Oxidative and electrophilic pathways in the reactions of pentaaquo(organo)chromium(2+) ions with nitrous acid

Journal Article · Wed Sep 10 04:00:00 EDT 1986 · Inorg. Chem.; (United States)

DOI:https://doi.org/10.1021/ic00239a010· OSTI ID:6952925

Melton, J D; Bakac, A; Espenson, J H

The reactions of HONO with (H/sub 2/O)/sub 5/CrR/sup 2 +/ complexes occur with a 1:1 stoichiometry at rates ranging from 0.12 (R = CH/sub 2/Br) to 1010 M/sup -2/ s/sup -1/ (R = rho-CH/sub 2/C/sub 6/H/sub 4/CH/sub 3/). The chromium product is Cr(H/sub 2/O)/sub 6//sup 3 +/ for R = alkyl, haloalkyl, and aralkyl but the kinetically stable nitrosyl complex (H/sub 2/O)/sub 5/CrNO/sup 2 +/ for R = ..cap alpha..-hydroxy- and ..cap alpha..-alkoxyalkyl. All of the reactions are believed to proceed by a bimolecular reaction between the nitrosyl cation NO/sup +/ and CrR/sup 2 +/. In the case of the aralkyl complexes, the data are consistent with an electrophilic process; correlations with data in the literature support the assignment of an S/sub E/2 mechanisms. The other reactions are best interpreted in terms of electron transfer to form CrR/sup 3 +/. The fate of the latter depends on the nature of the group R. Intramolecular electron transfer for R = CH/sub 2/OH, CH/sub 2/OCH/sub 3/, and CH(C-H/sub 3/)OC/sub 2/H/sub 5/ results in Cr/sup 2 +/, which is scavenged by NO to give CrNO/sup 2 +/. The rate constant for the reaction between Cr/sup 2 +/ and NO has been independently evaluated as 2.2 x 10/sup 6/ M/sup -1/ s/sup -1/ by competition methods. All the other CrR/sup 3 +/ complexes decompose by homolysis. The free radical so formed reacts with NO to yield RNO. 57 references, 7 figures, 3 tables.

• Research Organization: Iowa State Univ., Ames
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 6952925
• Journal Information: Inorg. Chem.; (United States), Journal Name: Inorg. Chem.; (United States) Vol. 25:19; ISSN INOCA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALKANES
CHEMICAL PREPARATION
CHROMIUM COMPLEXES
COMPLEXES
DATA
ELECTRON TRANSFER
EXPERIMENTAL DATA
HYDROCARBONS
HYDROGEN COMPOUNDS
INFORMATION
INORGANIC ACIDS
KINETICS
NITROUS ACID
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
ORGANOMETALLIC COMPOUNDS
OXYGEN COMPOUNDS
REACTION KINETICS
SYNTHESIS
TRANSITION ELEMENT COMPLEXES
WATER