Search results for "Magnetic Susceptibility"
showing 10 items of 516 documents
Spin crossover in hexakis(1-(2-chloroethyl)-tetrazole)iron(II) complexes; synthesis and magnetic properties
2002
Abstract The spin-crossover complexes [Fe(teec)6](X)2 (with teec=1-(2-chloroethyl)-tetrazole and X=BF4, ClO4, PF6) possess two iron(II) sites each having a different spin-crossover behaviour. The magnetic behaviour of the complexes obtained by slow crystallisation differs strongly from those obtained by precipitation. This difference results in either a spin crossover of 50% (X=ClO4, crystalline), two gradual steps (X=BF4, PF6), or two steps, of which one is gradual and the other having a thermal hysteresis (X=ClO4 precipitated). Both 57Fe Mossbauer spectroscopy and magnetic susceptibility measurements have been recorded as a function of T. The crystal structure of [Fe(teec)6](BF4)2 has bee…
Structural and magnetic diversity in metal-dicyanamido polymer moieties: Paramagnetic and antiferromagnetic 1D chain compound and weakly ferromagneti…
2009
Abstract The reaction of M(NO 3 ) 2 · x H 2 O (M = Cu, Ni and Co; x = 3 for Cu and x = 6 for Co/Ni), imidazole (Im) and sodium dicyanamide (dca) afforded the complexes [M(Im) 2 (dca) 2 ] (where M = Cu for 1 , M = Ni for 2 , and M = Co for 3 ). All of them have been characterized structurally by single crystal X-ray diffraction measurements. X-ray analysis reveals that the dicyanamido ligand features the μ 1,3 bridging mode that led to the formation of two-dimensional structure of complex 1 while complexes 2 and 3 attribute an infinite one-dimensional chain like structure to generate the fascinating molecular assemblies. The {N(CN) 2 } − ligands present in the complexes 2 and 3 are coordin…
New symmetrical dinucleating ligand based assembly of bridged dicopper(II) and dizinc(II) centers: Synthesis, structure, spectroscopy, magnetic prope…
2015
Two dinuclear copper(II) complexes Li(H2O)(3)(CH3OH)](4)Cu2Br4]Cu-2(cpdp)(mu-O2CCH3)](4)(OH)(2) (1), Cu (H2O)(4)]Cu-2(cpdp)(mu-O2CC6H5)](2)Cl-2 center dot 5H(2)O (2), and a dinuclear zinc(II) complex Zn-2(cpdp)(mu-O2CCH3)] (3) have been synthesized using pyridine and benzoate functionality based new symmetrical dinucleating ligand, N, N'-Bis2-carboxybenzomethyl]-N, N'-Bis2-pyridylmethyl]-1,3-diaminopropan-2-ol (H(3)cpdp). Complexes 1, 2 and 3 have been synthesized by carrying out reaction of the ligand H3cpdp with stoichiometric amounts of Cu-2(O2CCH3)(4)(H2O)(2)], CuCl2 center dot 2H(2)O/C6H5COONa, and Zn(CH3COO)(2)center dot 2H(2)O, respectively, in methanol in the presence of NaOH at amb…
A three-dimensional copper(ii) 12-metallacrown-4 complex with malonomonohydroxamic acid (H3mmh) as a ligand
2011
Slow diffusion of an ethanolic solution of copper(ii) into an aqueous solution of partially deprotonated malonodihydroxamic acid (H4mdh) affords the pentanuclear complex of formula {[K(H2O) 2]2[Cu5(mmh)4]}n (1) (H3mmh = malonomonohydroxamic acid) which is formed by 12-MC-4 metallacrown units with the fifth copper(ii) ion being placed at the center of the square metallacrown unit. The dianionic pentacopper(ii) planar entity interacts with diaquapotassium(i) counterions through the carboxylate-oxygen atoms resulting in a neutral three-dimensional structure. Magnetic susceptibility measurements in the temperature range 1.9-300 K for 1 show the occurrence of relatively strong antiferromagnetic …
Limiting nuclearity in formation of polynuclear metal complexes through [2 + 3] cycloaddition: synthesis and magnetic properties of tri- and pentanuc…
2014
A tridentate ligand p-chloro-2-{(2-(dimethylamino)ethylimino)methyl}phenol (HL) was used to generate an octahedral nickel complex [Ni(L)Cl(H2O)2] 1 which was further converted into a square-planar nickel complex [Ni(L)(N3)] 2. The [2 + 3] cycloaddition reaction between metal coordinated azide 2 and different organonitriles under microwave irradiation afforded tri- and pentanuclear nickel(II) complexes 4a-4c. Reaction with benzonitrile and 3-cyano pyridine furnished the trinuclear species [Ni3L2(5-phenyltetrazolato)4(DMF)2] 4a and [Ni3L2{5-(3-pyridyl)-tetrazolato}4(DMF)2]·2H2O 4b, respectively. The nickel centers were found to be linearly disposed to each other and the complex is formed by a…
Anion encapsulation promoted by anion⋯π interactions in rationally designed hexanuclear antiferromagnetic wheels: synthesis, structure and magnetic p…
2009
The reaction of Kpymca (pymca = pyrimidine-2-carboxylato anion) with MX2·6H2O and tmda (N,N,N′,N′-tetramethylethylenediamine) in 1 : 3 : 3 molar ratio, using a MeOH/water mixture (3 : 1) as solvent, afforded the hexanuclear complexes [M6(µ-pymca)6(tmda)6]X6·4H2O (M = NiII, X = ClO4−1, BF4−2; M = CoII, X = ClO4−3). The reaction of pymca with either Cu(ClO4)2·6H2O or Cu(BF4)2·6H2O did not lead to any definite product. However, in the presence of strong coordinating chloride anions the linear tetranuclear complex [Cu4(µ-pymca)3Cl(H2O)](ClO4)4·4.5H2O 4 could be obtained. The structures of 1–3 are very similar and consist of wheel-shaped hexanuclear [M6(µ-pymca)6(tmda)6]6+ cations, with pseudo-D…
New Reactivity of 4‐Amino‐3,5‐bis(pyridin‐2‐yl)‐1,2,4‐triazole: Synthesis and Structure of a Mononuclear Species, a Dinuclear Species, and a Novel Te…
2007
Reactions of Ni(O 2 CMe) 2 ·4H 2 O or NiCl 2 ·6H 2 O, 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole (abpt) and NaN 3 or KSCN in different molar ratios heated under reflux or hydrothermal conditions generate a mononuclear species with dimorphous phases, a dinuclear species incorporating an in situ deaminated [bpt-H] - ligand and a tetranuclear rectangle box incorporating an unprecedented μ:η 1 :η 2 :η 1 coordination mode of the deprotonated [abpt-H] - ligand. Structural analysis reveals that a pair of [Ni 2 (μ 1,1 -N 3 )(μ-OAc)] motifs in [Ni 4 (abpt) 2 -(abpt-H)(N3) 5 (Ο 2 CMe) 2 ]·5H 2 O (1) are bridged by two abpt and one [abpt-H] - units into a rectangle box. [Ni 2 (bpt-H) 2 -(SCN) 2 (H 2…
A novel dinuclear manganese(II) compound incorporating two bis(imidazolyl) based ligands with single μ2-η1:η1-carboxylato bridges. Molecular and crys…
2014
Abstract This paper reports the synthesis, X-ray structure and magnetic characterization of [Mn 2 Cl(BIP) (HBIMAM)(H 2 O) 5 ]Cl 3 ·4H 2 O a novel dinuclear manganese(II) incorporating two related bis(imidazolyl)-based ligands, BIP (3,3-di(2-1 H -2-imidazolyl)propanoate) and BIMAM ( N -methyldi(1 H -2-imidazolyl)methanamine). The metal atoms in the dinuclear entity are bridged by a μ 2 -η 1 :η 1 carboxylate group (from the propionate arm of the BIP ligand) acting in an anti – anti coordination bridging mode, with an intramolecular Mn⋯Mn distance of 6.47 A. The coordination around the Mn(II) ions shows a distorted octahedral geometry for both MnClN 2 O 3 and MnN 2 O 4 chromophores. Between th…
Spectroscopic, magnetic, and electrochemical studies of a dimeric N-substituted-sulfanilamide copper(II) complex. X-ray and molecular structure of th…
2010
Abstract A dinuclear copper(II) complex with a N-substituted sulfonamide as ligand has been investigated. The new N-(pyridin-2-yl)biphenyl-4-sulfonamide ligand has been prepared and structurally characterized. The copper(II) complex has been synthesized and its crystal structure, magnetic properties and EPR spectra were studied in detail. The metal centers are bridged by four nonlinear triatomic NCN groups. The coordination geometry of the copper(II) ions in the dinuclear entity is distorted square planar with two N-pyridyl and two N-sulfonamido atoms. Magnetic susceptibility data show a moderate antiferromagnetic coupling, with −2 J = 284 cm−1. The EPR spectrum of the polycrystalline sampl…
Phosphoraneiminato complexes of manganese and cobalt with heterocubane structure
1999
The phosphoraneiminato complexes [MnBr(NPEt3)]4 (1) and [M4Br5{NP(NMe2)3}3] with M = Mn (2) and M = Co (3) are prepared by melting reactions from the anhydrous metal dibromides with the silylated phosphaneimines Me3SiNPR3 (R = Et, NMe2) in the presence of potassium fluoride. All complexes are characterized by crystal structure analyses. 1 forms an only slightly distorted Mn4N4 heterocubane skeleton with an approximate Td symmetry and short Mn…Mn distances of average 295.7 pm. In the structures of 2 and 3 one μ3-NPEt3 ligand of 1 is replaced by one bromine atom with μ3-function. This leads to the novel heterocubane type M4N3Br with approximate C3 symmetry. The deformation of the cubic skelet…