A multinuclear NMR study of N-(chlorodimethylsilylmethyl) amides

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

“…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]. Table 2).…”

“…The silicon atom in monochlorides (Scheme 1) have the most ideal TBP configuration (D Si % 0; the sum of equatorial angles is %360°) among all neutral pentacoordinate (OSi)-monochelates [18]. As the silicon atom moves out of the equatorial plane towards the X substituent gradually increases the D Si value which is positive for X = Me, OAlk.…”

“…Activation parameters of permutational isomerization for compounds 1-21 (Table 4) were determined by the full line-shape analysis of two singlets of SiMe 2 groups (compounds 1-15) and AB-system quartets of NCH 2 protons (halides [16][17][18][19][20][21].…”

UV Curable Silicones from Acryloxymethyldimethylacryloxysilane

“…In our current studies, 29 Si-NMR of silane I (+15.5 ppm) and the intermediate silane (VI) (prepared from reaction of chloromethyldimethylchlorosilane with one equivalent each of acrylic acid and triethylamine) differs by less than 1 ppm and clearly indicates that both silanes are tetracoordinate. This tetracoordinancy of silane I is further supported by the reported pentacoordinate silane N-methyl-N-chlrodimethylsilylmethyl-acetamide (VII) having a chemical shift of -37.6 ppm (31 Although chloromethyldimethylacryloxysilane (VI) is the expected product, neither 1 H-nor 13 C-NMR is capable of distinguishing it from the isomeric (and possibly more thermodynamically favorable) acryloxymethyldimethylchlorosilane (VIII). Nucleophilic substitution reactions on chloromethyldimethylchlorosilane can take place on both silicon and methylene carbon centers.…”

“…The surprising reactivity of silane I toward silanol beg explanation. Several similar silanes with carbonyl group y-to silicon have been shown to possess pentacoordinate silicon structures (26)(27)(28)(29)(30)(31) with an intramolecular coordinate Si <-0=C bond. Extraordinary reactivities of many hypervalent silicon compounds have been observed (32,33) and are attributed to the hypervalency of these silanes.…”