Preparation of a Silanone through Oxygen Atom Transfer to a Stable Cyclic Silylene

Reactions of (mesityl)n(methyl)2-nsilylene complexes with pyridine-N-oxide (n = 1 and 0): formation of silanone complexes and a disiloxanyloxy complex

Silanones (OSiR2), a heavier congener of ketones (R2CO), are highly reactive species that are readily converted to oligomeric siloxane (O-SiR2)n. Coordination of silanones to the transition-metal fragments to afford silanone-coordinated complexes is a reliable silanone stabilization method. Recently, our group reported the synthesis, structures, and reactivity of dimesityl-substituted silanone complexes Cp*(OC)2M{OSiMes2(L)}(SiMe3) (M = W, Mo, L: Lewis base, Cp*: η5-C5Me5, Mes: 2,4,6-Me3C6H2). Herein, to investigate the effect of substituents on the silicon atom during the formation of a silanone complex, we demonstrated the use of Mes and smaller Me groups. As a result, the formation of Mes(Me)-substituted silanone molybdenum complex Cp*(OC)2Mo{OSiMes(Me)(py)}(SiMe3) (5b, py: pyridine) was suggested, the silanone tungsten complex Cp*(OC)2W{OSiMes(Me)(DMAP)}(SiMe3) (4a, DMAP: 4-(dimethylamino)pyridine) was obtained, and a dimethyl-substituted disiloxanyloxy(dioxo) complex Cp*(O)2W(OSiMe2OSiMe3) (9) was formed. The reaction of 4a with PMe3 proceeded via the elimination of DMAP and migration of the SiMe3 group to the oxygen atom of the silanone ligand to afford Cp*(OC)2W(SiMes(Me)OSiMe3)(PMe3) (11a). The Mo complex Cp*(OC)2Mo(SiMes(Me)OSiMe3)(PMe3) (11b) was produced by the reaction of Cp*(OC)2Mo{SiMes(Me)}(SiMe3) (7b) with pyridine-N-oxide in the presence of PMe3.

Synthesis and structure of a pyridine-stabilized silanone molybdenum complex and its reactions with PMe3 and acetone

The synthesis, structure and reactivity of a pyridine-stabilized silanone molybdenum complex are described.

Matrix Infrared Spectra of 1-Ethynyl-1H-Silole Species from Reaction of Silicon Atoms with Benzene

The reaction of silicon atoms with benzene molecule in solid neon are studied by matrix isolation infrared spectroscopy. Aided by carbon-13 and deuterium isotopic shifts as well as quantum-chemical predictions,...

Strained and Reactive Donor/Acceptor-Supported Metallasilanone

A novel stable donor/acceptor-supported Mn^I -metallasilanone 3 was synthesized. The intramolecular silanone-Mn^I interaction induces a highly strained three-membered cyclic structure, leading to an exceptionally high reactivity of 3 as a donor/acceptor complex of silanone. Indeed, metallasilanone 3 readily reacts with various small molecules such as H₂ or ethylene gas in mild conditions.

A Photoionization Study on the Detection of 1-Sila Glycolaldehyde (HSiOCH2 OH), 2-Sila Acetic Acid (H3 SiCOOH), and 1,2-Disila Acetaldehyde (HSiOSiH3 )

The identification of silicon-substituted, complex organics carrying multiple functional groups by classical infrared spectroscopy is challenging because the group frequencies of functional groups often overlap. Photoionization (PI) reflectron time-of-fight mass spectrometry (ReTOF-MS) in combination with temperature-programmed desorption (TPD) holds certain advantages because molecules are identified after sublimation from the matrix into in the gas phase based on distinct ionization energies and sublimation temperatures. In this study, we reveal the detection of 1-silaglycolaldehyde (HSiOCH₂ OH), 2-sila-acetic acid (H₃ SiCOOH), and 1,2-disila-acetaldehyde (H₃ SiSiHO)-the silicon analogues of the well-known glycolaldehyde (HCOCH₂ OH), acetic acid (H₃ CCOOH), and acetaldehyde (H₃ CCHO), in the gas phase after preparation in silane (SiH₄ )-carbon dioxide ices exposed to energetic electrons and subliming the neutral reaction products formed within the ices into the gas phase.

Cleavage of C–O and C–H bonds in ethers by a genuine SiO bond

A dialkylsilanone with a genuine SiO bond undergoes the cleavage of an ethereal C–O bond which is initiated by the coordination of the ethereal O atom to the electrophilic Si atom in the SiO bond.

Synthesis, structure, and reactivity of a pyridine-stabilized silanonetungsten complex

A pyridine-stabilized silanonetungsten complex Cp*(OC)₂W{O[double bond, length as m-dash]SiMes₂(py)}(SiMe₃) (1b, Cp* = η⁵-C₅Me₅, Mes = 2,4,6-Me₃C₆H₂, py = C₅H₅N) was obtained by the reaction of a silyl(silylene) complex Cp*(OC)₂W([double bond, length as m-dash]SiMes₂)(SiMe₃) (3) with pyridine-N-oxide in pyridine. X-ray crystal structure determination revealed that complex 1b shows a similar geometry to that observed for a previously synthesized DMAP-stabilized analogue, Cp*(OC)₂W{O[double bond, length as m-dash]SiMes₂(DMAP)}(SiMe₃) (1a, DMAP = 4-NMe₂C₆H₄N). The Si[double bond, length as m-dash]O and W-O bond distances in 1b are comparable to those observed in 1a, but the nitrogen to silicon coordination bond of 1b is slightly longer (ca. 0.05 Å) than that of 1a, indicating the weaker coordination of pyridine than that of DMAP. The reaction of 1b with excess PMe₃ in C₆D₆ at r. t. proceeded via elimination of pyridine to afford a five-membered metallacyclic carbene complex, Cp*(OC)W([double bond, length as m-dash]C(SiMe₃)OSiMes₂O)(PMe₃) (5), but that of 1a with PMe₃ did not proceed at all. Complex 5 was further transformed in C₇D₈ at 100 °C for 4 h to give a four-membered W-O-Si-O metallacyclic complex with carbyne and PMe₃ ligands, Cp*W(OSiMes₂O)([triple bond, length as m-dash]CSiMe₃)(PMe₃) (7). The structural features of complexes 1b, 5, and 7 are comparable to those suggested theoretically as intermediates in the reaction of 3 with a sulfuration reagent to afford a six-membered metallacyclic carbene complex, Cp*W(S){[double bond, length as m-dash]C(SiMe₃)C([double bond, length as m-dash]O)OSiMes₂S} (6), indicating that complex 1b and the theoretically proposed silanethione complex are transformed via a similar reaction pathway.

Donor-acceptor-stabilised germanium analogues of acid chloride, ester, and acyl pyrrole compounds: synthesis and reactivity

Germaacid chloride, germaester, and N-germaacyl pyrrole compounds were not known previously. Therefore, donor-acceptor-stabilised germaacid chloride (i-Bu)₂ATIGe(O)(Cl) → B(C₆F₅)₃ (1), germaester (i-Bu)₂ATIGe(O)(OSiPh₃) → B(C₆F₅)₃ (2), and N-germaacyl pyrrole (i-Bu)₂ATIGe(O)(NC₄H₄) → B(C₆F₅)₃ (3) compounds, with Cl-Ge[double bond, length as m-dash]O, Ph₃SiO-Ge[double bond, length as m-dash]O, and C₄H₄N-Ge[double bond, length as m-dash]O moieties, respectively, are reported here. Germaacid chloride 1 reacts with PhCCLi, KOt-Bu, and RLi (R = Ph, Me) to afford donor-acceptor-stabilised germaynone (i-Bu)₂ATIGe(O)(CCPh) → B(C₆F₅)₃ (4), germaester (i-Bu)₂ATIGe(O)(Ot-Bu) → B(C₆F₅)₃ (5), and germanone (i-Bu)₂ATIGe(O)(R) → B(C₆F₅)₃ (R = Ph 6, Me 7) compounds, respectively. Interconversion between a germaester and a germaacid chloride is achieved; reaction of germaesters 2 and 5 with TMSCl gave germaacid chloride 1, and 1 reacted with Ph₃SiOLi and KOt-Bu to produce germaesters 2 and 5. Reaction of N-germaacyl pyrrole 3 with thiophenol produced a donor-acceptor-stabilised germaacyl thioester (i-Bu)₂ATIGe(O)(SPh) → B(C₆F₅)₃ (10). Furthermore, the attempted syntheses of germaamides and germacarboxylic acids are also discussed.

Bis(trialkylsilyl) peroxides as alkylating agents in the copper-catalyzed selective mono-N-alkylation of primary amides

The copper-catalyzed selective mono-N-alkylation of primary amides with bis(trialkylsilyl) peroxides as alkylating agents was reported.

Synthesis and DFT Study of a Diphenylsilanone-Bridged Dimolybdenum Complex

Reaction of the 30-electron benzylidyne complex [Mo2 Cp2 (μ-CPh)(μ-PCy2 )(μ-CO)] with excess Ph2 SiH2 under visible-UV irradiation yields the silylene-bridged complex [Mo2 Cp2 (μ-CPh)(μ-PCy2 )(μ-SiPh2 )]. This compound undergoes selective oxidation with O2 to give the unsaturated complex [Mo2 Cp2 (μ-CPh)(μ-PCy2 )(μ-κ(1) :κ(1) -OSiPh2 )], which contains an unprecedented bridging diphenylsilanone ligand, as confirmed by X-ray diffraction analysis and DFT calculations. The bonding within the central Mo2 SiO ring of this complex approaches the extreme description of a dimetallacyclosiloxane according to the relevant solid-state bond lengths and theoretical calculations.