Intramolecular Lewis acid-base pairs based on 4-ethynyl-2,6-lutidineCCDC 869559, 869560, 869561, 869562. For crystallographic data in CIF or other electronic format see DOI: 10.1039/c2dt30719g

• Main Authors: Winkelhaus, Daniel, Neumann, Beate, Stammler, Hans-Georg, Mitzel, Norbert W
• Format: Journal Article
• Language: English
• Published: 10.07.2012
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c2dt30719g

The reaction of 4-ethynyl-2,6-lutidine, (2,6-Me 2 )(4-HC&z.tbd;C)C 5 H 2 N ( 2 ), with B(C 6 F 5 ) 3 afforded the zwitterion [(2,6-Me 2 )(4-(C 6 F 5 ) 3 BC&z.tbd;C)C 5 H 2 NH] ( 3 ) via a deprotonation pathway. By treatment of 2 with the group 13 trialkyls AlMe 3 , AlEt 3 , GaMe 3 , GaEt 3 and InMe 3 , metallation of the ethynyl group afforded compounds 4-8 under extrusion of the corresponding alkane. The resulting products were characterised by elemental analyses and NMR spectroscopy. Compounds 4 and 8 were crystallized from THF and were yielded as monomers with coordinated THF molecules. The gallium compound 7 could be crystallised from benzene and was afforded as coordination polymer. The structures of these three compounds ( 4 ·THF, 7 and 8 ·2THF) were determined by single-crystal X-ray diffraction experiments. The aluminium compounds 4 and 5 show redistribution reaction of their substituents. The reaction of 4-ethynyl-2,6-lutidine, (2,6-Me 2 )(4-HC&z.tbd;C)C 5 H 2 N, with the Lewis acid B(C 6 F 5 ) 3 leads to the zwitterion [(2,6-Me 2 )(4-(C 6 F 5 ) 3 BC&z.tbd;C)-C 5 H 2 NH], whereas its reactions with MR 3 (M = Al, Ga, In; R = Me, Et) lead exclusively to metallation of the ethynyl group and the products [(2,6-Me 2 )(R 2 MC&z.tbd;C)C 5 H 2 N].