Model of the SN2 nucleophilic substitution at the Si atom: X-ray structural study of N-(halogenodimethylsilylmethyl) lactams

Synthesis, molecular and crystal structure, and features of the electronic structure of bis(O’i)-chelated bis(2,2-dimethylbenzo-[2H]-4-oxo-1,3-oxazino-3-methyl)difluorosilane

“…The crystal packing of compound 1 also includes two molecules of solvated benzene which occupy a partial position in the crystallographic centre of inversion. The structure of the 2,2-dimethylbenzo[2H]-1,3-oxazine fragments in molecule 1 is close to that for the previously described BonCH 2 SiMe 2 Cl with a pentacoordinated silicon atom [9,12].…”

“…A similar behavior for the coordinated Si atom polyhedron in pentacoordinated derivatives has been studied in a series of publications concerned with investigations of different mono-chelate complexes by a structural correlation method and with the help of quantum-chemical calculations [12,[14][15][16].…”

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

“…Our calculations adequately reflect correlations between the type of the monodentate ligand X and geometric parameters of the N-C-O-Si-X fragment determined by NMR spectroscopy (see above) and X-ray analysis of compounds 4, 5 [25], and 15 [26]. Strong intramolecular O !…”

Pentacoordinated chlorosilanes with C,O-chelate ligands derived from N-methyl-N'-organosulfonyl-prolinamides*

“…29 Si NMR spectrum (СDCl 3 ), δ, ppm: -33. 5 Crystallization of hygroscopic amide (S)-2e (0.91 g, 2 mmol) from benzene (3 ml) without protection from a moist air gave 0.9 g (95%) (N'-(4-bromophenylsulfonyl)-N-methyl-(S)-prolinamidomethyl)dimethylsilyloxonium chloride (S)-5e; mp 95-97°С (C 6 B. SOCl 2 (0.30 g, 2.5 mmol) was added dropwise with stirring to a solution of disiloxane 6f (1.57 g, 2.0 mmol) in benzene (10 ml). The precipitate formed was filtered off and washed with absolute ether.…”

“…The strength of the intramolecular O→Si coordination bond in these compounds varies in a rather broad range depending on the nature of the monodentate ligands at the silicon atom and substituents in the five-membered chelate ring [1][2][3][4][5][6][7][8][9][10][11]. Investigation of the structure features of pentacoordinated C,O-chelates with the SiC 3 OX coordination unit (X = Hal, OAlk, OAr, ½O, and Otf) [5,10,[12][13][14][15][16][17] allows using these compounds as models for studying hypervalence problem [1, 18,19] and modeling pathways for S N reactions at the silicon atom [1-5, 7-10, 20, 21].…”