η5,η1-Coordinated cyclopentadienyl transition metal complexes featuring σ-metal–carbon ansa bridges

Synthesis and characterization of novel cyclopentadienyl molybdenum imidazo[1,5-a]pyridine-3-ylidene complexes and their application in olefin epoxidation catalysis

“…TG-MS analysis confirms the stability of 1 at ambient temperature, as decomposition starts at 241.5°C by loss of a carbonyl ligand relating to a MS signal with 28 m/z (CO). Complex 1 has been characterized by IR, NMR ( 1 H, 13 and significantly stronger r-donor properties than the imidazolylidenes originally described by Hor, Zhao et al (C: 1860, 1956 cm À1 ) [21].…”

“…Compound 2 is highly soluble in polar solvents such as methanol and acetonitrile, but poorly soluble in chloroform. The ionic complex 2 has been characterized by IR, NMR ( 1 H, 13 À as a counterion. The appearance of a signal in 1 H NMR at 1.96 ppm from acetonitrile, the elemental analysis and the MS spectrum indicate that one solvent molecule coordinates to molybdenum, as observed for D (Fig.…”

“…To date, a number of g 5 -cyclopentadienyl tricarbonyl molybdenum complexes with different ligand spheres have been investigated as pre-catalysts in olefin epoxidation [2,[9][10][11][12][13][14][15]. Of these, the ansa-bridged cyclopentadienyl Mo complex [{g 5 -C 5 H 4 [CH(CH 2 ) 3 ]-g 1 -CH}Mo(CO) 3 ] [16] shows the highest TOF in ciscyclooctene epoxidation, namely 11,800 h À1 in organic solvents [17] and TOFs up to 44,000 h À1 in room temperature ionic liquids (RTILs) [18].…”

Synthesis and Structure of Trisilane‐1,3‐diyl ansa Half‐Sandwich Complexes of Group 6 Metals

“…In contrast to carbon-bridged ansa half-sandwich complexes, which have been intensively studied over the past decades, [1] the knowledge of other main-group bridging moieties is rather limited, despite their similar reactivity to [n]metallocenophanes, which have found widespread applications in catalysis, particularly for the polymerization of olefins. [2] Their propensity to undergo substitution, insertion and ring-opening polymerisation reactions are also of considerable interest.…”

Insertion of Chalcogens and Bis(tert-butylisonitrile)palladium(0) into a Strained Ruthenium Half-sandwich Complex

“…In contrast to this rich field, related ansa half-sandwich complexes are still under-represented. While many efforts have been based on carbon as the bridging moiety [28], we and others recently focused on the synthesis of ansa half-sandwich complexes with heteroatomic bridging moieties in view of their use as precursors for ring-opening polymerization including a series of complexes with group 6, 8 and 10 metals and heavier group 14 elements as bridging moieties [29 -40]. Synthetic strategies for such complexes generally follow two routes.…”