Synthesis and characterisation of tetramethylfulvene complexes of ruthenium

Abstract

Reactions of [RuCp*Cl2]2 with dibenzoylmethane and triethylamine, in either dichloromethane or toluene, produced the complexes [RuCl(η(6)-C5Me4CH2)(PhCOCCOPh)] (1) and [RuCl3(η(6)-C5Me4CH2)][RuCp*(C6H5CH3)] (2) respectively under mild conditions. Both compounds 1 and 2 are examples of an unusual tetramethylfulvene-ruthenium structure, obtained by deprotonation of the pentamethylcyclopentadienyl ligand, and were characterised by single-crystal X-ray diffraction.

C–H Activation of Cp* Ligand Coordinated to Ruthenium Center: Synthesis and Reactivity of a Thiolate-Bridged Diruthenium Complex Featuring Fulvene-like Cp* Ligand

“…In the 1 H NMR spectrum of 2­[PF 6 ] , two sharp singlets appear at δ 1.97 and 2.15 ppm assigned to four methyl groups of the fulvene-like Cp* ligand. Remarkably, a broad signal appears at 3.79 ppm attributed to the two protons of the methylene group, which is obviously upfield-shifted compared with those of previously reported diruthenium complexes containing the fulvene-like Cp* ligand as η 2 :​η 4 -C 5 Me 4 ­CH 2 type (4.67–5.46 ppm). , This data may imply that the methylene group adopts σ-bonding interaction with the ruthenium center. Furthermore, the 13 C NMR data provide stronger evidence for the above assignment by 1 H NMR data.…”

“…In sharp contrast, late-transition metal complexes with Cp* favor the deprotonation of the ring methyl group to afford η 2 :η 4 -mode fulvene complexes . Especially in the known ruthenium fulvene complexes, most cases adopt the η 2 :η 4 coordination mode, , yet only a few cases possessing the fulvene-like Cp* ligand as an η 1 :η 5 bridge between two ruthenium centers were confirmed by X-ray diffraction analysis . Thus, clear structural characterization of dimetallic fulvene complexes is of great importance to getting deep insight into the bonding nature of fulvene group and the metal centers.…”

Increasing anti-cancer activity with longer tether lengths of group 9 Cp* complexes

“…21 In the hope to maximise the amount of metal that can reach the cancerous cells and to increase the drugs potency, the library of dimers has been tested against human colorectal adenocarcinoma (HT-29), human ovarian carcinoma (A2780) and cisplatinresistant human ovarian carcinoma (A2780cis). Due to the ability of the cyclopentadienyl hydroxyl-substituent to bind well to solid supports and with the previous evidence we have of the Cp* ligand binding to a metal centre, 23 it is proposed that this alcohol could provide stability to the metal centre if the dimer breaks apart during its interaction with cells. The preparation of the dimeric complexes 2a-2d, 3a and 3b are shown in Scheme 1.…”

Unveiling the Latent Reactivity of Cp* Ligands (C5Me5–) toward Carbon Nucleophiles on an Iridium Complex

“…However, even for the later ligand, there are increasing examples of its noninnocent character (Figure ). The methyl groups of Cp* can partake in several transformations, including, but not limited to, deprotonation by an external base or a bifunctional ligand, − hydride abstraction which tends to proceed through single-electron processes, − C–H oxidative addition to an adjacent transition metal in bimetallic structures, − or direct and reversible methyl-to-metal hydride migration, which was soon identified in early transition metals − and recently unlocked by our group as a viable process for late transition metals . In addition, the protonation of the internal ring has been exploited in proton-couple-electron-transfer (PCET) catalysis capitalizing on the reversible migration of the proton between the ring and the metal. − Moreover, several radical routes have been identified for Cp*-containing species resulting as well in ligand functionalization …”