Oxidative and electrophilic pathways in the reactions of organochromium(III) complexes with nitrous acid and tris(2,2'-bipyridyl)ruthenium(III)

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1986

OSTI ID:6855645

Melton, J D

The kinetics and mechanism of the reactions of nitrous acid with pentaaquoorganochromium(III) complexes were studied. Nitrous acid reacts with (H/sub 2/O)/sub 5/CrR/sup 2 +/ complexes via an NO/sup +/ intermediate by either an electrophilic or electron transfer mechanism depending on the nature of the R group. The lack of steric effects for the reactions of the alkyl-chromium complexes, and the detection of Cr/sup 2 +/ as an intermediate in the reactions of the ..cap alpha..-hydroxy- and ..cap alpha..-alkoxyalkylchromium complexes suggests that these complexes react with HONO by an electron transfer mechanism. A mechanism has been proposed in which NO/sup +/ is formed which then oxidizes CrR/sup 2 +/ by one electron to give CrR/sup 3 +/. This species decomposes to Cr/sup 3 +/ and R/sup ./ when R is an alkyl group, but forms Cr/sup 2 +/ and ROH when R is an ..cap alpha..-hydroxy-or ..cap alpha..-alkoxyalkyl group. R/sup ./ and Cr/sup 2 +/ react with the NO formed in the reaction to give RNO and CrNO/sup 2 +/, respectively. In contrast, aralkylchromium(III) complexes react with nitrous acid by an electrophilic mechanism as indicated by the products and correlations of the rate constants with other electrophilic reactions in the literature. Photochemically generated tris(2,2'-bipyridyl)-ruthenium(III) oxidizes a range of pentaaquoorganochromium(III) complexes by one electron. The trends in the rate constants and the usual behavior of Ru(bpy)/sub 3//sup 3 +/ suggest that electron transfer is occurring by an outersphere mechanism. In the case of CrCH/sub 2/CH/sub 3//sup 2 +/, the intermediate formed, CrCH/sub 2/CH/sub 3//sup 3 +/, decays to Cr/sup 3 +/ and .CH/sub 2/CH/sub 3/ as shown by kinetic studies and a product analysis.

• Research Organization: Iowa State Univ. of Science and Technology, Ames (USA)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 6855645
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
AZINES
BIPYRIDINES
CHEMICAL REACTIONS
CHROMIUM COMPLEXES
COMPLEXES
ELECTRON TRANSFER
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
INORGANIC ACIDS
NITROUS ACID
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANOMETALLIC COMPOUNDS
PYRIDINES
RUTHENIUM COMPLEXES
TRANSITION ELEMENT COMPLEXES