Abstract
Nickel(II) complexes of N 3O-donor tripodal ligands, 2,4-di-tert-butyl-6-{([bis(2-pyridyl)methyl]amino)methyl}phenol (HtbuL), 2,4-di-tert-butyl-6-{([(6-methyl-2-pyridyl)methyl](2-pyridylmethyl)amino)methyl} phenol (HtbuLMepy), and 2,4-di-tert-butyl-6-{([bis(6-methyl-2-pyridyl)methyl] amino)methyl}phenol (HtbuL(Mepy) 2), were prepared, and [Ni(tbuL)-Cl(H 2O)] (1), [Ni(tbuLMepy)Cl] (2), and [Ni(tbuL(Mepy) 2)Cl] (3) were structurally characterized by the X-ray diffraction method. Complexes 1 and 3 have a mononuclear structure with a coordinated phenolate moiety, while 2 has a dinuclear structure bridged by two chloride ions. The geometry of the Ni(II) center was found to be octahedral for 1 and 2 and 5-coordinate trigonal bipyramidal for 3. Complexes 1-3 exhibited similar absorption spectra in CH 3CN, indicating that they all have a mononuclear structure in solution. They were converted to the phenoxyl radicals upon oxidation with Ce(IV), giving a phenoxyl radical π-π* transition band at 394-407 nm. ESR spectra at low temperature and resonance Raman spectra established that the radical species has a Ni(II)-phenoxyl radical bond. The cyclic voltammograms showed a quasi-reversible redox wave at E 1/2 = 0.46-0.56 V (vs Ag/AgCl) corresponding to the formation of the phenoxyl radical, which displayed a first-order decay with a half-life of 45 min at room temperature for 1 and 26 and 5.9 min at -20°C for 2 and 3, respectively. The radical stability increased with the donor ability of the N ligands.
| Original language | English |
|---|---|
| Pages (from-to) | 7816-7822 |
| Number of pages | 7 |
| Journal | Inorganic Chemistry |
| Volume | 43 |
| Issue number | 24 |
| DOIs | |
| Publication status | Published - Nov 29 2004 |
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All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Inorganic Chemistry
Cite this
Nickel(II)-phenoxyl radical complexes : Structure-radical stability relationship. / Shimazaki, Yuichi; Huth, Stefan; Karasawa, Satoru; Hirota, Shun; Naruta, Yoshinori; Yamauchi, Osamu.
In: Inorganic Chemistry, Vol. 43, No. 24, 29.11.2004, p. 7816-7822.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Nickel(II)-phenoxyl radical complexes
T2 - Structure-radical stability relationship
AU - Shimazaki, Yuichi
AU - Huth, Stefan
AU - Karasawa, Satoru
AU - Hirota, Shun
AU - Naruta, Yoshinori
AU - Yamauchi, Osamu
PY - 2004/11/29
Y1 - 2004/11/29
N2 - Nickel(II) complexes of N 3O-donor tripodal ligands, 2,4-di-tert-butyl-6-{([bis(2-pyridyl)methyl]amino)methyl}phenol (HtbuL), 2,4-di-tert-butyl-6-{([(6-methyl-2-pyridyl)methyl](2-pyridylmethyl)amino)methyl} phenol (HtbuLMepy), and 2,4-di-tert-butyl-6-{([bis(6-methyl-2-pyridyl)methyl] amino)methyl}phenol (HtbuL(Mepy) 2), were prepared, and [Ni(tbuL)-Cl(H 2O)] (1), [Ni(tbuLMepy)Cl] (2), and [Ni(tbuL(Mepy) 2)Cl] (3) were structurally characterized by the X-ray diffraction method. Complexes 1 and 3 have a mononuclear structure with a coordinated phenolate moiety, while 2 has a dinuclear structure bridged by two chloride ions. The geometry of the Ni(II) center was found to be octahedral for 1 and 2 and 5-coordinate trigonal bipyramidal for 3. Complexes 1-3 exhibited similar absorption spectra in CH 3CN, indicating that they all have a mononuclear structure in solution. They were converted to the phenoxyl radicals upon oxidation with Ce(IV), giving a phenoxyl radical π-π* transition band at 394-407 nm. ESR spectra at low temperature and resonance Raman spectra established that the radical species has a Ni(II)-phenoxyl radical bond. The cyclic voltammograms showed a quasi-reversible redox wave at E 1/2 = 0.46-0.56 V (vs Ag/AgCl) corresponding to the formation of the phenoxyl radical, which displayed a first-order decay with a half-life of 45 min at room temperature for 1 and 26 and 5.9 min at -20°C for 2 and 3, respectively. The radical stability increased with the donor ability of the N ligands.
AB - Nickel(II) complexes of N 3O-donor tripodal ligands, 2,4-di-tert-butyl-6-{([bis(2-pyridyl)methyl]amino)methyl}phenol (HtbuL), 2,4-di-tert-butyl-6-{([(6-methyl-2-pyridyl)methyl](2-pyridylmethyl)amino)methyl} phenol (HtbuLMepy), and 2,4-di-tert-butyl-6-{([bis(6-methyl-2-pyridyl)methyl] amino)methyl}phenol (HtbuL(Mepy) 2), were prepared, and [Ni(tbuL)-Cl(H 2O)] (1), [Ni(tbuLMepy)Cl] (2), and [Ni(tbuL(Mepy) 2)Cl] (3) were structurally characterized by the X-ray diffraction method. Complexes 1 and 3 have a mononuclear structure with a coordinated phenolate moiety, while 2 has a dinuclear structure bridged by two chloride ions. The geometry of the Ni(II) center was found to be octahedral for 1 and 2 and 5-coordinate trigonal bipyramidal for 3. Complexes 1-3 exhibited similar absorption spectra in CH 3CN, indicating that they all have a mononuclear structure in solution. They were converted to the phenoxyl radicals upon oxidation with Ce(IV), giving a phenoxyl radical π-π* transition band at 394-407 nm. ESR spectra at low temperature and resonance Raman spectra established that the radical species has a Ni(II)-phenoxyl radical bond. The cyclic voltammograms showed a quasi-reversible redox wave at E 1/2 = 0.46-0.56 V (vs Ag/AgCl) corresponding to the formation of the phenoxyl radical, which displayed a first-order decay with a half-life of 45 min at room temperature for 1 and 26 and 5.9 min at -20°C for 2 and 3, respectively. The radical stability increased with the donor ability of the N ligands.
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U2 - 10.1021/ic049040k
DO - 10.1021/ic049040k
M3 - Article
C2 - 15554647
AN - SCOPUS:9444249868
VL - 43
SP - 7816
EP - 7822
JO - Inorganic Chemistry
JF - Inorganic Chemistry
SN - 0020-1669
IS - 24
ER -