“…The Me 3 Si−C−SiMe 3 angle (110.0(1)°) is notably small relative to the corresponding angles of 123.2° in (Me 3 Si) 2 CH 2 13a and 114.4(2)° in (Me 3 Si) 3 CH,13b but it is significantly larger than that (106°) in the 1,3-disilacyclobutane 10 . In both 3 and 10 one Me group (C2 and C7 in 3 ) of each Me 3 Si points in toward the ring and the other two point outward.…”
Section: Resultsmentioning
confidence: 85%
“…In both 3 and 10 one Me group (C2 and C7 in 3 ) of each Me 3 Si points in toward the ring and the other two point outward. (There is an analogous disposition in neutral species M{C(SiMe 3 ) 3 } 2 . 1a,b ) It was concluded in the case of the disilacyclobutane 10 that widening of the Me 3 Si−C−SiMe 3 angle is inhibited by interactions between the inward-pointing Me groups and the substituents on the ring atoms (the distance between the inward-pointing Me groups and the Me groups of the SiMe 2 fragment is 3.4 Å) that force the Me 3 Si groups together, and the analogous interactions between C2 and C8 (C···C 3.27 Å) and to a lesser extent between C7 and C9 (C···C 3.67 Å) as well as between C2 and Cl2 or C7 and Cl1 (C···Cl = 3.65 and 3.64 Å, respectively) appear to do the same in 3 . However, the sum of these interactions is evidently smaller than that in 10 , allowing the Me 3 Si−C−SiMe 3 angle to be some 4° larger than in the latter.…”
The lithiation reaction of 1,3-bis(dimethylaminomethyl)-4,6-dimethyl-2-(trimethylsilylmethyl)benzene 2 with Bu n Li (2 equiv.) affords a unique aggregated species 3 of the parent lithiated compound and Bu n Li in a 2 : 2 ratio in which the bridging carbon atoms and the lithium atoms are arranged in an unprecedented ladder-type arrangement with exclusively bridging alkyl groups.
“…The Me 3 Si−C−SiMe 3 angle (110.0(1)°) is notably small relative to the corresponding angles of 123.2° in (Me 3 Si) 2 CH 2 13a and 114.4(2)° in (Me 3 Si) 3 CH,13b but it is significantly larger than that (106°) in the 1,3-disilacyclobutane 10 . In both 3 and 10 one Me group (C2 and C7 in 3 ) of each Me 3 Si points in toward the ring and the other two point outward.…”
Section: Resultsmentioning
confidence: 85%
“…In both 3 and 10 one Me group (C2 and C7 in 3 ) of each Me 3 Si points in toward the ring and the other two point outward. (There is an analogous disposition in neutral species M{C(SiMe 3 ) 3 } 2 . 1a,b ) It was concluded in the case of the disilacyclobutane 10 that widening of the Me 3 Si−C−SiMe 3 angle is inhibited by interactions between the inward-pointing Me groups and the substituents on the ring atoms (the distance between the inward-pointing Me groups and the Me groups of the SiMe 2 fragment is 3.4 Å) that force the Me 3 Si groups together, and the analogous interactions between C2 and C8 (C···C 3.27 Å) and to a lesser extent between C7 and C9 (C···C 3.67 Å) as well as between C2 and Cl2 or C7 and Cl1 (C···Cl = 3.65 and 3.64 Å, respectively) appear to do the same in 3 . However, the sum of these interactions is evidently smaller than that in 10 , allowing the Me 3 Si−C−SiMe 3 angle to be some 4° larger than in the latter.…”
The lithiation reaction of 1,3-bis(dimethylaminomethyl)-4,6-dimethyl-2-(trimethylsilylmethyl)benzene 2 with Bu n Li (2 equiv.) affords a unique aggregated species 3 of the parent lithiated compound and Bu n Li in a 2 : 2 ratio in which the bridging carbon atoms and the lithium atoms are arranged in an unprecedented ladder-type arrangement with exclusively bridging alkyl groups.
“…It is noteworthy that two Me groups of each Me 3 Si lie in toward the center of the molecule, as they do in as in the anions [M{C(SiMe 3 ) 3 } 2 ] - ,1b whereas in neutral M{C(SiMe 3 ) 3 } 2 compounds only one does so, and much further in than do those in 1 1a. This conformation in the case of 1 avoids the contacts between Me substituents in the Me 3 Si groups and those on the ring that give rise to the small Me 3 Si−C−SiMe 3 angle when the arrangement with a single inward-pointing Me from each Me 3 Si group is adopted. 1a, 3 Molecular structure of 1 .…”
Reaction of the organolithium reagent
(THF = tetrahydrofuran), 1, with LiAlH4 gave the title organotrihydridoaluminate, 2, which is unusual for an alkali metal
organotrihydridoaluminate in being monomeric and in
having the Al linked to the Li not only through hydride
but also through another of its ligands. The corresponding reaction with AlCl3 gave the title organoaluminum
dichloride. The Si−O bonds in 1 and 2 are not significantly lengthened by the O−metal coordination. The
bond from Li to the OMe in 1 oxygen is not significantly
different in length from that to the THF oxygen.
“…Method validation : Geometries of a known disilacyclobutane (cyclo‐(Me 3 Si) 2 CSiMe 2 C(SiMe 3 ) 2 SiMe 2 ) and an alkyl‐substituted disilene (( E )‐[( t Bu 2 MeSi) 2 MeSi]( t Bu 2 MeSi)SiSiMe(SiMe t Bu 2 )) with reported crystal structures were compared by using B3LYP, MPW1K and M05‐2X methods. Selected bond lengths and bond angles along with the crystal structures are shown in Tables 1 and 2 28,29…”
Section: Methodsmentioning
confidence: 99%
“…Tables 1 and 2. [28,29] From Tables 1 and 2, it is clear that the MPW1K functional fares better than either B3LYP or M05-2X functionals. Geometry optimization of the Table 1.…”
Roark and Peddle first observed that, when not trapped, Me(2)Si=SiMe(2) underwent a series of rearrangements to give two major isomeric products: 1,1-dimethyl-1,3-disilacyclobutane and 1,3-dimethyl-1,3-disilacyclobutane. The widely accepted mechanism for this rearrangement was proposed by Barton and co-workers. However, little is known about the thermodynamic or kinetic properties of this reaction, because the relevant data are limited to the product ratios of the two isomers. Our calculations predict that the product ratio is driven by kinetic control rather than thermodynamic control. We also show that new DFT functionals, such as MPW1K and M052X, produce thermochemical results comparable with CCSD(T) calculations.
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