Search results for "Crystal"
showing 10 items of 22886 documents
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…
Functionalized phosphonates as building units for multi-dimensional homo- and heterometallic 3d-4f inorganic-organic hybrid-materials.
2016
Using the multifunctional ligand H4L (2,2'-bipyridinyl-5,5'-diphosphonic acid), a new family of inorganic-organic hybrid-materials was prepared. The ligand shows a very high flexibility regarding the coordination mode, leading to a large structural diversity. The compounds 1a, 1b ([M(H2L)(H2O)4]·2.5H2O; M = Co(2+) (a), Ni(2+) (b)), 2 ([Gd2(H2H'L)2(H2H'2L)(H2O)6]Cl4·14H2O), 3a, 3b, 3c ([MCo(iii)(H2L)3(H2O)2]·6.5H2O; M = Gd(3+) (a), Dy(3+) (b) and Tb(3+) (c)), and 4 ([GdNi(ii)(H2L)3(H2O)3]NaCl·6H2O) were isolated and characterized with single crystal X-ray diffraction. Depending on the used metal ions and on the stoichiometry, either discrete entities (0D), extended 2D layers or 3D frameworks…
Photomagnetic properties of an Fe(ii) spin-crossover complex of 6-(3,5-diamino-2,4,6-triazinyl)-2,2'-bipyridine and its insertion into 2D and 3D bime…
2017
International audience; The Fe(ii) complex of the L1 ligand (L1 = 6-(3,5-diamino-2,4,6-triazinyl)-2,2'-bipyridine) has been used as a templating cation for the growth of oxalate-based networks. The magnetic characterization of the [Fe(II)(L1)2](ClO4)2·CH3CN (1) precursor in the solid state has been performed for the first time showing that the low-spin (LS) state is predominating from 2 to 400 K with 10% of Fe(ii), which undergoes a gradual and irreversible spin-crossover above 350 K. 1 presents the LIESST effect with a photo-conversion close to 25% and a T(LIESST) of 49 K. During the preparation of 1, a secondary product of the formula [Fe(II)(L1)(CH3CN)2(H2O)](ClO4)2·CH3CN (2) has been ob…
Recent studies on RR′S·C2B9H11 charge-compensated ligands
2002
Abstract In this paper we report the synthesis of three new carborane derivatives of the series 7,8-R,R′-10-L-7,8-C2B9H9 (R=R′=H, L=SEtPh; R=CH3, R′=H, L=SMe2 and L=SEt2) along with the enhanced characterization of formerly described compounds 7,8-R,R′-10-L-7,8-C2B9H9 (R=R′=H, L=SMe2 (1), L=SEt2 (2) and L=S(CH2)4 (3)). They have been fully characterised using 1H-, 11B- and 13C-NMR spectroscopy. Their bridging proton resonances have been located for the first time. Individual sulfonium substituent contributions have been calculated that have permitted to establish a rule to predict its position in the 1H-NMR spectrum. The crystal structures of 1 and 3 have been resolved for the first time. T…
Solvent effects on the dimensionality of oxamato-bridged manganese(II) compounds
2018
Two new oxamate-containing manganese(II) complexes, [{Mn(H2edpba)(H2O)2}2]n (1) and [Mn(H2edpba)(dmso)2]∙dmso∙CH3COCH3∙H2O (2) (H4edpba = N,N′-ethylenediphenylenebis(oxamic acid) and dmso = dimethylsulfoxide), have been synthesized and the structures of 1 and 2 were characterized by single crystal X-ray diffraction. The structure of 1 consists of neutral honeycomb networks in which each manganese(II) is six-coordinate by one H2edpba2− ligand and two carboxylate–oxygens from two other H2edpba2− ligands building the equatorial plane. Each manganese is connected to its nearest neighbor through two carboxylate(monoprotonated oxamate) bridges in an anti-syn conformation. A dmso solution of singl…
Self‐Assembly and Characterisation of Grid‐Type Iron( II ), Cobalt( II ) and Zinc( II ) Complexes
2003
The reaction of the ligands 5 and 6, containing two tridentate binding units, with iron(II), cobalt(II) and zinc(II) leads to the self-assembly of supramolecular architectures of [2 × 2] grid type containing four ions in octahedral coordination sites. The grid-type structures have been assigned on the basis of the spectroscopic data in solution, and confirmed in the solid state in the case of complexes 6b and 6c by X-ray crystallography. The latter study revealed that each metal ion is situated in a distorted octahedral coordination environment comprising two N,N,O ligand donor sets. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
On the magneto-structural role of the coordinating anion in oxamato-bridged copper(ii) derivatives
2019
We herein present the synthesis, spectroscopic analysis, description of the crystal structures and magnetic properties of four new complexes of the formula [{Cu(opba)(H2O)1.2}{Cu(dmphen)(SCN)}2]·dmf (1), [{Cu(opba)}2{Cu(dmphen)Cl}4]·1.5dmf·2.5dmso (2), [{Cu(opba)}2{Cu(dmphen)Br}4]·dmf·2.3dmso (3) and [{Cu(opba)}{Cu(dmphen)(dca)}2]n (4) [H4opba = N,N′-1,2-phenylenebis(oxamic acid), dmphen = 2,9-dimethyl-1,10-phenanthroline and dca = dicyanamide anion]. 1 is a neutral tricopper(II) complex where an inner [Cu(opba)]2− fragment adopts a bis-bidentate coordination mode towards two outer [Cu(dmphen)(NCS)]+ units. 2 and 3 are bis-trinuclear species where two oxamato-bridged [Cu(opba){Cu(dmphen)X}2…
Effects of Remote Ligand Substituents on the Structures, Spectroscopic, and Magnetic Properties of Two-Coordinate Transition-Metal Thiolate Complexes
2018
The first-row transition-metal(II) dithiolates M(SAriPr4)2 [AriPr4 = C6H3-2,6-(C6H3-2,6-iPr2)2; M = Cr (1), Mn (3), Fe (4), Co (5), Ni (6), and Zn (7)] and Cr(SArMe6)2 [2; ArMe6 = C6H3-2,6-(C6H2-2,4,6-Me3)2] and the ligand-transfer reagent (NaSAriPr4)2 (8) are described. In contrast to their M(SAriPr6)2 (M = Cr, Mn, Fe, Co, Ni, and Zn; AriPr6 = C6H3-2,6-(C6H2-2,4,6-iPr3)2) congeners, which differ from 1 and 3-6 in having p-isopropyl groups on the flanking aryl rings of the terphenyl substituents, compounds 1 and 4-6 display highly bent coordination geometries with S-M-S angles of 109.802(2)° (1), 120.2828(3)° (4), 91.730(3)° (5), and 92.68(2)° (6) as well as relatively close metal-flanking …
A carboxylate-bridged NiII8 cluster with a distorted cubane topology: structure, magnetism and density functional studies
2016
Using a dicarboxylate ligand appended with (2-pyridyl)ethylamine unit, a new cluster [NiII8(L4)6(DMF)2(CH3OH)2(H2O)6][ClO4]4·2CH3OH·2CH3CO2C2H5 (1) [L4(2−): 3-[N-{2-(pyridin-2-yl)ethyl}amino]-bis(propionate)] has been synthesized, through ‘coordination-driven self-assembly’. The crystal structure of 1 reveals a centrosymmetric octanuclear carboxylate-bridged nickel(II) tetracation, with a distorted cubane topology. The four crystallographically independent nickel(II) centres differ markedly in their coordination environment. Magnetic studies (2–300 K) reveal that in 1 the net magnetic-exchange is antiferromagnetic. Based on geometric parameters associated with two interacting nickel(II) cen…
CuII2, CuII4 and CuII6 complexes with 3-(2-pyridyl)pyrazolate. Structure, magnetism and core interconversion
2019
Abstract Reactions of stoichiometric amounts of L1(−) (HL1 = 3-(2-pyridyl)pyrazole) with [Cu(H2O)6](ClO4)2, with or without PhCO2−, in MeOH or N,N′-dimethylformamide (dmf), led to the isolation of three copper(II) complexes of varying nuclearity, [CuII2(L1)2(ClO4)2(MeOH)2] (1), [CuII4(L1)4(O2CPh)2(MeOH)4](ClO4)2·2H2O (2) and [CuII6(L1)6(O2CPh)2(ClO4)2(dmf)4](ClO4)2·2dmf·2H2O (3). Structural analysis reveals two centrosymmetric four-coordinate {CuII(L1)(ClO4)(MeOH)} units are dipyrazolate-bridged in 1, giving rise to a square-pyramidal (SP; τ = 0.13) coordination to the CuII ion. In 2, two centrosymmetric four-coordinate dipyrazolate-bridged {CuII2(μ-L1)2(MeOH)2}2+ units in two layers are he…