Unusual conformations of isoelectronic (SiO)4, (SiOSiN)2 and (SiN)4 rings

1-Oxa-3-aza-2,4-disilacyclobutanes − Synthesis, X-ray Structures, and Reactivity

“…[9,10] Lithium derivatives of type I are found to be very stable; they can be distilled without decomposition. [11] However, they are direct precursors of four-membered (SiϪOϪSiϪN) rings when catalytic amounts (1Ϫ5%) of fluorosilanes are added to a solution of the lithium compounds.…”

Ammonolysis of 1,2‐Bis[dichloro(methyl)silyl]ethane. On the Structure of 1,3,6,8‐Tetramethyl‐2,7,11,12‐tetraaza‐1,3,6,8‐tetrasila‐tricyclo[6.2.1.13,6]‐dodecane

“…The normal at the planes Si1, N1, Si2A, N2A (or N2, Si2, N1A, Si1A) and at N2, Si1, N2A, Si1 enclose an angle of 120.2° and the Si–N bond lengths in 1 are in the expected range (171–173 pm). For example the corresponding values in N(SiMe 3 ) 3 , N(SiH 3 ) 3 and HNMe(SiMe 3 ) are 175.5 29, 172.9 20 and 172.0 pm 30, whereas in the cyclic compounds [ R 2 SiN R ′] 4 with R = Me, R ′ = H 172.0 (bowl) and 173.0 (chair) 28, R = R ′ = Me 173.0 (bowl) 31 and R = i Pr, R ′ = H 171.4 pm (bowl) 32 were found. The significant shortening of the Si–N bond lengths in comparison with the sum of the covalent radii (191 pm 33) is typical of aminosilanes 34.…”

Si−H-Functionalized Ferriodisiloxanes: Synthesis from the Ferriodimethylsilanols C5R5(OC)2Fe−SiMe2OH (R = H, Me) and Photoinduced Transformation into µ2-Disiloxanediyl-Bridged Dinuclear Iron Complexes

“…[32] The iron atoms show a pseudo-square-pyramidal arrangement, with the Cp ligand in the apical position and the two Si atoms at the tetragonal base arranged trans to each other [Si1ϪFe1ϪSi2 109.43 (4) For (R 2 SiO) 4 rings a variety of conformations (C i chair, C 2 boat, S 4 boat) has been found in the solid state, [32] with (tBu 2 SiOSiMe 2 O) 2 representing an exception, due to the planarity of the ring. [56] The eight-membered Fe 2 Si 4 O 2 arrangement of 6b adopts a chair conformation with both metal components bent in opposite directions out of the plane defined by the four silicon atoms (Figure 3). An identical situation holds for the oxygen atoms.…”