A new set of nickelacyclic carboxylates (“nickelalactones”) containing pyridine as supporting ligand: synthesis, structures and application in C–C– and C–S– linkage reactions

Nickelacyclic Carboxylates with Pyridine‐Based Ligand Sets – From Mononuclear Complexes to Supramolecular Architectures by Hydrogen Bonding

“…Similar to the recently reported synthesis of [Ni(C 2 H 4 -COO)(py) 2 ] [14] it is possible to derive the corresponding 4-picoline complex by evaporating a solution of [Ni(C 2 H 4 -COO)(tmeda)] (1) [20] in 4-picoline to dryness. The remaining residue was identified as [Ni(C 2 H 4 COO)(4-Me-py) 2 ] (2) by NMR measurement and elemental analysis.…”

“…Additionally, these amino-substituted nickelacyclic carboxylates should allow pre-coordination of organic substrates containing hydrogen-bond acceptors like carbonyl functions and therefore may offer enhanced reactivity or selectivity of such organonickel compounds in organic synthesis. [20,14] [(tBu)(Me) 2 Si-aminomethyl]pyridine was prepared in analogy to a known procedure but further purified by distillation in a vacuum to remove residual LiCl. [22] 4-(Dimethylamino)pyridine and 4-aminopyridine were purchased from Aldrich and used without further purification.…”

“…[13] We recently reported the preparation of pyridine-stabilized nickelacyclic carboxylates, which proved to be useful starting compounds for ligand-exchange reactions. [14] By utilizing these complexes it was possible to greatly enhance the ligand pool available for stabilizing nickelacyclic carboxylates. Besides N-heterocyclic carbenes [15] and 1,2-diiminoethane derivatives, [16] monodentate phosphane li-gands can be introduced in nickelacyclic carboxylates, resulting in the ligand-driven self-assembly to oligomeric derivatives by formation of Ni-O-C=O-Ni or Ni-O-Ni bridges.…”

Umwandlung von Kohlendioxid mit Übergangsmetall‐Homogenkatalysatoren: eine molekulare Lösung für ein globales Problem?

“…Sowohl das dcpe-Ferracyclopropionat als auch das PMe 3 -Oxaferracyclobutanon kçnnen mit CO 2 zu Dicarboxylaten weiterreagieren. [30] Die komplexvermittelte oxidative Kupplung von CO 2 [41] oder Pyridin [42] synthetisiert, jedoch mit unbefriedigenden Ergebnissen. [43] 2007 präsentierten Buntine und Mitarbeiter DFT-Rechnungen, denen zufolge die Bildung von Nickelhydriden aus der b-H-Eliminierung von Nickelalactonen wegen der Ringspannung und des weiten Abstandes von b-H-Atomen zum Nickelzentrum energetisch ungünstig ist.…”

Mild and highly efficient transformation of thiols to symmetrical disulfides using urea–hydrogen peroxide catalyzed by a Mn(III)–salen complex

“…Disulfides are of interest compounds in organic synthesis [1][2][3][4][5][6] and play significant roles in biological [7] and chemical processes [8][9]. Being readily available form commercial suppliers and easily synthesized, thiols serve as the most frequently employed precursors to disulfides.…”