Preparation and characterization of mixed alkyl amido complexes of gallium |
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Authors: | Sen T Barry Darrin S Richeson |
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Institution: | Department of Chemistry, University of Ottawa, Ottawa, Ont. K1N 6N5, Canada |
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Abstract: | A series of primary amido gallium alkyl complexes that includes a base free dimer, tBu2Ga(μ-N(H)tBu)]2 (1), Lewis base stabilized monomeric complexes, nBu2Ga(N(H)tBu)(THF) (2) and nBu2GaNH(2,6-Me2C6H3)]py (3) and an anionic complex, nBu2GaNH(2,6-Me2C6H3)]2Li(Et2O)] (4) is reported. Complex 1 crystallizes in the triclinic space group P-1 (a = 10.265(5) Å, B = 15.752(6) Å, C = 8.932(4) Å, = 90.32(3)°, β = 105.61(3)°, γ = 88.24(4)°) with two molecules, each residing on an inversion center, in the asymmetric unit. Structural analysis revealed a planar Ga2N2 core with both the bridging N and the Ga centers in distorted tetrahedral environments (Ga---C distances 2.052(3)-2.065(3) Å and Ga---N distances 2.060(3)-2.069(3) Å). The use of excess amido ligand allowed the isolation and crystallization of 4. Complex 4 crystallized in the monoclinic space group P21/n (a = 8.666(2) Å, B = 22.305(3) Å, C = 15.570(3) Å, β = 103.47(2)) with Z = 4. The pseudotetrahedral gallium center has a coordination sphere composed of two amido ligands (Ga---N1 = 2.011(8) Å, Ga---N2 = 2.006(7) Å), and two nBu ligands (Ga---C17 = 2.002(9) Å Ga---C21 = 1.985(12) Å). A bridging interaction of the lithium cation with the lone pair of electrons on each of amido nitrogen atoms generates a molecular core which is made up of a planar Ga---N1---Li---N2 distorted square (N1---Gal---N2 94.4°, Gal---N2---Lil 86.2°, N1---Li1---N2 92.2°, Gal---N1---Li1 87.1°). |
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Keywords: | Gallium Amines Alkyls |
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