Final Exam

December 21, 2000

1. D. L. Fiacco, A. Toro, and K. R. Leopold (p. 37-43) investigated the gas phase structure of the Lewis acid/base complex (CH₃)₃N–SO₃. Draw the Lewis dot structure for this compound, estimate the C-N-S and N-S-O bond angles (± 2^o), and indicate the hybridization at the N and S atoms.

Answer:

The C-N-S angle should be very close to the ideal tetrahedral angle, 109^o. The high electron density in the S=O bonds will cause repulsion between the S=O groups, thereby increasing the O-S-O angle and reducing the N-S-O angle to ~107^o. Both the S and N are sp³ hybridized.