Direct determination of self-exchange electron-transfer rate constants of nickel(III,II) complexes by sup 62 Ni EPR line broadening

Journal Article · Wed Sep 06 04:00:00 EDT 1989 · Inorganic Chemistry; (USA)

DOI:https://doi.org/10.1021/ic00317a017· OSTI ID:6985557

Wang, Jean-Fu; Kumar, K; Margerum, D W ^[1]

---

1. Purdue Univ., West Lafayette, IN (USA)

A novel method, based on the influence of {sup 61}Ni on the room-temperature electron paramagnetic resonance spectra of Ni(III) complexes, is used for the measurement of electron-transfer self-exchange rate constants of nickel(III,II) complexes. An electron-transfer self-exchange rate constant (k{sub 11} = 450 {plus minus} 50 M{sup {minus}1} s{sup {minus}1} at 24{degree}C) is measured for the Ni{sup III}(H{sub {minus}2}Aib{sub 3})(H{sub 2}O){sub 2} and Ni{sup II}(H{sub {minus}2}Aib{sub 3}){sup {minus}} couple, where Aib{sub 3} is the tripeptide of {alpha}-aminoisobutyric acid and H{sub {minus}2} designates two deprotonated-N(peptide) groups. This k{sub 11} value reflects an inner-sphere enhancement attributed to bridging by an axial water molecule. The exchange rate decreases when pyridine replaces one of the axial water molecules of the nickel(III) complexes. The electron-transfer rate constant between Ni{sup III}(H{sub {minus}2}Aib{sub 3})(py)(H{sub 2}O) and Ni{sup II}(H{sub {minus}2}Aib{sub 3}){sup {minus}} is 103 {plus minus} 8 M{sup {minus}1} s{sup {minus}1} at 23{degree}C. 36 refs., 4 figs., 3 tabs.

• OSTI ID: 6985557
• Journal Information: Inorganic Chemistry; (USA), Journal Name: Inorganic Chemistry; (USA) Vol. 28:18; 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
400202 -- Isotope Effects
Isotope Exchange
& Isotope Separation
COMPLEXES
DATA
ELECTRON SPIN RESONANCE
ELECTRON TRANSFER
EVEN-ODD NUCLEI
EXPERIMENTAL DATA
INFORMATION
INTERMEDIATE MASS NUCLEI
ISOTOPES
MAGNETIC RESONANCE
NICKEL 61
NICKEL COMPLEXES
NICKEL ISOTOPES
NUCLEI
NUMERICAL DATA
RESONANCE
STABLE ISOTOPES
TRANSITION ELEMENT COMPLEXES