Chemistry of metal oxo alkyl complexes. Mechanistic studies on the anaerobic and aerobic decompositions of molybdenum(VI) dioxo dialkyl complexes

Journal Article · Tue Jan 01 00:00:00 EST 1991 · Organometallics; (United States)

DOI:https://doi.org/10.1021/om00047a056· OSTI ID:6110121

Vetter, W M; Sen, A ^[1]

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1. Pennsylvania State Univ., University Park (United States)

The anaerobic and aerobic decompositions of L{sub 2}Mo(O){sub 2}R{sub 2} (L{sub 2} = 4,4{prime}-dimethyl-2,2{prime}-dipyridyl, R = CH{sub 2}Ph, 1; R = CH{sub 2}C{sub 6}H{sub 4}CH{sub 3}-p, 2; R = (CH{sub 2}){sub 4}CH:CH{sub 2}, 3; R = CH{sub 2}CHMe{sub 2}, 4; R = CH{sub 2}CMe{sub 3}, 5; R = CH{sub 2}CMe{sub 2}Ph, 6) were studied. The anaerobic decomposition mode chosen by a given L{sub 2}Mo(O){sub 2}R{sub 2} complex is a sensitive function of the hydrocarbyl group, R. If accessible {beta}-hydrogens are present on R (as in 3 and 4), equal amounts of alkane and alkene are formed through a {beta}-hydrogen abstraction pathway. In the case of 4, an additional pathway involving Mo-R bond homolysis accounts for 10% of the products formed. When {beta}-hydrogens are absent from R (as in 1, 2, and 6), the free radical, R{sup {sm bullet}}, formed by Mo-R bond homolysis is the predominant product. The reaction of the L{sub 2}Mo(O){sub 2}R{sub 2} complexes with O{sub 2} appears to proceed almost exclusively through the intermediacy of the free radical, R{sup {sm bullet}}. In inert solvents, the principal organic product is the corresponding aldehyde, and the role of O{sub 2} in its formation from L{sub 2}Mo(O){sub 2}R{sub 2} is 2-fold: (a) O{sub 2} promotes the homolysis of the Mo-R bond to form R{sup {sm bullet}}, and (b) O{sub 2} traps the resultant radical to yield the aldehyde. Labeling studies indicated that O{sub 2}, rather than the Mo{double bond}O group, was the predominant source of oxygen for the aldehydes. Mechanistic implications of the authors' observations for the heterogeneous oxidation of alkanes and alkenes by Mo(VI)- and V(V)-oxo species are discussed.

• DOE Contract Number: FG02-84ER13295
• OSTI ID: 6110121
• Journal Information: Organometallics; (United States), Vol. 10:1; ISSN 0276-7333
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ALKANES
OXIDATION
MOLYBDENUM COMPLEXES
CATALYTIC EFFECTS
AEROBIC CONDITIONS
ANAEROBIC CONDITIONS
ARYL RADICALS
CHEMICAL REACTION KINETICS
DECOMPOSITION
DEUTERIUM
GRIGNARD REAGENTS
LABELLING
LIGANDS
NMR SPECTRA
OXYGEN
OXYGEN 18
TOLYL RADICALS
ALKALINE EARTH METAL COMPOUNDS
CHEMICAL REACTIONS
COMPLEXES
ELEMENTS
EVEN-EVEN NUCLEI
HYDROCARBONS
HYDROGEN ISOTOPES
ISOTOPES
KINETICS
LIGHT NUCLEI
MAGNESIUM COMPOUNDS
NONMETALS
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANOMETALLIC COMPOUNDS
OXYGEN ISOTOPES
RADICALS
REACTION KINETICS
SPECTRA
STABLE ISOTOPES
TRANSITION ELEMENT COMPLEXES
400201* - Chemical & Physicochemical Properties