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Inorganic Chemistry
Volumn 47, Issue 5, 2008, Pages 1532-1547
Platinum(II) diimine complexes with catecholate ligands bearing imide electron-acceptor groups: Synthesis, crystal structures, (spectro) electrochemical and EPR studies, and electronic structure
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EID: 41849087339     PISSN: 00201669     EISSN: None     Source Type: Journal    
DOI: 10.1021/ic701821d     Document Type: Article
Times cited : (54)
References (103)
  • 73
    • 41849089176 scopus 로고    scopus 로고
    • The following abbreviations are used: For a general reference to the new class of ligands and complexes, cat-imide and Pt(bpy*)(cat-imide) are used. For individual catechol ligands, PHT, NAP, NDI, NAP-NDI, and 3,5-cat are used. For individual complexes, Pt(bpy*)PHT, Pt(bpy*)NAP, Pt(bpy*)NDI, Pt(bpy*)NAP-NDI, and Pt(bpy*)(3,5-cat). The imide complexes are also referred to in the text as the PHT complex, NAP complex, etc.
    • The following abbreviations are used: For a general reference to the new class of ligands and complexes, cat-imide and Pt(bpy*)(cat-imide) are used. For individual catechol ligands, PHT, NAP, NDI, NAP-NDI, and 3,5-cat are used. For individual complexes, Pt(bpy*)PHT, Pt(bpy*)NAP, Pt(bpy*)NDI, Pt(bpy*)NAP-NDI, and Pt(bpy*)(3,5-cat). The imide complexes are also referred to in the text as the PHT complex, NAP complex, etc.
  • 85
    • 41849136682 scopus 로고    scopus 로고
    • The first reduction potential of imide group follows the trend phthalimide, ∼-1.9 V < 1,8-naphthalimide, ∼-1.8 V < 1,4,5,8-naphthalenediimide, ∼-1.0 V. The 1,4,5,8-naphthalenediimide undergoes two consecutive one-electron reductions with a difference in potential between those of ∼0.4 V. (See refs 26 and 3.)
    • The first reduction potential of imide group follows the trend phthalimide, ∼-1.9 V < 1,8-naphthalimide, ∼-1.8 V < 1,4,5,8-naphthalenediimide, ∼-1.0 V. The 1,4,5,8-naphthalenediimide undergoes two consecutive one-electron reductions with a difference in potential between those of ∼0.4 V. (See refs 26 and 3.)
  • 93
    • 41849092019 scopus 로고    scopus 로고
    • Although the structure of the proposed dimers cannot be stated unambiguously on the basis of our data, three arrangements might be speculated upon: (i) imide-imide stacking, ii) bpy*-bpy* stacking, and (iii) Pt-Pt interaction. The imide-imide and bpy*-bpy* stacking are unlikely because in that case the dimerization would occur also in the course of the reduction. The X-ray structure suggests a likelihood of Pt-Pt interaction in the dimers. The electronic communication within the dimer is evident from the CV data; therefore, the proposed dimer will be a delocalized one, with two equivalent Pt centers. In principle, delocalization of electron density between two Pt centers will be reflected in the reduction of the A values extracted from the EPR spectra of the dimeric vs monomelic oxidized species. However, the A values in the EPR spectra of oxidized species (Table 5) are virtually identical for Pt(bpy*)(cat-imide) and Pt(bpy*)3,5- cat
    • +•, decreases with an increase of the size of the appended imide group.
  • 98
    • 41849116512 scopus 로고    scopus 로고
    • We have also considered a possibility that the form of the 50% oxidized spectra represent a triplet (S =1) species with significant rhombic distortion E/D ≈ 1/3, However, simulation of the experimental data as S, 1 species failed to give an adequate reproduction of the observed spectra, and those parameters gave a simulated half-field signal that was not found experimentally, even at the high spectrometer gain that was indicated by the results of the simulation
    • We have also considered a possibility that the form of the 50% oxidized spectra represent a triplet (S =1) species with significant rhombic distortion (E/D ≈ 1/3). However, simulation of the experimental data as S = 1 species failed to give an adequate reproduction of the observed spectra, and those parameters gave a simulated half-field signal that was not found experimentally, even at the high spectrometer gain that was indicated by the results of the simulation.
  • 101
    • 41849104334 scopus 로고    scopus 로고
    • The second reduction results in a spectrum essentially identical in shape but depleted relative to that obtained for the one-electron reduced species (∼20% of the one-electron reduced species by double integration of spectra, The spectra of doubly reduced Pt(bpy*)NDI can be simulated with the same hyperfine parameters as [Pt(bpy*)NDI]-• albeit with a slightly reduced line width (a possible consequence of effectively using a more magnetically dilute sample, thus reducing dipolar broadening effects, consequently the spectrum of the two electron reduced species appears better resolved and is used as a representative spectrum. The signal observed for the two-electron reduced species is considered to represent a residual component arising from the presence of monoanion radical, with the majority product, the dianion [Pt(bpy*)NDI]2, as an EPR silent, S, 0, species resulting from the spin pairing of electrons in the 1,4,5,8- naphthal
    • 2-, as an EPR silent, S = 0, species resulting from the spin pairing of electrons in the 1,4,5,8- naphthalenediimide group orbital manifold. This residual signal is not apparent in either fluid or frozen solution spectra of the three electron reduced species, suggested some reoxidation had occurred during sample preparation at the two-electron reduced level.

* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.