Search results for "Paramagnetism"
showing 10 items of 354 documents
NMR T1-Relaxation Measurements on Paramagnetic Organolanthanides: An Alternative Tool for Structure Determination in Solution
2005
1H NMR investigations were conducted on four paramagnetic organolanthanides, all bearing the tetraisopropylcyclopentadienyl ligand Cp4i (HC5iPr4) in order to verify whether or not interactions observed in the solid state are maintained in solution. In some cases variable-temperature experiments were necessary to enhance the resolution and determine the best conditions for the study. The 1D NMR spectrum could be interpreted in every case. Complementary 2D COSY experiments allowed the full attribution of the signals. T1 (1H) relaxation values were determined for all the paramagnetic complexes at the most suitable temperature, and compared with those of the diamagnetic KCp4i. The same tendency…
Diferratricarbaboranes of thesubcloso-[(η5-C5H5)2Fe2C3B8H11] Type, the First Representatives of the 13-Vertex Dimetallatricarbaborane Series
2003
Treatment of the [2-Cp-9-tBuNH-closo-2,1,7,9-FeC 3 B 8 H 1 0 ] (1) ferratricarbollide (Cp = η 5 -C 5 H 5 -) with Na + C 1 0 H 8 - in 1,2-dimethoxyethane (DME) at room temperature produced an air-sensitive transient anion with a tentatively identified nido-[tBUNH-CpFeC 3 B 8 H 1 0 ] 2 - constitution. In-situ reaction of this low-stability ion with [CpFe(CO) 2 I] or [CpFe(CO) 2 ] 2 generated three violet diferratricarbaboranes identified as paramagnetic subcloso complexes [4,5-Cp 2 - -4,5,1,6,7-Fe 2 C 3 B 8 H 1 1 ] (2; yield 2%), [4,5-Cp 2 - -4,5,1,7,12-Fe 2 C 3 B 8 H 1 1 ] (3; yield 2%), and [7-tBuNH-4,5-Cp 2 - -4,5,1,7,12-Fe 2 C 3 B 8 H 1 0 ] (4; yield 14%). These first representatives of t…
Synthesis, molecular structures and EPR spectra of the paramagnetic cuboidal clusters with Mo3S4Ga cores
2017
Electron precise [Mo3(l3-S)(l-S)3(diphos)3Br3]Br (diphos = dppe, dmpe) incomplete cuboidal clusters with six cluster skeletal electrons (CSE) were converted into paramagnetic cuboidal [Mo3(GaBr)(l3-S)4- (diphos)3Br3] clusters by treatment with elemental Ga. The new heterobimetallic complexes with nine CSE possess a doublet ground state with the unpaired electron density delocalized over the three molybdenum atoms.
Molecular materials based upon organic π-donors and magnetic anions
2000
Electrochemical combination of the magnetic dinuclear anion [MM'(C 2 O 4 )(NCS) 8 ] 4- (MM' = CrCr, CrFe) or paramagnetic mononuclear anion [Cr(NCS) 6 ] 3- with the ET organic π-donor (ET = BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene) gives rise to two new series of molecular hybrid salts formulated (ET) 5 [MM'(C 2 O 4 )(NCS) 8 (MM' = CrCr (1), CrFe (2)), (ET) 8 [MM'(C 2 O 4 )(NCS) 8 ] (3), (ET) 5.5 f Cr(NCS) 6 ] (4) and (ET) 5 [(C 2 H 5 ) 4 N] [Cr(NCS) 6 ](THF) (5) (THF = tetrahydrofuran). The crystal structures consist of alternating organic and inorganic layers. The organic part does not produce any detectable effect on the magnetic properties coming from the inorganic sublattice. T…
New, Multi‐Dimensional Cu(tn)‐[M(CN) 6 ] n – Cyano‐Bridged, Bimetallic Coordination Materials (M = Fe II , Co III , Cr III and tn = 1,3‐Diaminopropan…
2005
Reaction of the [Fe I I I (CN) 6 ] 3 - anion with [Cu I I (tn)(H 2 O) n ] 2 + (tn = 1,3-diaminopropane) affords the compounds [{Cu I I (tn)} 2 -{Fe I I (CN) 6 }].KCl.5H 2 O (1), [(Cu"(tn))2(Fe"(CN) 6 )].4H 2 O (2), and [{Cu I I (tnH) 2 (H 2 O) 2 }{Fe I I (CN) 6 }].2H 2 O (3). Each iron center in 1 and 2 is linked to six copper(II) ions by six cyanide bridges, while each copper ion is linked to three equivalent iron(II) ions. Despite these resemblances, the two compounds present large structural differences caused by two different orientations of the Cu-NC-Fe bridges: compound 1 has a 2D structure which can be described as successions of "Cu 4 Fe 3 " defective cubane units, while compound 2 …
NIR-absorbing transition metal complexes with redox-active ligands
2020
Bench top stable transition metal (M = Co, Ni, Cu) complexes with a non-innocent ortho-aminophenol derivative were synthesized by the reaction of metal(II)acetates with a ligand precursor in 2:1 ratio. The solid-state structures reveal the formation of neutral molecular complexes with square planar coordination geometries. The Co(II) and Cu(II) complexes are paramagnetic, whereas the Ni complex is a diamagnetic square planar low-spin Ni(II) complex. All complexes, and Ni(II) complex in particular, show strong absorption in the near-IR region. Peer reviewed
Investigation into the reaction of (t-BuC5H4)2Nb(η2-Te2)H with CH3Li: Hydride abstraction versus telluride methylation
2007
Abstract The reaction of [ Cp 2 ′ Nb ( Te 2 ) H ] ( 1 ) (Cp′ = t -BuC 5 H 4 ) with CH 3 Li in THF was examined by variable temperature 1 H NMR, ESR and mass spectroscopic means. From these methods it is evident that the diamagnetic compounds [ Cp 2 ′ NbH 2 ( TeCH 3 ) ] ( 2 ) and [ Cp 2 ′ Nb ( Te ) CH 3 ] ( 3 ) as well as the paramagnetic compound [ Cp 2 ′ Nb ( TeCH 3 ) 2 ] ( 4 ) form simultaneously. In the subsequent reaction of the intermediate solution with [Co 2 (CO) 8 ] compound 4 was consumed and the compound [ Cp 2 ′ Nb ( μ - TeCH 3 ) 2 Co(CO) 2 ] ( 5 ) formed in good yield. Complex 5 was characterized by IR and variable temperature 1 H NMR spectroscopies. Electrochemical two-electro…
Micro magnetofluidics: droplet manipulation of double emulsions based on paramagnetic ionic liquids
2013
The ability to control and manipulate discrete fluid droplets by magnetic fields offers new opportunities in microfluidics. A surfactant-free and easy to realize technique for the continuous generation of double emulsion droplets, composed of an organic solvent and a paramagnetic ionic liquid, is applied. The inner phase of the emulsion droplet consists of imidazolium-based ionic liquids with either iron, manganese, nickel or dysprosium containing anions which provide paramagnetic behaviour. The double emulsion droplets are dispersed in a continuous phase of FC-40. All substances - the organic phase, the paramagnetic ionic liquid and the continuous phase -are immiscible. The magnetic proper…
Cu2+and AMP complexation of enlarged tripodal polyamines
2006
The synthesis, characterization, Cu2+ coordination and interaction with AMP of three tripodal polyamines are reported. The polyamines are based on the structure of the tetraamine (tren) which has been enlarged with three propylamino functionalities (TAL), with a further anthrylmethyl fragment at one of its terminal primary nitrogens (ATAL) or with naphthylmethyl fragments at its three ends (N3TAL). The protonation constants of all three polyamines show that at pH 6, all six primary and secondary nitrogen atoms in the arms are protonated. The interaction with Cu2+ and AMP (adenosine-5′-monophosphate) has been studied by potentiometric, UV-Vis, ESI-MS spectroscopy and NMR techniques. pH-Metri…
Synthesis, crystal structure and magnetic properties of the complex [ReCl3(tppz)]·MeCN
2015
The reaction of the starting materials [ReIIICl3(MeCN)(PPh3)2] or [ReVOCl3(PPh3)2] with 2,3,5,6-tetrakis(2-pyridyl)pyrazine (tppz) in acetonitrile yielded the Re(III) complex [ReCl3(tppz)]·MeCN (1). This complex crystallizes in the monoclinic space group P21/n and its crystal structure consists of neutral mononuclear entities with meridional geometry of the chloride ligands, and the six-coordination of the Re(III) ion being completed by the tridentate tppz ligand. Each metal centre exhibits a highly distorted octahedral coordination with Re–Cl and Re–Ntppz bond lengths covering the ranges 2.3590(9)–2.3606(8) and 1.971(2)–2.096(2) A, respectively. The magnetic properties of 1 have been inves…