Syntheses of MSn(OH)6 by coprecipitation and of MSnO3 by thermal decomposition (M = Mg,Co, Zn,Mn, Cd,Ca, Sr,Ba)

MSn(OH)₆ (M = Mg, Co, Zn, Mn, Cd, Ca, Sr, and Ba) and their solid solutions were synthesized by coprecipitation from aqueous solutions of Na₂Sn(OH)₆ complex and MCl₂. MSnO₃ and their solid solutions were prepared by thermal decomposition of these MSn(OH)₆ precipitates. Coprecipitation procedures were established, and structures of MSn(OH)₆ and MSnO₃ were discussed in relation to mean radius of M²⁺ ions. The morphology of particles of these hydroxides and oxides were also observed. In order to obtain a single phase precipitate MSn(OH)₆, the concentration of both solutions of Na₂Sn(OH)₆ and MCl₂ had to be as low as 0.1 mol/l. The pH-value was kept above 11, and so acidic solution of MCl₂ was added slowly to basic solution of Na₂Sn(OH)₆. The structure of MSn(OH)₆ depended strongly of mean radius of M²⁺ ions, being cubic with NaCl-type arrangement of M²⁺ and Sn⁴⁺ cations below 1.26 Å and hexagonal above 1.26 Å. Crystalline MSnO₃ was obtained by the decomposition of MSn(OH)₆ precipitates above 500–600°C. The structure of MSnO₃ was also related with mean radius of M²⁺ ions closely, ilmenite-type below 1.09 Å and pervoskite-type above 1.14 Å. In perovskite-type structure, a gradual decrease in lattice distortion and rapid increase in crystal volume were observed with the increase in radius of M²⁺ ions. An interesting morphology change was observed from CaSn(OH)₆ precipitates to CaSnO₃, the particles with either cubic or flower-like appearance in hydroxide becoming porous in oxide without appreciable change in particle appearance.     

Über Hexafluorotitanate (IV): M11TiF6 mit M = Zn,Cd, Mn,Co, Ni

Hitherto unknown anhydrous GUINER patterns show that all these hexagonal compounds – except CdTiF₆ (LiSbF₆-structure type) – are isostructural with VF₃.     

Cyano-bridged hexanuclear Fe4M2 (M = Ni, Co, Mn) clusters: spin-canted antiferromagnetic ordering of Fe4Ni2 cluster

Heterobimetallic hexanuclear cyano-bridged complexes, [{Fe(Tp)(CN)3}4{M(MeCN)(H2O)2}(2)].10H2O.2MeCN [M = Ni (1), Co (2), Mn (3); Tp = hydrotris(1-pyrazolyl)borate], have been synthesized in H2O-MeCN solution. Complexes 1-3 are isostructural and hexanuclear with [{Fe(Tp)(CN)3}4{M(MeCN)(H2O)2}2] units linked by hydrogen bonds to form a 2D-structure in the solid state. Complex 1 is a canted antiferromagnet that undergoes a field-induced spin-flop-like transition at approximately 1 T and 2 K. At 4.45 K 1 has a transition to paramagnetic state of noninteracting S = 4 magnetic clusters. However, 2 and 3 show antiferromagnetic intracluster coupling. Facile loss of solvent from 2 alters the local symmetry resulting in changing the intracluster interaction from antiferro- to ferromagnetic.     

Inorganic-organic framework structures; M(II) ethylenediphosphonates (M = Co, Ni, Mn) and a Mn(II) ethylenediphosphonato-phenanthroline

The reaction of nickel, cobalt, and manganese with 1,2-ethylenediphosphonic acid or 1,2-ethylenediphosphonic acid and 1,10-phenanthroline under hydrothermal conditions resulted in the pillared layered structures Co2(H2O)2(O3PC2H4PO3) (I) and Ni2(H2O)2(O3PC2H4PO3) (II), which are isostructural to a zinc phase that has previously been characterized by X-ray powder methods. In addition, a 1D chain structure, Mn(HO3P(CH2)2PO3H)(H2O)2(C12H8N2) (III), and a pillared layered structure, Mn(HO3P(CH2)2PO3H) (IV), were obtained. The structures of these phases were solved by single-crystal X-ray diffraction methods. The crystallographic data are as follows: compound I P21/n (No. 14), a = 5.6500(11) A, b = 4.7800(10) A, c = 15.330(3) A, beta = 98.50(3) degrees, V = 409.47(14) A3, Z = 2; compound II P21/n (No. 14), a = 5.5807(11) A, b = 4.7205(9) A, c = 15.250(3) A, beta = 98.55(3) degrees, V = 397.28(13) A3, Z = 2; compound III C2/c (No. 15), a = 12.109(2) A, b = 15.328(3) A, c = 9.848(2) A, beta = 108.88(3) degrees, V = 1729.5(6) A3, Z = 4; compound IV P (No. 2), a = 5.498(5) A, b = 7.715(6) A, c = 8.093(7) A, alpha = 82.986(12) degrees, beta = 75.565(12) degrees, gamma = 80.582(12)degrees, V = 326.7(5) A3, Z = 2. Magnetic measurements show antiferromagnetic behavior below TN = 7 K for I and 13 K for II.     

FT-IR spectroscopic investigation of some Hofmann type complexes: M(1-phenylpiperazine)2Ni(CN)4 (M=Ni, Co, Cd, Pd or Mn)

New Hofmann type complexes in the form of M(pp)(2)Ni(CN)(4) (where pp=1-phenylpiperazine and M=Ni, Co, Cd, Pd or Mn) have been prepared in powder form and their infrared spectra have been reported in the range of (4000-400) cm(-1). The thermal behaviours of these complexes have been investigated by differential thermal analysis (DTA) and thermo-gravimetric analysis (TGA). Ni(pp)(2)Ni(CN)(4) complex has been examined via transmission electron microscope (TEM). The results suggest that these compounds are similar in structure to Hofmann type complexes and their structures consist of polymeric layers |M-Ni(CN)(4)|(infinity) with the pp molecule bounded to the metal atom (M).     

Phase Transitions in Crystalline [M(H2O)6](ClO4)2 (M=Mg,Mn, Fe,Co, Ni,Cu, Zn,Cd and Hg)

The results of DSC measurements in the temperature range 140–370 K on nine crystalline compounds of the type [M(H₂O)₆](ClO₄)₂, where M=Mg, Mn, Fe, Co, Ni, Cu, Zn, Cd and Hg, are discussed. Anomalies detected in the DSC curves are related to the existence of solid-solid phase transitions and/or to the melting points of these compounds. In consequence of two different hypothetical structural modifications of [Fe(H₂O)₆](ClO₄)₂, two DSC curves are obtained. For the compounds with M=Fe, Cd and Hg, new phase transitions have been discovered. The transition temperatures of the other phase transitions are in good agreement with literature data obtained by adiabatic calorimetry. For the compounds with M=Mg, Ni and Cd, DTA measurements were also carried out and the melting points of theses compounds were established. This revised version was published online in August 2006 with corrections to the Cover Date.     

Zur Polymorphie und Pseudosymmetrie der Hydrate MSeO3 · H2O (M = Mn,Co, Ni,Zn, Cd)

Polymorphic and Pseudosymmetrical Hydrates MSeO₃ · H₂O (M = Mn, Co, Ni, Zn, Cd) By crystallization from aqueous solutions of MSeO₃ and M(HSeO₃)₂, the selenites MSeO₃ · H₂O (M = Mn, Co, Ni, Zn, Cd) were obtained and characterized by means of X-ray diffraction and IR-spectroscopy. The crystal structure of ZnSeO₃ · H₂O was determined. The IR spectra indicate that the hydrates are isotypic and contain H₂O molecules of symmetry mm2. However, the X-ray data show different structure types with H₂O molecules of site symmetry m or 1. CdSeO₃ · H₂O and MnSeO₃ · H₂O are isotypic (o.rh., MnSeO₃ · D₂O type). CoSeO₃ · H₂O (mon.) as well as the isotypic NiSeO₃ · H₂O and ZnSeO₃ · H₂O (mon.) form new structure types. These findings are discussed on the basis of the crystal structure of ZnSeO₃ · H₂O (P2₁/n, a = 477.9(1), b = 1319.4(5), c = 570.1(1) pm, β = 90.84(2)°, Z = 4, D_x = 3.886 g · cm^?3, R = 0.035 for 722 reflections with I > 2σ₁) and the local pseudosymmetry of its components, i.e., layers [ZnSeO₃ · H₂O] of ZnO₆ octahedra sharing four equatorial vertices, SeO₃^2? anions and H₂O molecules.     

[MPy4(NCO)2]-2Py clathrates (M = M(II) = Mn,Fe, Co,Ni, Cu,Zn, Cd; Py = pyridine)

The title compounds form an iso structural series and are isomorphic with other [MPy₄X₂]-2Py clathrates (XRD, KM4 diffractometer, cell parameters and space group Ccca from 17–80 reflections). In the clathrate [NiPy₄(NCO)₂]-2Py studied in detail (XRD, CAD-4 diffractom eter, λCuK_α, Ω/2θ scan mode, θ_max = 78‡, 990 strong reflections, 104 parameters, R = 0.053), the host molecule has 222 symmetry, and the twofold axes run along the coordination bonds. The transoctahedral environment of nickel consists of six nitrogen atoms of four pyridine and two isocyanate ligands. The coordination polyhedron is slightly distorted due to changes in the bond lengths. The molecule has a propeller conformation. The guest molecules lie in the cavities of the crystal structure in conformity with the van der Waals type of packing. The host complex [NiPy₄(NCO)₂] (XRD, CAD-4 diffractometer, 4615 strong reflections, 560 parameters, R-0.037) crystallizes in the triclinic crystal system (space group P1) with two independent asymmetric molecules in the unit cell. The molecular structure is analogous to that in the ciathrate phase, but the coordination angles are severely distorted; one of the molecules acquires a distorted propeller conformation, and the other, a centrosvmmetric conformation, which is less favorable. While being structurally identical, the [MPy₄(NCO)₂]-2Py clathrates differ heavily in the properties. The first four complexes dissociate to host complexes, and their thermal stability changes in the sequence Mn< Fe< Co< Ni; the Cu and Zn clathrates decompose in one step to dipyridine complexes with decomposition of host complexes. Decomposition of the Cd ciathrate follows one of these patterns depending on conditions. The results are compared with those for other known systems. Synthetic procedures are given. Translated fromZhurnal Strukturnoi Khimii, Vol. 40, No. 5, pp. 935–953, September–October, 1999.     

NaM2OH(SO3)2 · 1 H2O mit M = Mg,Mn, Fe,Co, Ni und Zn Ein neuer Typ basischer Sulfite

NaM₂OH(SO₃)₂ · 1 H₂O with M = Mg, Mn, Fe, Co, Ni, and Zn. A New Class of Basic Sulfites Hitherto unknown hydroxide sulfites of the type NaM₂OH(SO₃)₂ · 1 H₂O with M = Mg, Mn, Fe, Co, Ni, and Zn have been obtained by crystallization from aqueous sulfite solutions containing Na⁺ and M²⁺ ions. Crystal structure, IR and Raman data, and the results of thermoanalytical studies are reported and discussed. The hydroxide sulfites show a strongly anisotropic thermal expansion due to the layer structure and exhibit an unusually high thermal stability compared to other solid hydrates. The magnesium compound, for example, decomposes at 355°C. The crystal data of the triclinic compounds see “Inhaltsübersicht”.     

半水榴石型化合物Sr_6Sb_4M_3O_(14)(OH)_(10)(M=Co,Mn)的合成、结构与性质

在强碱性水热条件下合成了两种新化合物Sr6Sb4Co3O14(OH)10(SSC)与Sr6Sb4Mn3O14(OH)10(SSM).采用粉末X射线衍射数据,通过Rietveld方法进行了结构分析,讨论了金属离子的拓扑结构.两种化合物均为石榴石-水榴石相关结构,空间群I43d,晶胞参数a分别为1.30634(2)nm(SSC)和1.31367(1)nm(SSM).结构中,SbO6八面体与MO4(M=Co,Mn)四面体共顶点连接,Sb5+-M2+(M=Co,Mn)离子表现为ctn即C3N4型的拓扑结构.拓扑结构中,Sb5+为三连接,过渡金属离子M2+(M=Co,Mn)为四连接.Sb5+离子的拓扑结构为体心立方,而M2+(M=Co,Mn)分布呈类风扇状,相互连接形成thp型拓扑结构(即Th3P4中Th原子之间连接关系).过渡金属离子的分布与化合物表现出的磁性质密切相关,Co2+(Mn2+)间存在反铁磁相互作用.Sr6Sb4Co3O14(OH)10在低温下表现出反铁磁倾斜有序.Sr6Sb4Co3O14(OH)10和Sr6Sb4Mn3O14(OH)10在高温下发生分解,产物主相为双钙钛矿Sr2(Sb,M)2O6(M=Co,Mn).     

Symmetry-breaking substitutions of [Re(CN)8]3- into the centered, face-capped octahedral clusters (CH3OH)24M9M'6(CN)48 (M = Mn, Co; M = Mo, W)

The diamagnetic complex [Re(CN)8]3- is shown to react with Mn2+ ions in methanol to generate the centered, face-capped octahedral cluster (CH3OH)24Mn9Re6(CN)48, which is structurally analogous to (CH3OH)24Mn9Mo6(CN)48. Related reactions involving stoichiometric mixtures of octacyanometalate complexes generate the substituted species (CH3OH)24Mn9Mo5Re(CN)48, (CH3OH)24Co9Mo5Re(CN)48, (CH3OH)24Mn9Mo3Re3(CN)48, (CH3OH)24Mn9W5Re(CN)48 and (CH3OH)24Co9W5Re(CN)48, in which the O(h) symmetry of the cluster core is broken. Reassessment of the magnetic properties of the Mn9Mo6(CN)48 cluster confirm that it possesses a ground state spin of S = 39/2, but does not exhibit single-molecule-magnet behavior. Lowering the symmetry of the molecule by substitutions of ReV at one or three of the MoV sites does not lead to an overall increase in the magnetic anisotropy, as probed by ac magnetic susceptibility measurements. A similar result occurs for the other substituted species, with the important exception of the new single-molecule magnet (CH3OH)24Co9W5Re(CN)48, for which the spin reversal barrier is significantly reduced relative to that observed previously in (CH3OH)24Co9W6(CN)48.     

First-principles study on MRh12 (M = Rh, Fe, Co, AND Ni) clusters

In this paper, a first-principles study on the stability, electronic and magnetic properties of MRh₁₂ (M = Rh, Fe, Co and Ni) clusters is performed. By optimizing the geometrical structure, we find that MRh₁₂ clusters change from a perfect icosahedron to a distorted structure and have an obvious bond length contraction as compared with the corresponding bulk phase; FeRh₁₂, CoRh₁₂, and NiRh₁₂ clusters are more energetically stable than the RhRh₁₂ cluster. The effect of the impurity M on the density of states, valence band width, HOMO and LUMO for MRh₁₂ clusters is not significant, but when the central Rh atom is substituted with M, the magnetic moment of MRh₁₂ reduces dramatically. The Mulliken population analysis indicates that there are more charge transfers from other orbitals to Rh4d and M3d orbitals, and the spd hybrid effect in d orbitals of MRh₁₂ clusters is stronger than that in the RhRh₁₂ cluster. this situation means that the unpaired d electrons have more chance to be paired, and the magnetic moments of MRh₁₂ clusters can be reduced reasonably.     

Retrieval of thermodynamic properties of M(OH)2 (M=Mn,Ni and Cd) phases from hydrothermal phase equilibria of MO-H2O systems

The standard thermodynamic properties of M(OH)₂ (M=Mn, Ni and Cd) solid phases have been retrieved using a graphical approach based on the already reportedP vs. T curves obtained from hydrothermal studies of MO-H₂O systems. This approach avoids the use of heat capacity effects. The values retrieved by this modified approach are in good agreement with the calorimetric values.

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Zusammenfassung Basierend auf unlängst beschriebenen, aus hydrothermischen Untersuchungen von MO-H₂O Systemen gewonnenenp-T Kurven wurden mittels einer graphischen Näherung die thermodynamischen Standardeigenschaften von M(OH)₂ Festphasen (M=Mn, Ni und Cd) bestimmt. Dieses Verfahren umgeht den Gebrauch von Wärmekapazitätseffekten. Die durch dieses modifizierte Verfahren erhaltenen Werte stehen in guter Übereinstimmung mit den kalorimetrischen Werten.

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- , O-H₂O, M(OH)₂, M=, . . .

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The authors express their grateful thanks to Prof. V. Venkatachalapathy, Director of the Minerological Institute, for his encouragement during the course of this work.     

Weak M(II)-azide-4,4'-bipy ferromagnets based on unusual diamondoid (M = Mn) and 2D arrays (M = Co, Ni)

Four compounds of general formula [M(4,4'bipy)(N(3))2](n) (M = Mn (1), Zn (2), Co (3), Ni (4)) have been synthesized and magnetostructurally characterized by means of X-ray diffraction analysis, IR and ESR spectroscopies, and measurements of the magnetic susceptibility and magnetization. Compound 1 (C(10)H(8)N(8)Mn) crystallizes in the tetragonal P4(3)2(1)2 space group, Z = 4, with a = 8.229(2), b = 8.229(2), and c = 16.915(2) A. It exhibits an acentric 3D structure where Mn(II) ions are linked through EE-azide groups resulting in a diamondoid network. The 4,4'bipy ligands are coordinated on the axial positions of the octahedral spheres reinforcing the intermetallic connections. Weak ferromagnetism arising from spin canting is observed for compound 1. Compounds 2, 3, and 4 are proposed to be isomorphous and would consist of a 2D array where alternating EO + EE/EO + EE/EO + EO azide-chains are linked by 4,4'bipy ligands resulting in pi-pi stacked pyridyl-columns. The azido ligand dispositions in compounds 3 and 4 make possible systems of type -AF-AF-F-, which would give rise to a topological ferromagnetic behavior.     

Magneto-structural studies on heterobimetallic malonate-bridged M(II)Re(IV) complexes (M = Mn, Co, Ni and Cu)

The mononuclear Re(IV) compound of formula (PPh(4))(2)[ReBr(4)(mal)] (1) was used as a ligand to obtain the heterobimetallic species [ReBr(4)(μ-mal)Co(dmphen)(2)]· MeCN (2), [ReBr(4)(μ-mal)Ni(dmphen)(2)] (3), [ReBr(4)(μ-mal)Mn(dmphen)(2)] (4a), [ReBr(4)(μ-mal)Mn(dmphen)(H(2)O)(2)]·dmphen·MeCN·H(2)O (4b), [ReBr(4)(μ-mal)Cu(phen)(2)]·1/4H(2)O (5) and [ReBr(4)(μ-mal)Cu(bipy)(2)] (6) (mal = malonate dianion, dmphen = 2,9-dimethyl-1,10-phenanthroline, phen = 1,10-phenanthroline and bipy = 2,2'-bipyridine). The structures of 2 and 5 (single-crystal X-ray diffraction) are made up of neutral [ReBr(4)(μ-mal)M(AA)] dinuclear units [AA = dmphen with M = Co (2) and AA = phen with M = Cu (5)] where the metal ions are connected through a malonate ligand which exhibits simultaneously the bidentate [at the Re(IV)] and monodentate [at the M(II)] coordination modes. The carboxylate-malonate group in them adopts the anti-syn conformation with intramolecular ReM separation of 5.098(8) (2) and 4.947(2) ? (5). The magnetic properties of 1-6 were investigated in the temperature range 1.9-295 K. The magnetic behaviour of 1 is the expected for a magnetically isolated Re(IV) complex with a large value of the zero-field splitting (2D ca. -70 cm(-1)) whereas weak antiferromagnetic interactions between Re(IV) and M(II) are observed in the heterobimetallic compounds 2 (J = -0.63 cm(-1)), 3 (J = -1.37 cm(-1)), 4a (J = -1.29 cm(-1)), 5 (J = -1.83 cm(-1)) and 6 (J = -0.26 cm(-1)). Remarkably, 4b behaves as a ferrimagnetic chain with regular alternating Re(IV) and Mn(II) cations (J = -2.64 cm(-1)).     

Cyano-bridged pentanuclear Fe(III)3M(II)2 (M = Ni, Co, Fe) clusters: synthesis, structures, and magnetic properties

The reactions of [M(II)(Tpm(Me))(H2O)3]2+ (M = Ni, Co, Fe; Tpm(Me) = tris(3,5-dimethyl-1-pyrazoyl)methane) with [Bu4N][(Tp)Fe(III)(CN)3] (Bu4N+ = tetrabutylammonium cation; Tp = tris(pyrazolyl)hydroborate) in MeCN-Et2O afford three pentanuclear cyano-bridged clusters, [(Tp)3(Tpm(Me))2Fe(III)3M(II)2(CN)9]ClO4.15H2O (M = Ni, 1; M = Co, 2) and [(Tp)3(Tpm(Me))2Fe(III)3Fe(II)2(CN)9]BF4.15H2O (3). Single-crystal X-ray analyses reveal that they show the same trigonal bipyramidal structure featuring a D3h-symmetry core, in which two opposing Tpm(Me)-ligated M(II) ions situated in the two apical positions are linked through cyanide bridges to an equatorial triangle of three Tp-ligated Fe(III) (S = 1/2) centers. Magnetic studies for complex 1 show ferromagnetic coupling giving an S = 7/2 ground state and an appreciable magnetic anisotropy with a negative D(7/2) value equal to -0.79 cm(-1). Complex 2 shows zero-field splitting parameters deducted from the magnetization data with D = -1.33 cm(-1) and g = 2.81. Antiferromagnetic interaction was observed in complex 3.     

FT-IR Spectroscopic Study of M(1,2-Ethanedithiol)Ni(CN)4·Benzene (M=Co,Cd) Clathrates

New Hofmann-ethanedithiol-type clathrates, M(1,2-Ethanedithiol)Ni(CN)₄·Benzene (M=Cd,Co), have been obtained in the powdered form. By vibrational spectroscopy of these two new compounds, it is exhibited that their structures are similar to those of the other Hofmann-type clathrates.