Search results for "Pentagon"

Cover Picture: Dynamic Magnetic and Optical Insight into a High Performance Pentagonal Bipyramidal DyIII Single-Ion Magnet (Chem. Eur. J. 24/2017)

2017

Thermal expansion and magnetic properties of benzoquinone-bridged dinuclear rare-earth complexes.

2017

The synthesis and structural characterization of two benzoquinone-bridged dinuclear rare-earth complexes [BQ(MCl2·THF3)2] (BQ = 2,5-bisoxide-1,4-benzoquinone; M = Y (1), Dy (2)) are described. Of these reported metal complexes, the dysprosium analogue 2 is the first discrete bridged dinuclear lanthanide complex in which both metal centres reside in pentagonal bipyramidal environments. Interestingly, both complexes undergo significant thermal expansion upon heating from 120 K to 293 K as illustrated by single-crystal X-ray and powder diffraction experiments. AC magnetic susceptibility measurements reveal that 2 does not show the slow relation of magnetization in zero dc field. The absent of …

A new N6 hexadentate ligand and a novel heptacoordinated N6O-type Fe(III) compounds: Synthesis, characterization and structure of [Fe(dimpyen)(OH)](A…

2011

Abstract In this contribution, we report the syntheses of a novel N6 donor set ligand, dimpyen = N1,N2-di[(1-methyl-1H-2-imidazolyl) methyl]-N1,N2-di(2-pyridilmethyl)-1,2-ethanediamine. This type of ligand was designed to modulate the properties of the metal ions bound to it. The reaction with Fe(II) gives off a new heptacoordinated iron(III) complex. We study the spectroscopic (UV–Vis), magnetic and electrochemical behavior and also made the structural determination with X-ray diffraction at 134 K and a heptacoordinated N6O-type derivative of Fe(III) is reported as well. This complex crystallize as perchlorate or hexafluorophosphate and the formula of these derivatives are [Fe(dimpyen)(OH)…

Electron-Sponge Behavior and Electronic Structures in Cobalt-Centered Pentagonal Prismatic Co11Te7(CO)10 and Co11Te5(CO)15 Cluster Anions

2006

The novel cluster anion [Co11Te5(CO)15]- ([3]-) has been isolated and structurally characterized as part of the salt [Cp*2Nb(CO)2][3] (Cp* = C5Me5). The cobalt-centered Co10 pentagonal prism is surrounded by a shell of two μ5-Te, three μ4-Te ligands, and 15 CO groups in terminal, symmetrical, and σ-semibridging bonding modes. The hybrid carbonyl-telluride character of the ligand shell is reflected in the solid state by a one-dimensional assembly of polyhedral prisms along a backbone of [Cp*2Nb(CO)2]+ cations. Electrochemical studies reveal the presence of four redox couples of [3]n (n = −1 to −5). The electronic structures of various metal-centered and empty pentagonal-prismatic (PP) M10 cl…

Synthesis, structure and magnetic properties of the one-dimensional chain compound {K[Fe(1,3,5-triazine-2,4,6-tricarboxylate)(H2O)2]·2H2O}∞

2002

The one-dimensional chain compound {[Fe(1,3,5-triazine-2,4,6-tricarboxylate)(H2O)2]}n−n was obtained from a reaction of 1,3,5-triazine-2,4,6-tricarboxylate with Fe(II) in water at room temperature. The high-spin Fe(II) centers adopt a pentagonal bipyramid geometry with unusual ligand binding modes. Magnetic measurements revealed weak magnetic interactions between paramagnetic centers; these were modeled with both axial and rhombic distortions.

Timing and Side Channel Attacks

2015

How would you know the US pentagon is planning an attack on Iraq? One possible plan is to infiltrate the pentagon using spies, flipping traitors etc. But this sounds like lots of work and it is a dangerous work. That is the direct approach. Another possible plan is to ask the pizza delivery guys in the area. People planning an attack probably adds up to lots of people urgently trying to meet deadlines, staying late in the office and ordering pizza. So the pizza delivery guys know about a pending attack! The pizza delivery guys do not know the nature of the attack but they know “something is up” in the pentagon because for a few days people are staying late at the office and ordering pizza a…

Bootstrapping pentagon functions

2018

In PRL 116 (2016) no.6, 062001, the space of planar pentagon functions that describes all two-loop on-shell five-particle scattering amplitudes was introduced. In the present paper we present a natural extension of this space to non-planar pentagon functions. This provides the basis for our pentagon bootstrap program. We classify the relevant functions up to weight four, which is relevant for two-loop scattering amplitudes. We constrain the first entry of the symbol of the functions using information on branch cuts. Drawing on an analogy from the planar case, we introduce a conjectural second-entry condition on the symbol. We then show that the information on the function space, when comple…

A novel octacyanido dicobalt(iii) building block for the construction of heterometallic compounds

2019

The first bimetallic octacyanido complex of CoIII, (PPh4)2[Co2(μ-2,5-dpp)(CN)8] (1), was synthesized and used as a metalloligand with [Mn(MAC)(H2O)2]Cl2·4H2O to give a new {CoIIIMnII} heterometallic chain of formula [MnII(MAC)(μ-NC)2Co2III(μ-2,5-dpp)(CN)6]n·7nH2O (2) (PPh4+ = tetraphenylphosphonium cation; 2,5-dpp = 2,5-bis(2-pyridyl)pyrazine and MAC = 2,13-dimethyl-3,6,9,12,18-pentaazabicyclo-[12.3.1]octadeca-1(18),2,12,14,16-pentaene). Both compounds were characterized by single-crystal X-ray diffraction. Compound 1 contains a diamagnetic 2,5-dpp-bridged dicobalt(III) unit with four peripheral cyanide ligands at each cobalt center achieving a six-coordinate surrounding, the electroneutral…

Electronic Structure Study of Seven-Coordinate First-Row Transition Metal Complexes Derived from 1,10-Diaza-15-crown-5:  A Successful Marriage of The…

2005

A detailed study of the electronic structure of seven-coordinate Mn(II), Co(II), and Ni(II) complexes with the lariat ether N,N'-bis(2-aminobenzyl)-1,10-diaza-15-crown-5 (L(1)) is presented. These complexes represent new examples of structurally characterized seven-coordinate (pentagonal bipyramidal) complexes for the Mn(II), Co(II), and Ni(II) ions. The X-ray crystal structures of the Mn(II) and Co(II) complexes show C(2) symmetries for the [M(L(1))](2+) cations, whereas the structures of the Ni(II) complexes show a more distorted coordination environment. The magnetic properties of the Mn(II) complex display a characteristic Curie law, whereas those of the Co(II) and Ni(II) ions show the …

Compressed Drinfeld associators

2004

Drinfeld associator is a key tool in computing the Kontsevich integral of knots. A Drinfeld associator is a series in two non-commuting variables, satisfying highly complicated algebraic equations - hexagon and pentagon. The logarithm of a Drinfeld associator lives in the Lie algbera L generated by the symbols a,b,c modulo [a,b]=[b,c]=[c,a]. The main result is a description of compressed associators that satisfy the compressed pentagon and hexagon in the quotient L/[[L,L],[L,L]]. The key ingredient is an explicit form of Campbell-Baker-Hausdorff formula in the case when all commutators commute.