4‐Alkyl‐2,2,6,6‐tetramethyl‐1,4,2,6‐oxaazadisilinanes: synthesis, structure, and conformational analysis

4‐Alkyl‐2,2,6,6‐tetramethyl‐1,4,2,6‐oxaazadisilinanes RN[CH 2 Si(Me) 2 ] 2 O [R = Me ( 1 ), i ‐Pr ( 2 )] were synthesized by two methods which provided good yields up to 84%. Low temperature NMR study of compounds ( 1 ) and ( 2 ) revealed a frozen ring inversion with the energy barriers of 8.5 and 7.7 kcal/mol at 163 and 143 K, respectively, which is substantially lower than that for their carbon analog, N ‐methylmorpholine. DFT calculations performed on the example of molecule ( 1 ) showed that NMe ax conformer to exist in the sofa conformation with the coplanar fragment CSiOSiC, and its NMe eq conformer in a flattened chair conformation. Copyright © 2009 John Wiley & Sons, Ltd.