Effect of counteranion X on the spin crossover properties of a family of diiron(II) triazole complexes [Fe(II)2(PMAT)2](X)4

Seven diiron(II) complexes, [Fe(II)(2)(PMAT)(2)](X)(4), varying only in the anion X, have been prepared, where PMAT is 4-amino-3,5-bis{[(2-pyridylmethyl)-amino]methyl}-4H-1,2,4-triazole and X = BF(4)(-) (1), Cl(-) (2), PF(6)(-) (3), SbF(6)(-) (4), CF(3)SO(3)(-) (5), B(PhF)(4)(-) (6), and C(16)H(33)SO(3)(-) (7). Most were isolated as solvates, and the microcrystalline ([3], [4]·2H(2)O, [5]·H(2)O, and [6]·?MeCN) or powder ([2]·4H(2)O, and [7]·2H(2)O) samples obtained were studied by variable-temperature magnetic susceptibility and Mo?ssbauer methods. A structure determination on a crystal of [2]·2MeOH·H(2)O, revealed it to be a [LS-HS] mixed low spin (LS)-high spin (HS) state dinuclear complex at 90 K, but fully high spin, [HS-HS], at 293 K. In contrast, structures of both [5]·?IPA·H(2)O and [7]·1.6MeOH·0.4H(2)O showed them to be [HS-HS] at 90 K, whereas magnetic and M?ssbauer studies on [5]·H(2)O and [7]·2H(2)O revealed a different spin state, [LS-HS], at 90 K, presumably because of the difference in solvation. None of these complexes undergo thermal spin crossover (SCO) to the fully LS form, [LS-LS]. The PF(6)(-) and SbF(6)(-) complexes, 3 and [4]·2H(2)O, appear to be a mixture of [HS-LS] and [HS-HS] at low temperature, and undergo gradual SCO to [HS-HS] on warming. The CF(3)SO(3)(-) complex [5]·H(2)O undergoes gradual, partial SCO from [HS-LS] to a mixture of [HS-LS] and [HS-HS] at T(1/2) ≈ 180 K. The B(PhF)(4)(-) and C(16)H(33)SO(3)(-) complexes, [6]·(1)/(2)MeCN and [7]·2H(2)O, are approximately [LS-HS] at all temperatures, with an onset of gradual SCO with T(1/2) > 300 K.     

Two novel iron(II) materials based on dianionic N4O2 Schiff bases: structural properties and spin-crossover characteristics in the series [Fe(3-X,5-NO2-sal-N(1,4,7,10)] (X = H, 3-MeO, 3-EtO)

Two spin-crossover (SCO) complexes [Fe(II)(3-MeO,5-NO2-sal-N(1,4,7,10)] (1) and [Fe(II)(3-EtO,5-NO2-sal-N(1,4,7,10)] (2) have been prepared and studied (3-MeO,5-NO2-sal-N(1,4,7,10) and 3-EtO,5-NO2-sal-N(1,4,7,10) are deprotonated 2-[12-(hydroxy-3-methoxy-5-nitrophenyl)-2,5,8,11-tetraazadodeca-1,11-dien-1-yl]-2-methoxy-4-nitrophenol and 2-[12-(hydroxy-3-ethoxy-5-nitrophenyl)-2,5,8,11-tetraazadodeca-1,11-dien-1-yl]-2-ethoxy-4-nitrophenol, respectively). The X-ray diffraction analysis of complex 1 (C22H26N6O8Fe) evidenced the same Pbnb orthorhombic system at 160 K (high-spin (HS) state) and 100 K (low-spin (LS) state). At 160 K, a = 8.4810(9) A, b = 14.7704(14) A, c = 18.769(2) A, V = 2351.2(4) A3, and Z = 4. At 100 K, a = 8.5317(8) A, b = 14.4674(15) A, c = 18.814(2) A, and V = 2322.2(4) A3. Complex 2 (C28H38N6O9Fe) crystallizes in the P1 triclinic system. At 160 K (HS state), a = 10.265(4) A, b = 10.861(4) A, c = 14.181(5) A, alpha = 84.18(4) degrees, beta = 70.53(5) degrees, gamma = 88.95(5) degrees, V = 1482.6(10) A3, and Z = 2. The iron(II) coordination sphere is distorted octahedral in 1 and 2 with a cis-alpha arrangement of the N4O2 donor set of the hexadentate ligand. The molecules are connected into 1D infinite chains through hydrogen contacts involving the secondary amine functions and O(nitro) atoms of the ligands in adjacent molecules. Investigation of their magnetic properties and Mossbauer spectra has revealed very different SCO behaviors: complex 1 exhibits a cooperative SCO without residual LS or HS fraction; complex 2 shows a LS <--> HS SCO involving approximately 5% of the Fe(II) ions in the 30-150 K range. The phenomenological cooperative interaction parameter J = 138 K evaluated from the area of the hysteresis loop indicates a cooperative effect weaker in 1 than in [Fe(II)(5NO2-sal-N(1,4,7,10))]. The theoretical approach to the SCO in 2 indicates a HS ground state and a LS first excited level 53 K above: the thermal dependence of the system occurs through population of vibrational states. Comparison of the structural and electronic properties of the ferrous SCO materials with parent N4O2 ligands shows that the properties of SCO are closely related to intermolecular interactions and crystal packing.     

Lanthanide-3d cyanometalate chains Ln(III)-M(III) (Ln=Pr, Nd, Sm, Eu, Gd, Tb; M=Fe) with the tridentate ligand 2,4,6-tri(2-pyridyl)-1,3,5-triazine (tptz): evidence of ferromagnetic interactions for the Sm(III)-M(III) compounds (M=Fe, Cr)

A series of cyanide-bridged chain mixed Fe(III)/Ln(III) (Ln=Pr, Nd, Sm, Eu, Gd, Tb) complexes with the tridentate ligand 2,4,6-tri(2-pyridyl)-1,3,5-triazine (tptz) used as a capping group has been prepared. Reactions of tptz and LnCl3 with K3Fe(CN)6 yield a family of air-stable 1-D compounds {[Pr(tptz)(H2O)4Fe(CN)6].8H2O}infinity, {[Nd(tptz)(H2O)4Fe(CN)6].8H2O}infinity, {[Sm(tptz)(H2O)4Fe(CN)6].8H2O}, {[Eu(tptz)(H2O)4Fe(CN)6].6H2O}infinity, {[Gd(tptz)(H2O)4Fe(CN)6].6H2O}infinity, and {[Tb(tptz)(H2O)4Fe(CN)6].8H2O}infinity. Temperature dependent magnetic susceptibility studies of reveal that in , the Sm(III) and Fe(III) ions are ferromagnetically coupled with 3-D ordering occurring below 3.5 K. The appearance of the frequency dependent out-of-phase signal is explained in terms of an ordering with a spin glass-like behavior. To compare the magnetic behavior of with related compounds, {[Sm(tptz)(H2O)4Co(CN)6].8H2O}infinity and {[La(tptz)(DMF)(H2O)3Fe(CN)6].5H2O}infinity, {[Sm(tmphen)(DMF)3(H2O)Fe(CN)6].2H2O}infinity, {[Sm(tmphen)2(H2O)2Fe(CN)6].MeOH.13H2O}infinity and {[Sm(tmphen)2(H2O)2Cr(CN)6].MeOH.9H2O}infinity with 3,4,7,8-tetramethyl-1,10-phenanthroline (tmphen) were also prepared.     

Molecular and electronic structures of iron(II)/(III) complexes containing N,S-coordinated,closed-shell o-aminothiophenolato(1-) and o-iminothiophenolato(2-) ligands

The coordination chemistry of the ligands o-aminothiophenol, H(abt), 4,6-di-tert-butyl-2-aminothiophenol, H[L(AP)], and 1,2-ethanediamine-N,N'-bis(2-benzenethiol), H(4)('N(2)S(2')), with FeCl(2) under strictly anaerobic and increasingly aerobic conditions has been systematically investigated. Using strictly anaerobic conditions, the neutral, air-sensitive, yellow complexes (mu-S,S)[Fe(II)(abt)(2)](2) (1), (mu-S,S)[Fe(II)(L(AP))(2)](2).8CH(3)OH (2), and (mu-S,S)[Fe(II)('H(2)N(2)S(2'))](2).CH(3)CN (3) containing high spin ferrous ions have been isolated where (abt)(1-), (L(AP))(1-), and ('H(2)N(2)S(2'))(2-) represent the respective N,S-coordinated, aromatic o-aminothiophenolate derivative of these ligands. When the described reaction was carried out in the presence of trace amounts of O(2) and [PPh(4)]Br, light-green crystals of [PPh(4)][Fe(II)(abt)(2)(itbs)].[PPh(4)]Br (4) were isolated. The anion [Fe(II)(abt)(2)(itbs)](-) contains a high spin ferrous ion, two N,S-coordinated o-aminophenolate(1-) ligands, and an S-bound, monoanionic o-iminothionebenzosemiquinonate(1-) pi radical, (itbs)(-). Complex 4 possesses an S(t) = 3/2 ground state. In the absence of [PPh(4)]Br and presence of a base NEt(3) and a little O(2), the ferric dimer (mu-NH,NH)[Fe(III)(L(AP))(L(IP))](2) (5a) and its isomer (mu-S,S)[Fe(III)(L(AP))(L(IP))](2) (5b) formed. (L(IP))(2-) represents the aromatic o-iminothiophenolate(2-) dianion of H[L(AP)]. The structures of compounds 2, 4, and 5a have been determined by X-ray crystallography at 100(2) K. Zero-field M?ssbauer spectroscopy of 1, 2, 3, and 4 unambiguously shows the presence of high spin ferrous ions: The isomer shift at 80 K is in the narrow range 0.85-0.92 mm s(-1), and a large quadrupole splitting, |DeltaE(Q)|, in the range 3.24-4.10 mm s(-1), is observed. In contrast, 5a and 5b comprise both intermediate spin ferric ions (S(Fe) = 3/2) which couple antiferromagnetically in the dinuclear molecules yielding an S(t) = 0 ground state.     

Substituted N-picolylethylenediamines of the type (ArNHCH2CH2){(2-C5H4N)CH2}NR [R = Me, 4-CH2=CH(C6H4)CH2, (2-C5H4N)CH2] and their transition metal(II) halide complexes

Alkylation of (ArNHCH2CH2){(2-C5H4N)CH2}NH with RX [RX = MeI, 4-CH2=CH(C6H4)CH2Cl) and (2-C5H5N)CH2Cl] in the presence of base has allowed access to the sterically demanding multidentate nitrogen donor ligands, {(2,4,6-Me3C6H2)NHCH2CH2}{(2-C5H4N)CH2}NMe (L1), {(2,6-Me3C6H3)NHCH2CH2}{(2-C5H4N)CH2}NCH2(C6H4)-4-CH=CH2 (L2) and (ArNHCH2CH2){(2-C5H4N)CH2}2N (Ar = 2,4-Me2C6H3 L3a, 2,6-Me2C6H3 L3b) in moderate yield. L3 can also be prepared in higher yield by the reaction of (NH2CH2CH2){(2-C5H4N)CH2}2N with the corresponding aryl bromide in the presence of base and a palladium(0) catalyst. Treatment of L1 or L2 with MCl2 [MCl2 = CoCl2.6H2O or FeCl2(THF)1.5] in THF affords the high spin complexes [(L1)MCl2](M = Co 1a, Fe 1b) and [(L2)MCl2](M = Co 2a, Fe 2b) in good yield, respectively; the molecular structure of reveals a five-coordinate metal centre with bound in a facial fashion. The six-coordinate complexes, [(L3a)MCl2](M = Co 3a, Fe 3b, Mn 3c) are accessible on treatment of tripodal L3a with MCl2. In contrast, the reaction with the more sterically encumbered leads to the pseudo-five-coordinate species [(L3b)MCl2](M = Co 4a, Fe 4b) and, in the case of manganese, dimeric [(L3b)MnCl(mu-Cl)]2 (4c); in 4a and 4b the aryl-substituted amine arm forms a partial interaction with the metal centre while in 4c the arm is pendant. The single crystal X-ray structures of , 1a, 3b.MeCN, 3c.MeCN, 4b.MeCN and 4c are described as are the solution state properties of 3b and 4b.     

Heterospin systems constructed from [Cu2Ln]3+ and [Ni(mnt)2]1-,2- Tectons: First 3p-3d-4f complexes (mnt = maleonitriledithiolato)

New heterospin complexes have been obtained by combining the binuclear complexes [{Cu(H(2)O)L(1)}Ln(O(2)NO)(3)] or [{CuL(2)}Ln(O(2)NO)(3)] (L(1) = N,N'-propylene-di(3-methoxysalicylideneiminato); L(2) = N,N'-ethylene-di(3-methoxysalicylideneiminato); Ln = Gd(3+), Sm(3+), Tb(3+)), with the mononuclear [CuL(1)(2)] and the nickel dithiolene complexes [Ni(mnt)(2)](q)- (q = 1, 2; mnt = maleonitriledithiolate), as follows: (1)infinity[{CuL(1)}(2)Ln(O(2)NO){Ni(mnt)(2)}].Solv.CH(3)CN (Ln = Gd(3+), Solv = CH(3)OH (1), Ln = Sm(3+), Solv = CH(3)CN (2)) and [{(CH(3)OH)CuL(2)}(2)Sm(O(2)NO)][Ni(mnt)(2)] (3) with [Ni(mnt)2]2-, [{(CH(3)CN)CuL(1)}(2)Ln(H(2)O)][Ni(mnt)(2)]3.2CH(3)CN (Ln = Gd(3+) (4), Sm(3+) (5), Tb(3+) (6)), and [{(CH(3)OH)CuL(2)}{CuL(2)}Gd(O(2)NO){Ni(mnt)(2)}][Ni(mnt)(2)].CH(2)Cl(2) (7) with [Ni(mnt))(2]*-. Trinuclear, almost linear, [CuLnCu] motifs are found in all the compounds. In the isostructural 1 and 2, two trans cyano groups from a [Ni(mnt)2]2- unit bridge two trimetallic nodes through axial coordination to the Cu centers, thus leading to the establishment of infinite chains. 3 is an ionic compound, containing discrete [{(CH(3)OH)CuL(2)}(2)Sm(O(2)NO)](2+) cations and [Ni(mnt)(2)](2-) anions. Within the series 4-6, layers of discrete [CuLnCu](3+) motifs alternate with stacks of interacting [Ni(mnt)(2)](*-) radical anions, for which two overlap modes, providing two different types of stacks, can be disclosed. The strength of the intermolecular interactions between the open-shell species is estimated through extended Hückel calculations. In compound 7, [Ni(mnt)(2)](*-) radical anions coordinate group one of the Cu centers of a trinuclear [Cu(2)Gd] motif through a CN, while discrete [Ni(mnt)(2)](*-) units are also present, overlapping in between, but also with the coordinated ones. Furthermore, the [Cu(2)Gd] moieties dimerize each other upon linkage by two nitrato groups, both acting as chelate toward the gadolinium ion from one unit and monodentate toward a Cu ion from the other unit. The magnetic properties of the gadolinium-containing complexes have been determined. Ferromagnetic exchange interactions within the trinuclear [Cu(2)Gd] motifs occur. In the compounds 4 and 7, the [Ni(mnt)(2)](*-) radical anions contribution to the magnetization is clearly observed in the high-temperature regime, and most of it vanishes upon temperature decrease, very likely because of the rather strong antiferromagnetic exchange interactions between the open-shell species. The extent of the exchange interaction in the compound 7, which was found to be antiferromagnetic, between the coordinated Cu center and the corresponding [Ni(mnt)(2)](*-) radical anion, bearing mostly a 3p spin type, was estimated through CASSCF/CASPT2 calculations. Compound 6 exhibits a slow relaxation of the magnetization.     

New lanthanide-containing polytungstates derived from the cyclic P8W48 Anion: {Ln4(H2O)28[K subset P8W48O184(H4W4O12)2Ln2(H2O)10]13-}x, Ln = La, Ce, Pr, Nd

The reaction of K28Li5H7[P8W48O184].92H2O with early lanthanides under hydrothermal and conventional conditions yields novel structures of the molecular formula Ln4(H2O)28K6Li7[K subsetP8W48O184(H4W4O12)2Ln2(H2O)10] congruent with 57H2O, Ln = La (1), Ce (2, 2a), Pr (3), Nd (4), in which the central cavity of the precursor anion is occupied by lanthanide cations and H4W4O12 moieties. The new heteropolyanions were characterized by elemental analysis, infrared spectroscopy, 31P NMR, and X-ray crystallography. All of the crystals are monoclinic, space group C2/m, with lattice constants (A, Epsilon) a = 33.061(3), b = 30.986(3), c = 15.1649(13), beta = 103.607(2), (1); a = 33.0577(16), b = 31.0562(15), c = 15.2320(7), beta = 104.015(2), (2); a = 33.0577(16), b = 31.0562(15), c = 15.2320(7), beta = 104.015(2), (2a); a = 33.007(2), b = 31.060(2), c = 15.2129(10), beta = 104.0140(10), (3); a = 32.913(19), b = 31.155(18), c = 15.135(9), beta = 103.495(11), (4); and Z = 2.     

Lattice effects on the spin-crossover profile of a mononuclear manganese(III) cation

Six solvated salts of a mononuclear manganese(III) complex with a chelating hexadentate Schiff base ligand are reported. One member of the series, [MnL]PF(6)?0.5?CH(3)OH (1), shows a rare low-spin (LS) electronic configuration between 10-300?K. The remaining five salts, [MnL]NO(3)?C(2)H(5)OH(2), [MnL]BF(4)?C(2)H(5)OH(3), [MnL]CF(3)SO(3)?C(2)H(5)OH (4), [MnL]ClO(4)?C(2)H(5)OH (5) and [MnL]ClO(4)?0.5?CH(3)CN (6), all show gradual incomplete spin-crossover (SCO) behaviour. The structures of all were determined at 100?K, and also at 293?K in the case of 3-6. The LS salt [MnL]PF(6)?0.5?CH(3)OH is the only member of the series that does not exhibit strong hydrogen bonding. At 100?K two of the four SCO complexes (2 and 4) assemble into 1D hydrogen-bonded chains, which weaken or rupture on warming. The remaining SCO complexes 3, 5 and 6 do not form 1D hydrogen-bonded chains, but instead exhibit discrete hydrogen bonding between cation/counterion, cation/solvent or counterion/solvent and show no significant change on warming.     

Polynuclear vanadium complexes from thermal decomposition of [V3O(O2CPh)6(H2O)3]Cl

Solid-state decomposition of [V3O(O2CPh)6(H2O)3]Cl at 300 degrees C followed by alcoholysis of the product gives the new vanadium complexes [V6O6(PhCO2)6(CH3O)6(CH3OH)3] (1), [V6O6(PhCO2)6(C2H5O)6(C2H5OH)3] (2), [V6O6(PhCO2)6(C3H7O)6(C3H7OH)3] (3), [V6O6(PhCO2)6(C4H9O)6(C4H9OH)3] (4) and [V4O4(OCH3)6(O2CPh)2(HOCH3)2] (5). Complexes 2, 3 and 5 have been crystallographically characterised. DC magnetic susceptibility studies on complex shows antiferromagnetic coupling leading to a S = 0 spin ground state.     

Structural and spectroscopic features of a cis (hydroxo)-Fe(III)-(carboxylato) configuration as an active site model for lipoxygenases

In our preliminary communication (Ogo, S.; Wada, S.; Watanabe, Y.; Iwase, M.; Wada, A.; Harata, M.; Jitsukawa, K.; Masuda, H.; Einaga, H. Angew. Chem., Int. Ed. 1998, 37, 2102-2104), we reported the first example of X-ray analysis of a mononuclear six-coordinate (hydroxo)iron(III) non-heme complex, [Fe(III)(tnpa)(OH)(RCO(2))]ClO(4) [tnpa = tris(6-neopentylamino-2-pyridylmethyl)amine; for 1, R = C(6)H(5)], which has a characteristic cis (hydroxo)-Fe(III)-(carboxylato) configuration that models the cis (hydroxo)-Fe(III)-(carboxylato) moiety of the proposed (hydroxo)iron(III) species of lipoxygenases. In this full account, we report structural and spectroscopic characterization of the cis (hydroxo)-Fe(III)-(carboxylato) configuration by extending the model complexes from 1 to [Fe(III)(tnpa)(OH)(RCO(2))]ClO(4) (2, R = CH(3); 3, R = H) whose cis (hydroxo)-Fe(III)-(carboxylato) moieties are isotopically labeled by (18)OH(-), (16)OD(-), (18)OD(-), (12)CH(3)(12)C(18)O(2)(-), (12)CH(3)(13)C(16)O(2)(-), (13)CH(3)(12)C(16)O(2)(-), (13)CH(3)(13)C(16)O(2)(-), and H(13)C(16)O(2)(-). Complexes 1-3 are characterized by X-ray analysis, IR, EPR, and UV-vis spectroscopy, and electrospray ionization mass spectrometry (ESI-MS).     

Cyano-bridged bimetallic assemblies from hexacyanometalate, [M(CN)6](3-) (M = Mn(III) and Fe(III)), and [M(N4-macrocycle)]2+ (M=Fe(III), Ni(II) and Zn(II)) building blocks. Syntheses, multidimensional structures, and magnetic properties

Reactions between [M(N(4)-macrocycle)](2+) (M = Zn(II) and Ni(II); macrocycle ligands are either CTH = d,l-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane or cyclam = 1,4, 8, 11-tetrazaazaciclotetradecane) and [M(CN)(6)](3-) (M = Fe(III) and Mn(III)) give rise to cyano-bridged assemblies with 1D linear chain and 2D honeycomblike structures. The magnetic measurements on the 1D linear chain complex [Fe(cyclam)][Fe(CN)(6)].6H(2)O 1 points out its metamagnetic behavior, where the ferromagnetic interaction operates within the chain and the antiferromagnetic one between chains. The Neel temperature, T(N), is 5.5 K and the critical field at 2 K is 1 T. The unexpected ferromagnetic intrachain interaction can be rationalized on the basis of the axially elongated octahedral geometry of the low spin Fe(III) ion of the [Fe(cyclam)](3+) unit. The isostructural substitution of [Fe(CN)(6)](3-) by [Mn(CN)(6)](3-) in the previously reported complex [Ni(cyclam)](3)[Fe(CN)(6)](2).12H(2)O 2 leads to [Ni(cyclam)](3)[Mn(CN)(6)](2).16 H(2)O 3, which exhibits a corrugated 2D honeycomblike structure and a metamagnetic behavior with T(N) = 16 K and a critical field of 1 T. In the ferromagnetic phase (H > 1 T) this compound shows a very important coercitive field of 2900 G at 2 K. Compound [Ni(CTH)](3)[Fe(CN)(6)](2).13H(2)O 4, C(60)H(116)Fe(2)N(24)Ni(3)O(13), monoclinic, A 2/n, a = 20.462(7), b = 16.292(4), c = 27.262(7) A, beta = 101.29(4) degrees, Z = 4, also has a corrugated 2D honeycomblike structure and a ferromagnetic intralayer interaction, but, in contrast to 2 and 3, does not exhibit any magnetic ordering. This fact is likely due to the increase of the interlayer separation in this compound. ([Zn(cyclam)Fe(CN)(6)Zn(cyclam)] [Zn(cyclam)Fe(CN)(6)].22H(2)O.EtOH) 5, C(44)H(122)Fe(2)N(24)O(23)Zn(3), monoclinic, A 2/n, a = 14.5474(11), b = 37.056(2), c = 14.7173(13) A, beta = 93.94(1) degrees, Z = 4, presents an unique structure made of anionic linear chains containing alternating [Zn(cyclam)](2+) and [Fe(CN)(6)](3)(-) units and cationic trinuclear units [Zn(cyclam)Fe(CN)(6)Zn(cyclam)](+). Their magnetic properties agree well with those expected for two [Fe(CN)(6)](3-) units with spin-orbit coupling effect of the low spin iron(III) ions.     

mer-[Fe(pcq)(CN)3]-: a novel cyanide-containing building block and its application to assembling cyanide-bridged trinuclear FeIII2MnII complexes [pcq- = 8-(pyridine-2-carboxamido)quinoline anion

A new cyanide-containing building block K[Fe(pcq)(CN)(3)] [1; pcq(-) = 8-(pyridine-2-carboxamido)quinoline anion] containing a low-spin Fe(III) center with three cyanide groups in a meridional arrangement has been successfully designed and synthesized. Three cyanide-bridged trinuclear Fe(III)(2)Mn(II) complexes, [Fe(pcq)(CN)(3)](2)[Mn(CH(3)OH)(2)(H(2)O)(2)].2H(2)O (2), [Fe(pcq)(CN)(3)](2)[Mn(bipy)(2)].CH(3)OH.2H(2)O (3), and [Fe(pcq)(CN)(3)](2)[Mn(phen)(2)].CH(3)OH.2H(2)O (4), have been synthesized and structurally characterized. The magnetic susceptibilities of the three heterometallic complexes have been investigated.     

Monomeric oxovanadium(IV) compounds of the general formula cis-[V(IV)(=O)(X)(L(NN))(2)](+/0) [X = OH(-), Cl(-), SO(4)(2)(-) and L(NN) = 2,2'-bipyridine (bipy) or 4,4'-disubstituted bipy

Reaction of [V(IV)OCl(2)(THF)(2)] in aqueous solution with 2 equiv of AgBF(4) or AgSbF(6) and then with 2 equiv of 2,2'-bipyridine (bipy), 4,4'-di-tert-butyl-2,2'-bipyridine (4,4'-dtbipy), or 4,4'-di-methyl-2,2'-bipyridine (4,4'-dmbipy) affords compounds of the general formula cis-[V(IV)O(OH)(L(NN))(2)]Y [where L(NN) = bipy, Y = BF(4)(-) (1), L(NN) = 4,4'-dtbipy, Y = BF(4)(-) (2.1.2H(2)O), L(NN) = 4,4'-dmbipy, Y = BF(4)(-) (3.2H(2)O), and L(NN) = 4,4'-dtbipy, Y = SbF(6)(-) (4)]. Sequential addition of 1 equiv of Ba(ClO(4))(2) and then of 2 equiv of bipy to an aqueous solution containing 1 equiv of V(IV)OSO(4).5H(2)O yields cis-[V(IV)O(OH)(bipy)(2)]ClO(4) (5). The monomeric compounds 1-5 contain the cis-[V(IV)O(OH)](+) structural unit. Reaction of 1 equiv of V(IV)OSO(4).5H(2)O in water and of 1 equiv of [V(IV)OCl(2)(THF)(2)] in ethanol with 2 equiv of bipy gives the compounds cis-[V(IV)O(OSO(3))(bipy)(2)].CH(3)OH.1.5H(2)O (6.CH(3)OH.1.5H(2)O) and cis-[V(IV)OCl(bipy)(2)]Cl (7), respectively, while reaction of 1 equiv of [V(IV)OCl(2)(THF)(2)] in CH(2)Cl(2) with 2 equiv of 4,4'-dtbipy gives the compound cis-[V(IV)OCl(4,4'-dtbipy)(2)]Cl.0.5CH(2)Cl(2) (8.0.5CH(2)Cl(2)). Compounds cis-[V(IV)O(BF(4))(4,4'-dtbipy)(2)]BF(4) (9), cis-[V(IV)O(BF(4))(4,4'-dmbipy)(2)]BF(4) (10), and cis-[V(IV)O(SbF(6))(4,4'-dtbipy)(2)]SbF(6) (11) were synthesized by sequential addition of 2 equiv of 4,4'-dtbipy or 4,4'-dmbipy and 2 equiv of AgBF(4) or AgSbF(6) to a dichloromethane solution containing 1 equiv of [V(IV)OCl(2)(THF)(2)]. The crystal structures of 2.1.2H(2)O, 6.CH(3)OH.1.5H(2)O, and 8.0.5CH(2)Cl(2) were demonstrated by X-ray diffraction analysis. Crystal data are as follows: Compound 2.1.2H(2)O crystallizes in the orthorhombic space group Pbca with (at 298 K) a = 21.62(1) A, b = 13.33(1) A, c = 27.25(2) A, V = 7851(2) A(3), Z = 8. Compound 6.CH(3)OH.1.5H(2)O crystallizes in the monoclinic space group P2(1)/a with (at 298 K) a = 12.581(4) A, b = 14.204(5) A, c = 14.613(6) A, beta = 114.88(1) degrees, V = 2369(1), Z = 4. Compound 8.0.5CH(2)Cl(2) crystallizes in the orthorhombic space group Pca2(1) with (at 298 K) a = 23.072(2) A, b = 24.176(2) A, c = 13.676(1) A, V = 7628(2) A(3), Z = 8 with two crystallographically independent molecules per asymmetric unit. In addition to the synthesis and crystallographic studies, we report the optical, infrared, magnetic, conductivity, and CW EPR properties of these oxovanadium(IV) compounds as well as theoretical studies on [V(IV)O(bipy)(2)](2+) and [V(IV)OX(bipy)(2)](+/0) species (X = OH(-), SO(4)(2)(-), Cl(-)).     

Coordination algorithms control molecular architecture: [CuI4(L2)4]4+ grid complex versus [MII2(L2)2X4]y+ side-by-side complexes (M=Mn,Co, Ni,Zn; X=solvent or anion) and [FeII(L2)3][Cl3FeIIIOFeIIICl3

The synthesis and characterisation of a pyridazine-containing two-armed grid ligand L2 (prepared from one equivalent of 3,6-diformylpyridazine and two equivalents of p-anisidine) and the resulting transition metal (Zn, Cu, Ni, Co, Fe, Mn) complexes (1-9) are reported. Single-crystal X-ray structure determinations revealed that the copper(I) complex had self-assembled as a [2 x 2] grid, [Cu(I) (4)(L2)(4)][PF(6)](4).(CH(3)CN)(H(2)O)(CH(3)CH(2)OCH(2)CH(3))(0.25) (2.(CH(3)CN)(H(2)O)(CH(3)CH(2)OCH(2)CH(3))(0.25)), whereas the [Zn(2)(L2)(2)(CH(3)CN)(2)(H(2)O)(2)][ClO(4)](4).CH(3)CN (1.CH(3)CN), [Ni(II) (2)(L2)(2)(CH(3)CN)(4)][BF(4)](4).(CH(3)CH(2)OCH(2)CH(3))(0.25) (5 a.(CH(3)CH(2)OCH(2)CH(3))(0.25)) and [Co(II) (2)(L2)(2)(H(2)O)(2)(CH(3)CN)(2)][ClO(4)](4).(H(2)O)(CH(3)CN)(0.5) (6 a.(H(2)O)(CH(3)CN)(0.5)) complexes adopt a side-by-side architecture; iron(II) forms a monometallic cation binding three L2 ligands, [Fe(II)(L2)(3)][Fe(III)Cl(3)OCl(3)Fe(III)].CH(3)CN (7.CH(3)CN). A more soluble salt of the cation of 7, the diamagnetic complex [Fe(II)(L2)(3)][BF(4)](2).2 H(2)O (8), was prepared, as well as two derivatives of 2, [Cu(I) (2)(L2)(2)(NCS)(2)].H(2)O (3) and [Cu(I) (2)(L2)(NCS)(2)] (4). The manganese complex, [Mn(II) (2)(L2)(2)Cl(4)].3 H(2)O (9), was not structurally characterised, but is proposed to adopt a side-by-side architecture. Variable temperature magnetic susceptibility studies yielded small negative J values for the side-by-side complexes: J=-21.6 cm(-1) and g=2.17 for S=1 dinickel(II) complex [Ni(II) (2)(L2)(2)(H(2)O)(4)][BF(4)](4) (5 b) (fraction monomer 0.02); J=-7.6 cm(-1) and g=2.44 for S= 3/2 dicobalt(II) complex [Co(II) (2)(L2)(2)(H(2)O)(4)][ClO(4)](4) (6 b) (fraction monomer 0.02); J=-3.2 cm(-1) and g=1.95 for S= 5/2 dimanganese(II) complex 9 (fraction monomer 0.02). The double salt, mixed valent iron complex 7.H(2)O gave J=-75 cm(-1) and g=1.81 for the S= 5/2 diiron(III) anion (fraction monomer=0.025). These parameters are lower than normal for Fe(III)OFe(III) species because of fitting of superimposed monomer and dimer susceptibilities arising from trace impurities. The iron(II) centre in 7.H(2)O is low spin and hence diamagnetic, a fact confirmed by the preparation and characterisation of the simple diamagnetic iron(II) complex 8. M?ssbauer measurements at 77 K confirmed that there are two iron sites in 7.H(2)O, a low-spin iron(II) site and a high-spin diiron(III) site. A full electrochemical investigation was undertaken for complexes 1, 2, 5 b, 6 b and 8 and this showed that multiple redox processes are a feature of all of them.     

Solid- and solution-state studies of the novel mu-dicyanamide-bridged dinuclear spin-crossover system {[(Fe(bztpen)]2[mu-N(CN)2]}(PF6)3 x n H2O

The mononuclear diamagnetic compound {Fe(bztpen)[N(CN)2]}(PF6)CH3OH (1) (bztpen = N-benzyl-N,N',N'-tris(2-pyridylmethyl)ethylenediamine) has been synthesized and its crystal structure studied. Complex 1 can be considered to be the formal precursor of two new dinuclear, dicyanamide-bridged iron(II) complexes with the generic formula {[(Fe(bztpen)]2[mu-N(CN)2]}(PF6)3 x n H2O (n = 1 (2) or 0 (3)), which have been characterized in the solid state and in solution. In all three complexes, the iron atoms have a distorted [FeN6] octahedral coordination defined by a bztpen ligand and a terminal (1) or a bridging dicyanamide ligand (2 and 3). In the solid state, 2 and 3 can be considered to be molecular isomers that differ by the relative position of the phenyl ring of the two {Fe(bztpen)[N(CN)2]}+ halves (cis and trans, respectively). Depending on the texture of the sample, 2 exhibits paramagnetic behavior or displays a very incomplete spin transition at atmospheric pressure. Complex 3 undergoes a gradual two-step spin transition with no observed hysteresis in the solid state. Both steps are approximately 100 K wide, centered at approximately 200 K and approximately 350 K, with a plateau of approximately 80 K separating the transitions. The crystal structure of 3 has been determined in steps of approximately 50 K between 400 K and 90 K, which provides a fascinating insight into the structural behavior of the complex and the nature of the spin transition. Order-disorder transitions occur in the dicyanamide bridge and the PF6(-) ions simultaneously, with the spin-crossover behavior suggesting that these transitions may trigger the two-step character. In solution, 2 and 3 display very similar continuous spin conversions. Electrochemical studies of 2 and 3 show that the voltammograms are typical of dimeric systems with electronic coupling of the metals through the dicyanamide ligand.     

[NH3(CH2)5NH3][Fe2{O3PC(CH3)(OH)(PO3H)}2]@2H2O:一个新的二膦酸亚铁化合物的合成、结构与性质研究（英文）

通过水热合成得到一个新的有机二膦酸亚铁化合物[NH3(CH2)5NH3][Fe2Ⅱ(O3PC(CH3)(OH)(PO3H)}2]·2H2O,该化合物包含阴离子型共价双链[Fe2Ⅱ{O3PC(CH3)(OH)PO3H}2]n2n-,质子化的戊二胺和结晶水,双链之间通过强氢键构成一个开放型的骨架结构.另外,观察到亚铁离子之间存在弱铁磁性相互作用.     

Oxo-, hydroxo-, and peroxo-bridged Fe(III) phosphonate cages

A series of five Fe(III) phosphonate clusters with four different topologies is reported. The choice of coligand carboxylate plays an important role in directing the structure of the molecule. [Fe9(O)4(O2CCMe3)13(C10P)3] (1) and [Fe9(O)2(OH)(CO2Ph)10(C10P)6(H2O)2](CH3CN)7 (2; camphyl phosphonic acid, C10H17PO3H2 = C10PH2) represent two unprecedented nonanuclear Fe(III) cages having Fe9O4 and Fe9(O)2(OH) core structures, respectively. Whereas [Fe6O2(O)2(O2CCMe3)8(C10P)2 (H2O)2](CH3CN)4 (3) is a peroxo-bridged hexameric compound with an Fe6(O)2(O2) core. [Fe4(O)(O2CCMe3)4(C10P)3(Py)4](CH3CN)3 (4) and [Fe4(O)(O2CPh)4(C10P)3(Py)4](Py)3(CH3CN)2 (5; Py = pyridine) represents two tetranuclear clusters with the same Fe4O core structure.     

Ferrimagnetic Mixed-Valency and Mixed-Metal Tris(oxalato)iron(III) Compounds: Synthesis, Structure, and Magnetism

The synthesis and structural and magnetic characterization of 16 compounds AM(II)Fe(III)(C(2)O(4))(3) (A = N(n-C(3)H(7))(4), N(n-C(4)H(9))(4), N(n-C(5)H(11))(4), P(n-C(4)H(9))(4), P(C(6)H(5))(4), N(n-C(4)H(9))(3)(C(6)H(5)CH(2)), (C(6)H(5))(3)PNP(C(6)H(5))(3), As(C(6)H(5))(4); M(II) = Mn, Fe) are reported. X-ray powder diffraction profiles are indexed in R3c or its subgroup P6(5)22 or P6/mmm to derive unit cell constants. The structures of all the compounds consist of two-dimensional honeycomb networks [M(II)Fe(III)(C(2)O(4))(3)(-)](infinity). The M(II) = Fe compounds behave as ferrimagnets with T(c) between 33 and 48 K, but five exhibit a crossover from positive to negative magnetization near 30 K when cooled in a field of 10 mT. The compounds exhibiting this unusual magnetic behavior are those that have the highest T(c). Within the set N(n-C(n)()H(2)(n)()(+1))(4)Fe(II)Fe(III)(C(2)O(4))(3) (n = 3-5), T(c) increases with interlayer separation and the low-temperature magnetization changes from positive (n = 3) to negative (n = 4, 5). In the M = Mn(II) compounds, the in-plane cell parameter a(0) is approximately 0.03 ? greater than in the corresponding M = Fe(II) ones while the interlayer separation (c(0)/6) is on average 0.08 ? smaller. All members of the M(II) = Mn series have magnetic susceptibilities showing broad maxima at 55 K characteristic of two-dimensional antiferromagnetism, but the magnetization of several of the salts increases sharply below 27 K due to the onset of spin canting, the magnitude of which varies significantly with A.     

Unusual structural types in polynuclear iron chemistry from the use of N,N,N',N'-tetrakis(2-hydroxyethyl)ethylenediamine (edteH4): Fe5, Fe6, and Fe12 clusters

The syntheses, crystal structures, and magnetochemical characterization of five new iron clusters [Fe5O2(O2CPh)7(edte)(H2O)] (1), [Fe6O2(O2CBut)8(edteH)2] (2), [Fe12O4(OH)2(O2CMe)6(edte)4(H2O)2](ClO4)4 (3), [Fe12O4(OH)8(edte)4(H2O)2](ClO4)4 (4), and [Fe12O4(OH)8(edte)4(H2O)2](NO3)4 (5) (edteH4= N,N,N',N'-tetrakis(2-hydroxyethyl) ethylenediamine) are reported. The reaction of edteH4 with [Fe3O(O2CPh)6(H2O)3](NO3) and [Fe3O(O2CBut)6(H2O)3](OH) gave 1 and 2, respectively. Complex 3 was obtained from the reaction of edteH4 and NaO2CMe with Fe(ClO4)3, whereas 4 and 5 were obtained from the reaction of edteH4 with Fe(ClO4)3 and Fe(NO3)3, respectively. The core of 1 consists of a [Fe4(mu3-O)2]8+ butterfly unit to which is attached a fifth Fe atom by four bridging O atoms. The core of 2 consists of two triangular [Fe3(mu3-O)]7+ units linked together by six bridging O atoms. Finally, the cores of 3-5 consist of an [Fe12(mu4-O)4(mu-OH)2]26+ unit. Variable-temperature (T) and -field (H) solid-state direct and alternating current magnetization (M) studies were carried out on complexes 1-3 in the 1.8-300 K range. Analysis of the obtained data revealed that 1, 2, and 3-5 possess an S = 5/2, 5, and 0 ground-state spin, respectively. The fitting of the obtained M/N(muB) vs H/T data was carried out by matrix diagonalization, and this gave values for the axial zero-field splitting (ZFS) parameter D of -0.50 cm-1 for 1 and -0.28 cm-1 for 2.     

Tuning anisotropy barriers in a family of tetrairon(III) single-molecule magnets with an S = 5 ground state

Tetrairon(III) Single-Molecule Magnets (SMMs) with a propeller-like structure exhibit tuneable magnetic anisotropy barriers in both height and shape. The clusters [Fe4(L1)2(dpm)6] (1), [Fe4(L2)2(dpm)6] (2), [Fe4(L3)2(dpm)6].Et2O (3.Et2O), and [Fe4(OEt)3(L4)(dpm)6] (4) have been prepared by reaction of [Fe4(OMe)6(dpm)6] (5) with tripodal ligands R-C(CH2OH)3 (H3L1, R = Me; H3L2, R = CH2Br; H3L3, R = Ph; H3L4, R = tBu; Hdpm = dipivaloylmethane). The iron(III) ions exhibit a centered-triangular topology and are linked by six alkoxo bridges, which propagate antiferromagnetic interactions resulting in an S = 5 ground spin state. Single crystals of 4 reproducibly contain at least two geometric isomers. From high-frequency EPR studies, the axial zero-field splitting parameter (D) is invariably negative, as found in 5 (D = -0.21 cm(-1)) and amounts to -0.445 cm(-1) in 1, -0.432 cm(-1) in 2, -0.42 cm(-1) in 3.Et2O, and -0.27 cm(-1) in 4 (dominant isomer). The anisotropy barrier Ueff determined by AC magnetic susceptibility measurements is Ueff/kB = 17.0 K in 1, 16.6 K in 2, 15.6 K in 3.Et2O, 5.95 K in 4, and 3.5 K in 5. Both |D| and U(eff) are found to increase with increasing helical pitch of the Fe(O2Fe)3 core. The fourth-order longitudinal anisotropy parameter B4(0), which affects the shape of the anisotropy barrier, concomitantly changes from positive in 1 ("compressed parabola") to negative in 5 ("stretched parabola"). With the aid of spin Hamiltonian calculations the observed trends have been attributed to fine modulation of single-ion anisotropies induced by a change of helical pitch.