[W(CO)(dppe)₂] Cumulenylidene and Acetylide Complexes Accessed via Stannylated Acetylenes and Butadiynes

Abstract

The tungsten butatrienylidenes [cis-W(CO)(dppe) 2 {CdCdCdC(R)(SnMe 3 )}] (R=SnMe 3 (2) and SiMe 3 (3); dppe = 1,2-bis(diphenylphosphinoethane)) were prepared from the reactions of [trans-W(CO)(N 2 )(dppe) 2 ] (1) and the respective butadiynes displaying a 1,4-shift of the respective SnMe 3 groups along the butadiyne chains. Stannyl deprotection of 2 with NBu 4 F 3 3H 2 O led to the anionic butadiyne derivative [trans-W(CO)(dppe) 2 (CtCCtCH)][NBu 4 ] (10). The reaction of 1 with stannylated acetylenes gave the vinylidene derivatives [cis-W(CO)(dppe) 2 {CdC(SnMe 3 )(R)}] (R=Ph (5) or SnMe 3 (6)), which lost a SnMe 3 group, yielding W(I) acetylides of the type [trans-W(CO)(dppe) 2 -(CtCR)] (R=Ph (7), SnMe 3 (8), and SiMe 3 (9)). They were studied by cyclic voltammetry and EPR spectroscopy.

Stepwise Construction of an Iron-Substituted Rigid-Rod Molecular Wire: Targeting a Tetraferra–Tetracosa–Decayne

“…As shown in Scheme 1, transmetalating two units of the mononuclear precursor trans-Fe(depe) 2 I 2 44 (1) with Me 3 Sn CCCCSnMe 3 45 in refluxing tetrahydrofuran gave the butadiyne-bridged dinuclear complex 2 as a burgundy red solid of low solubility in good yield (88%). The 31 P{ 1 H} NMR of 2 showed a singlet at 69.8 ppm for the eight equivalent P atoms, which is shifted slightly downfield compared to the mononuclear precursor (δ = 65.9 ppm).…”

Migration of Condensed Aromatic Hydrocarbons During Alkyne‐Vinylidene Rearrangements

“…However, whilst metal‐mediated alkyne‐vinylidene isomerizations are now well‐known examples of 1,2‐rearrangements, the alkyne substrate scope remains limited to para ‐functionalized substrates, and steric congestion has only been explored for a few ortho‐ NHR and ortho ‐CH=CH 2 substitued examples (Figure 1a). Although 1,2‐disubstituted hetero‐acetylenes PhC≡CE bearing main‐group moieties of increasing steric demand (E=Bpin<SiR 3 <SO 2 R<SnR 3 ) have been successfully converted into vinylidene complexes (Figure 1b), [11,12,13,14,15,16,17,18,19,20] the asymmetric substitution pattern complicates identification of the migrating group ( vide supra ) and underlying mechanistic details.…”

“… Sterically demanding substrates in alkyne/ vinylidene rearrangements: a) mono ortho amide [9] and vinyl [10] tolanes; b) heteroatomic groups ( Bpin : Ir; [11] SiMe 3 : Ru, [12] Rh, Ir, [13] Os; [14] SiPh 3 : Rh; [15] SO 2 Ph : Mo; [16] Ru; [17] SnMe 3 : Mn [18] W; [19] SnPh 3 : Rh [20] ); c) 3D (non‐planar) substrates. Herein: d) di‐ and tetra‐ ortho ‐substitution.…”

Stannylenes: Structures, Electron Affinities, Ionization Energies, and Singlet–Triplet Gaps of SnX2/SnXY and XSnR/SnR2/RSnR′ Species (X; Y = H, F, Cl, Br, I, and R; R′ = CH3, SiH3, GeH3, SnH3)

“…The ultraprecision construction of semiconductors 1−3 and the exploration of stannylenes 4,5 with novel properties for microelectronic engineering 6 are important areas of research. These species play significant roles in chemical vapor deposition (CVD) processes.…”

“…The ultraprecision construction of semiconductors − and the exploration of stannylenes , with novel properties for microelectronic engineering are important areas of research. These species play significant roles in chemical vapor deposition (CVD) processes. , Stannylenes have also proved to be important in understanding new organometallic chemistry, a pivotal contribution being Sekiguchi’s work , on structure and bonding of distannenes.…”