New azasilatranes: synthesis and substitution reactions

Abstract

The syntheses of new azasilatranes of the type XSi(NRCH2CH2)3N (R = H, X = OEt (2f), OPh (2g); R = Me, X = H (Sa), OEt (8b); R = SiMe3, X = H (9a)) via condensation reactions of tetraamines N(CH2CH2NHR)3 and substituted tris(dimethylamino)silanes, XSi(NMeJ3, are described. In the case of 2g, the required silane PhOSi(NMeJ3 was generated in situ from the reaction of PhOH and Si(NMez),. The chloroazasilatrane, 2h (R = H, X = Cl), whose synthesis was not feasible by the above method, was obtained by reaction of hydroazasilatrane, 2a (R = H, X = H), with CCl, in the presence of a platinum or palladium catalyst. Reaction of azasilatranes 2a and 2f with C1SiMe2R (R' = H, Me, Ph) in the presence of triethylamine affords the silyl-substituted azasilatranes XSi(N(SiMeZR')CH2CHJ3N (X = H, R' = H (9b), Me (9a), Ph (9c); X = OEt, R' = H (14a)) and XSi(N(SiMezR')CHzCHz)2NHCH2CH2N (X = OEt;R' = Me (14b), Ph (14d)), respectively, while no reaction was observed between either 2a or 2f and C1SiMe2-t-Bu. The new azasilatranes are characterized by 'H, 13C, and 29Si NMR spectroscopy, by high-resolution mass spectroscopy, and by an X-ray crystal structure determination in the case of 8b. , I , 1

Synthesis and Characterization of Group 14 1-Haloazametallatranes

“…With the same formal substitution in silatranes this leads to the opposite change in the SiϪX and SiϪN ax bond lengths, as found previously for the compounds N(CH 2 CH 2 O) 3 SiϪOEt [d(SiϪO ax ) ϭ 1.699(2) Å , d(SiϪN ax ) ϭ 2.135(2) Å ] and N(CH 2 CH 2 NMe) 3 SiϪOEt [d(SiϪO ax ) ϭ 1.658 Å , d(SiϪN ax ) ϭ 2.152 Å (averaged for two independent molecules)]. [24,25] The GeϪN ax distance in 3 [2.278(2) Å ] lies within the typical range for germatranes [2.081(5)Ϫ2. 32(1) Å ] [26,27] and clearly verifies the existence of a GeϪN transannular bond in 3.…”

Syntheses and Characterization of 1-Haloazagermatranes

“…It is worth noting that the results of these reac tions differ from those of (Me2N)3SiCl with 5 and 6 , which gave mixtures of polymers [8]. For this rea son a convenient approach to 1 -haloazasilatranes is essentially a complex multistep process [6 ].…”

Silatranes and Their Tricyclic Analogs

“…presence of a catalytic amount of a bis(phosphine)platinum or -palladium dichloride 312,409 . It should be noted that similar nucleophilic chloride substitution reactions in the tetracoordinate compound ClSi(NMe 2 ) 3 occur only at higher temperatures over prolonged reaction times 312 .…”

“…In the 2,8,9-tris-TMS derivative of 1-hydrotriazasilatrane the corresponding downfield 29 Si chemical shift is about 13 ppm, whereas in 1-ethoxytriazasilatrane bearing three Me 2 HSi groups at the N eq atoms this shift is 24 ppm 414 . This indicates a strong weakening of the Si N bond owing to steric crowding by bulky substituents attached to both the silicon and the equatorial nitrogen atoms 312,409,411,414 . However, 2,8,9-trimethyltriazasilatranes, XSi(NMeCH 2 CH 2 ) 3 N, with relatively small electronegative groups X (Cl, MeO, H 2 N and Me) are characterized by upfield shifts relative to their unsubstituted analogs 312 .…”

“…Investigations carried out by Verkade and coworkers show that the 29 Si shielding of most 1-substituted triazasilatranes are sensitive to the phase and temperature 312,409,411,414 . In this respect triazasilatranes resemble silatranes.…”