Search results for "rr"
showing 10 items of 41198 documents
A hybrid magnet with coexistence of ferromagnetism and photoinduced Fe(iii) spin-crossover
2011
International audience; The insertion of a [Fe(sal2-trien)]+ complex cation into a 2D oxalate network results in a hybrid magnet with coexistence of magnetic ordering and photoinduced spin-crossover (LIESST effect) in compound [FeIII(sal2-trien)][MnIICrIII(ox)3]*(CH2Cl2) (1). A complete photomagnetic characterization together with a detailed structural analysis of the low-spin (LS) and high-spin (HS) structures of 1 is presented in order to understand such unusual behavior. This very rare and unexpected property in a FeIII spin-crossover complex, has been attributed to the strong distortion exhibited by the metastable HS state. Furthermore, 1 has shown that, in contrast to what has been pre…
Oxotris(oxalate)niobate(V): An oxalate delivery agent in the design of building blocks
2018
This work concerns the oxalate delivery process that occurs when using (NH4)3[NbO(C2O4)3]·6H2O as a suitable oxalate source in the synthesis of two compounds, [Cu(dmphen)(C2O4)(H2O)] (1) and [{Cu(dmphen)(CH3OH)}2(μ-C2O4)](ClO4)2 (2) (dmphen = 2,9-dimethyl-1,10-phenanthroline). {[Fe{HB(pz)3}(CN)2(μ-CN)]2[{Cu(dmphen)}2(μ-C2O4)]}∙xCH3OH (3) (2.0 ≤ x ≤ 2.4) was obtained by reacting 2 and PPh4[Fe{HB(pz)3}(CN)3]∙H2O [ = tetraphenylphosphonium and = tris(pyrazolyl)borate]. Crystal structures of 1–3 have been determined by single-crystal X-ray diffraction experiments: 1 is a mononuclear trigonal bipyramidal copper(II) species, 2 is a centrosymmetric oxalato-bridged dicopper(II) complex, and 3 consi…
Strecker reactions with hexacyanoferrates as non-toxic cyanide sources
2019
The Strecker reaction is the most widely applied three-component reaction. Although highly useful for the preparation of α-amino nitriles, α-amino acids, hydantoins and numerous related compounds, the need for the application of toxic sources of HCN limits its application in both academic and industrial settings. Here, we present a facile protocol for Strecker reactions using a mixture of potassium ferri- and ferrocyanides as a non-toxic substitute.
Synthesis, crystal structures and magnetic properties of picolinate-bridged copper(II) chains
2018
The paper reports the synthesis, crystal structures, and magnetic properties of two copper(II) coordination polymers, Cu2(L1)4 (1) and Cu3(L2)6 (2), based on rigid ethynylene-bridged ditopic ligands containing one picolinate subunit (L1 = 5-(pyridin-3-ylethynyl)picolinate anion; L2 = 5-((4-(methoxycarbonyl)phenyl)ethynyl)picolinate anion). Both 1 and 2 have a chain structure. In 1, the repeating unit in the chain is a doubly bridged picolinate dicopper(II) complex, whereas 2 is built upon trimeric units where the Cu2+ ions are also connected by double picolinate bridges. Both compounds exhibit antiferromagnetic interactions in the solid state. The magnetic properties of 1 and 2 were analyze…
Solution Conformation and Self‐Assembly of Ferrocenyl(thio)ureas
2016
Conformations and (dis)assembly processes of ureas and thioureas are of fundamental importance in supramolecular chemistry, anion binding, or crystal engineering, both in solution and in the solid state. For sensing and switching processes a redox-active unit, such as the ferrocene/ferrocenium couple, is especially suitable. Here, self-assembly processes of redox-active ferrocenyl(thio)ureas FcNHC(X)NHR [X = O, R = Fc (1), Ph (2), 1-naphthyl (3), Me (4), Et (5); X = S, R = Fc (6), 1-anthracenyl (7)] through hydrogen bonds – both in the solid state and in THF and CH2Cl2 solution – are reported. Special emphasis is placed on the impact of nonclassical intramolecular NH···Fe hydrogen bonds in …
Synthesis, Crystal Structure and Magnetic Properties of Heteropolynuclear Re IV M II Complexes Based on the Robust [ReCl 5 (pyzCOO)] 2– Unit (pyzCOO …
2016
The syntheses, crystal structures and magnetic properties of four rhenium(IV) compounds of formulae NBu4[ReCl5(pyzCOOH)]·H2O (1), [ReCl5(µ-pyzCOO)M(dmphen)2]·2CH3CN [M = Ni (2) and Co (3)] and {[ReCl5(µ3-pyzCOO)]2Mn2(dmphen)3}n (4) (NBu4 = tetra-n-butylammonium cation, pyzCOOH = 2-pyrazinecarboxylic acid, dmphen = 2,9-dimethyl-1,10-phenanthroline) are reported herein. Compound 1 was obtained by the reaction of NBu4[ReCl5(dmf)] (dmf = dimethylformamide) with pyzCOOH in acetone, whereas the other complexes were obtained by the reaction of 1 with M(ClO4)2·6H2O [M = Ni (2), Co (3), Mn (4)] and dmphen in acetonitrile. Complex 1 is a mononuclear compound, 2 and 3 are neutral heterodinuclear compl…
Selective Metal–Ligand Bond-Breaking Driven by Weak Intermolecular Interactions: From Metamagnetic Mn(III)-Monomer to Hexacyanoferrate(II)-Bridged Me…
2020
Metal–ligand coordination interactions are usually much stronger than weak intermolecular interactions. Nevertheless, here, we show experimental evidence and theoretical confirmation of a very rare...
Highly Stable Neutral and Positively Charged Dicarbollide Sandwich Complexes
2005
Novel sandwich metallacarboranes commo-[3,3'-Ni(8-SMe2-1,2-C2B9H10)2] (1), commo-[3,3'-Co(8-SMe2-1,2-C2B9H10)2]+ (2+), commo-[3,3'-Ru(8-SMe2-1,2-C2B9H10)2] (4) and commo-[3,3'-Fe(8-SMe2-1,2-C2B9H10)2] (5) have been prepared by reaction of [10-SMe2-7,8-nido-C2B9H10]- with NiCl2 x 6 H2O, CoCl2, [RuCl2(dmso)4] and [FeCl2(dppe)], respectively. Reduction of 2+ with metallic Zn leads to the neutral and isolable complex commo-[3,3'-Co(8-SMe2-1,2-C2B9H10)2] (3). Theoretical calculations using the ZINDO/1 semiempirical method show three energy minima for complexes 1-3 and 5 that agree with the presence of three different rotamers in solution at low temperature, while four relative energy minima have…
Palladium Catalyzed [3+2] Cycloaddition of Vinyl Aziridine and Indane-1,3-diones: Diastereo- and Enantioselective Access to Spiro-Pyrrolidines
2020
A mild and efficient palladium-catalyzed [3+2] cycloaddition of vinylaziridine and indane-1,3-diones has been realized. The resulting spiro-pyrrolidines were provided in excellent yields and, with the introduction of the leucine-derived phosphine ligand, moderate to good enantio- and diastereoselectivities.
Design of bimetallic magnetic chains based on oxalate complexes: towards single chain magnets
2009
We describe the synthesis, structure and magnetic characterization of several oxalate-based bimetallic 1D systems. We will exemplify how by suitable choice of the molecular building blocks and strict control of their arrangement in the solid state, the magnetic properties of these low-dimensional materials can be tuned to finally obtain bimetallic oxalate chains behaving as single-chain magnets (SCM). First, we will focus on compounds [K(18-crown-6)][MII(bpy)Cr(ox)3] (1, 2; MII = Mn, Co; bpy = C10N2H8). The MnCr derivative behaves as a 1D ferromagnet down to 2 K, the lowest investigated temperature. The lack of magnetic ordering in this chain prompted us to prepare the more anisotropic MnCo…