Synthesis, structure and reactivity of sterically demanding oligosilanylmagnesium compounds

Planar three-coordinate iron(II) complexes supported by sterically demanding -Si(SiMe3)2(SiMe2tBu) ligands

Sterically demanding organosilyl ligands support the formation of coordinatively unsaturated complexes. In this study, we found that using the ligand -Si(SiMe3)2(SiMe2tBu) affords exclusively planar three-coordinate iron bis(silyl) complexes that show good catalytic performance in the hydrosilylation of acetophenone.

Metallacyclosilanes of Calcium, Yttrium, and Iron

Utilizing a choice of α,ω-oligosilanylene diides, it is possible to synthesize a number of heterocyclosilanes with heteroelements of calcium, yttrium, and iron by metathesis reactions with respective metal halides CaI₂, YCl₃, and FeBr₂. ²⁹Si NMR spectroscopic analysis of the calcacyclosilanes suggests that these compounds retain a strong oligosilanylene dianion character, which is more pronounced than in the analogous magnesacyclosilanes. As the electronegativity of calcium lies between potassium and magnesium, silyl calcium reagents should be considered as building blocks with an attractive reactivity profile. Reaction of a 1,4-oligosilanylene diide with YCl₃ gave the five-membered yttracyclosilane as an ate-complex with two chlorides still attached to the yttrium atom. Reaction of the obtained compound with two equivalents of NaCp led to another five-membered yttracyclosilane ate-complex with an yttracene fragment. When using a dianionic oligosilanylene ligand containing a siloxane unit, the siloxane oxygen acted as an additional coordination site for Ca and Y. When the same ligand was used to prepare a cyclic 1-ferra-4-oxatetrasilacyclohexane, an analogous transannular interaction between the iron and oxygen atoms is missing.

Reactions of some α,ω-oligosilanylene diides with CaI₂, YCl₃, and FeBr₂ allow convenient access to metallocyclosilanes with Ca, Y, and Fe as heteroatoms. The calcium and yttrium compounds resemble previously prepared magnesacyclosilanes, retaining a strong silanide character. The only related compounds to the described ferracyclosilanes are acyclic examples.

Crystal structure of 1,2-bis(2,2,3,3,5,5,5-heptamethyl-1,1,4,4- tetrakis(trimethylsilyl)pentasilan-1-yl)ditellane, C38H114Si18Te2

C38H114Si18Te2, triclinic, P 1 ‾ $\overline{1}$ (no. 2), a = 9.0857(18) Å, b = 9.7412(19) Å, c = 24.213(5) Å, α = 94.25(3)°, β = 95.26(3)°, γ = 117.58(3)°, V = 1874.9(6) Å3, Z = 1, R gt (F) = 0.0425, wR ref (F 2) = 0.1580, T = 296(2) K.

Diverse Reactivity of a Magnesium Silanide toward Ketones

The reactivity of a molecular magnesium silanide toward ketones displays a significant variability of outcome, resulting in adduct formation, deprotonation, dearomatisation or deoxygenation, that is dependent on the structure and...

The crystal structure of 1,6-di-tert-butyl-1,1,3,3,4,4,6,6-octamethyl-2,2,5,5-tetrakis (trimethylsilyl)hexasilane, C28H78Si10

C28H78Si10, monoclinic, Pn (no. 7), a = 21.413(4) Å, b = 9.8568(17) Å, c = 22.074(4) Å, β = 93.426(4)°, V = 4650.6(14) Å3, Z = 4, Rgt(F) = 0.0613, wRref(F2) = 0.1750, T = 296(2) K.

Cation-Triggered Stannate(II)/Stannylenoid/Stannylene Conversion

The reaction of dipotassio-tetrasilan-1,4-diide (4) with anhydrous SnCl₂ at low temperature results in the formation of a five-membered cyclic potassio chlorostannate(II) ([(18-C-6)K](1)). By careful cation exchange reactions, it was transformed into the sodium chlorostannylenoid 2 (by using Na₂ [B₁₂ Cl₁₂ ]) or into the non-stabilized cyclic bissilylstannylene 3 (through applying Li[Al(OC(CF₃ )₃ )₄ ]). The increasing Lewis basicity of the bissilylstannylene 3 was analyzed by combined methods of DFT calculations and NMR spectroscopy and substantiated by the synthesis of the corresponding iron carbonyl complexes 7 and 8 from the chlorostannate 1 and the stannylene 3, respectively.