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  • Synthesis, Characterization...
    Zhu, Zhongliang; Fischer, Roland C.; Ellis, Bobby D.; Rivard, Eric; Merrill, W. Alexander; Olmstead, Marilyn M.; Power, Philip P.; Guo, J. D.; Nagase, Shigeru; Pu, Lihung

    Chemistry : a European journal, May 18, 2009, Volume: 15, Issue: 21
    Journal Article

    Move closer: The galliumgallium bond strength in terphenyl gallium(I) dimers ArGaGaAr (see figure) is similar to those in other molecules with closed shell interactions, implying that the GaGa bond in doubly reduced Na2ArGaGaAr is much closer to a single than a triple one. A series of stable aryl gallium(I) terphenyl derivatives was synthesized and characterized spectroscopically, structurally and by density functional calculations. Dimeric structures with trans‐bent planar CGaGaC core arrangements were observed for (GaAr*‐4‐tBu)2 (7, Ar*‐4‐tBu=C6H2‐2,6(C6H2‐2,4,6‐iPr3)2‐4‐tBu) and (GaAr*‐4‐CF3)2 (8, Ar*‐4‐CF3=C6H2‐2,6(C6H2‐2,4,6‐iPr3)2‐4‐CF3), whereas monomeric structures featuring one coordinate gallium were observed for the more crowded complexes :GaAr*‐3,5‐iPr2 (10, Ar*‐3,5‐iPr2=C6H‐2,6(C6H2‐2,4‐6‐iPr3)2‐3,5‐iPr2) and GaAr′‐3,5‐iPr2 (11, Ar′‐3,5‐iPr2=C6H‐2,6(C6H3‐2,6‐iPr2)2‐3,5‐iPr2). Complexes 7 and 8 dissociate to monomers in hydrocarbon solution and their electronic spectra closely resemble those of 10 and 11 as well as those of Ar′GaGaAr′ (Ar′=C6H3‐2,6(C6H3‐2,6‐iPr3)2) and (GaAr*)n (Ar*=C6H3‐2,6(C6H2‐2,4,6‐iPr3)2). The calculations showed that the binding energies of the compounds are weak, resemble closed‐shell interactions and average ≈5 kcal mol−1, as in Ar*GaGaAr* with a lowest value of ≈−2 kcal mol−1 for monomeric 10 and a highest value ≈9 kcal mol−1 for the least crowded species Ar′GaGaAr′. The weak bonding in the complexes supports the view that the GaGa bonding in the previously published doubly reduced Na2Ar*GaGaAr* and Na2Ar′GaGaAr′ is also weak and is consistent with approximate single bonding. Move closer: The galliumgallium bond strength in terphenyl gallium(I) dimers ArGaGaAr (see figure) is similar to those in other molecules with closed shell interactions, implying that the GaGa bond in doubly reduced Na2ArGaGaAr is much closer to a single than a triple one.