(Amidomethyl)dimethylsilanol hydrohalides: Synthesis, NMR and IR studies. Characteristic features of the electronic structure from high-resolution X-ray study and quantum chemical calculation

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

“…We have already noted the high tendency of chlorosilanes 2 to undergo hydrolysis, which is markedly greater than for previously reported C,O-chelate pentacoordinated chlorosilanes [15,28]. Thus, recrystallization in the air led to the formation of silyloxonium chlorides [RSO 2 -Pro-N(Me)CH 2 SiMe 2 OH 2 ]Cl 5a-f.…”

“…Weak intermolecular interactions in the crystal also apparently have a significant effect on this bond length in addition to the inductive effect in the structures of chlorosilanes 2a-f. Structures analogous to complexes 5a-d were discussed in our previous work [28] for two salts with the (benzoylamido)methyl ligand. The lengths of the Si(1)-O(1) bonds in these salts are 0.03-0.08 Å greater than in 5a-d, while the Si(1)-O(1) bond length varies only slightly (by 0.01-0.03 Å).…”

“…Thus, recrystallization in the air led to the formation of silyloxonium chlorides [RSO 2 -Pro-N(Me)CH 2 SiMe 2 OH 2 ]Cl 5a-f. The general sequence of transformations presented below has been proposed for describing the formation of various compounds in the hydrolysis of pentacoordinated C,O-chelate chlorosilanes A' on the basis of the structures established for the intermediate and final hydrolysis products [25,28].…”

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

“…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].…”

“…Their values in the case of the Si-O bonds prove to be less than in the pentacoordinated silicon derivatives 6-8 [14][15][16] which contain O-Si-O and O-Si-Cl(OTf) (Si…O interatomic distances close to that in 1). Comparison of the charge values calculated from AM theory with literature data for compound 5 has shown that the electron density in the O→Si-F fragments is redistributed such that the value of the silicon atom positive charge (+ 2.48 e) and negative O and F atom charges (-1.12 and -0.76 e) are decreased somewhat (Table 4).…”