Reduction-induced cleavage of the cobalt-carbon bond in macrocyclic organocobalt complexes

Journal Article · Wed Sep 04 04:00:00 EDT 1991 · Inorganic Chemistry; (United States)

DOI:https://doi.org/10.1021/ic00018a009· OSTI ID:7163428

Shi, Shu; Bakac, A; Espenson, J H ^[1]

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1. Iowa State Univ., Ames (United States)

The one-electron reduction of RCo(dmgBF{sub 2}){sub 2}A (dmgBF{sub 2} = (difluoroboryl)dimethylglyoximato, A = pyridine or H{sub 2}O, R = CH{sub 3}, C{sub 2}H{sub 5}, C{sub 3}H{sub 7}, C{sub 6}H{sub 5}CH{sub 2}, or 4-XC{sub 6}H{sub 4}CH{sub 2}) yields RCo(dmgBF{sub 2}){sub 2}A{sup {minus}} as transients. The ESR parameters (R = 4-BrC{sub 6}H{sub 4}CH{sub 2}, g{sub {parallel}} = 2.23, A {sub {parallel}} = 111 {times} 10{sup {minus} 4} cm{sup {minus} 1}, g{perpendicular} = 2.07, A{perpendicular} = 54 {times} 10{sup {minus} 4} cm{sup {minus} 1}) indicate that the unpaired electron resides in the d{sub x{sup 2}{minus}y{sup 2}} orbital of the cobalt. The reduced complexes hydrolyze in H{sub 2}O to yield the alkanes RH and Co(dmgBF{sub 2}){sub 2}(H{sub 2}O){sub 2}. In acetonitrile the decomposition mode depends on the availability of {beta}-hydrogens. For R = C{sub 2}H{sub 5} and 1-C{sub 3}H{sub 7}, the final products are the corresponding alkenes and a cobalt(II) complex of a modified macrocycle. The benzyl and substituted benzyl complexes yield the hydrolysis products 4-SC{sub 6}H{sub 4}CH{sub 3} and the unchanged cobalt(II) macrocycle. The kinetics of the reduction of RCo(dmgBF{sub 2}){sub 2}A by R,S,-R,S-Ni(tmc){sup {plus}} (tmc = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane) in H{sub 2}O, pH 12, are biphasic for R = benzyl and substituted benzyl and monophasic for the primary alkyl complexes, consistent with the expected effect of the organic group on the lifetimes of the RCo(dmgBF{sub 2}){sub 2}A{sup {minus}} transients.

• OSTI ID: 7163428
• Journal Information: Inorganic Chemistry; (United States), Journal Name: Inorganic Chemistry; (United States) Vol. 30:18; ISSN 0020-1669; ISSN INOCA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
550200 -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISTRY
COBALT COMPLEXES
COMPLEXES
DECOMPOSITION
ELECTROCHEMISTRY
ELECTRON SPIN RESONANCE
HYDROLYSIS
KINETICS
LYSIS
MAGNETIC RESONANCE
NMR SPECTRA
ORGANIC COMPOUNDS
ORGANOMETALLIC COMPOUNDS
REACTION KINETICS
REDUCTION
RESONANCE
SOLVOLYSIS
SPECTRA
TRANSITION ELEMENT COMPLEXES
VOLTAMETRY