/sup 2/delta/sup 2/ electronic configuration. The nonbonded ditantalum(IV) intermediate in the reduction, (C/sub 5/Me/sub 4/R)Ta/sub 2/(..mu..-..xi..)/sub 2/..xi../sub 4/, has been characterized. The Ta = Ta complexes insert into the vinylic C/minus/H bond of 1-alkenes under mild conditions to yield the ditantalum vinyl hydride (C/sub 5/Me/sub 4/R)/sub 2/Ta/sub 2/..xi../sub 4/(..mu..-H)(..mu.., /eta//sup 2/-CHCHR'). The Ta = Ta complex inserts into other sigma-bonds, adding H/sub 2/ to yield (C/sub 5/Me/sub 4/R)/sub 2/Ta/sub 2/(..mu..-H)/sub 2/..xi../sub 4/. It inserts into B/minus/H bonds, resulting in dehydrodimerization of BH/sub 4//sup /minus// groups to (C/sub 5/Me/sub 4/R)/sub 2/Ta/sub 2/(..mu..-..xi..)/sub 2/(..mu..-B/sub 2/H/sub 6/) with a ..mu..-diborane group. These reactions with olefins and BH/sub 4//sup /minus// are unprecedented in dinuclear M/minus/M multiple bond and early metal chemistry. We have also found an example of direct enolate generation from CO insertion into a metal alkyl, and have made a major breakthrough for developing lower-valent organovanadium and divanadium chemistry. 8 figs.
Research Organization:
Iowa Univ., Iowa City (USA). Dept. of Chemistry
DOE Contract Number:
FG22-85PC80513
OSTI ID:
6185692
Report Number(s):
DOE/PC/80513-T5; ON: DE89004348
Country of Publication:
United States
Language:
English

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Related Subjects

090100* -- Hydrocarbon Fuels-- (-1989)
10 SYNTHETIC FUELS
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
BROMINE COMPLEXES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYSTS
CHALCOGENIDES
CHEMICAL ACTIVATION
CHEMICAL BONDS
CHEMICAL PREPARATION
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
COMPLEXES
DOCUMENT TYPES
HYDROGENATION
MOLECULAR STRUCTURE
OXIDES
OXYGEN COMPOUNDS
PROGRESS REPORT
RESEARCH PROGRAMS
SYNTHESIS
TANTALUM COMPLEXES
TRANSITION ELEMENT COMPLEXES
YIELDS