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  • 1
    Electronic Resource
    Electronic Resource
    Synthesis, molecular structure, and magnetic properties of bis(3,6-di-tert-butyl-o-benzosemiquinone)nickel(II) and -copper(II) (1992)
    Springer
    Russian chemical bulletin 41 (1992), S. 1813-1818 
    Details
    ISSN: 1573-9171
    Keywords: ferromagnetic and antiferromagnetic exchange interactions ; free-radical o-semiquinone ligands ; square-planar coordination ; d 8- andd 9-transition-metal complexes ; x-ray structural and EPR studies ; vacant and occupied atomic and molecular orbitals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The title complexes of Ni and Cu with symmetrical 3,6-di-tert-butyl-o-benzosemiquinone are synthesized. Their EPR spectra and magnetic properties are investigated. The x-ray structure studies [Siemens R3/PC diffractometer, λ MoKα, ϑ/20-scanning in the rang 2 ≤ 2ϑ ≤ 54°, 2084 reflections withF 〉 4σ(F),R = 0.034,R w = 0.039, monoclinic crystals,a = 9.982(2),b = 11.548(2),c = 12.145(2) Å, β = 95.05(3)°,Z = 2,d calc = 1.19 g/cm−3, space groupP2 l/c) demonstrated that the complex is monomeric with square-planar coordination for the Ni with theo-semiquinone ligands. The Cu complex is isostructural with the Ni (a = 9.88,b = 11.60,c = 12.15 Å, β = 95°]. The dependence of the magnetic moment of the Cu complex on temperature is consistent with the presence in it of two pathways for exchange interaction. These are antiferromagnetic ligand-ligandJ 12 = −179 cm−1 and ferromagnetic metal-ligandJ 13 = 100 cm−1 (mean-square deviation 2%). The Ni complex is diamagnetic over the whole studied temperature range despite the fact that it contains free-radicalo-semiquinone ligands. Such an effect involving electrons belonging to the free-radical ligands is observed for the first time in the magnetochemistry ofd 8- andd 9-transition-metal complexes. It is explained by incorporation of vacantp z- and/or occupiedd xz- andd yz-orbitals of Ni in molecular orbitals containing the π-MO of the semiquinone ligands.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00863815
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis, structure, and properties of 2-(triphenylstannyloxy)-3,6-di-tert butyl-1,4-benzoquinone (1992)
    Springer
    Russian chemical bulletin 41 (1992), S. 2224-2229 
    Details
    ISSN: 1573-9171
    Keywords: 2-triphenylstannyloxy-3,6-di-tert-butyl-1,4-benzoquinone ; synthesis ; x-ray diffraction analysis ; electronic absorption spectra ; IR spectroscopy ; NMR spectroscopy ; reaction with radicals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract 2-(Triphenylstannyloxy)-3,6-di-tert-butyl-1,4-benzoquinone (1) was obtained from the potassium salt of 3,6-di-tert-butyl-2-hydroxy-1,4-benzoquinone and triphenyltin bromide in methanol and characterized by x-ray diffraction analysis, electronic, IR, and NMR spectroscopy. According to x-ray diffraction data, the single crystal of1 has the structure of a chain metal polymer with bridging hydroxy-para-quinone ligands; the coordination number of tin is six. Complex1 is reduced by cobaltocene to the corresponding radical anion. In solutions,1 reacts with metal-centered radicals $$\dot SnPh_3 , \dot PbPh_3 $$ , and $$\dot Mn(CO)_5 $$ with formation of paramagnetic binuclearortho-semiquinone complexes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01150751
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis and thermal transformations of molecular complexes of bis[tris(trifluoromethyl)germyl]mercury(ii witho-quinones (1995)
    Springer
    Russian chemical bulletin 44 (1995), S. 1508-1512 
    Details
    ISSN: 1573-9171
    Keywords: synthesis ; molecular complexes ; o-quinones ; bis[tris(trifluoromethyl)germyl]-mercury(n) ; thermolysis ; one-electron oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Stable molecular complexes of bis[tris(trifluoromethyl)germyl]mercury(II) Hg[(CF3)3Ge]2 (1) witho-quinones (3,6-di-tert-butylbenzoquinone-1,2 (2), 3,6-di-tert-butyl-4,5-dimethoxybenzoquinone-1,2 (3), and 1,4,5,7-tetra-tert-butyldibenzo[1,4]dioxin-2,3-dione (4)) have been synthesized and characterized by elemental analysis and IR and electronic absorption spectroscopies. Depending on the ratio between the starting reactants, the reactions ofo-quinones with1 gave complexes of the composition R2Hg · Q (5,7,9) or R2Hg · Q2 (6,8,10), where Q=2 (5,6),3 (7,8),4 (9,10); R=Ge(CF3)3. According to the spectral data, the molecule ofo-quinone in R2Hg · Q acts as a neutral ligand, whereas the second molecule ofo-quinone in R2Hg · Q2 is not coordinated to1. It has been found by ESR that thermolysis of polycrystalline samples of complexes6 and10 involves intermediate formation of radical pairs and finally yields paramagnetico-semiquinone complexes, SQGe(CF3)3, which are typical products of one-electron oxidation of Organometallic compounds byo-quinones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00714442
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