Ethylene Dehydroaromatization over Ga-ZSM-5 Catalysts: Nature and Role of Gallium Speciation.

Bifunctional catalysis in zeolites possessing both Brønsted and Lewis acid sites offers unique opportunities to tailor shape selectivity and enhance catalyst performance. Here, we examine the impact of framework and extra-framework gallium species on enriched aromatics production in zeolite ZSM-5. We compare three distinct methods of preparing Ga-ZSM-5 and reveal direct (single step) synthesis leads to optimal catalysts compared to post-synthesis methods. Using a combination of state-of-the-art characterization, catalyst testing, and density functional theory calculations, we show that Ga Lewis acid sites strongly favor aromatization. Our findings also suggest Ga(framework)-Ga(extra-framework) pairings, which can only be achieved in materials prepared by direct synthesis, are the most energetically favorable sites for reaction pathways leading to aromatics. Calculated acid site exchange energies between extra-framework Ga at framework sites comprised of either Al or Ga reveal a site-specific preference for stabilizing Lewis acids, which is qualitatively consistent with experimental measurements. These findings indicate the possibility of tailoring Lewis acid siting by the placement of Ga heteroatoms at distinct tetrahedral sites in the zeolite framework, which can have a marked impact on catalyst performance relative to conventional H-ZSM-5.

Synthesis of Hexagonal FeMnP Thin Films from a Single-Source Molecular Precursor.

The first heterobimetallic phosphide thin film containing iron, manganese, and phosphorus, derived from the single-source precursor FeMn(CO)8 (µ-PH2 ), has been prepared using a home-built metal-organic chemical vapor deposition apparatus. The thin film contains the same ratio of iron, manganese, and phosphorus as the initial precursor. The film becomes oxidized when deposited on a quartz substrate, whereas the film deposited on an alumina substrate provides a more homogeneous product. Powder X-ray diffraction confirms the formation of a metastable, hexagonal FeMnP phase that was previously only observed at temperatures above 1200 °C. Selected area electron diffraction on single crystals isolated from the films was indexed to the hexagonal phase. The effective moment of the films (µeff =3.68 µB ) matches the previously reported theoretical value for the metastable hexagonal phase, whereas the more stable orthorhombic phase is known to be antiferromagnetic. These results not only demonstrate the successful synthesis of a bimetallic, ternary thin film from a single-source precursor, but also the first low temperature approach to the hexagonal phase of FeMnP.

New Main-Group-Element-Rich nido-Octahedral Cluster System: Synthesis and Characterization of [Et4N][Fe2(CO)6(µ3-As){µ3-EFe(CO)4}2].

A series of clusters of the form [Et4N][Fe2(CO)6(µ3-As)}(µ3-EFe(CO)4)], where E is either P or As, were synthesized from [Et4N]2[HAs{Fe(CO)4}3] and ECl3. AsCl3 gives the As-only compound; PCl3 produces compounds having two As atoms with one P atom, or one As atom and two P atoms, and they can exist as two possible isomers, one of which is chiral. The As2P and AsP2 clusters cocrystallize, and their structure as determined by single-crystal X-ray diffraction is given along with the structure of the As-only cluster. Analytical data as well as density functional theory calculations support the formation and geometries of the new molecules.

Anionic Bismuth-Oxido Carboxylate Clusters with Transition Metal Countercations.

Six new anionic bismuth-oxido clusters containing trifluoroacetate ligands were prepared. These include two new Bi6O8 clusters: [M(NCMe)2(H2O)4]3[Bi6(µ3-O)4(µ3-OH)4(CF3CO2)12] with an octahedral Bi6O4(OH)4 core (M = Ni, 1a; Co, 1b) and four Bi4O2 clusters, {[Co(NCMe)6][Bi4(µ3-O)2(CF3CO2)10]}n (2a), {[Co{HC(MeCO)2(MeCNH)}2][Bi4(µ3-O)2(CF3CO2)10]·2[CF3CO2]·2[CF3CO2H]·2[H2O]}n (2b), {[Cu(NCMe)4]2[Bi4(µ3-O)2(CF3CO2)10]·2[CF3CO2H]}n (2c), and {[Me4N]2[Bi4(µ3-O)2(CF3CO2)10]·2[CF3CO2H]}n (2d). These are among the first bismuth-oxido anionic clusters synthesized, and the first to have transition metal countercations. The Bi6O8 anion in 1a and 1b is a high-symmetry octahedron. Additionally, two of the new Bi4O2 clusters are arranged in 1D polymeric structures via bridging carboxylate ligands. The cation in compound 2c had not been previously characterized and was also observed in the synthesis of [Co{HC(MeCO)2(MeCNH)}2][Bi(NO3)6] (3). The new compounds were characterized using single crystal X-ray crystallography and elemental analysis.

Aluminum nanocrystals.

We demonstrate the facile synthesis of high purity aluminum nanocrystals over a range of controlled sizes from 70 to 220 nm diameter with size control achieved through a simple modification of solvent ratios in the reaction solution. The monodisperse, icosahedral, and trigonal bipyramidal nanocrystals are air-stable for weeks, due to the formation of a 2-4 nm thick passivating oxide layer on their surfaces. We show that the nanocrystals support size-dependent ultraviolet and visible plasmon modes, providing a far more sustainable alternative to gold and silver nanoparticles currently in widespread use.

Hexaaquacobalt(II) and hexaaquanickel(II) bis(µ-pyridine-2,6-dicarboxylato)bis[(pyridine-2,6-dicarboxylato)bismuthate(III)] dihydrate.

The title complexes, hexaaquacobalt(II) bis(µ-pyridine-2,6-dicarboxylato)bis[(pyridine-2,6-dicarboxylato)bismuthate(III)] dihydrate, [Co(H(2)O)(6)][Bi(2)(C(7)H(4)NO(4))(4)]·2H(2)O, (I), and hexaaquanickel(II) bis(µ-pyridine-2,6-dicarboxylato)bis[(pyridine-2,6-dicarboxylato)bismuthate(III)] dihydrate, [Ni(H(2)O)(6)][Bi(2)(C(7)H(4)NO(4))(4)]·2H(2)O, (II), are isomorphous and crystallize in the triclinic space group P-1. The transition metal ions are located on the inversion centre and adopt slightly distorted MO(6) (M = Co or Ni) octahedral geometries. Two [Bi(pydc)(2)](-) units (pydc is pyridine-2,6-dicarboxylate) are linked via bridging carboxylate groups into centrosymmetric [Bi(2)(pydc)(4)](2-) dianions. The crystal packing reveals that the [M(H(2)O)(6)](2+) cations, [Bi(2)(pydc)(4)](2-) anions and solvent water molecules form multiple hydrogen bonds to generate a supramolecular three-dimensional network. The formation of secondary Bi...O bonds between adjacent [Bi(2)(pydc)(4)](2-) dimers provides an additional supramolecular synthon that directs and facilitates the crystal packing of both (I) and (II).

(N,N-Dimethyl-formamide-κO)bis-(3-hy-droxy-picolinato-κN,O)phenyl-bis-muth(III).

The title organometallic complex, [Bi(C(6)H(5))(C(6)H(4)NO(3))(2)(C(3)H(7)NO)], features a Bi(III) atom in a distorted pentagonal-pyramidal coordination by two N,O-donating bidentate 3-hy-droxy-picolinate (3-hpic) ligands, one monodentate dimethyl-formamide (dmf) mol-ecule and one phenyl ring. The C atom of the aryl ligand occupies the apical position of the BiCN(2)O(3) coordination polyhedron, while the equatorial plane is formed by one O atom of the dmf ligand and two sets of N and O atoms from the chelating 3-hpic ligands. Inter-molecular secondary Bi⋯O [3.485 (3) Å] and O-H⋯O hydrogen-bonding inter-actions connect the complexes into a three-dimensional network. Intramolecular O-H⋯O hydrogen bonds are also observed.

Selective arylation reactions of bismuth-transition metal salicylate complexes.

Heterometallic bismuth-niobium or -tantalum salicylate complexes react with sodium tetraphenylborate to produce complexes in which one or more aryl groups have been transferred from boron to bismuth with the concomitant displacement of a eta(2)-salicylato ligand. When the previously reported Bi(2)Ta(2)(sal)(4)(Hsal)(4)(OEt)(4) (1) and BiTa(4)(mu-O)(4)(sal)(4)(Hsal)(3)(O(i)Pr)(4) (2) are treated with an alcoholic solution of NaBPh(4), the compounds [PhBi(Hsal)Ta(sal)(2)(OEt)(2) x EtOH](2) (3) and PhBiTa(4)(mu-O)(4)(Hsal)(2)(sal)(4)(OEt)(4) x CH(2)Cl(2) (4) are produced (sal = O(2)CC(6)H(4)-2-O(2-), Hsal = O(2)CC(6)H(4)-2-OH(-)). The core geometries of the heterometallic complexes are retained. However, if preparations of compound 1 are treated with NaBPh(4) without prior isolation of 1, [Ph(2)BiNb(sal)(2)(OMe)(2)](infinity) (5) is produced instead. This compound was characterized both as a solvent-free crystalline form and as one containing a lattice diethyl ether. The compound exhibits a polymeric chain structure that can be viewed as alternating [Ph(2)Bi](+) and [Nb(sal)(2)(OMe)(2)](-) units connected via bridging carboxylate groups. The arylation of the bismuth(III) center proceeds smoothly under mild conditions at room temperature, affording a new means for the mild functionalization of bismuth-transition metal heterometallic complexes.

In pursuit of advanced materials from single-source precursors based on metal carbonyls.

In this perspective, the development of single-source precursors and their relative advantages over multiple source approaches for the synthesis of metal pnictide solid state materials is explored. Particular efforts in the selective production of iron phosphide materials for catalytic applications are discussed, especially directed towards the hydrogen evolution and oxygen evolution reactions of water splitting.

High-Performance Hybrid Bismuth-Carbon Nanotube Based Contrast Agent for X-ray CT Imaging.

Carbon nanotubes (CNTs) have been used for a plethora of biomedical applications, including their use as delivery vehicles for drugs, imaging agents, proteins, DNA, and other materials. Here, we describe the synthesis and characterization of a new CNT-based contrast agent (CA) for X-ray computed tomography (CT) imaging. The CA is a hybrid material derived from ultrashort single-walled carbon nanotubes (20-80 nm long, US-tubes) and Bi(III) oxo-salicylate clusters with four Bi(III) ions per cluster (Bi4C). The element bismuth was chosen over iodine, which is the conventional element used for CT CAs in the clinic today due to its high X-ray attenuation capability and its low toxicity, which makes bismuth a more-promising element for new CT CA design. The new CA contains 20% by weight bismuth with no detectable release of bismuth after a 48 h challenge by various biological media at 37 °C, demonstrating the presence of a strong interaction between the two components of the hybrid material. The performance of the new Bi4C@US-tubes solid material as a CT CA has been assessed using a clinical scanner and found to possess an X-ray attenuation ability of >2000 Hounsfield units (HU).

A TiO2/FeMnP Core/Shell Nanorod Array Photoanode for Efficient Photoelectrochemical Oxygen Evolution.

A variety of catalysts have recently been developed for electrocatalytic oxygen evolution, but very few of them can be readily integrated with semiconducting light absorbers for photoelectrochemical or photocatalytic water splitting. Here, we demonstrate an efficient core/shell photoanode with a highly active oxygen evolution electrocatalyst shell (FeMnP) and semiconductor core (rutile TiO2) for photoelectrochemical oxygen evolution reaction. Metal-organic chemical vapor deposition from a single-source precursor was used to ensure good contact between the FeMnP and the TiO2. The TiO2/FeMnP core/shell photoanode reaches the theoretical photocurrent density for rutile TiO2 of 1.8 mA cm-2 at 1.23 V vs reversible hydrogen electrode under simulated 100 mW cm-2 (1 sun) irradiation. The dramatic enhancement is a result of the synergistic effects of the high oxygen evolution reaction activity of FeMnP (delivering an overpotential of 300 mV with a Tafel slope of 65 mV dec-1 in 1 M KOH) and the conductive interlayer between the surface active sites and semiconductor core which boosts the interfacial charge transfer and photocarrier collection. The facile fabrication of the TiO2/FeMnP core/shell nanorod array photoanode offers a compelling strategy for preparing highly efficient photoelectrochemical solar energy conversion devices.

Model platinum nucleobase and nucleoside complexes and antitumor activity: X-ray crystal structure of [PtIV(trans-1R,2R-diaminocyclohexane)trans-(acetate)2(9-ethylguanine)Cl]NO3.H2O.

A series of platinum(II) and (IV) monoadducts of the type [Pt(II)(DACH)LCl]NO3 and [Pt(IV)(DACH)trans-(X)2LCl]NO3 (where DACH=trans-1R,2R-diaminocyclohexane, L=adenine, guanine, hypoxanthine, cytosine, adenosine, guanosine, inosine, cytidine, 9-ethylguanine (9-EtGua), or 1-methylcytosine and X=hydroxo or acetato ligand) have been synthesized and characterized by elemental analysis and by 1H and 195Pt nuclear magnetic resonance (NMR) spectroscopy. The crystal structure of the model nucleobase complex [Pt(IV)(trans-1R,2R-diaminocyclohexane)trans-(acetate)2(9-EtGua)Cl]NO3.H2O was determined using a single crystal X-ray diffraction method. The compound crystallized in the monoclinic space group P2(1), with a=10.446(2) A, b=22.906(5) A, c=10.978(2) A, Z=4, and R=0.0718, based upon the total of 11,724 collected reflections. In this complex, platinum had a slightly distorted octahedron geometry owing to the presence of a geometrically strained five-member ring. The two adjacent corners of the platinum plane were occupied by the two amino nitrogen of DACH, whereas, the other two equatorial positions occupied by chloride ion and 9-ethylguanine. The remaining two axial positions were occupied by the oxygen atoms of acetato ligands. The DACH ring was in a chair configuration. An intricate network of intermolecular hydrogen bonds held the crystal lattice together. Some of these synthesized models of DACH-Pt-DNA adducts have good in vitro cytotoxic activity against the cisplatin-sensitive human cancer ovarian A2780 cell line (IC50=1-8 microM). Interestingly, a substituted nucleobase (9-ethylguanine) adduct was over 6-fold more potent than regular adducts. The cross-resistance factor against the 44-fold cisplatin-resistant 2780CP/clone 16 cells was about 3-9; thus, the cytotoxicity of adducts was indicative of low potency, but the resistance factors were also substantially low. These results suggest that DNA adducts of DACH-Pt are cytotoxic with low cross-resistance.

Towards a molecular model for bismuth(III) subsalicylate. Synthesis and solid-state structure of [Bi(Hsal)3(bipy)(C7H8]2 and [Bi(Hsal)(sal)(1,10-phenanthroline)(C7H8]2.

The synthesis and characterization of the first bismuth salicylate complexes, stabilized by chelating amine ligands, offers the possibility for detailed investigation of molecular precursors of the biologically significant compound bismuth subsalicylate (BSS).

Oligomerization and Oxide Formation in Bismuth Aryloxides: Synthesis, Characterization, and Structures of [NaBi(OC(6)F(5))(4)(THF)](infinity) and Na(4)Bi(2)(&mgr;(6)-O)(OC(6)F(5))(8)(THF)(4).

The reaction of [Bi(OR(f))(3).C(7)H(8)](2) (R(f) = C(6)F(5)) with sodium pentafluorophenolate leads to two new mixed-metal aryloxide complexes depending upon stoichiometry. Using 1 equiv of NaOR(f) per bismuth atom, a polymeric chain with the formula [NaBi(OC(6)F(5))(4)(THF)](infinity), 1, was isolated. If 2 equiv of NaOR(f) is used, the heterometallic oxo/aryloxide Na(4)Bi(2)(&mgr;(6)-O)(OC(6)F(5))(8)(THF)(4), 2, is formed. The mass spectroscopic data confirms the elimination of the bis(pentafluorophenyl) ether, R(f)OR(f), concomitant with oxo-ligand formation. The compounds have been characterized spectroscopically and by single-crystal X-ray diffraction: Compound 1 crystallizes in the chiral monoclinic space group P2(1), with a= 12.324(2) Å, b = 10.934(2) Å, c = 13.334(3) Å, beta = 91.19(3) degrees, V = 1796.4(6) Å(3), and Z = 2. The polymeric chain in 1 sits about the 2-fold screw axis and is the source of chirality for the compound. Compound 2 crystallizes in the triclinic space group P&onemacr;, with a = 14.059(3) Å, b = 14.060(3) Å, c = 11.531(2) Å, alpha = 108.47(3) degrees, beta = 102.78(3) degrees, gamma = 108.61(3) degrees, V=1912.6(7) Å(3), and Z = 1 and shows occupational disorder of the sodium and bismuth atom positions. Variable-temperature (19)F-NMR studies show dynamic behavior of these bismuth aryloxide complexes in solution.

Isolation of a Bismuth Chloride-Iron Carbonyl Adduct: Synthesis and Structural Characterization of [PhCH(2)NMe(3)](2)[Bi(2)Cl(4)(&mgr;-Cl)(2){&mgr;-Fe(CO)(4)}].

The reaction of bismuth(III) chloride with [PhCH(2)NMe(3)](2)[Fe(CO)(4)] at a ratio of 2:1 in acetonitrile yields the iron carbonyl-bismuth chloride adduct [PhCH(2)NMe(3)](2)[Bi(2)Cl(4)(&mgr;-Cl)(2){&mgr;-Fe(CO)(4)}] cleanly in high yield. The complex consists of two BiCl(3) groups bridged by an [Fe(CO)(4)](2)(-) unit. Two chloride ligands are shared between the Bi atoms, producing square-pyramidal coordination at bismuth and octahedral coordination at the iron center. The production of this complex represents the synthesis of a stable adduct of a highly nucleophilic metal carbonyl anion with a strongly Lewis acidic main group halide. The compound C(24)H(32)N(2)O(4)Bi(2)Cl(6)Fe crystallizes in the orthorhombic space group Pba2 (No. 32) with cell parameters a = 14.624(3) Å, b = 17.010(3) Å, c = 7.1990(10) Å, V = 1790.8(5) Å(3), and Z = 2.

Solution Dynamics of Thallium-Metal Carbonyl Compounds Using (205)Tl NMR Spectroscopy.

A (205)Tl NMR study to probe the solution structure and dynamics of a series of thallium-containing metal complexes has been conducted. The following compounds were examined: Tl{Co(CO)(4)}(3) (Ia), [BnMe(3)N](3)[Tl{Fe(CO)(4)}(3)] ([BnMe(3)N](3)[Ib]), Tl{M(CO)(3)Cp}(3) (Ic, M = Cr; Id, M = Mo; Ie, M = W), TlFp(3) (If; Fp = CpFe(CO)(2)), [PPN](2)[Tl(2)Fe(6)(CO)(24)] ([PPN](2)[II]), [Et(4)N](2)[Tl(2)Fe(4)(CO)(16)] ([Et(4)N](2)[III]), [Et(4)N][L(2)Tl{Fe(CO)(4)}(2)] ([Et(4)N][IV]: [IVa](-), L(2) = bipy; [IVb](-), L(2) = en; [IVc](-), L(2) = phen; [IVd](-), L(2) = tmeda; [IVe](-), L(2) = dien), [Et(4)N](4)[Tl(4)Fe(8)(CO)(30)] ([Et(4)N](4)[V]), and TlCo(CO)(4) (VI). The (205)Tl NMR technique was used to probe the dynamic behavior of the Tl-metal cluster complexes [II](2-), [III](2-), and [V](4-) in solution and the formation of Lewis base adducts of [III](-), as well as the possibility of formation of carbonylate anion adducts of Ia, Ic, Id, and If. [IVb](-) reacted with acetone and formed, after fortuitous oxidation, [{(CO)(4)FeL(2)'Tl}(2)Fe(CO)(4)] (L(2)' = Me(2)C=NCH(2)CH(2)N=CMe(2)) (VII). The initially formed complex [L(2)'Tl{Fe(CO)(4)}(2)](-) ([Et(4)N][IVf]) was spectroscopically characterized. Additionally, the two known but structurally uncharacterized complexes Ia and If as well as the new complexes [BnMe(3)N](3)[Ib] and VII were characterized by single-crystal X-ray diffraction. Compound Ia crystallizes in the monoclinic space group P2(1)/n with a = 16.855(3) Å, b = 6.7790(10) Å, c = 19.049(4) Å, beta = 113.84(3) degrees, V = 1990.8(6) Å(3), Z = 4, R(1)(F) = 0.0221, and wR(2)(F(2)) = 0.0542 [I > 2sigma(I)]. Compound If was synthesized from K[Fp] and TlCl(3).4H(2)O and crystallizes in the triclinic space group P&onemacr; with a = 10.789(2) Å, b = 14.239(3) Å, c = 16.703(3) Å, alpha = 69.39(3) degrees, beta = 89.50(3) degrees, gamma = 69.07(3) degrees, V = 2223.1(7) Å(3), Z = 4, R(1)(F) = 0.0350, and wR(2)(F(2)) = 0.0877 [I > 2sigma(I)]. Compound [BnMe(3)N](3)[Ib] was synthesized from Na(2)Fe(CO)(4).(3)/(2)diox and Tl(OAc)(3) in MeCN and crystallizes in the hexagonal space group P6(3)/m with a = 18.290(3) Å, c = 8.479(2) Å, V = 2456.4(8) Å(3), Z = 2, R(1)(F) = 0.0235, and wR(2)(F(2)) = 0.0494 [I > 2sigma(I)]. Compound VII crystallizes in the triclinic space group P&onemacr; with a = 13.597(3) Å, b = 15.040(3) Å, c = 10.536(2) Å, alpha = 92.75(3) degrees, beta = 95.07(3) degrees, gamma = 114.40(3) degrees, V = 1946.0(7) Å(3), Z = 2, R(1)(F) = 0.0461, and wR(2)(F(2)) = 0.1295 [I > 2sigma(I)].

Halide Ion Addition to Bismuth-Containing Iron Carbonyl Compounds: Synthesis and Characterization of the Two Bridged-Butterfly Cluster Compounds [Et(4)N][(&mgr;-H)Fe(2)(CO)(6)Bi(2){&mgr;-Fe(CO)(4)}] and [{PhCH(2)NMe(3)}{(&mgr;-H)Fe(2)(CO)(6)Bi(2)(&mgr;-Cl)(2)}](infinity) and Stabilization of Reduced-Hypervalent Bismuth Centers by Coordination to a Metal Center in [PhCH(2)NMe(3)](3)[Bi(3)Cl(4)(&mgr;-Cl)(4){Fe(CO)(3)}].

The reaction of [Q](2)[Bi(4)Fe(4)(CO)(13)] ([Q](2)[1]; [Q] = [Et(4)N](+), [PhCH(2)NMe(3)](+)) with MePCl(2) in MeCN is a complicated reaction which gives different results depending upon the stoichiometry of the reaction. At a ratio of 1:1.33 (cluster:phosphine), the reaction yields a mixture of the new bismuth-iron carbonyl compounds [Q][(&mgr;-H)Fe(2)(CO)(6)Bi(2){Fe(CO)(4)}] ([Q][2]), which has a tetrahedral Fe(2)Bi(2) core edge-bridged across the bismuth centers by an [Fe(CO)(4)](2)(-) fragment, and [Q](3)[Bi(3)Cl(4)(&mgr;-Cl)(4){Fe(CO)(3)}] ([Q](3)[3]), containing a reduced complex ion [Bi(3)Cl(8)](-) stabilized by coordination to an iron tricarbonyl fragment. Extended Hückel molecular orbital calculations on this unusual anion are consistent with each bismuth atom possessing the same reduced oxidation state of +2.33. The compound [Et(4)N][2] crystallizes in the triclinic space group P&onemacr; (No. 2) with a = 10.246(2) Å, b = 11.859(2) Å, c = 12.474(2) Å, alpha = 71.11(3) degrees, beta = 79.60(3) degrees, gamma = 76.37(3) degrees, V = 1384.7(4) Å(3), and Z = 2, while [PhCH(2)NMe(3)](3)[3].0.87Et(2)O was characterized in the orthorhombic space group Pbca (No. 61) with a = 20.801(4) Å, b = 19.937(4) Å, c = 25.480(5) Å, V = 10566.8(36) Å(3), and Z = 8. When the reaction is carried out at a ratio of 1:2, the novel hydride [{Q}{(&mgr;-H)Fe(2)(CO)(6)Bi(2){&mgr;-Cl}(2)}](infinity) ([{Q}{4}](infinity)) is isolated. This cluster also has a "tetrahedral" core, with the Bi-Bi vector bridged by a chloride ligand and the molecules joined into infinite polymeric chains in the solid state by the second intermolecularly-bridging chloride ligand. [{PhCH(2)NMe(3)}{4}](infinity) crystallizes in the monoclinic space group P2(1)/n (No. 14) with a = 7.864(2) Å, b = 22.465(4) Å, c = 13.797(3) Å, beta = 105.96(3) degrees, V = 2343.5(9) Å(3), and Z = 4. The metal framework of [4](-) is similar to that of [2](-) with the notable exception that the Bi-Bi bond present in [2](-) is missing in [4](-) because of the additional electrons provided by the chloride ions. At stoichiometries greater than 2:1, the previously reported [Fe(CO)(4)Bi(2)Cl(6)](2)(-) ion is formed.

Preparation, characterization, and antitumor activity of new cisplatin analogues with 1-methyl-4-(methylamino)piperidine: crystal structure of [PtII(1-methyl-4-(methylamino) piperidine)(oxalate)].

A series of new platinum(II) complexes of the type [Pt(II)(mmap)X] (where mmap, 1-methyl-4-(methylamino)piperidine and X, 1,1-cyclobutanedicarboxylato (CBDCA), oxalato, malonato, methylmalonato, dimethylmalonato, ethylmalonato, diethylmalonato or 2,3-naphthalene dicarboxylato (NDCA)) have been synthesized and characterized by elemental analysis, infrared (IR), and 13C and 195Pt nuclear magnetic resonance (NMR) spectroscopy. The crystal structure of the analogue [Pt(II)(mmap)(oxalate)] was determined using the single crystal X-ray diffraction method. Based upon a total of 4964 collected reflections, we determined that the compound crystallizes in the monoclinic space group P2(1)/c (with a=11.890(2) A, b=9.6695(19) A, c=9.875(2) A, beta=102.03(3) degrees, Z=4, and R=0.0428). In this complex, platinum has a slightly distorted square planar geometry with the two adjacent corners being occupied by two nitrogen atoms of the mmap ligand, whereas the remaining cis positions are occupied by two oxygen atoms of the oxalate molecule. The mmap ligand is in a boat conformation and forms six-membered chelating rings as well as the oxalate molecule forms five-membered chelating rings with platinum. The complexes were evaluated for their cytotoxic potential against the sensitive A2780 tumor model and cisplatin-resistant clone derived in vitro from potential cells.

Synthesis and structural studies of the simplest bismuth(III) oxo-salicylate complex: [Bi4(µ3-O)2(HO-2-C6H4CO2)8]·2Solv (Solv = MeCN or MeNO2).

Reaction of BiPh3 with salicylic acid (HO-2-C6H4CO2H, H2Sal) at room temperature in wet acetonitrile or nitromethane leads to the facile formation of an oxo cluster compound with formula [Bi4(µ3-O)2(HSal)8] solvated by either MeCN and MeNO2 (1·2MeCN or 1·2MeNO2). This simple procedure affords a convenient, high yield (>80%) synthesis of a single bismuth oxo cluster. Both adducts exhibit a nearly planar Bi4(µ3-O)2 core. The solvent ligands are situated in the same coordination sites in both but at long Bi-N and Bi-O distances. The ease of preparation as a pure compound makes this an ideal starting material for study of bismuth oxo-salicylate chemistry.