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.

Triple C-H bond activation of a nickel-bound methyl group: synthesis and X-ray structure of a carbide cluster (NiCp)6(µ6-C).

A new hexanuclear cyclopentadienylnickel carbide cluster (NiCp)(6)(µ(6)-C) (1) was obtained through the thermolysis of the alkene complex [NiCp(CH(3))(η(2)-CH(2)═CHC(4)H(9))] (4). The X-ray molecular structure of 1 (monoclinic; P2(1)/c; Ni-C(carbide) = 1.767(4)-2.109(4) Å) reveals a highly deformed octahedral arrangement of nickel atoms with two octahedron edges opened (Ni-Ni bonding distances = 2.410(1)-2.623(1) Å, Ni···Ni nonbonding distances = 3.107(2) and 3.108(2) Å). Cluster 1 is the first example of a homoleptic, cyclopentadienylnickel carbide cluster. Moreover, (13)C-labeling studies proved that the carbido ligand in cluster 1 originated from the Ni-bound methyl group. This transformation requires a triple C-H bond activation in the methyl group, which has not been observed so far for late transition metal compounds.

Synthesis of functionalized materials using aryloxo-organometallic compounds toward spinel-like MM'2O4 (M = Ba2+, Sr2+; M' = In3+, Al3+) double oxides.

The predesigned single-source precursors [Ba{(µ-ddbfo)(2)InMe(2)}(2)] (1), [Me(2)In(µ-ddbfo)](2) (2), [Sr{(µ-ddbfo)(2)AlMe(2)}(2)] (4), and [Me(2)Al(µ-ddbfo)](2) (5) (ddbfoH = 2,3-dihydro-2,2-dimethylbenzofuran-7-ol) for spinel-like double oxides and group 13 oxide materials were prepared via the direct reaction of the homoleptic aryloxide [M(ddbfoH)(4)](ddbfo)(2)·ddbfoH (M = Ba(2+), Sr(2+) (3)) and InMe(3) or AlMe(3) in toluene. In all of the reactions, there was an organometallic-driven abstraction of the OH protons from the 7-benzofuranols in the Ba(2+) and Sr(2+) cation sphere. All compounds were characterized by elemental analysis, (1)H NMR, and FT-IR spectroscopy. In addition, the molecular structures of 1, 2, and 3 were determined by single-crystal X-ray diffraction. The oxide products derived from the compounds mentioned above were studied using elemental analysis, Raman spectroscopy, X-ray powder diffraction, and scanning and transmission electron microscopy equipped with an energy-dispersive spectrometer. Moreover, their specific surface area and mesopore size distribution were evaluated using nitrogen porosimetry. Preliminary investigations of the Eu-doped SrAl(2)O(4) and In(2)O(3) phosphors revealed that the oxides obtained could be considered as matrices for lanthanide ions.

On the nature of Ni···Ni interaction in a model dimeric Ni complex.

A new dinuclear complex (NiC(5)H(4)SiMe(2)CHCH(2))(2) (2) was prepared by reacting nickelocene derivative [(C(5)H(4)SiMe(2)CH=CH(2))(2)Ni] (1) with methyllithium (MeLi). Good quality crystals were subjected to a high-resolution X-ray measurement. Subsequent multipole refinement yielded accurate description of electron density distribution. Detailed inspection of experimental electron density in Ni···Ni contact revealed that the nickel atoms are bonded and significant deformation of the metal valence shell is related to different populations of the d-orbitals. The existence of the Ni···Ni bond path explains the lack of unpaired electrons in the complex due to a possible exchange channel.

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.

trans-Bis(methanol-κO)bis-(quinoline-2-carboxyl-ato-κN,O)manganese(II).

The title compound, [Mn(C(10)H(6)NO(2))(2)(CH(4)O)(2)], was obtained unintentionally as the product of an attempt to synthesize a polynuclear carboxyl-ate bridged manganese(III/IV) complex, using methanol to reduce the permanganate ion. The mol-ecule is centrosymmetric; the pairs of equivalent ligands coordinate trans to each other in a distorted octa-hedral geometry. Intra-molecular C-H⋯O bonds lying in the equatorial plane stabilize the mol-ecule. In the crystal, mol-ecules are linked by O-H⋯O and C-H⋯O hydrogen bonds, creating a three-dimensional supra-molecular structure. π-π and C-H⋯π inter-actions are also observed. The dihedral angle and centroid-to-centroid distance between the pyridine ring (A) and the benzene ring (B(i)) of a symmetrically related mol-ecule [symmetry code: (i) -1 - x, -y, -z] are 1.27 (11)° and 3.974 (2) Å, respectively. For the C-H⋯π inter-actions, the relevant distances and angles are: C⋯Cg[A(ii)] = 3.643 (2) Å, H⋯Cg[A(ii)] = 2.750 (2) Šand C-H⋯Cg[A(ii)] = 155 (1)° [symmetry code: (ii) x, -1 + y, z].

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.

X-ray structure of the dipotassium salt of D-mannose 1-phosphate 3.25 hydrate.

The first crystal structure of mannose 1-phosphate is described. The dipotassium hydrate salt crystallizes in the P2(1)2(1)2 space group. There are two independent dianions (I and II) in the asymmetric unit, which are alpha anomers adopting the 4C(1) chair conformation. The main difference between the two mannose 1-phosphate dianions is the orientation of the phosphate group with relation to the pyranosyl ring. In I, one of the phosphate oxygen atoms is antiperiplanar positions with respect to carbon atom C-1, whereas the two others are situated synclinally. The corresponding orientations of the terminal phosphate oxygen atoms in II are synperiplanar and anticlinal. The potassium cations are six- and seven-coordinate, mainly with O atoms of hydroxyl groups and water molecules. There are potassium channels extending along the c-axis. In the packing arrangement, water molecules and mannose phosphate groups also define two different types of layers parallel to a-axis. Within water channels there are extensive hydrogen-bonding networks.

Flux-Aided Synthesis of Lu2O3 and Lu2O3:Eu-Single Crystal Structure, Morphology Control and Radioluminescence Efficiency.

Li2SO4 or (Li2SO4 + SiO2)-mixture fluxes were used to prepare a Lu2O3:Eu powder phosphor as well as an undoped Lu2O3 utilizing commercial lutetia and europia as starting reagents. SEM images showed that the fabricated powders were non-agglomerated and the particles sizes varied from single microns to tens of micrometers depending largely on the flux composition rather than the oxide(s)-to-flux ratio. In the presence of SiO2 in the flux, certain grains grew up to 300-400 µm. The lack of agglomeration and the large sizes of crystallites allowed making single crystal structural measurements and analysis on an undoped Lu2O3 obtained by means of the flux technique. The cubic structure with a = 10.393(2) Å, and Ia space group at 298 K was determined. The most efficient radioluminescence of Lu2O3:Eu powders reached 95%-105% of the commercial Gd2O2S:Eu.

Magnesium, zinc and aluminium complexes supported by tripodal diaminebis(aryloxido) ligands: synthesis, solid state and solution structure.

The reactions of the diaminebis(aryloxido) ligand precursors [Me2NCH2CH2N(CH2-4-R-C6H3OH)2] [R = C(CH3)2CH2C(CH3)3, H2L(1); R = CH3, H2L(2)] with Mg(n)Bu2, ZnEt2 and AlEt3 create complexes of general formula [M2(µ-L-κ(4)O,N,N,O)2] (M = Mg, 1a for L(1) and 1b for L(2); M = Zn, 2a for L(1) and 2b for L(2)) and [Al2(µ-L-κ(3)O,N,N,O)2Et2] (3 for L(1)) in good yields. Compounds 1a-3 were characterized by NMR spectroscopy and ESI-MS experiments. The definitive molecular structure of 1b·CH2Cl2, 2a·H2O, 2b·CH2Cl2 and 3 was provided by a single-crystal analysis and revealed their dimeric nature with an M2O2 planar core. The L(1) and L(2) ligands coordinate as the dianions in a tetradentate/bridging manner in 1b, 2a, 2b and in a tridentate/bridging mode in 3. The NMR spectra showed that the solid state of these compounds is essentially retained in solution.

Vanadate complexes bearing an imidazolidine-bridged bis(aryloxido) ligand: synthesis and solid state and solution structure.

A new imidazolidine-bridged bis(aryloxido) ligand precursor (H(2)L) [H(2)L = 2,2'-(imidazolidine-1,3-diylbis(methylene))bis(4-(1,1,3,3-tetramethylbutyl-2-yl)phenol)] was prepared in a relatively high yield (∼60%) via a single-step Mannich condensation of 4-(1,1,3,3-tetramethylbutyl)phenol, ethylenediamine and paraformaldehyde at 2:1:3 molar ratio and characterized by chemical and physical techniques including X-ray crystallography. Reactions of H(2)L with [VO(OEt)(3)] at 1:1 and 1:2 molar ratios in toluene afforded [V(L-κ(3)O,N,N,O)(O)(OEt)] (1) and [V(2)(µ-L-κ(4)O,N,N,O)(µ-OEt)(2)(O)(2)(OEt)(2)] (2), respectively. Alcoholysis of 1 with EtOH enables elimination of one molecule of H(2)L and the formation of 2. Compounds 1 and 2 were characterized by IR and NMR spectroscopy as well as ES-MS experiments. The definitive molecular structure of 2 was provided by a single-crystal analysis and revealed its dinuclear nature, featuring two octahedral vanadium centres bridged by both OEt groups and the L ligand. The (51)V, (1)H and (13)C NMR spectra as well as ES-MS showed that 2 does not stay intact in solution and undergoes dissociation to give 1 and [VO(OEt)(3)].

Lithium complexes supported by tripodal diaminebis(aryloxido) ligands: synthesis and structure.

The diaminebis(aryloxido) ligand precursors H(2)L(1) and H(2)L(2) [H(2)L(1) = Me(2)NCH(2)CH(2)N(CH(2)-4-CMe(2)CH(2)CMe(3)-C(6)H(3)OH)(2); H(2)L(2) = Me(2)NCH(2)CH(2)N(CH(2)-4-Me-C(6)H(3)OH)(2)] were synthesized by a straightforward single-step Mannich condensation. Their reactions with 2 molar equivalents of MeLi in thf afforded [Li(4)(µ-L-κ(4)O,N,N,O)(2)(thf)(2)] (1a, L(1); 1b, L(2)) and unexpectedly small amounts (∼9%) of [Li(6)(µ-L-κ(4)O,N,N,O)(2)(µ(3)-Cl)(2)(thf)(4)]·thf (2a·thf; L(1); 2b·thf, L(2)). Stoichiometric reactions of LiCl, MeLi and ligand precursors H(2)L led to the formation of 2a and 2b in high yield (∼80%). All compounds were characterized by chemical and physical techniques including X-ray crystallography for H(2)L(1), H(2)L(2), 1b, 2a and 2b.

Chemoselective alcoholysis of lactide mediated by a magnesium catalyst: an efficient route to alkyl lactyllactate.

Alkyl-(S,S)-O-lactyllactate was prepared by chemoselective alcoholysis of lactide LA mediated by a magnesium catalyst. When ROH reacted with LA it yielded the ring-opened product R-(S,S)-O-lactyllactate exclusively, which remained intact as long as LA was present in the reaction mixture. Consumption of LA caused the reaction to proceed further giving R-(S)-lactate.

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.

Supramolecular stores of acetic acid--an alternative for metal-organic frameworks.

A series of new complexes: [M(quin-2-c)(2)(H(2)O)(2)]x 4CH(3)COOH (M=Mn(2+), Co(2+) or Ni(2+), quin-2-c is quinoline-2-carboxylate ion) have been synthesized and characterized by X-ray single crystal study. The crystals of the complexes reveal very interesting 1D structures comprising acetic acid molecules. The processes of re- and desolvation of acetic acid by the manganese complex in mild conditions have been studied. The de- and resolvated materials were characterized by elemental analysis, IR spectroscopy and XRD study. The results show that binding of acetic acid is reversible and stoichiometric.

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.

Homo- and heteroleptic zinc aminophenolates as initiators for lactide polymerization.

The reaction of ZnEt2 with one or two equivalents of aminophenolate ligand N-[methyl(2-hydroxy-3,5-di-tert-butylphenyl)]-N-methyl-N-cyclohexylamine gives hetero- and homoleptic molecular compounds [(micro,eta2-L2)ZnEt]2 and [Zn(eta2-L2)2]. The later is most probably a mixture of diastereoisomers that in solution shows an interesting dynamic behaviour. Both complexes as well as the BnOH derivative of the latter, [(eta2-L2)Zn(micro-BnO)]2, proved excellent initiators for lactide polymerization.

X-ray crystal structure and magnetic and photophysical properties of novel copper(II) N-oxide adduct [(4-MPyO)2(CuCl2)2(H2O)(C2H5OH)] (4-MPyO = 4-(4-methoxystyryl)pyridine N-oxide).

A new mixed adduct, (4-MPyO)2(CuCl2)2(H2O)(C2H5OH) [where 4-MPyO is the 4-(4-methoxystyryl)pyridine N-oxide], was obtained for the first time. It has been characterized by X-ray studies, IR, electronic absorption, and emission spectra, lifetime measurements, and variable-temperature magnetic susceptibility measurements in the range 80-300 K. The single-crystal X-ray diffraction shows that the geometry around both of the copper(II) ions can be described as a tetragonal pyramid with a trapezoidal base at the corners of which are two oxygen atoms of N-oxide and two chlorine atoms. The oxygen atoms of either water or ethanol are at the apex of the pyramid. Besides that, two molecules of the adduct form a double-hydrogen-bonded superdimer in which they are connected to each other through hydrogen bonds of the O-H...Cl type as formed between the chlorine atoms and ethanol molecule (Cl...O 3.22 A). The copper(II) atoms are antiferromagnetically coupled within a dimeric unit, and a singlet-triplet separation of 2 J value (1100 cm(-1)) is greater than the value expected from Hatfield's rule for the bridging angles Cu-O-Cu equal 108.9 degrees and 110.2 degrees . By means of the PM3-calculated values of vertical excitation energies, the ligand-to-metal charge-transfer (LMCT) and the metal-to-ligand charge-transfer transitions in the unresolved experimental absorption spectra of I have been revealed. From the large Stokes shift value of emission spectra in solvents of different polarity (more than 6500 cm(-1) in acetonitrile), the charge-transfer (CT) nature of the emissive (LMCT) state of I has been concluded. Biexponential decay of the excited complex in acetonitrile and frozen propanol suggests that the two different CT conformers (0.8, 4.12 ns and 1.99, 15.2 ns, respectively) are present in the excited state in solution while only one CT form is indicated by a monoexponential decay (9.0 micros) in the solid.

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.