Organochromium(III) macrocyclic complexes. Factors controlling homolytic vs heterolytic cleavage of the chromium-carbon bond

Journal Article · Wed Oct 17 04:00:00 EDT 1990 · Inorganic Chemistry; (USA)

DOI:https://doi.org/10.1021/ic00346a030· OSTI ID:5958783

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

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1. Iowa State Univ., Ames (USA)

Kinetics studies were done of the homolytic and heterolytic cleavage reactions of the chromium-carbon bonds in the complexes RCr(L)A{sup n+} (where L = (15)aneN{sub 4} = 1,4,8,12-tetraazacyclopentadecane; A = H{sub 2}O, OH{sup {minus}}). Activation parameters for homolysis of RCrL(H{sub 2}O){sup 2+} are as follows: 111 {plus minus} 2, 54 {plus minus} 6 (R = p-CH{sub 3}C{sub 6}H{sub 4}CH{sub 2}); 103 {plus minus} 2, 28 {plus minus} 5 (C{sub 6}H{sub 5}CH{sub 2}); 101 {plus minus} 3, 22 {plus minus} 9 (p-BrC{sub 6}H{sub 4}CH{sub 2}); 110 {plus minus} 3, 62 {plus minus} 6 (i-C{sub 3}H{sub 7}). The {Delta}H{sup {double dagger}} and {Delta}S{sup {double dagger}} parameters are considerably smaller than those for homolysis of (H{sub 2}O){sub 5}CrR{sup 2+} analogues. Primary alkyl macrocyclic complexes do not undergo homolysis. The complexes RCrL(OH){sup +} slowly hydrolyze for R = n-C{sub 3}H{sub 7} and i-C{sub 3}H{sub 7} whereas those for which R = ArCH{sub 2} do not. The activation parameters for hydrolysis are 78 {plus minus} 1, {minus}53 {plus minus} 2 (R = i-C{sub 3}H{sub 7}) and 83 {plus minus} 3, {minus}46 {plus minus} 9 (n-C{sub 3}H{sub 7}). This pathway shows no solvent deuterium isotope effect. The complexes RCrL(H{sub 2}O){sup 2+} are not subject to acidolysis by H{sub 3}O{sup +} or H{sub 2}O, unlike their (H{sub 2}O){sub 5}CrR{sup 2+} analogues. 23 refs., 3 figs., 2 tabs.

• OSTI ID: 5958783
• Journal Information: Inorganic Chemistry; (USA), Journal Name: Inorganic Chemistry; (USA) Vol. 29:21; 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
400202 -- Isotope Effects
Isotope Exchange
& Isotope Separation
ALKANES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHROMIUM COMPLEXES
COMPLEXES
DATA
DECOMPOSITION
DEUTERIUM
EXPERIMENTAL DATA
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
HYDROGEN ISOTOPES
HYDROLYSIS
INFORMATION
ISOTOPE EFFECTS
ISOTOPES
KINETICS
LIGHT NUCLEI
LYSIS
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
REACTION KINETICS
SOLVOLYSIS
STABLE ISOTOPES
TRANSITION ELEMENT COMPLEXES