Synthesis, Characterization and Real Molecule DFT Calculations for Neutral Organogallium(I) Aryl Dimers and Monomers: Weakness of Gallium-Gallium Bonds in Digallenes and Digallynes.

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

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A series of stable aryl gallium(I) terphenyl derivs. was synthesized and characterized spectroscopically, structurally and by d. functional calcns. Dimeric structures with trans-bent planar CGaGaC core arrangements were obsd. 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 obsd. 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 dissoc. to monomers in hydrocarbon soln. 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 calcns. showed that the binding energies of the compds. are weak, resemble closed-shell interactions and av. ≈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 Na2[Ar*GaGaAr*] and Na2[Ar'GaGaAr'] is also weak and is consistent with approx. single bonding. [on SciFinder(R)]
Original languageEnglish
Pages (from-to)5263-5272
Number of pages10
JournalChemistry - a European Journal
Issue number21
Publication statusPublished - 2009

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