Hydrido methylidene, hydrido vinylidene, hydrido oxo, and hydrido formaldehyde derivatives of bis(pentamethylcyclopentadienyl)tantalum

Journal Article · Wed Aug 20 04:00:00 EDT 1986 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00277a051· OSTI ID:5458769

van Asselt, A; Burger, B J; Gibson, V C; Bercaw, J E

Transition-metal complexes of the general class L/sub n/M(H)(=X) (X = CH/sub 2/; C = CH/sub 2/, O) are of interest as models for reactive intermediates in a variety of catalytic processes. Hydrido alkylidene complexes, generated by a 1,2-hydrogen shift from metal alkyls, have been postulated to play an important role in the metathesis and polymerization of olefins, while surface-bound vinyldene species have been detected and recently proposed to account for linear/branched hydrocarbon distributions in Fischer-Tropsch synthesis. The third member of the class described here, L/sub n/M(H)(=O), is of fundamental importance in reactions involving H/sub 2/O, O/sub 2/, or peroxides. Although an example of an oxo hydride has not previously been reported, several oxo alkyl species have been characterized recently. The authors have described the preparation of a number of permethyltantalocene derivatives and commented on the remarkable stability conferred by two pentamethylcyclopentadienyl ligands. This important facet and a general reluctance for permethyl-metallocene derivatives to undergo oligomerization processes have allowed us to prepare and investigate the reaction chemistry of a number of monomeric hydrido derivatives of general formula Cp*/sub 2/ Ta(H)(=X) (Cp* = eta/sup 5/-C/sub 5/Me/sub 5/; X = CH/sub 2/ (1), C = CH/sub 2/. We have also isolated an eta/sup 2/-formaldehyde adduct CP*/sub 2/Ta(H)(eta/sup 2/-CH/sub 2/O). Such species continue to attract interest as models for possible intermediates in CO hydrogenation, and they describe herein a novel C-O bond cleavage reaction at elevated temperatures to afford the oxo alkyl derivative, Cp*/sub 2/ Ta(CH/sub 3/)(=O).

• Research Organization: California Institute of Technology, Pasadena
• DOE Contract Number: FG03-85ER13431
• OSTI ID: 5458769
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 108:17; ISSN JACSA
• Country of Publication: United States
• Language: English

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ADDUCTS
CHEMICAL PREPARATION
CHEMICAL REACTIONS
COMPLEXES
DATA
DERIVATIZATION
EXPERIMENTAL DATA
INFORMATION
IODINE COMPLEXES
LIGANDS
NUMERICAL DATA
ORGANIC COMPOUNDS
SYNTHESIS