Abstract
Lewis acid-base adducts [LGa-M(C6F5)3] (M = B 1, Al 2, Ga 3) were prepared by the reaction of gallanediyl LGa {L = HC[C(Me)N(2,6-i-Pr2C6H3)]2} with the Lewis acids M(C6F5)3 (M = B, Al, Ga). Benzaldehyde reacts with [LGa-M(C6F5)3] (M = B 1, Al 2) at room temperature with the insertion and formation of [LGa(C6F5){CH(Ph)(OB(C6F5)2)}] (4) and the zwitterionic species [LGa(C6F5){CH(Ph)(OAl(C6F5)2)}] (5), respectively, which was found to decompose at 80 °C with the formation of {(C6F5)2Al(OCH2Ph)}2 (6). Any attempts to isolate the insertion complex of [LGa-Ga(C6F5)3] with benzaldehyde failed and only {(C6F5)2Ga(OCH2Ph)}2 (7) was isolated at elevated temperatures. 2-5 and 7 were structurally characterized by heteronuclear NMR spectroscopy and single crystal X-ray diffraction.
Highlights
The activation of small molecules including the reversible splitting of H2 by frustrated Lewis pairs (FLP) has received growing interest since the initial report of Stephan et al in 2006.1 Most FLPs contain the strong Lewis acid B(C6F5)[3] and Lewis basic phosphines PR3, but other Lewis acids such Al(C6F5)[3 2] and Lewis bases such as N-bases[3] and singlet carbenes CR2 4 have been successfully applied for the synthesis of FLP
LGa readily reacts at ambient temperature with M(C6F5)[3] (M = Al, Ga) to form the Lewis acid–base adducts [LGa-Al(C6F5)3] 2 and [LGa-Ga(C6F5)3] 3 in good yields as was previously reported for the reaction of LGa and B(C6F5)[3] (Scheme 1).[9 2] and 3 are colourless solids, which are moderately stable toward air and can be stored at room temperature under an Institute of Inorganic Chemistry, University of Duisburg-Essen, 45117 Essen, Germany
Benzaldehyde readily reacts with the Lewis acid–base adducts [LGa-M(C6F5)3] (M = B 1, Al 2), which were quantitatively formed in the reaction of LGa and M(C6F5)[3], with the formation of the insertion product 4 as well as the zwitterionic compound 5. 5 is formed by the attack of the strongly Lewisacidic aluminum atom on the γ-C atom of the β-diketiminate ligand
Summary
The activation of small molecules including the reversible splitting of H2 by frustrated Lewis pairs (FLP) has received growing interest since the initial report of Stephan et al in 2006.1 Most FLPs contain the strong Lewis acid B(C6F5)[3] and Lewis basic phosphines PR3, but other Lewis acids such Al(C6F5)[3 2] and Lewis bases such as N-bases[3] and singlet carbenes CR2 4 have been successfully applied for the synthesis of FLP. Due to our general interest in Lewis acid–base reactions,[11] we investigated the reactions of group 13 Lewis acid MR3 (M = Al, Ga, In) and group 15 Lewis bases ER3 (E = N, P, As, Sb, Bi)[12] and E2R4 (E = Sb, Bi).[13] In addition, these studies were expanded to group 13 diyl compounds Cp*M (M = Al, Ga, In), which serve as Lewis bases due to the presence of an electron lone pair.[14] More recently, we started to investigate the reactions of LGa with different main group metal compounds including InEt3,15 BiEt3,16 Sb(NMe2)[3,17] E2Et4 (E = Sb, Bi)[18] as well as TeEt2 and Te2Et2,19 respectively, in detail.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
