Search results for "Metalation"
showing 10 items of 68 documents
Synthesis of copper(II) and gold(III) bis(NHC)-pincer complexes
2016
Abstract CuII and AuIII chlorido complexes bearing the bis(NHC) carbazolide pincer ligand (bimca) were synthesized by transmetallation from the respective lithium complex [Li(bimca)] (NHC=N-heterocyclic carbene). In the case of copper, two different molecular structures were obtained depending on the copper source. With Cu(II) chloride the paramagnetic mononuclear [Cu(bimca)Cl] complex is formed and has been characterized by EPR spectroscopy and X-ray structure analysis, while copper(I) chloride leads under oxidation to a dinuclear structure in which two cationic [CuII(bimca)] moieties are bridged by one chlorido ligand. The positive charge is compensated by the [CuCl2]− counter ion, as pro…
A Molecular Electron Density Theory Study of the Role of the Copper Metalation of Azomethine Ylides in [3 + 2] Cycloaddition Reactions.
2018
The copper metalation of azomethine ylides (AYs) in [3 + 2] cycloaddition (32CA) reactions with electron-deficient ethylenes has been studied within the Molecular Electron Density Theory (MEDT) at the MPWB1K/6-311G(d,p) level, in order to shed light on the electronic effect of the metalation in the course of the reaction. Analysis of the Conceptual Density Functional Theory reactivity indices indicates that the metalation of AYs markedly enhances the nucleophilicity of these species given the anionic character of the AY framework. These 32CA reactions take place through stepwise mechanisms characterized by the formation of a molecular complex. Both nonmetalated and metalated 32CA reactions …
Versatile behavior of conjugated diynes with zirconocene reactive species
2008
Thermal decomposition of Cp2ZrPh2 in the presence of the buta-1,3-diynes RC≡CC≡CR (R = Ph, SiMe3) can lead to seven- or five-membered metallacycles. In both cases a stable benzo-fused seven-membered zirconacyclocumulene arising from a 2-fold insertion of the triple bonds of the dialkyne in the in situ generated zirconocene benzyne is formed. In the case of Me3SiC≡CC≡CSiMe3 a second minor complex is isolated: a 3-alkynyl-substituted zirconaindene arising from a β monoinsertion of one acetylenic function of the conjugated diyne in the zirconocene benzyne. No stable 2-alkynyl-substituted zirconacycle was isolated. This α monoinsertion complex is an intermediate in the exchange of the metalated…
Endohedral Mixed Aggregates: Sodium Alkoxide Cages with Organic or Inorganic Central Anions and Variable Hull.
2021
Abstract Alkali metal alkoxides are widely used in chemistry due to their Brønsted basic and nucleophilic properties. Potassium alkoxides assist alkyllithium in the metalation of hydrocarbons in Lochmann‐Schlosser‐bases. Both compounds form mixed aggregates, which enhance the thermal stability, solubility, and the basic reactivity of these mixtures. A very unusual spherical mixed alkoxy aggregate was discovered by Grützmacher et al., where a central dihydrogen phosphide anion is surrounded by a highly dynamic shell of thirteen sodium atoms and a hull of twelve tert‐butoxide groups. This structural motif can be reproduced by a reaction of trimethylsilyl compounds of methane, halogens, or pse…
Recognition of oxovanadium(V) species and its separation from other metal species through selective complexation by some acyclic ligands
1998
Acyclic molecules possessing –OH (phenoxo and alkoxo type) groups and imine or amine moieties have been developed to sense the specific preference for VO3+ species. These molecules also showed a capability to quantitatively separate oxovanadium(V) species from a reaction mixture containing metal species of V, Mo, U, Fe, and Mn ions in solution. A cascade quantitative separation of VO3+ followed by cis–MoO2+2 followed by trans –UO2+2 species is demonstrated from their mixture. Synthesis and structural details of oxo-species of vanadium molybdenum and uranium are also discussed. Factors influencing the complexation of these molecules towards oxo metal species of V, Mo and U are also addressed.
Investigation of the aqueous transmetalation of π-allylpalladium with indium salt: the use of the Pd(OAc)2–TPPTS catalyst
2005
pi-Allylpalladium complexes could be generated in water by the palladium(0) water soluble catalyst prepared in situ from palladium acetate and TPPTS. These complexes were transmetalated with indium to react with benzaldehyde. The aqueous solution of Pd(0)(TPPTS)(n) could be reused without deterioration of the catalyst in the first and second recycling. The system proved to be efficient with primary and secondary allylic substrates. The stereochemical outcome of the allylation through umpolung of allylpalladium, was also studied using models with a restraint conformation.
Synthesis of borylindenides. Complexes with iron and rhenium moieties
1999
Abstract Borylation of lithium indenide with BBrMe 2 gives the allylic 1-indenyl derivative (1-Ind)BMe 2 ( 1c ) together with the bis-allylic connected species (1-Ind) 2 BMe ( 3 ) and with BCl i Pr 2 , the allylic 1-indenyl (1-Ind)B i Pr 2 ( 1d ); the latter, with Et 3 N or Py added, rearranges to the vinylic 3-indenyl isomer (3-Ind)B i Pr 2 ( 2d ). The disubstituted indene C 9 H 6 Ind(SiMe 3 )B(O 2 C 2 Me 4 ) ( 5 ) was prepared from Li[C 9 H 6 B(O 2 C 2 Me 4 )] ( 4b ) and Me 3 SiCl. Both (1-Ind)BMe 2 and (1-Ind)B i Pr 2 readily undergo metalation when treated with LiTMP or LiInd to give pure 1-borylindenides Li(C 9 H 6 BMe 2 ) ( 4c ) and Li(C 9 H 6 B i Pr 2 ) ( 4d ). A barrier to internal …
Synthesis of borylindenides; structure of [Li(N,N′,N″-Me3-1,3,5-C3H6N3)][1-C9H6{B(NMe2)2}]
1998
Abstract Borylation of lithium indenide (LiInd) affords indenylboranes. With BCl(NMe2)2 the primary allylic 1-indenyl derivative IndB(NMe2)2 (1) readily rearranges to the more stable vinylic bis(dimethylamino)(3-indenyl)borane 1′. With BCl(OCMe2)2 the (1-indenyl)-1,3,2-dioxaborolane IndB(OCMe2)2 (2) is obtained. Both indenylboranes 1′ and 2 readily undergo metalation when treated with lithium amides such as LiTMP or LDA to give 1-borylindenides Li[C9H6B(NMe2)2] [Li(3)] and Li[C9H6B(OCMe2)2] [Li(5)] in high yields. In the systems 1′/LiInd and 2/LiInd metalation equilibria are established with equlibrium constants K≈1 (1'/LiInd) and K≈1.4 (2/LiInd). The structure of the solvate [Li(TMHT)][1-C…
The role of post-transcriptional modulators of metalloproteins in response to metal deficiencies
2021
Copper and iron proteins play a wide range of functions in living organisms. Metal assembly into metalloproteins is a complex process, where mismetalation is detrimental and energy-consuming to cells. Under metal deficiency, metal distribution is expected to reach a metalation ranking, prioritizing essential versus dispensable metalloproteins, while avoiding interferences with other metals and protecting metal-sensitive processes. In this review, we propose that posttranscriptional Modulators of Metalloprotein messenger RNA (ModMeR) are good candidates in metal prioritization under metal-limited conditions. ModMeR target high quota or redundant metalloproteins and, by adjusting their synthe…
The selective synthesis of metallanucleosides and metallanucleotides: a new tool for the functionalization of nucleic acids.
2012
Nucleobases team up: the efficient and selective preparation of purine-derived metallanucleosides, metallanucleotides, and metalladinucleotides having M-C bonds (M=Ir(III), Rh(III)) is reported for the first time. The results presented may be applied to the synthesis of functionalized nucleic acids, or DNA/RNA-modified segments.