Metal, bond energy, and ancillary ligand effects on actinide-carbon sigma-bond hydrogenolysis. A kinetic and mechanistic study

Journal Article · Wed Dec 23 04:00:00 EST 1987 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00260a007· OSTI ID:7246803

Lin, Z; Marks, T J

A kineticmechanistic study of actinide hydrocarbyl ligand hydrogenolysis (An-R + H/sub 2/ ..-->.. An-H + RH) is reported. For the complex Cp'/sub 2/TH(CH/sub 2/-t-Bu)(O-t-Bu)(Cp' = eta/sup 5/-Me/sub 5/C/sub 5/), the rate law is first-order in organoactinide and first-order in H/sub 2/, with k/sub H2/k/sub D2/ = 2.5 (4) and k/sub THF/k/sub toluene/ = 2.9 (4). For a series of complexes, hydrogenolysis rates span a range of ca. 10/sup 5/ with Cp'/sub 2/ThCH/sub 2/C(CH/sub 3/)/sub 2/CH/sub 2/ approx. = Cp'/sub 2/U(CH/sub 2/-t-Bu) (too rapid to measure accurately) > Cp'/sub 2/Th(CH/sub 2/-t-Bu)(OCH(t-Bu)/sub 2/) = Cp'/sub 2/Th(CH/sub 2/-t-Bu)(O-t-Bu) > Cp'/sub 2/Th(CH/sub 2/-t-Bu)(Cl) > Me/sub 2/Si(Me/sub 4/C/sub 5/)/sub 2/Th(n-Bu)/sub 2/ > Cp'/sub 2/Th(n-Bu)/sub 2/ approx. = Cp'/sub 2/ThMe/sub 2/ > Cp'/sub 2/Th(Me)(O/sub 3/SCF/sub 3/) > Cp'/sub 2/Th(n-Bu)(OCG(t-Bu)/sub 2/) approx. = Cp'/sub 2/Th(Me)(OSiMe/sub 2/(t-Bu)) > Cp'/sub 2/ZrMe/sub 2/ = Cp'/sub 2/Th(rho-C/sub 6/H/sub 4/NMe/sub 2/)(O-tu-Bu) > Cp'/sub 2/Th(Ph)(O-t-Bu) > Cp'/sub 2/U(Me)(OCH(t-Bu)/sub 2/) > Cp'/sub 2/Th(Me)(OCH(t-Bu)/sub 2/). In the majority of cases, the rate law is cleanly first-order in organoactinide over 3 or more half-lives. However, for Cp'/sub 2/ThMe/sub 2/ ..-->.. (Cp'/sub 2/ThH/sub 2/)/sub 2/, an intermediate is observe by NMR that is probably (Cp'/sub 2/Th(Me)(..mu..-H))/sub 2/. For Cp'/sub 2/Th(Me)(O/sub 3/SCF/sub 3/), a follow-up reaction, which consumes Cp'/sub 2/TH(H)(O/sub 3/SCF/sub 3/) is detected. Variable-temperature kinetic studies yield ..delta..H** = 3.7 (2) kcalmol and ..delta..S double dagger = -50.8 (7) eu for Cp'/sub 2/Th(CH/sub 2/-t-Bu)(O-t-Bu) and ..delta..H double dagger = 9 (2) kcalmol and ..delta..S double dagger = -45 (5) eu for Cp'/sub 2/U(Me)(OCH(O-t-Bu)/sub 2/).

• Research Organization: Northwestern Univ., Evanston, IL (USA)
• DOE Contract Number: AC02-81ER10980; FG02-86ER13511
• OSTI ID: 7246803
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 109:26; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400702* -- Radiochemistry & Nuclear Chemistry-- Properties of Radioactive Materials
ACTINIDE COMPLEXES
ACTIVATION ENERGY
ARRHENIUS EQUATION
CHEMICAL BONDS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COMPLEXES
DATA
ELEMENTS
ENERGY
EQUATIONS
EXPERIMENTAL DATA
HYDROGEN
INFORMATION
KINETICS
LIGANDS
MAGNETIC RESONANCE
NMR SPECTRA
NONMETALS
NUCLEAR MAGNETIC RESONANCE
NUMERICAL DATA
PHYSICAL PROPERTIES
REACTION KINETICS
RESONANCE
SPECTRA
THERMODYNAMIC PROPERTIES
THORIUM COMPLEXES
URANIUM COMPLEXES