Homolysis and acidolysis reactions of (. cap alpha. -hydroxyalkyl)- and (. cap alpha. -alkoxyalkyl)chromium(III) complexes: kinetics, steric effects, and bond energies

Journal Article · Wed Mar 10 04:00:00 EST 1982 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00369a018· OSTI ID:5611455

Kirker, G W; Bakac, A; Espenson, J H

The rates of homolysis of 12 organochromium complexes were determined by the addition of oxidizing scavengers to prevent recombination of Cr/sup 2 +/ and the carbon-centered radicals. The rate constants for complexes derived from aliphatic alcohols span the range 3.7 x 10/sup -5/to approx. 3 x 10/sup 2/s/sup -1/ CrCH/sub 2/OH/sup 2 +/s/sup -1/ for CrC(CH/sub 3/)(t-C/sub 4/H/sub 9/)OH/sup 2 +/ at 25/sup 0/C. There is a good correlation between the free energies of activation for homolysis of the organochromium complexes and corresponding substituted symmetrical ethanes. On the basis of the activation parameters and the literature data, estimates of the Cr-C bond dissociation enthalpies were made. Rate constants for the acidolysis reaction, previously known for some of these complexes, were evaluated for the others. Means were developed, by control of reaction conditions, to permit independent measurements of homolysis and acidolysis. The organochromium complex derived from isopropyl ether, CrC(CH/sub 3/)/sub 2/OCH(CH/sub 3/)/sub 2//sup 2 +/, undergoes a rapid (0.05 < k < 2 s/sup -1/) conversion to CrC(CH/sub 3/)/sub 2/OH/sup 2 +/ in dilute perchloric acid. 5 figures, 6 tables.

• Research Organization: Iowa State Univ., Ames
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 5611455
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 104:5; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301* -- Organic Chemistry-- Chemical &amp; Physicochemical Properties-- (-1987)
ACIDIFICATION
ALCOHOLS
ALKOXY RADICALS
BINDING ENERGY
CHEMICAL REACTION KINETICS
CHROMIUM COMPLEXES
COMPLEXES
ENERGY
HYDROXY COMPOUNDS
KINETICS
ORGANIC COMPOUNDS
ORGANOMETALLIC COMPOUNDS
RADICALS
REACTION KINETICS
TRANSITION ELEMENT COMPLEXES