Synthesis of an organogallium(I) compound [Ga(CH2CMe2Ph)]n with EPR spectral evidence for gallium clusters

The organogallium(I) compound [Ga(CH2CMe2Ph)](n) has been prepared by the reduction of Ga(CH2CMe2Ph)(2)Cl by using either sodium or lithium with naphthalene in THF. The yellow dihydronaphthalene gallium(III) intermediate M-2(C10H8[Ga(CH2CMe2Ph)(2)Cl](2)) initially formed at -78 degrees C but then decomposed at higher temperatures to form [Ga(CH2CMe2Ph)](n), Ga(CH2CMe2Ph)(3) and MCl. EPR spectra, which were recorded as the two yellow intermediates Na-2(C10H8[Ga(CH2CMe2R)(2)Cl](2)) (R = Ph, Me) decomposed, indicated the presence of radicals. The first and second derivatives of the EPR signals, line-widths, g-values and hyperfine coupling constants are consistent with the radicals being clusters of organogallium species. The experimental spectra were simulated by the superposition of two spectra, a single Gaussian shaped line with a peak-to-peak width of 14 mT (92%) with the spectrum of five equivalent gallium nuclei, A = 2.1 mT (8%). The even number of lines observed in the experimental spectra indicate an odd number of gallium nuclei with at least five bring required to give the number of observed lines. (C) 1999 Elsevier Science S.A. All rights reserved.