Reactivity of bis(η6-arene) derivatives of titanium, vanadium and niobium with fulvenes bearing electron-withdrawing substituents

Synthesis and characterization of chromium(I) bis(η6-toluene) derivatives containing sterically demanding anions

“…In the solid state, the aromatic ligands are locked in place by the surrounding anions and the cation adopts the conformation dictated by the energetics of the lattice formation: on going from [dbcp] À to the less sterically demanding [pcmcp] À the cation adopts both the cis-and a pseudo trans-disposition of the methyl groups. Finally, the results reported in this paper have to be considered complementary to those obtained with the bis(arene) derivatives of titanium(0), vanadium(0) and niobium(0) which react with the fulvene species of Scheme 1 with oxidation of the metal and loss of the aromatic ligands to give O,O 0 -coordination compounds of vanadium(II) or titanium(III) and niobium(III) [33]. This trend is probably related to both the higher aptitude to oxidation with consequent loss of the p-acid arene ligands (the Cr(0) !…”

Highly Selective Ortho‐Directed Dicarboxylation of Cyclopentadiene by Methylcarbonates and CO2 or COS – First Insight into Co‐ordination Chemistry of New Ambident Ligands

“…The synthesized [Cat] 2 [C 5 H 3 (COX) 2 H] salts 1 a – d and 2 a – c can be used as ambident ligands bearing two coordination sites – the soft carbanionic backbone [41,42,60] and the hard “acac‐related” O,O‐ chelating bidentate two carboxyl groups [41] . Such coordination of biscarboxylated cyclopentadienes or higher carboxylated PCCPs as chelating ligand motif is unexplored.…”

“…Due to the incorporation of electron‐withdrawing ring substituents they approach the acidity of HCl(aq) [37] . These pentacarboxycyclopentadienes (PCCPs) have been used as cyclopentadienyl‐type ligands [40–42] in coordination chemistry. They served as a novel class of enantioselective Brønsted acid catalysts [43] and Lewis acids [44] .…”

π-Coordinated arene metal complexes and catalysis

“…1 This section seeks to summarise recent examples from groups 6-8 and discuss {(η 6 -arene)M} complexes from groups 9 and 10. Although π-arene complexes of group 4 and 5 metals exist, [2][3][4][5][6][7][8][9] in the interest of brevity, this review will not cover these species in detail. To the authors' knowledge, there have been no reports of π-arene complexes of the coinage metals Ag and Au, however, a very recent contribution describes the first synthesis and isolation of {(η 6 -arene)Cu I } complexes of benzene and hexamethylbenzene, stabilised by a silylene ligand.…”