Synthesis, Crystal Structures, and Optical and Magnetic Properties of Samarium, Terbium, and Erbium Coordination Entities Containing Mono-Substituted Imine Silsesquioxane Ligands.

Mono-substituted cage-like silsesquioxanes of the T8-type can play the role of potential ligands in the coordination chemistry. In this paper, we report on imine derivatives as ligands for samarium, terbium, and erbium cations and discuss their efficient synthesis, crystal structures, and magnetic and optical properties. X-ray analysis of the lanthanide coordination entities [MCl3(POSS)3]·2THF [M = Er3+ (3), Tb3+ (4), Sm3+ (5)] showed that all three compounds crystallize in the same space group with similar lattice parameters. All compounds contain an octahedrally coordinated metal atom, and additionally, 3 and 5 structures are strictly isomorphous. However, surprisingly, there are two different molecules in the crystal structure of the terbium coordination entity 4, monomer (sof 65%) and dimer (sof 35%), with one and two metal centers. Absorption measurements of the investigated materials recorded at 300 K showed that regardless of the lanthanide involved, their energy band gap equals 2.7 eV. Moreover, the analogues containing Tb3+ and Sm3+ exhibit luminescence typical of these rare earth ions in the visible and infrared spectral range, while the compound with Er3+ does not generate any emission. Direct current variable-temperature magnetic susceptibility measurements on polycrystalline samples of 3-5 were performed between 1.8 and 300 K. The magnetic properties of 3 and 4 are dominated by the crystal field effect on the Er3+ and Tb3+ ions, respectively, hiding the magnetic influence between the magnetic cations of adjacent molecules. Complex 5 exhibits a nature typical for the paramagnetism of the samarium(III) cation.

Heterometallic 3d-4f Alkoxide Precursors for the Synthesis of Binary Oxide Nanomaterials.

In this study, a new method for the synthesis of heterometallic 3d-4f alkoxides by the direct reaction of metallic lanthanides (La, Pr, Nd, Gd) with MCl2 (M = Mn, Ni, Co) in 2-methoxyethanol was developed. The method was applied to the synthesis of the heterometallic oxo-alkoxide clusters [Ln4Mn2(µ6-O)(µ3-OR)8(HOR)xCl6] (Ln = La (1), Nd (2), Gd (3); x = 0, 2, 4); [Pr4M2(µ6-O)(µ3-OR)8(HOR)xCl6] (M = Co (4), Ni (5); x = 2, 4); and [Ln4Mn2(µ3-OH)2(µ3-OR)4(µ-OR)4(µ-Cl)2(HOR)4Cl6] (Ln = La (11) and Pr (12)). Mechanistic investigation led to the isolation of the homo- and heterometallic intermediates [Pr(µ-OR)(µ-Cl)(HOR)Cl]n (6), [Co4(µ3-OR)4(HOR)4Cl4] (7), [Ni4(µ3-OR)4(HOEt)4Cl4] (8), [Mn4(µ3-OR)4(HOR)2(HOEt)2Cl4] (9), and [Nd(HOR)4Cl][CoCl4] (10). In the presence of an external M(II) source at 1100 °C, 1-4 and 12 were selectively converted into binary metal oxide nanomaterials with trigonal or orthorhombic perovskite structures, i.e., LaMnO3, GdMnO3, NdMnO3, Pr0.9MnO3, and PrCoO3. Compound 5 decomposed into a mixture of homo- and heterometallic oxides. The method presented provides a valuable platform for the preparation of advanced heterometallic oxide materials with promising magnetic, luminescence, and/or catalytic applications.

Use of group 13 aryloxides for the synthesis of green chemicals and oxide materials.

In this work, group 13 metal aryloxides [Al(MesalO)3] (1), [Me2Ga(MesalO)]2 (2), [AlLi3(MesalO)6] (3) and [Me2GaLi(MesalO)2(THF)] (4) were obtained by the reaction of methyl salicylate (MesalOH) with group-13 alkyls MMe3 (for M = Al, Ga) or their combination with BuLi in a THF/alcohol solution. The direct reaction of MMe3 (for M = Al, Ga) and MesalOH (1 : 3) led to compound 1 or 2, respectively. When the same reactions were carried out with additional BuLi, the heterometallic compound 3 or the mixture of 4 and [Li6(MesalO)6] (5) was obtained. Compounds 1-5 were used for the chemical conversion of glycerol to α-hydroxy acid glyceryl esters by alcoholysis of L-lactide (L-LA), glycolide (GA), and ε-caprolactone (ε-CL). Compounds 1-5 were also efficient initiators for the ring-opening polymerization (ROP) of L-LA, GA, and ε-CL using glycerol as a branching agent to synthesize 3-arm polyesters. Heterometallic compounds 3 and 4 were attractive molecular precursors for the preparation of group 13-lithium ceramics, i.e. γ-LiAlO2 and ß-LiGaO2.

Polyoxometalate-like structure of new potassium triphenylsiloxides: [K6(OSiPh3)6(C3H7OH)(H2O)]·2C6H5CH3 and [K6(OSiPh3)6(H2O)2].

The synthesis and structural characterization of two new potassium triphenylsiloxides, namely, aqua(propan-2-ol)hexakis(triphenylsilanolato)hexapotassium toluene disolvate, [K6(C18H15OSi)6(C3H8O)(H2O)]·2C7H8, and diaquahexakis(triphenylsilanolato)hexapotassium, [K6(C18H15OSi)6(H2O)2], are reported. Both compounds crystallize in the triclinic space group P-1. The structure in each case resembles an alkali metal polyoxometalate-like structure, in which electrostatic interactions are observed in the metal-oxygen core. Furthermore, both compounds also resemble a reverse micelles-like architecture, in which the hydrophilic core is enclosed in a hydrophobic shell. The cores of the complexes are flanked by hydrophobic aromatic rings derived from Ph3SiO- anions, where intramolecular π-interactions between the aromatic rings and potassium cations stabilize the cores of the crystals. Moreover, in both structures, the presence of hydrogen bonds is observed; until now, no crystal structures have been described containing K atoms and triphenylsiloxide molecules in which the presence of hydrogen bonds was confirmed. Thus, these coordination entities could be considered as attractive reagents for further synthetic protocols towards heterometallic complexes.

Synthesis, Crystal Structures, and Spectroscopic Properties of Novel Gadolinium and Erbium Triphenylsiloxide Coordination Entities.

In alkali metal and lanthanide coordination chemistry, triphenylsiloxides seem to be unduly underappreciated ligands. This is as surprising as that such substituents play a crucial role, among others, in stabilizing rare oxidation states of lanthanide ions, taking a part of intramolecular and molecular interactions stabilizing metal-oxygen cores and many others. This paper reports the synthesis and characterization of new lithium [Li4(OSiPh3)4(THF)2] (1), and sodium [Na4(OSiPh3)4] (2) species, which were later used in obtaining novel gadolinium [Gd(OSiPh3)3(THF)3]·THF (3), and erbium [Er(OSiPh3)3(THF)3]·THF (4) configuration, it can result in res were determined for all 1-4 compounds, and in addition, IR, Raman, absorption spectroscopy studies were conducted for 3 and 4 lanthanide compounds. Furthermore, direct current (dc) variable-temperature magnetic susceptibility measurements on polycrystalline samples of 3 and 4 were carried out in the temperature range 1.8-300 K. The 3 shows behavior characteristics for the paramagnetism of the Gd3+ ion. In contrast, the magnetic properties of 4 are dominated by the crystal field effect on the Er3+ ion, masking the magnetic interaction between magnetic centers of neighboring molecules.

Heterometallic Group 4-Lanthanide Oxo-alkoxide Precursors for Synthesis of Binary Oxide Nanomaterials.

In this study, an efficient procedure for the synthesis of uncommon group 4-lanthanide oxo-alkoxide derivatives was developed. Heterometallic clusters with the structures [La2Ti4(µ4-O)2(µ3-OEt)2(µ-OEt)8(OEt)6(Cl)2(HOEt)2] (1), [La2Zr2(µ3-O)(µ-OEt)5(µ-Cl)(OEt)2(HOEt)4(Cl)4]n (2), [La2Hf2(µ3-O)(µ-OEt)5(µ-Cl)(OEt)2(HOEt)4(Cl)4]n (3), [Nd2Ti4(µ4-O)2(µ3-OEt)2(µ-OEt)8(OEt)6(HOEt)2(Cl)2] (4), [Nd4Zr4(µ3-O)2(µ-OEt)10(µ-Cl)4(OEt)8(HOEt)10(Cl)2] (5), and [Nd4Hf4(µ3-O)2(µ-OEt)10(µ-Cl)4(OEt)8(HOEt)10(Cl)2] (6) were synthesized via the reaction of a metallocene dichloride, Cp2M'Cl2 (where M' = Ti, Zr, and Hf), and metallic lanthanum or neodymium in the presence of excess ethanol. This procedure gave crystalline precursors with molecular stoichiometries suitable for obtaining group 4-lanthanide oxide materials. Compounds 1-6 were examined by analytical and spectroscopic techniques and single-crystal X-ray diffraction. The magnetic properties of 5 and 6 were investigated by using direct and alternating current (dc and ac) susceptibility measurements. The results indicated weak antiferromagnetic interactions between NdIII ions and a field-supported slow magnetic relaxation. Lanthanum-titanium compound 1 decomposed at 950 °C to give the perovskite compound La0.66TiO3 and small amounts of rutile TiO2. Under the same conditions, 4 decomposed to give a mixture of Nd4Ti9O24 and Nd0.66TiO3. When 4 was calcined at 1300 °C, decomposition of Nd4Ti9O24 to Nd0.66TiO3 and TiO2 was observed. Calcination of 2, 3, 5, and 6 at 950-1500 °C led to the selective formation of heterometallic La2Zr2O7, La2Hf2O7, Nd2Zr2O7, and Nd2Hf2O7 phases, respectively.

Convenient Route to Heterometallic Group 4-Zinc Precursors for Binary Oxide Nanomaterials.

In this study, simple and efficient synthetic routes to a family of uncommon group 4-zinc heterometallic alkoxides were developed. Single-source molecular precursors with the structures [Cp2TiZn(µ,η-OR)(THF)Cl2] (1), [Zr3Zn7(µ3-O)(µ3,η2-OR)3(µ-OH)3(µ,η2-OR)6(µ,η-OR)6Cl6] (2), and [Hf3Zn7(µ3-O)(µ3,η2-OR)3(µ-OH)3(µ,η2-OR)6(µ,η-OR)6Cl6] (3) were prepared via reduction of Cp2TiCl2 with metallic zinc or protonolysis of the metal-cyclopentadienyl bond in Cp2M'Cl2 (M' = Zr or Hf) in the presence of 2-methoxyethanol (ROH) and Zn(OR)2. This synthetic route enables the creation of compounds with well-defined molecular structures and therefore provides precursors suitable for obtaining group 4-zinc oxides. Precursors 1-3 were characterized by elemental analysis, nuclear magnetic resonance and infrared spectroscopies, and single-crystal X-ray diffraction. Compound 1 decomposed at 800-900 °C to give a mixture of binary metal oxides (i.e., Zn2Ti3O8, ZnTiO3, or Zn2TiO4) and common polymorphs of TiO2 and ZnO. After calcination at 1000 °C, only TiO2 and the high-temperature-stable phase Zn2TiO4 were observed. Thermolysis of compounds 2 and 3 gave mixtures of ZnO and ZrO2 or HfO2, respectively. The obtained ZnO-ZrO2 and ZnO-HfO2 mixed oxide materials have constant phase compositions across a broad temperature range and therefore are attractive host lattices for Eu3+ for applications as yellow/red double-light-emitting phosphors. It was established that Eu3+ ions were successfully introduced into the ZnO and ZrO2/HfO2 lattices. It was revealed that Eu3+ ions prefer to occupy low-symmetry sites in ZrO2/HfO2 rather than in ZnO.

Molecular Routes to Group IV Magnesium and Calcium Nanocrystalline Ceramics.

The effect of alkaline-earth-metal alkoxides on the protonolysis of Cp2M'Cl2 (M' = Ti, Zr, Hf; Cp = cyclopentadiene) was investigated. This approach enabled the design of compounds with well-defined molecular structures to generate high-purity binary metal oxides. Single-source molecular precursors with structures of [M2M'2(µ3-OEt)2(µ-OEt)4(OEt)6(EtOH)4] with M = Mg and M' = Ti (1), Zr (2), and Hf (3), [Ca6Ti4(µ6-O)2(µ4-O)2(µ3-OEt)12(OEt)12(EtOH)6Cl4] (4), and [M2M'2(µ4-O)(µ-OEt)5(OEt)4(EtOH)4Cl]n with M = Ca and M' = Zr (5) and Hf (6) were prepared via elimination of the cyclopentadienyl ring from Cp2M'Cl2 as CpH in the presence of M(OEt)2 and ethanol (EtOH) as a source of protons. Meanwhile, similar reactions involving the initial substitution of Cl ligands by OEt groups in Cp2M'Cl2 (M' = Ti, Zr, Hf) resulted in the formation of [M2M'2(µ3-OEt)2(µ-OEt)4(OEt)6(EtOH)4] with M = Ca and M' = Ti (7), Zr (8), and Hf (9). The precursors were characterized by elemental analysis, NMR spectroscopy, and single-crystal X-ray structural analysis. Magnesium compounds 1-3 decomposed at 750-850 °C to give MgTiO3 along with small amounts of Mg2TiO4, Mg2Zr5O12, or Mg2Hf5O12 binary metal oxides. The thermolysis of calcium compounds 4 and 7-9 led to highly pure CaTiO3, CaZrO3, or CaHfO3 perovskite-like oxide particles with diameters of 20-30 nm.

Impact of Group 13 Metals on Cp2TiCl2 Reduction and Structural Characterization of Resulting Compounds.

The aim of the current study was to examine the effects of group 13 metals on Cp2TiCl2 reduction in the presence of 2-methoxyethanol (MeOEtOH) or ethanol (EtOH) and the compositions of the resulting products. Direct reaction of Cp2TiCl2 and M [Al, Al (Fe contaminated), Ga, In] in toluene/alcohol for 2 h gave a new family of uncommon homo- and heterometallic compounds: [Cp2Ti2Al(µ,η2-OEtOMe)4Cl2][Ti2(µ,η2-OEtOMe)3(η2-OEtOMe)2Cl4] (1), [Cp2Ti2Al(µ,η2-OEtOMe)4Cl2]Cl (2), [Cp2Ti2Al(µ,η2-OEtOMe)4Cl2][Cp2Ti(η2-HOEtOMe)][FeCl4] (3), [Cp2Ti(η2-HOEtOMe)][Ga2Cl6]0.25[Cl]0.5 (4), [Cp3Ti2(µ-OEt)2(OEt)][GaCl4] (5), [CpTi(µ,η2-OEtOMe)Cl]2 (6), and [Cp3Ti2(µ,η2-OEtOMe)(µ-OEtOMe)Cl] (7). The reaction with indium for 48 h resulted in isolation of [TiIn2(µ,η2-OEtOMe)4(OEtOMe)2Cl4] (8), [In2(µ-OEtOMe)2(HOEtOMe)4Cl4]2 (9), and [Ti(OEtOMe)4] (10). The complexes were characterized using elemental analysis, IR and NMR spectroscopies, and, for 1-9, single-crystal X-ray diffraction. The use of metallic gallium and indium to reduce Cp2TiCl2 opens up a previously unexplored path that may provide access to novel and unique compounds.

Unexpected Reactions between Ziegler-Natta Catalyst Components and Structural Characterization of Resulting Intermediates.

In this work, we investigated precursors and procatalysts with well-defined crystal structures and morphologies in Ziegler-Natta systems to improve our understanding of the nature of the active metal sites. Molecular cluster precursors such as [Mg4Ti3(µ6-O)(µ3-OH)3(µ-OEt)9(OEt)3(EtOH)3Cl3], [Mg4Ti3(µ6-O)(µ3-OH)(µ3-OEt)2(µ-OEt)9(OEt)3(EtOH)3Cl3], and [Mg6Ti4(µ6-O)2(µ3-OH)4(µ-OEt)14(OEt)4(EtOH)2Cl2] were prepared via simple elimination of the cyclopentadienyl ring from Cp2TiCl2 as CpH in the presence of magnesium metal and ethanol. Titanocene dichloride acts as both a source of titanium and a magnesium-chlorinating agent. The resulting novel complexes were characterized using single-crystal X-ray diffraction. In these compounds, Ti(OEt)4 molecules are grafted onto Mg4 and Mg6 ethoxide cubane-like surfaces; this strongly affects the procatalyst morphology, which is transferred to the polymer. Mg4(OR)8 units act as carriers for the AlR3 co-catalyst, resulting in return of alkyl functions to the Ti center.

Crystal structure of a mixed-ligand dinuclear Ba-Zn complex with 2-meth-oxy-ethanol having tri-phenyl-acetate and chloride bridges.

The dinuclear barium-zinc complex, µ-chlorido-1:2κ(2) Cl:Cl-chlorido-2κCl-bis-(2-meth-oxy-ethanol-1κO)bis-(2-meth-oxy-ethanol-1κ(2) O,O')bis-(µ-tri-phenyl-acetato-1:2κ(2) O:O')bariumzinc, [BaZn(C20H15O2)2Cl2(C3H8O2)4], has been synthesized by the reaction of barium tri-phenyl-acetate, anhydrous zinc chloride and 2-meth-oxy-ethanol in the presence of toluene. The barium and zinc metal cations in the dinuclear complex are linked via one chloride anion and carboxyl-ate O atoms of the tri-phenyl-acetate ligands, giving a Ba⋯Zn separation of 3.9335 (11) Å. The irregular nine-coordinate BaO8Cl coordination centres comprise eight O-atom donors, six of them from 2-meth-oxy-ethanol ligands (four from two bidentate O,O'-chelate inter-actions and two from monodentate inter-actions), two from bridging tri-phenyl-acetate ligands and one from a bridging Cl donor. The distorted tetra-hedral coordination sphere of zinc comprises two O-atom donors from the tri-phenyl-acetate ligands and two Cl donors (one bridging and one terminal). In the crystal, O-H⋯Cl, O-H⋯O and C-H⋯Cl inter-molecular inter-actions form a layered structure, lying parallel to (001).

Transformation of barium-titanium chloro-alkoxide compound to BaTiO3 nanoparticles by BaCl2 elimination.

In this Article, we present how the molecular precursor of binary oxide material having an excess of alkali earth metal can be transformed to the highly phase pure BaTiO3 perovskite. Here, we synthesized and compared two barium-titanium complexes with and without chloride ligands to determine the influences of different ligands on the phase purity of binary oxide nanoparticles. We prepared two barium-titanium complexes, i.e., [Ba4Ti2(µ6-O)(OCH2CH2OCH3)10(HOCH2CH2OCH3)2(HOOCCPh3)4] (1) and [Ba4Ti2(µ6-O)(µ3,η2-OCH2CH2OCH3)8(µ-OCH2CH2OCH3)2(µ-HOCH2CH2OCH3)4Cl4] (2). The barium-titanium precursors were characterized using elemental analysis, infrared and nuclear magnetic resonance spectroscopies, and single-crystal X-ray structural analysis, and their thermal decomposition products were compared. The complex 1 decomposed at 800 °C to give a mixture of BaTiO3 and Ba2TiO4, whereas 2 gave a BaCl2/BaTiO3 mixture. Particles of submicrometer size (30-50 nm) were obtained after leaching of BaCl2 from the raw powder using deionized water. Preliminary studies of barium titanate doped with Eu(3+) sintered at 900 °C showed that the dominant luminescence band arose from the strong electric dipole transition, (5)D0-(7)F2.

Design of a magnesium-pridinolum complex for polylactide-drug conjugates formation.

Polylactide conjugates of the muscle contraction agent Pridinolum (PriOH = 1,1-diphenyl-3-(1-piperidinyl)-1-propanol) were prepared directly by ring-opening polymerization of L-lactide (L-LA) mediated by the pridinolum magnesium complex [Mg(µ,η(2)-OPri)(η(1)-OPri)](2). The ancillary O,N - bifunctional drug as a ligand stabilizes the magnesium species and initiates L-LA polymerization affording a polymer chain terminated by covalently attached drug molecules to the PLLA through ester linkers to form PriO-PLLA conjugate. Up to 80% of the pridinolum can be released from the conjugate by treatment with deuterated hydrochloric acid DCl at pH = 1.5 for 10 h at 37 °C.

Titanocene as a precursor for a cyclopentadienyl-free titanium(III)-manganese(II) cluster: a new approach for nano-size materials.

A simple and unique route to access the heterometallic cluster [Mn4Ti4(micro-Cl)2(micro3,eta2-L)2(micro,eta2-L)10Cl6] (1) with two Mn2Ti2 butterfly core motifs is reported. This method comprises elimination of the Cp ring from Cp2TiCl2 as CpH in the presence of metallic Mn in 2-methoxoethanol (LH) as a proton source. Complex 1 belongs to a group of magnetic clusters, which consists of two weakly interacting M4 subunits.

Cyclopentadienyl/alkoxo ligand exchange in group 4 metallocenes: a convenient route to heterometallic species.

A simple and efficient strategy for the synthesis of nonorganometallic heterometallic clusters from cheap organometallic precursors is reported. This unique synthetic method involves elimination of the cyclopentadienyl ring from Cp(2)MCl(2) (M = Ti, Zr, Hf) as CpH in the presence of M'L(2) or M'L'(2) (M' = Ca, Sr, Mn; CH(3)OCH(2)CH(2)OH = LH or (CH(3))(2)NCH(2)CH(2)OH = L'H) in an alcohol as a source of protons. In the reactions presented, a series of compounds, [Ca(4)Ti(2)(mu(6)-O)(mu(3),eta(2)-L)(8)(eta-L)(2)Cl(4)] (1), [Sr(4)Hf(2)(mu(6)-O)(mu(3),eta(2)-L)(8)(eta-L)(2)(eta-LH)(4)Cl(4)] (2), [Ca(4)Zr(2)(mu(6)-O)(mu-Cl)(4)(mu,eta(2)-L)(8)Cl(2)] (3), [Sr(4)Ti(2)(mu(6)-O)(mu(3),eta(2)-L)(8)(eta-L)(2)(eta-LH)(2)Cl(4)] (4), [Ca(4)Zr(2)Cp(2)(mu(4)-Cl)(mu-Cl)(3)(mu(3),eta(2)-L)(4)(mu,eta(2)-L)(4)Cl(2)] (5), [CaTiCl(2)(mu,eta(2)-L')(3)(eta-L'H)(3)][L'] (6), [Ca(2)Ti(mu,eta(2)-L')(6)Cl(2)] (7), [Mn(4)Ti(4)(mu-Cl)(2)(mu(3),eta(2)-L)(2)(mu,eta(2)-L)(10)Cl(6)] (8), and [Mn(10)Zr(10)(mu(4)-O)(10)(mu(3)-O)(4)(mu(3),eta(2)-L)(2)(mu,eta(2)-L)(16)(mu,eta-L)(4)(eta-L)(2)Cl(8)] (9), were obtained in good yield. All of the complexes were characterized by elemental analysis, IR and NMR spectroscopy, and single-crystal X-ray structural analysis. Complex 8 belongs to a group of magnetic clusters that consists of Mn(4) subunits held together by two mu-Cl bridges. Compounds 6 and 7 underwent thermal decomposition, yielding an alternative source for some heterometallic oxides, which were analyzed by X-ray powder diffraction.

Unexpected cyclopentadienyl/alkoxo ligand exchange in titano- and zirconocene. New opportunities.

A simple new route to access heterometallic alkoxo precursors for a wide range of materials is reported. This unique synthetic method comprises elimination of the cyclopentadienyl ring from Cp2MCl2 (M = Ti, Zr) as CpH in the presence of M'(OR)2 (M' = Ca, Mn; OR = OCH2CH2OCH3 or OEt) in an alcohol as a source of protons. In one-pot reactions, we have prepared four different compounds with Ti2Ca4(mu6-O), Cp2Zr2Ca4(mu4-Cl), Zr10Mn10(mu3-O) 14, and Cp3Ti2(mu-OEt)2 motifs. The compounds were characterized by single-crystal X-ray structural analysis and NMR spectroscopy.

cis-Dichloridobis[2-(hydroxy-meth-yl)tetra-hydro-furan-κO,O']manganese(II).

The structure of the title compound, [MnCl(2)(C(5)H(10)O(2))(2)], was solved from low-temperature data collected at 100 (2) K. The asymmetric unit contains one half-mol-ecule with the Mn(II) ion located on a twofold axis. A distorted octa-hedral environment around the Mn atom is formed by two ether and two hydroxyl O atoms of two 2-(hydroxy-methyl)tetra-hydro-furan ligands, and by two chloride ions. The chelating tetra-hydro-furan ligands, which form five-membered rings, are cis oriented. The crystal structure is stabilized by hydrogen bonding between the coordinated OH groups and the chloride ions.

A pentanuclear bimetallic complex of manganese(II) and aluminium(III) ions: tetra-mu2-iodido-iodidobis(mu3-2-methoxyethanolato)bis(mu2-2-methoxyethanolato)dimethyl(tetrahydrofuran-kappaO)aluminium(III)tetramanganese(II).

The molecule of the title compound, [Mn(4)Al(CH(3))(2)(C(3)H(7)O(2))(4)I(5)(C(4)H(8)O)], contains one Al(III) and four Mn(II) ions. Two Mn atoms are five-coordinate in the form of a trigonal bipyramid or a square pyramid. The two other Mn atoms are six-coordinate with an octahedral geometry. The fourcoordinate Al atom is linked to the manganese core by mu-O(alkoxo) bridges, forming an almost planar five-membered ring.

Titanium-manganese compound with a chiral Mn3Ti center.

We have shown here for the first time a facile route to the molecular compound [Mn3Ti(mu3-OCH2CH2OCH3)2(mu-OCH2CH2OCH3)3(mu-Cl)Cl2(OiPr)2] with a Mn3Ti motif, where the Ti atom is in the chiral position and the Mn atoms occupy nonchiral sites.

Syntheses, structure, and properties of a manganese-calcium cluster containing a Mn4Ca2 core.

We describe here a novel, simple, efficient self-assembly method for the in situ generation of [Mn4Cl4(micro-OCH2CH2OMe)4(EtOH)4] and [Mn4(micro-Cl)Cl3(micro-OCH2CH2OMe)4(HOCH2CH2OMe)3]2 cubane-type compounds which react readily with calcium species to form cluster [Mn4Ca2Cl4(micro-OCH2CH2OMe)8], the calcium atoms attached to the Mn4 unit of flatten out the cubane inducing significant conformational changes.