A novel heterotetranuclear [Cr2III(µ3-O)2Fe2III]8+ core and ground-state variability due to molecular spin frustration

The reaction of LCrIII units with FeII(salox) units, (L = 1,4,7-trimethyl-1,4,7-triazacyclononane and H2salox = salicylaldehyde oxime), produces in situ in methanol and in the presence of air, a small amount of triethylamine, NaClO4 and the dark-brown complex [L2Cr2(OMe)2O2(salox)2Fe2](ClO4)2·3H2O, which has been characterized by X-ray crystallography and magnetic susceptibility measurements and found to have a non-diamagnetic (ST≠ 0) ground state due to spin frustration.

[1]  R. Robson,et al.  Synthesis, x-ray crystal structures, and magnetic properties of tetranickel complexes of a macrocyclic tetranucleating ligand , 1992 .

[2]  U. Flörke,et al.  Isolation of a spin-frustrated imidazolate-bridged trinuclear copper(II) complex potentially relevant to the multicopper oxidases , 1992 .

[3]  W. Haase,et al.  Synthesis, electrochemistry, magnetic and spectroscopic properties of an exchange-coupled iron(III)-nickel(II)-iron(III) complex. Crystal structure of [L2Fe2(dmg)3Ni](PF6)2.0.5CH3OH (L = 1,4,7-trimethyl-1,4,7-triazacyclononane; dmg = dimethylglyoximate(2-)) , 1991 .

[4]  H. O̅kawa,et al.  Ferromagnetic dihydroxo-bridged Cr(III)-Cu(II) and Cr(III)-Cu(II)-Cr(III) complexes, [Cr(tet b)(OH)2Cu(bpy)(CH3OH)](ClO4)3 and {Cu[Cr(tet b)(OH)2]2}(ClO4)4·H 2O (tet b = racemic 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane and bpy = 2,2′-bipyridine) , 1991 .

[5]  W. Haase,et al.  Long-range magnetic interactions between manganese centers separated by 7 .ANG. in MnIIIZnIIMnIII and MnIVZnIIMnIV complexes , 1991 .

[6]  S. E. Vitols,et al.  Structure of the linear trinuclear complex hexakis(acetato)bis(2,2'-bipyridine)trimanganese (II). Determination of the J electron-exchange parameter through magnetic susceptibility and high-field magnetization measurements , 1991 .

[7]  S. Gehring,et al.  Syntheses, redox behavior, and magnetic and spectroscopic properties of copper(II)copper(II)copper(II), copper(II)nickel(II)copper(II), and copper(II)palladium(II)copper(II) species. Crystal structure of [L2Cu2Cu(dmg)2Br]ClO4.cntdot.CH3OH (L = 1,4,7-trimethyl-1,4,7-triazacyclononane; dmg = dimethylg , 1991 .

[8]  J. McCusker,et al.  Molecular spin frustration in the [Fe4O2]8+ core: synthesis, structure, and magnetochemistry of tetranuclear iron-oxo complex [Fe4O2(O2CR)7(bpy)2](C1O4) (R = Me, Ph) , 1991 .

[9]  A. Spek,et al.  A pyrazole ligand yielding both chloro-bridged dinuclear and tetranuclear copper(II) compounds. The crystal and molecular structure of bis[μ-chloro-chloro(3,4-dimethyl-5-phenylpyrazole)(4,5-dimethyl-3-phenylpyrazole)copper(II)] and of (μ4-oxo)hexakis(μ-chloro)tetrakis(3,4-dimethyl-5-phenylpyrazole)t , 1991 .

[10]  G. Papaefthymiou,et al.  Physical properties of a manganese tetramer with all-oxygen coordination , 1991 .

[11]  E. Pedersen,et al.  Tetranuclear heterometallic complexes of the general types [M{(OH)2CrA4}3]5+ and [M{(OH)2CoA4}3]5+ , 1991 .

[12]  R. Sessoli,et al.  Synthesis, crystal and molecular structure and magnetic properties of [Ni3(L1)4(NCS)4(OH)2(OH2)2](L1= 2,5-diamino-1,3,4-thiadiazole) , 1991 .

[13]  M. Chan,et al.  Tetranuclear manganese-oxo complex with a 2.7-.ANG. manganese.cntdot..cntdot..cntdot.manganese separation and intramolecular water.cntdot..cntdot..cntdot.(.mu.-oxygen) hydrogen-bonded contacts: [Mn4O2(TPHPN)2(H2O)2(CF3SO3)2](CF3SO3)3. Possible mode for binding of water at the active site of the oxyg , 1990 .

[14]  Masatatsu Suzuki,et al.  Synthesis and characterization of a novel linear tetranuclear manganese complex with three different oxidation states (II, III, IV, II). , 1990 .

[15]  C. Mathonière,et al.  Structure and magnetic and spectroscopic properties of a nickelIIcopperIInickelII trinuclear species , 1990 .

[16]  G. Brewer,et al.  Ferromagnetic coupling via imidazolate in an iron(III)-porphyrin-dicopper(II) system , 1989 .

[17]  J. Tuchagues,et al.  Calculation of the theoretical magnetic susceptibility of the four S = 5/2 spin system. Application to tetranuclear manganese(II) complexes , 1989 .

[18]  P. Boyd,et al.  Modeling the photosynthetic water oxidation center. Preparation and properties of tetranuclear manganese complexes containing [Mn4O2]6+,7+,8+ cores, and the crystal structures of Mn4O2(O2CMe)6(bipy)2 and [Mn4O2(O2CMe)7(bipy)2](ClO4) , 1989 .

[19]  D. Luneau,et al.  Synthesis and Structure of Completely Spin-coupled Trinuclear Copper(II) Complex, [Cu(dmg)2{Cu(bipy)(CH3OH)}2](NO3)2, Bridged by Bis(dimethylglyoximato)cuprate(II) Dianion , 1989 .

[20]  Karl Wieghardt,et al.  Synthesis, crystal structures, reactivity, and magnetochemistry of a series of binuclear complexes of manganese(II), -(III), and -(IV) of biological relevance. The crystal structure of [L'MnIV(.mu.-O)3MnIVL'](PF6)2.H2O containing an unprecedented short Mn.cntdot..cntdot..cntdot.Mn distance of 2.296 , 1988 .

[21]  S. Lippard,et al.  Tetranuclear iron-oxo complexes. Synthesis, structure, and properties of species containing the nonplanar {Fe4O2}8+ core and seven bridging carboxylate ligands , 1987 .

[22]  K. Wieghardt,et al.  General route to .mu.-hydroxo-bis(.mu.-acetato)-bridged heterometal dinuclear complexes. Syntheses, magnetic and redox properties, electronic spectra, and molecular structures of the [Cr(III)-Co(II)] and [Cr(III)-Fe(II)] species , 1987 .

[23]  W. Haase,et al.  Crystal and molecular structure and magnetic properties of linear trimeric copper(II) complexes with predominant ferromagnetic exchange interaction , 1985 .

[24]  O. Kahn,et al.  Crystal structures and magnetic properties of (.mu.-terephthalato)bis[(N,N,N',N",N"-pentamethyldiethylenetriamine)aquocopper(II)] perchlorate and (.mu.-terephthalato)bis[(N,N,N',N",N"-pentaethyldiethylenetriamine)copper(II)] perchlorate , 1984 .

[25]  R. L. Martin,et al.  Magnetic exchange in transition metal complexes. IV. Linear trimeric bis(acetylacetonato)nickel(II) , 1968 .

[26]  Vasant Shankar Jatkar,et al.  Electric and magnetic susceptibilities , 1962 .

[27]  K. Kambe.  On the Paramagnetic Susceptibilities of Some Polynuclear Complex Salts , 1950 .