Microwave survey of the conformational landscape exhibited by the propeller molecule triethyl amineElectronic supplementary information (ESI) available. See DOI: 10.1039/c2cp41385j

• Main Authors: Nguyen, Ha Vinh Lam, Kannengießer, Raphaela, Stahl, Wolfgang
• Format: Journal Article
• Language: English
• Published: 01.08.2012
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c2cp41385j

Conformational studies with quantum chemical methods yielded for the most stable conformer of triethyl amine a propeller-like structure belonging to the point group C 3 , which corresponds to an oblate top. The microwave spectrum of this conformer with 14 N hyperfine splitting of all rotational transitions was assigned and molecular parameters were determined. The rotational constants were found to be A = B = 2.314873978(11) GHz, the 14 N quadrupole coupling constant cc = 5.2444(07) MHz. The observed spectrum could be reproduced within experimental accuracy. The standard deviation of a global fit with 48 rotational transitions is 1.5 kHz. The propeller-like structure seems to be energetically favorable and therefore also typical for related systems like triethyl phosphine, triisopropyl amine, tri- n -propyl amine, and tri- tert -butyl amine. Furthermore, the rotational transitions of two isotopologues, 13 C 2 and 13 C 5 , could be measured in natural abundance and fitted with an excellent standard deviation. The C rotational constants could be determined to be 1.32681(96) GHz and 1.32989(18) GHz for the 13 C 2 and 13 C 5 isotopologues, respectively. The energetically favorable structure of triethyl amine has a chiral propeller form with a C 3 v symmetry transition state.