Synthesis and coordination ability of a partially silicon based crown ether

Abstract

The first hybrid crown ether with two adjacent disilane fragments was synthesized through reaction of O(SiMeCl) (3) with O(CHOH). By means of DFT calculations, the complexation ability of 1,2,4,5-tetrasila[12]crown-4 (7) towards Li was determined to be considerably higher compared to [12]crown-4.

Crown Ether Complexes of Alkali‐Metal Chlorides from SO2

“…[26,28,29] Notwithstanding the previously reported structure of the chlorosulfite anion, both SÀOb onds in compound 1 show only as mall disparity,w ith values of 145.7(1) (S1ÀO5) and 144.5(2) pm (S1ÀO6). [30,31] The NMR spectroscopy measurements were performed with a1 :1 ratio of LiCl to 1,2-disila-12-crown-4 in SO 2 .Inthe 29 Si{ 1 H} NMR spectrum,compound 1 showedasignal at d = 17.1 ppm and was considerably shifted downfield compared with the free ligand (Table 2), due to the coordination of the Lewis acidic Li + .F urthermore, small amountso ft he decomposition productso f1 ,2-disila-12crown-4 were identified by using NMR spectroscopy.T hese are octamethyltetrasila-1,4-dioxane( 2 D 2 ) [40] and the open-chain glycol. [36,37] ].…”

“…[30] In an analogouss ynthetic approach, 12-crown-4 and LiCl were suspended in SO 2 to give ac lear solution within one day at ambient temperature. [30,31] The stronger coordination is supported by as lightly narrower line width in the 7 Li NMR spectrum of compound 1 (w 1/2 = 2.6 Hz) compared with compound 2 (w 1/2 = 3.4 Hz), whereas the 7 Li NMR chemical shift is identical for both compounds within the error margin of the spectrometer. Compound 2 crystallises in the tetragonal crystal system,space group P4/n,w ith two molecules per unit cell.…”

“…[26,28,29] We recently reported on hybrid crown ethers that incorporate Si 2 Me 4 bridges insteado fC 2 H 4 bridgesb etween the O crown atoms. [30,31] By using theoretical and experimental methods, the complexation ability of these ligandsw as determined to be superior to that of organic crown ethers. However,a ll reporteda lkali-metal complexes include weakly coordinating anions, such as PF 6 À or (SO 3 CF 3 ) À .…”

Alkaline Earth Metal Template (Cross‐)Coupling Reactions with Hybrid Disila‐Crown Ether Analogues

“…Given that the understanding of the Si−O bond was established in this case, research in the field of coordination chemistry with cyclosiloxanes and related ligand systems showed clearly that these effects have to be taken into account. Nonetheless, the coordination chemistry turned out to be very suitable for early Group 1 and 2 metal ions, especially within disila‐ligands, which provide more suitable bite angles than cyclosiloxanes of D n type (D=Me 2 SiO, n =6, 7) . The nature of a cation, which shall be complexed within siloxane moieties, is preferably hard .…”

Hybrid Disila-Crown Ethers as Hosts for Ammonium Cations: The O–Si–Si–O Linkage as an Acceptor for Hydrogen Bonding

“…Simple substitution of -SiMe 2 -units with -Si 2 Me 4 -units in a residuary -C 2 H 4 O-framework yields framework yields disilane-bearing ligands with a respectable coordination ability very close to their organic analogs. Alkali and alkaline earth metal salts could easily be coordinated by ligands of this class, so the coordination ability of siloxane compounds should be reconsidered [11][12][13][14][15]. However, the discussion around siloxane bonding is not restricted to the coordination of Lewis acids and includes the ability to form hydrogen bonds.…”