1613378-93-0Relevant articles and documents
Alkenyl-alkynylgermanes functionalised by lewis acids: Intramolecular aluminium- and gallium-alkyne interactions and potential Ge-C bond activation
Uhl, Werner,Pelties, Stefan,Rohling, Martina,Tannert, Jens
, p. 2809 - 2818 (2014/06/24)
Treatment of various diethynylgermanes, (R1) 2Ge(C≡C-R2)2 (R1 = C 6H5, CH3; R1-R1 = C 6H4-C6H4; R2 = CH 3, CMe3, nBu, C6H5), with equimolar quantities of di(tert-butyl)aluminium or -gallium hydride, R2E-H (E = Al, Ga), afforded mixed alkenyl-alkynylgermanes, (R1) 2Ge(C≡C-R2)[C{E(CMe3)2}=C(H)- R2], by reduction of one of their C≡C triple bonds. The alkenyl groups have a cis arrangement of H and Al or Ga atoms across the C=C double bonds, which reflects the kinetically favoured situation. The cis/trans isomerisation is probably prevented from yielding thermodynamically favoured trans isomers; this is a result of an intramolecular bonding interaction between the α-carbon atoms of the remaining ethynyl groups and the coordinatively unsaturated metal atoms. The higher Lewis acidity of Al compared to Ga results in relatively short Al?C(ethynyl) contacts (>231.2 pm) and a concomitant lengthening of the Ge-C bonds. Bond activation by intramolecular interactions of alkynyl carbon with highly Lewis acidic aluminium atoms was observed for functionalised alkenyl-alkynylgermanes. Such mixed germanium-aluminum or -gallium compounds were obtained by hydrometallation of dialkynylgermanes and are promising candidates for secondary reactions such as cyclisation or insertion. Copyright
