Search results for "SSB"

A Novel Dinuclear Fe II Spin‐Crossover Complex Based on a 2,2‐Bipyrimidine Bridge Ligand: [Fe(CH 3 bipy)(NCS) 2 ] 2 bpym

2004

The dinuclear iron(II) complex {[Fe(CH3bipy)(NCS)2]2bpym} has been synthesised and its crystal structure determined at 293 K. The magnetic properties display intramolecular antiferromagnetic coupling at 1 bar (J = −4.2 cm−1), and the onset of a pressure-induced spin conversion is observed at 11 kbar. Magnetic field Mossbauer measurements have been carried out at 4.2 K, and indicate that the HS species correspond to [HS-HS] pairs. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Towards Molecular Conductors with a Spin‐Crossover Phenomenon:Crystal Structures, Magnetic Properties and Mössbauer Spectra of[Fe(salten)Mepepy][M(dm…

2005

Three new iron(III) compounds of formula [Fe(salten)Mepepy][M(dmit)2]·CH3CN (M = Ni, Pd, Pt; H2salten = 4-azaheptamethylene-1,7-bis(salicylideneiminate); Mepepy = 1-(pyridin-4-yl)-2-(N-methylpyrrol-2-yl) ethane; dmit2– = 1,3-dithiole-2-thione-4,5-dithiolato) have been synthesised and the crystal structure of each compound has been solved at different temperatures. The structures consist of alternating layers of [M(dmit)2]– units and [Fe(salten)Mepepy] cations. In the Ni compound photo-isomerisation of the Mepepy ligand can be observed in dichloromethane solution. The temperature dependence of the magnetic susceptibility of the compounds reveals a gradual S = 5/2 blabla S = 1/2 spin crossove…

Synthese und Strukturen neuer Eisen-Sauerstoff-Alkoxid-Cluster

2004

Der Eisen-Sauerstoff-Alkoxy-Cluster [Fe9O3(OC2H5)21]·C2H5OH kann unter unterschiedlichen Bedingungen zu Molekulen umgesetzt werden, denen alle die allgemeine Formel [Fe5O(OR)8(OR′)5] gemeinsam ist. Erwarmt man [Fe9O3(OC2H5)21]·C2H5OH in Toluol, so entsteht [Fe5O(OC2H5)13], das durch Kristallisation abgetrennt werden kann, wohingegen ein Auflosen von [Fe9O3(OC2H5)21]·C2H5OH in tert-Butylamin zum 1 : 2-Addukt [Fe5O(OC2H5)13]·2 t-Bu-NH2 fuhrt. Mit Triethyl- oder Triphenylsilanol entsteht aus [Fe9O3(OC2H5)21]·C2H5OH wieder ein Sauerstoff-Eisencluster des gleichen Motivs: [Fe5O(OC2H5)8{OSi(C2H5)3}5] bzw. [Fe5O(OC2H5)8{OSi(C6H5)3}5]. Die Molekulstruktur [Fe5O(OC2H5)8{OSi(C2H5)3}5], die uber Rontg…

Crystal structure, magnetic properties and Mössbauer studies of [Fe(qsal)2][Ni(dmit)2]

2007

Abstract A new compound of formula [Fe(qsal)2][Ni(dmit)2] (1) has been synthesised, structurally and magnetically characterised (qsalH = N-(8-quinolyl)salicylaldimine, dmit2− = 1,3-dithiol-2-thione-4,5-dithiolato). Its structural features and its magnetic behaviour were compared with those of [Fe(qsal)2]-based complexes, and more particularly [Fe(qsal)2][Ni(dmit)2] · 2CH3CN.

Thermal and Light-Induced Spin Transition in the High- and Low-Temperature Structure of [Fe0.35Ni0.65(mtz)6](ClO4)2

1996

The thermal and light induced spin transition in [Fe(0.35)Ni(0.65)(mtz)(6)](ClO(4))(2) (mtz = 1-methyl-1H-tetrazole) was studied by (57)Fe Mössbauer spectroscopy and magnetic susceptibility measurements. In addition to the spin transition of the iron(II) complexes the compound undergoes a structural phase transition. The high-temperature structure could be determined by X-ray crystallography of the isomorphous [Fe(0.25)Ni(0.75)(mtz)(6)](ClO(4))(2) complex at room temperature. The X-ray structural analysis shows this complex to be rhombohedric, space group Rthremacr;, with a = 10.865(2) Å and c = 23.65(1) Å with three molecules in the unit cell. The transition to the low-temperature structur…

Synthesis, crystal structure, magnetic properties and 57Fe Mossbauer spectroscopy of the new trinuclear [Fe3(4-(2'-hydroxyethyl)-1,2,4- triazole)6(H2…

2000

Hyetrz = 4-(2prime-hydroxyethyl)-1,2,4-triazole represents the first structurally characterized iron(II) spin crossover compound for which the structure has been solved above and below room temperature in both spin states. The compound crystallizes in the trigonal system, space group R3, a = 12.763(1) b= 67.144(1), V = 1684.3(1) 3, Z = 6 at 120K. At 330K the space group is retained and a = 13.0183(3) b=67.376(3), V = 1805.8(1) 3. The molecular structure consists of trinuclear FeII entities linked together by an unprecedented three-dimensional network of hydrogen bonds. This compound shows a gradual spin crossover behavior centered around room temperature, which has been followed by temperat…

Mononuclear Complexes of Iron(II) Based on Symmetrical Tripodand Ligands: Novel Parent Systems for the Development of New Spin Crossover Metallomesog…

2011

The synthesis and characterization of a series of mononuclear tripodand-based FeII complexes by means of Mossbauer andUV/Vis spectroscopic as well as magnetic methods is reported. The complexes were obtained from the reactions of FeII salt with heterocyclic aldehydes (imd = imidazole-4(5)-carboxaldehyde, py = picolinaldehyde, or 6-Mepy = 6-methylpicolinaldehyde) and a symmetric triamine [tren = tris(2-aminoethyl)amine, tame = 2,2,2-tris(aminomethyl)ethane, or tach = 1,3,5-cis,cis-cyclohexanetriamin]. Because of extreme rigidity of the capping triamine tach, the molecular structure of {Fe[tach(imd)3](BF4)2} (1) features an unprecedented tapered trigonal prismatic FeN6 polyhedron. The molecul…

Iron(II) Spin Transition Complexes with Dendritic Ligands, Part I

2008

The ligands G1- and G2-oligo (benzyl ether) (PBE) dendrons and their iron(II) complexes [Fe(Gn-PBE)3]A2·xH2O (with n = 1, 2 and A = triflate, tosylate) were prepared. The magnetic properties of the complexes were investigated by a SQUID magnetometer. All complexes exhibit gradual spin transition below room temperature. At very low temperatures the magnetic behaviour reflects zero-field splitting (ZFS) effects. 57Fe-Mossbauer spectroscopy was performed to distinguish between ZFS of high spin species and spin state conversion into the low spin state. Further characterisation was carried out by thermogravimetric analysis (TGA) and FT-IR spectroscopy. Structural features have been determined by…

Complexes of organometallic compounds. LII. 119Sn Mössbauer isomer shifts, partial atomic charges on tin, and structure, in triorganotin(IV) halides

1988

A heptanuclear Fe(II)–Fe(III)6 system with twelve unpaired electrons

2000

Abstract The pentadentate ligand 5 LH2 = saldptn = N,N′-bis(1-hydroxy-2-benzyliden)-1,7-diamino-4-azaheptane has been prepared by a Schiff base condensation between 1,7-diamino-4-azaheptane and the corresponding salicyaldehyde. Its complexation with Fe(III) gave the high-spin (S=5/2) complex of [Fe III ( 5 L)Cl]. This precursor was combined with [Fe(CN)6]4− and a blue heptanuclear complex [FeII{(CN)Fe III ( 5 L)}6]Cl2 resulted. This system belongs to the class of high-spin molecules possessing twelve unpaired electrons (S=6) as proven by the magnetic susceptibility measurements and Mossbauer spectra.