Studies on the Reaction between Bis((trimethylsilyl)cyclopentadienyl)niobium Trihydride and Styrene

Chemistry of η2-CS2 Niobocene Complexes: Synthesis and Characterization of New 1,3-Dithiol-2-ylidene Complexes via Reactions with Activated Alkynes

“…We have previously reported the preparation of a niobocene−hydride−styrene complex, Cp‘ 2 Nb(H)(η 2 -CH 2 CHPh), as well as an extensive study on the kinetics of the hydride−olefin insertion to give the alkyl derivative . Pursuing this work, we recently prepared the analogous niobocene−hydride−ethylene species Cp‘ 2 Nb(H)(η 2 -CH 2 CH 2 ) from the reaction of Cp‘ 2 NbCl with 1 equiv of EtMgBr, and an exhaustive variable-temperature NMR study of the hydride−olefin insertion ⇄ β-elimination equilibrium was performed…”

ansa-Niobocene Complexes: Synthesis and Characterization of Novel Complexes [Me2Si(η5-C5H4)2]NbCl2and [Me2Si(η5-C5H4)2]NbCl(RC⋮CR) (R = Me, Ph). X-ray Crystal Structure of [Me2Si(η5-C5H4)2]NbCl(MeC⋮CMe)

“…The known niobocene complexes have in most cases been restricted to conventional cyclopentadienyl ligands such as C 5 H 5 , C 5 Me 5 , or C 5 H 4 SiMe 3 , and the chemistry of the C 5 H 4 SiMe 3 niobocene complexes has been developed by our group …”

Molecular Structure of a Hydridoniobocene Complex [Nb(η5‐C5H4SiMe3)2(H)3] and Its Use as Catalyst for the Ring‐Opening Polymerization of Cyclic Esters

“…This intermediate has previously been proposed to be present in different processes. [4,6] Subsequently, a lactone monomer would coordinate to the metal center through the acyl oxygen atom. At this point, two pathways were envisaged for the opening of the lactone ring: cleavage of the bond between the oxygen atom and the alkyl carbon atom (C-O), to form carboxylate active centers, or cleavage of the bond between the oxygen atom and the acyl carbon atom [C(O)-O], resulting in the formation of alkoxide active centers.…”

“…H-Ge, H-N, H-Si, H-Sn, etc. ); [5] (3) insertion reactions of alkynes into the Nb-H bond; [6] (4) formation of acid-base adducts with Lewis acidic coinage (group 11) metal cations [7] or borane few hours to yield high-to-medium-molecular-weight polymers with medium to broad polydispersities. Polymer endgroup analysis showed that the polymerization proceeds through a coordination-insertion mechanism based on the cleavage of the ring between the oxygen atom and the acyl carbon atom.…”

“…[6] This broad reactivity makes it possible to consider 1 in a prominent place in group 5 transition metal polyhydride derivatives. Over 80 references evidence its impact in the scientific literature, describing its reactivity and special spectroscopic properties.…”