Alkane Metathesis with the Tantalum Methylidene [(≡SiO)Ta(═CH₂)Me₂]/[(≡SiO)₂Ta(═CH₂)Me] Generated from Well-Defined Surface Organometallic Complex [(≡SiO)Ta^VMe₄]

Abstract

By grafting TaMe5 on Aerosil700, a stable, well-defined, silica-supported tetramethyl tantalum(V) complex, [(≡SiO)TaMe4], is obtained on the silica surface. After thermal treatment at 150 °C, the complex is transformed into two surface tantalum methylidenes, [(≡SiO)2Ta(═CH2)Me] and [(≡SiO)Ta(═CH2)Me2], which are active in alkane metathesis and comparable to the previously reported [(≡SiO)2TaHx]. Here we present the first experimental study to isolate and identify a surface tantalum carbene as the intermediate in alkane metathesis. A systematic experimental study reveals a new reasonable pathway for this reaction.

Single site silica supported tetramethyl niobium by the SOMC strategy: synthesis, characterization and structure–activity relationship in the ethylene oligomerization reaction

“…Suface organometallic chemistry (SOMC) allows isolation, characterizion and study of the catalytic properties of those organometallic compounds (Surface OrganoMetallic Fragments, SOMF) which are highly unstable at room temperature or below. [11][12][13] In addition, SOMC based catalysts are easily separated from the products which is highly preferable. [14][15][16] Another major advantage of SOMC based catalysts is the ability to isolate reaction intermediates, propose reaction mechanisms, and study the structure activity relationship.…”

Synthesis and reactivity of Li and TaMe3 complexes supported by N,N′-bis(2,6-diisopropylphenyl)-o-phenylenediamido ligands

“…6 Ta methyls have also been grafted onto silica supports for use as well-defined heterogeneous precatalysts for ethylene trimerization 7 and alkane metathesis. 8 Multiple reports have emerged on the synthesis and reactivity of tantalum complexes of diamido ligands with pendant neutral donor functionalities. Fryzuk's work with diamidophosphine 5,[9][10][11][12][13][14][15][16][17][18][19] and diamidodiphosphine [20][21][22] ligand families is very well-represented.…”

Solid‐State NMR and DFT Studies on the Formation of Well‐Defined Silica‐Supported Tantallaaziridines: From Synthesis to Catalytic Application

“…[12] Molecular metallaaziridine complexes have been documented for two decades, but have only recently been explored within the framework of surfaceo rganometallic chemistry.T his field has as olid track record in isolating and identifying transition metal catalysts with unusual reactivities. [13] Recent advances include the isolation of single-site, well-defined surfaces peciess uch as [(Si-O-Ta (=CH 2 )Me 2 ]( an active catalystf or alkane metathesis) [14] and [Si-O-Zr(HNMe 2 )(h 2 NMeCH 2 )(NMe 2 )]. [15] The reactivityo ft he latter species was harnessed, and the surfacem onohydride [Si-O-Zr(HNMe 2 )(NMe 2 ) 2 H] was selectively isolated and shown to be an active catalyst for alkene hydrogenation.…”