| Abstract: | Lithium and potassium silyloxide complexes Li(OSiPh3)]n (1), K(thf)0.2 (OSiPh3)]n (3) and K(OSiMe2tBu)]n (6) were prepared by deprotonation of HOSiPh3 or HOSiMe2tBu with Li(nBu)] in hexane or KH in THF, respectively. Crystalline DME adducts Li(μ-OSiPh3)(η2-DME)]2 (2) and K4(μ3-OSiPh3)3(μ3-OSiPh2(η1-Ph))(η2-DME)]2 (μ-DME) (4) were prepared by dissolving 1 or 3, respectively, in dimethoxyethane followed by precipitation with alkane. The potassium-sequestered complexes K(18-crown-6) (OSiPh3)]2 (5) and K(18-crown-6)(OSiMe2tBu)]n (7) were prepared from 3 or 5, respectively, and one equiv. of 18-crown-6 ether. The complexes were characterized by single-crystal X-ray diffraction: Li(μ-OSiPh3)(η2-DME)]2 (2): a dimer featuring tetrahedral lithium centres linked by bridging —OSiPh3 ligands. Crystal data ( − 156°C): space group P
, a = 14.238(6), b = 15.182(7), c = 11.796(5) Å, α = 110.57(2), β = 112.02(2), γ = 63.02(1) Å, V = 2055.33 Å3, Z = 2.] K4(μ3-OSiPh3)3{μ3-OSiPh2(η1-Ph)}(η2-DME)]2(μ-DME) (4): (1) two cubanes each having every potassium vertex chemically distinct; (2) one chelating DME ligand, one DME ligand bridging between two cubanes; and (3) a K-ipso-phenyl carbon contact. Crystal data ( − 133°C): a = 14.246(4), b = 30.939(9), c = 17.981(5) Å, β = 112.33(1)° with Z = 2 in space group P21/c.] K(18-crown-6)OSiPh3]2 (5): A dimer with slipped face-to-face stacking of the quasi-planar K(18-crown-6)+ part of the two Ph3SiOK(18-crown-6) molecules; these are linked by a dative bond from one ether oxygen of a given crown to potassium contained in the other crown. Crystal data ( − 155°C): a = 9.324(2), b = 17.640(5), c = 18.148(15) Å, β = 91.60(1)° with Z = 4 in space group P21/c.] |
