New aryloxybenzylidene ruthenium chelates – synthesis, reactivity and catalytic performance in ROMP

• Patrycja Żak,
• Szymon Rogalski,
• Mariusz Majchrzak,
• Maciej Kubicki and
• Cezary Pietraszuk

Beilstein J. Org. Chem. 2015, 11, 1910–1916, doi:10.3762/bjoc.11.206

• ) and a single selected norbornene derivative. Keywords: chemoactivation; latent catalysts; metathesis; ROMP; ruthenium; Introduction Olefin metathesis is nowadays one of the most important methods for the formation of carbon–carbon bonds in organic and polymer chemistry [1][2]. The availability of

• latent catalysts have been reported which permit control of initiation and efficient propagation of the reaction [3][4][5]. Among numerous examples of latent catalysts, the complexes representing the structural motif illustrated in Figure 1 have been relative poorly investigated. Known examples include

• have also been independently studied by Skowerski and Grela [10]. Phenoxybenzylidene complexes have been demonstrated to behave like latent catalysts in common testing reactions involving ring opening metathesis polymerisation (ROMP) of COD, norbornene derivative and dicyclopentadiene as well as cross

Latent ruthenium–indenylidene catalysts bearing a N-heterocyclic carbene and a bidentate picolinate ligand

• Thibault E. Schmid,
• Florian Modicom,
• Adrien Dumas,
• Etienne Borré,
• Loic Toupet,
• Olivier Baslé and
• Marc Mauduit

Beilstein J. Org. Chem. 2015, 11, 1541–1546, doi:10.3762/bjoc.11.169

• for the preparation of latent catalysts is to incorporate additional strongly binding chelating ligands to the ruthenium coordination sphere [8]. Thus, activation of the catalyst is made possible by liberation of coordination vacancy under specific conditions, such as elevated temperature or addition

• of cocatalyst. While first examples of latent catalysts were based on phosphine-containing ruthenium complexes bearing a Schiff base ligand (O–N) [9] replacement of the phosphine ligand by sterically demanding and strongly σ-donor N-heterocyclic carbenes (NHC) afforded catalysts with improved

• catalytic performance [10][11][12]. Among the different [N–O]-chelating ligands that have been previously considered [13][14][15][16][17], the pyridyl-2-carboxylate (picolinate) ligand has demonstrated its usefulness in the preparation of efficient latent catalysts based on (NHC)Ru–alkylidene complexes [18

Mechanical stability of bivalent transition metal complexes analyzed by single-molecule force spectroscopy

• Manuel Gensler,
• Christian Eidamshaus,
• Maurice Taszarek,
• Hans-Ulrich Reissig and
• Jürgen P. Rabe

Beilstein J. Org. Chem. 2015, 11, 817–827, doi:10.3762/bjoc.11.91

• latent catalysts for self-healing, mechanochroism or mechanoluminescence [14]. The thermal stability of a molecular system is inversely proportional to the thermal off-rate. However, this alone gives an incomplete image of bond rupture under physiological conditions. For example, depending on the