The crystal and molecular structure of oxobis[triphenylsilicon(IV)]

Abstract

Crystals of oxobis(triphenylsilicon), O(SiPh3)2, are triclinic, space group P|, a = 11.301 (2), b = 9-539 (2), c = 8.771 (2) A, tt = 66.34 (1), fl = 114.35 (I), y = 114.24 (1) °, Z = 1. The structure was solved by direct methods using diffractometer data and refined by full-matrix least squares to R = 0.0374. The molecules are centrosymmetric, so that the SiOSi fragment is strictly linear: principal interatomic distances are Si-O 1.616 (1) A, and Si-C 1.864 (5) A; the central C6Si20 part of the molecule exhibits almost exact 3m symmetry.

Synthesis of Tris(pentafluoroethyl)germanes

“…This angle is more obtuse than in the nonfluorinated germanes (H 3 Ge) 2 O (126.5°), (Ph 3 Ge) 2 O (135.2(2)°) and [(CH 3 ) 3 Ge] 2 O (141°) . The Ge−O separations of 175.0(2) pm and 174.3(1) pm are also comparable with those in the trifluoromethyl derivative (172 pm), but 2–3 pm shorter than in (H 3 Ge) 2 O (176 pm), (Ph 3 Ge) 2 O (176.5(3)/176.9(3) pm), and [(CH 3 ) 3 Ge] 2 O (177.0 pm) …”

1-Hydroxy-1,1,3,3,3-pentaphenyldisiloxane, [Si2O(OH)(Ph)5], at 100 K

“…It is of considerable importance to note that while for the disiloxanes which have identical coordination environments for the Si centres the internal Si-O-Si bridge is almost linear, such as for the compounds reported by Glidewell & Liles (1978), Hönle et al (1990) and Suwińska et al (1986), the presence of distinct coordinating chemical moieties and their interaction with adjacent species in (I) induces a kink in this µ 2 -bridge. Indeed, the Si-O-Si bond angles for (I) range from 147.7 (2)° to 166.0 (2)°, values which are consistent with that reported by Wojnowski et al (2004) for [Si 2 O(H) (Ph) 5 ] (ca 163°).…”

“…centre is bound to a hydroxyl group are unknown as revealed by a search of the literature in conjunction with another of the Cambridge Structural Database (CSD, Version 5.28 with three updates -August 2007;Allen, 2002). Moreover, disiloxanes having one of the two Si centres bound to three phenyl groups are scarce, with only a handful of compounds being available in the literature (Glidewell & Liles, 1978;Hönle et al, 1990;Morosin & Harrah, 1981;Suwińska et al, 1986;Wojnowski et al, 2004). Following our on-going research toward the synthesis, structural characterization and catalytic application of novel triphenylsiloxy derivatives (Abrantes et al, 2002;Bruno et al, 2006Bruno et al, , 2007Nunes et al, 2003), we have recently isolated the unprecedented [Si 2 O(OH)(Ph) 5 ] disiloxane, in which one Si(Ph) 3 residue is bound to another Si(OH)(Ph) 2 residue via a non-linear Si-O-Si bridge.…”

Hexakis(4-methylphenoxy)disiloxane

“…In hexamethyldisiloxane the Si-O-Si angle is 148.78 and the Si-O distance is 1.626 Å (Barrow et al, 1979). In hexaphenyldisiloxane the equivalent values are 180 and 1.616 Å (Glidewell & Liles, 1978). Generally the Si-O distances in the disiloxane unit for siloxanes with six alkoxy or aryloxy substituents are shorter than for disiloxanes with six aryl or alkyl groups.…”