Organoaluminum and -gallium Formamidinate Complexes

• Published in: European journal of inorganic chemistry 2013-05, Vol.2013 (13), p.2460-2466
• Main Authors: Hamidi, Shima, Dietrich, H. Martin, Werner, Daniel, Jende, Lars N., Maichle-Mössmer, Cäcilia, Törnroos, Karl W., Deacon, Glen B., Junk, Peter C., Anwander, Reiner
• Format: Article
• Language: English
• Subjects: Aluminum; Bridging; Bridging ligands; Dipping; Distortion; Formamidines; Gallium; Ligands; Spectra; Stoichiometry; X-ray diffraction
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.201201515

Dialuminum formamidinate complexes [Me2Al(μ‐Form)(μ‐Me)AlMe2] [Form (ArNCHNAr) = EtForm (Ar = 2,6‐Et2C6H3) or DippForm (Ar = 2,6‐iPr2C6H3)] were obtained in good yields by treatment of formamidines (FormH) with trimethylaluminum in a 1:3 stoichiometry. The products contain both a bridging Form ligand and a bridging methyl group between the two aluminum centers. [M(Form)Me2] (M = Al, Form = DippForm, EtForm; M = Ga, Form = DippForm) were prepared in high yields by the protonolysis reactions of MMe3 (M = Al, Ga) with formamidines (FormH) in a 1:1 stoichiometry. [Al(DippForm)Me2] was also synthesized by other methods including concentration of the tetrahydrofuran/n‐hexane solution of [Me2Al(μ‐DippForm)(μ‐Me)AlMe2] to dryness and also by reaction of AlMe3 with [Ga(DippForm)Me2] in a 1:1 ratio. Partial dissociation of the dialuminum to monoaluminum complexes was detected in the 1H NMR spectra of [Me2Al(μ‐Form)(μ‐Me)AlMe2] complexes. All complexes exhibit a distorted tetrahedral stereochemistry of the Group 13 metal atoms. Equimolar protonolysis reactions of MMe3 (M = Al, Ga) with formamidines (FormH) afford monometallic complexes [M(Form)Me2]. The addition of excess amounts of MMe3 produces dimetallic [Me2M(μ‐Form)(μ‐Me)MMe2] for aluminum only.