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

• Published in: Organometallics Vol. 31; no. 11; pp. 4331 - 4339
• Main Authors: Sanden, Tanja, Gamer, Michael T, Fagin, Anatoly A, Chudakova, Valentina A, Konchenko, Sergey N, Fedushkin, Igor L, Roesky, Peter W
• Format: Journal Article
• Language: English
• Published: American Chemical Society 11.06.2012
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om300309b

Three gallyl lanthanide complexes [{(dipp-Bian)Ga}2Ln(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 LnI2. Moreover, the samarium compound [{(dipp-Bian)Ga}2Sm(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 [(dipp-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)}(C4H8O)DyI(thf)5] were also obtained in an alternative approach by reacting LnI2(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.