Crystal and molecular structure of 1-(iododimethylsilylmethyl)piperidone-2

Structures and stereochemical non-rigidity of Si-substituted N-(dimethylsilylmethyl)- and N-(methylphenylsilylmethyl)amides and -lactams

“…The structures of new silicon derivatives 1, 2, 7, 8, 14, and 16-21 were confirmed by IR and 1 H, 13 C, 15 N, 17 O, and 29 Si NMR spectroscopic studies (Tables 1 and 2) and elemental analysis (see Section 4).…”

“…The IR and 1 H, 13 C, and 29 Si NMR spectroscopic data confirming the structure of compounds 3-6, 9-12, 13, and 15 were reported earlier [4,[6][7][8]. The structures of new silicon derivatives 1, 2, 7, 8, 14, and 16-21 were confirmed by IR and 1 H, 13 C, 15 N, 17 O, and 29 Si NMR spectroscopic studies (Tables 1 and 2) and elemental analysis (see Section 4).…”

“…According to the liquid-state 29 Si NMR and solid-state X-ray data (D Si ), the compounds reported in this paper may be divided into several groups. Group (a) includes methyl and alkoxy derivatives 1-3 with either absent or very weak OÁ Á ÁSi coordination.…”

“…The comparison of chemical shifts of signals in the 29 Si NMR spectra of compounds 1-3 [d( 29 Si) % 4-7 ppm] and the corresponding tetracoordinate silanes suggest that the coordination interaction, OÁ Á ÁSi, in these compounds [ÀDd( 29 Si) % À8 to +12 ppm] is either absent or at least is much weaker than that in other (O-Si)-chelate halides, triflates, acylates, and aryloxides of pentacoordinate silicon [4]. This conclusion is also supported by more downfield (up to 100 ppm) shift of signals in 17 [4,18], and iodide 7 ( Table 2) and also by the upfield shift of d[ 13 C(@O)] in compounds 1-3 (%170 ppm, see [4] and Table 1) which is similar to that observed for N,N-dimethylacetamide 22 (169.36 ppm [19]) used as a model compound [20].…”

“…The model tetracoordinate compounds are usually selected from chloromethylsilanes ClCH 2 SiMe 2 X [15] or trimethylsilyl derivatives Me 3 SiX [4]. In this paper the latter compounds were used (see Table 2) as the 29 Si NMR chemical shifts are readily available.…”