0000000000240137
AUTHOR
Alan R. Kennedy
Titelbild: Direct CH Metalation with Chromium(II) and Iron(II): Transition-Metal Host / Benzenediide Guest Magnetic Inverse-Crown Complexes (Angew. Chem. 18/2009)
Chrom und Eisen als die neuesten Erganzungen des Konzepts der alkalimetallvermittelten Metallierung stellen J. Klett, R. E. Mulvey et al. in ihrer Zuschrift auf S. 3367 ff. vor. Das elektropositivere Natrium ist wesentlich fur die Reaktion, doch das weniger elektropositive Chrom oder Eisen ist es, das Benzol tatsachlich deprotoniert. Diese neuartige Reaktivitat kann mit einem Schachspiel verglichen werden, bei dem die Konigin (Na) dem Konig Schach bietet und der Springer (Cr, Fe) Matt setzt.
Bis[(trimethylsilyl)methyl]manganese: Structural Variations of Its Solvent-Free and TMEDA-, Pyridine-, and Dioxane-Complexed Forms
First synthesized in 1976 and recently taking on a new significance as a key precursor to heterobimetallic alkali-metal-manganese(II) complexes, bis[(trimethylsilyl)methyl] manganese has been structurally characterized by X-ray crystallography. It forms a polymeric chain structure of formula [{Mn(CH2SiMe3)(2)}(infinity)], 1, in which distorted tetrahedral, spiro Mn atoms are linked together via mu(2)-bonding alkyl ligands. The structure is notable for displaying two distinct categories of Mn-C bond lengths with a mean size differential of 0.225 angstrom and for being the first fully crystallographically characterized polymeric manganese(II) dialkyl compound. Magnetic measurements of 1 indic…
Sodium-mediated manganation: direct mono- and dimanganation of benzene and synthesis of a transition-metal inverse-crown complex.
Inside out approach: Twofold deprotonation of benzene by a sodium monoalkyl bisamido manganate(II) reagent derived from BuNa, 2,2,6,6-tetramethylpiperidine, and Mn(CH2SiMe3)2 has produced the first inverse-crown complex in which the transition-metal atoms are incorporated in the host (see X-ray structure, blue N, green Na, purple Mn). Variable-temperature magnetization measurements show that the complex is antiferromagnetic.
Assessing the reactivity of sodium alkyl-magnesiates towards quinoxaline : single electron transfer (SET) vs. nucleophilic alkylation processes
By exploring the reactivity of sodium butyl-magnesiate (1) supported by the bulky chelating silyl(bisamido) ligand {Ph2Si(NAr*)2}(2-) (Ar* = 2,6-iPr2-C6H3) towards Quinoxaline (Qx), the ability of this bimetallic system to effectively promote SET processes has been disclosed. Thus 1 executes the single-electron reduction of Qx affording complex (2) whose structure in the solid state contains two quinaxolyl radical anions Qx˙ stabilised within a dimeric magnesiate framework. Combining multinuclear NMR and EPR measurements with DFT calculations, new insights into the constitution of 2 in solution and its magnetic behaviour have been gained. Further evidence on the SET reactivity of 1 was foun…
Synthesis and Structure of a Potassium Potassiochromate: A Bis-Chromium(II) Molecule Held Together by Near-Square-Planar Potassium−Ligand Bridges
No Cr-Cr bonding is found in a new type of mixed-metal ate complex having two coordinatively unsaturated but sterically saturated bisamido-monoalkyl Cr(II) groups linked via an unusual near-square-planar-coordinated K atom in the moiety of the ate, while the cationic moiety is a separated iris-tmeda solvated second potassium atom.
Cover Picture: Direct CH Metalation with Chromium(II) and Iron(II): Transition-Metal Host / Benzenediide Guest Magnetic Inverse-Crown Complexes (Angew. Chem. Int. Ed. 18/2009)
Chromation and ferration are the latest additions to the concept of alkali-metal-mediated metalation, as described by J. Klett, R. E. Mulvey, and co-workers in their Communication on page 3317 ff. While the more electropositive sodium is essential for the reaction, it is the less electropositive chromium or iron that actually performs deprotonation of benzene. This novel reactivity can be likened to a game of chess in which the queen (Na) holds the king in check, while the knight (Cr, Fe) scores checkm(etal)ate.
Direct C-H metalation with chromium(ii) and iron(ii): transition- metal host/benzenediide guest magnetic inverse-crown complexes
Check M(etal)ate: The chessboard and the figures represent a special reaction in which different low-polarity metals can metalate arenes directly when they are brought into the right position. In a combination of queen (sodium) and knight (chromium or iron), it is possible for the knight (usually the weaker piece) to make a direct deadly hit on the king (benzene) in this game of elemental chess. Fil: Alborés, Pablo. Johannes Gutenberg Universitat Mainz; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Carrella, Luca M.. Johannes Gutenberg Universitat Mainz; Alemania Fil: Clegg, William. University of Newcastle; Reino Unido Fil: García Álvarez, Pablo. Univ…
CCDC 1431264: Experimental Crystal Structure Determination
Related Article: Zoe Livingstone, Alberto Hernán-Gómez, Sharon E. Baillie, David R. Armstrong, Luca M. Carrella, William Clegg, Ross W. Harrington, Alan R. Kennedy, Eva Rentschler, Eva Hevia|2016|Dalton Trans.|45|6175|doi:10.1039/C5DT04044B
CCDC 1431266: Experimental Crystal Structure Determination
Related Article: Zoe Livingstone, Alberto Hernán-Gómez, Sharon E. Baillie, David R. Armstrong, Luca M. Carrella, William Clegg, Ross W. Harrington, Alan R. Kennedy, Eva Rentschler, Eva Hevia|2016|Dalton Trans.|45|6175|doi:10.1039/C5DT04044B
CCDC 1431263: Experimental Crystal Structure Determination
Related Article: Zoe Livingstone, Alberto Hernán-Gómez, Sharon E. Baillie, David R. Armstrong, Luca M. Carrella, William Clegg, Ross W. Harrington, Alan R. Kennedy, Eva Rentschler, Eva Hevia|2016|Dalton Trans.|45|6175|doi:10.1039/C5DT04044B
CCDC 1431265: Experimental Crystal Structure Determination
Related Article: Zoe Livingstone, Alberto Hernán-Gómez, Sharon E. Baillie, David R. Armstrong, Luca M. Carrella, William Clegg, Ross W. Harrington, Alan R. Kennedy, Eva Rentschler, Eva Hevia|2016|Dalton Trans.|45|6175|doi:10.1039/C5DT04044B