Synthesis of Unsupported Ln-Ga Bonds by Salt Metathesis and Ga-Ga Bond Reduction

Three gallyl lanthanide complexes [{(dipp-Bian)Ga}(2)Ln(thf)(4)] (Ln = Sm, Eu, Yb; dipp-Bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene), in which the lanthanide atoms are coordinated by only two {(dipp-Bian)Ga}(-) ligands and THF, are reported. Two unsupported Ln-Ga bonds are found in each compound. The gallyl lanthanide complexes have been obtained by two synthetic pathways: (1) reductive insertion of the lanthanide metals into the Ga-Ga bond of [{(dipp-Bian)Ga}](2) and (2) salt metathesis of [(dipp-Bian)GaK(thf)(5)] with LnI(2). Moreover, the samarium compound [{(dipp-Bian)Ga}(2)Sm(thf)(4)] was additionally obtained in a reductive pathway from SmI3 and [(dipp-Bian)GaK(thf)(5)]. The length of the Ln-Ga bond strongly depends on packing effects. The reaction of TmI2(thf)(5) and Rdipp-Bian)GaK(thf)(5)] gave the Tm(III) complex [{(dipp-Bian)Ga-Ga(dipp-Bian)}(C4H8O)TmI(thf)(5)], in which one THF ring was opened and reduced twice, forming the formal double negative charged anion (O-CH2-CH2-CH2-CH2)(2-). This thulium compound and its dysprosium analogue [{(dipp-Bian)Ga-Ga(dipp-Bian)}(C4H5O)Dyl(thf)(5)] were also obtained in an alternative approach by reacting LnI(2)(thf)(x) (Ln = Tm, Dy) with [(dipp-Bian)Ga](2) in THF. All new compounds were structurally characterized by single-crystal X-ray diffraction. The ytterbium complex shows the shortest Yb(II)-Ga bond distances reported so far.