Thermodynamics and high-pressure kinetics of a fast carbon dioxide fixation reaction by a (2,6-pyridinedicarboxamidato-hydroxo)nickel(II) complex

The previously reported carbon dioxide fixation reaction by the planar terminal hydroxide complex [Ni(pyN2Me2)(OH)]1− in DMF has been further characterized by determination of the equilibrium constants K298eq = 2.4 ± 0.2 × 105 M−1 and K223eq = 1.3 ± 0.1 × 107 M−1, as well as the volume of activation for the CO2 binding (ΔV≠223on = −21 ± 3 cm3 mol−1) and back decarboxylation (ΔV≠223off = −13 ± 1 cm3 mol−1) by high-pressure kinetics. The data are consistent with an earlier DFT computation, including the probable nature of the transition state, and support designating the reaction as one of the most completely investigated carbon dioxide fixation reactions of any type

Thermodynamics and high-pressure kinetics of a fast carbon dioxide fixation reaction by a (2,6-pyridinedicarboxamidato-hydroxo)nickel(II) complex

The previously reported carbon dioxide fixation reaction by the planar terminal hydroxide complex [Ni(pyN2Me2)(OH)]1− in DMF has been further characterized by determination of the equilibrium constants K298eq = 2.4 ± 0.2 × 105 M−1 and K223eq = 1.3 ± 0.1 × 107 M−1, as well as the volume of activation for the CO2 binding (ΔV≠223on = −21 ± 3 cm3 mol−1) and back decarboxylation (ΔV≠223off = −13 ± 1 cm3 mol−1) by high-pressure kinetics. The data are consistent with an earlier DFT computation, including the probable nature of the transition state, and support designating the reaction as one of the most completely investigated carbon dioxide fixation reactions of any type

Encapsulation of Metalloporphyrins in a Self-Assembled Cubic M8L6 Cage: A New Molecular Flask for Cobalt-Porphyrin-Catalysed Radical-Type Reactions

The synthesis of a new, cubic M8L6 cage is described. This new assembly was characterised by using NMR spectroscopy, DOSY, TGA, MS, and molecular modelling techniques. Interestingly, the enlarged cavity size of this new supramolecular assembly allows the selective encapsulation of tetra(4-pyridyl)metalloporphyrins (M-II(TPyP), M=Zn, Co). The obtained encapsulated cobalt-porphyrin embedded in the cubic zinc-porphyrin assembly is the first example of a catalytically active encapsulated transition-metal complex in a cubic M8L6 cage. The substrate accessibility of this system was demonstrated through radical-trapping experiments, and its catalytic activity was demonstrated in two different radical-type transformations. The reactivity of the encapsulated Co-II(TPyP) complex is significantly increased compared to free Co-II(TPyP) and other cobalt-porphyrin complexes. The reactions catalysed by this system are the first examples of cobalt-porphyrin-catalysed radical-type transformations involving diazo compounds which occur inside a supramolecular cage

Dramatically Accelerated Selective Oxygen-Atom Transfer by a Nonheme Iron(IV)-Oxo Complex: Tuning of the First and Second Coordination Spheres

The new ligand N3Py(amide)SR and its Fe(II) complex [Fe(II)(N3Py(amide)SR)](BF4)2 (1) are described. Reaction of 1 with PhIO at -40 °C gives metastable [Fe(IV)(O)(N3Py(amide)SR)](2+) (2), containing a sulfide ligand and a single amide H-bond donor in proximity to the terminal oxo group. Direct evidence for H-bonding is seen in a structural analogue, [Fe(II)(Cl)(N3Py(amide)SR)](BF4)2 (3). Complex 2 exhibits rapid O-atom transfer (OAT) toward external sulfide substrates, but no intramolecular OAT. However, direct S-oxygenation does occur in the reaction of 1 with mCPBA, yielding sulfoxide-ligated [Fe(II)(N3Py(amide)S(O)R)](BF4)2 (4). Catalytic OAT with 1 was also observed

Stereospecific carbene polymerization with oxygenated Rh(diene) species

Breath-taking activation: Stereoregular carbene polymerization proceeds via cationic [(allyl)RhIII-polymeryl]+ species. These are most efficiently generated by oxygenation of the [(diene)RhI] precatalysts, which involves an unusual rearrangement of 2-rhodaoxetane intermediates. This discovery gives detailed insight in the reaction mechanism