B. Wrackmeyer, G. Kehr, R. Boese
Mar 1, 1992
Citations
0
Influential Citations
35
Citations
Journal
Chemische Berichte
Abstract
Organoboration of Tetrakis(trimethylsilylethynyl)stannane – X-ray Structure of a 5-Stannaspiro[4.4]nona-1,3,6,8-tetraene Derivative Tetrakis(trimethylsilylethynyl)stannane (1) reacts with non-cyclic trialkylboranes BR3 [2, R = Me (a), Et (b), Pr (c), iPr (d)] and 9-alkyl-9-borabicyclo[3.3.1]nonanes[2e (alkyl = Et), 2f (alkyl = neopentyl)] to give the 3,8-dialkyl-2,7-bis(dialkylboryl)-1,4,6,9-tetrakis(trimethylsilyl)-5-stannaspiro[4.4]nona-1,3,6,8-tetraenes 5a to f in high yield. The reaction proceeds stepwise, and intermediates as well as final products were characterized by 1H, 11B, 13C, 29Si, 119Sn NMR spectroscopy. According to an X-ray structure analysis of 5f · 0.5 CH2Cl2 (space group P2/c) the endocyclic CSnC bond angles are small [84.9(2) and 84.2(2)°] and the two five-membered rings are not exactly planar. Steric crowding causes a strong twist of the skeleton of the other ring systems. The agreement between solid-state and liquid-phase NMR data shows that main structural features are retained in solution.