IR flash kinetic spectroscopy of C-H bond activation of cyclohexane-d[sub 0] and -d[sub 12] by Cp*Rh(CO)[sub 2] in liquid rare gases. Kinetics, thermodynamics, and an unusual isotope effect

Journal Article · Wed Aug 10 04:00:00 UTC 1994 · Journal of the American Chemical Society; (United States)

DOI:https://doi.org/10.1021/ja00095a047· OSTI ID:7178489

Schultz, R H; Bengali, A A; Tauber, M J; Weiller, B H; Wasserman, E P; Kyle, K R; Moore, C B; Bergman, R G ^[1]

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1. Univ. of California, Berkeley, CA (United States) Lawrence Berkeley Lab., CA (United States)

Flash kinetic spectroscopy with infrared detection is used to prove C-H activation of cyclohexane-d[sub 0] and -d[sub 12] by intermediates generated upon ultraviolet irradiation of Cp*Rh(CO)[sub 2] (Cp* = C[sub 5](CH[sub 3])[sub 5]) in liquid rare gas (Rg = Kr or Xe) solution at low temperature (163-193 K). Upon UV photolysis, a new C-O stretching band (at 1946.5 cm[sup [minus]1] in Kr and at 1941.5 cm[sup [minus]1] in Xe) appears promptly, which we attribute to Cp*Rh(CO)(Rg). In the presence of hydrocarbon a second C-O stretching band (2002.5 cm[sup [minus]1] in Kr and 1998 cm[sup [minus]1] in Xe) grows in at the same observed rate as the disappearance of the 1946.5-cm[sup [minus]1] band. We attribute this second band to the alkyl hydride product, Cp*Rh(CO)(H)(C[sub 6]H[sub 11]). The concentration dependence of the observed reaction rate in Kr solution shows behavior consistent with a preequilibrium mechanism in which the initial Cp*Rh(CO)(Rg) complex equilibrates with a weakly bound Cp*Rh(CO)(alkane) complex (which has an IR carbonyl frequency unresolvable from that of the rare gas complex) followed by C-H activation of the latter. 53 refs., 13 figs., 1 tab.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 7178489
• Journal Information: Journal of the American Chemical Society; (United States), Journal Name: Journal of the American Chemical Society; (United States) Vol. 116:16; ISSN JACSAT; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102 -- Chemical & Spectral Procedures
400201* -- Chemical & Physicochemical Properties
400500 -- Photochemistry
661300 -- Other Aspects of Physical Science-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALKANES
CHEMICAL ACTIVATION
CHEMICAL BONDS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COMPLEXES
CYCLOALKANES
CYCLOHEXANE
DECOMPOSITION
DEUTERIUM COMPOUNDS
DISPERSIONS
ELECTROMAGNETIC RADIATION
ELEMENTS
FLUIDS
GASES
HYDROCARBONS
HYDROGEN COMPOUNDS
INFRARED SPECTRA
ISOTOPE EFFECTS
KINETICS
KRYPTON
LASERS
LIQUEFIED GASES
MIXTURES
NONMETALS
ORGANIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
RADIATIONS
RARE GASES
REACTION KINETICS
RHODIUM COMPLEXES
SOLUTIONS
SPECTRA
THERMODYNAMICS
TRANSITION ELEMENT COMPLEXES
ULTRAVIOLET RADIATION
XENON