Dihaloheptasilanes X2Si[SiMe(SiMe3)2]2 as potential precursors for silylenes, disilenes and cyclotrisilanes

The synthesis of new dihaloheptasilanes X₂Si[SiMe(SiMe₃)₂]₂ (X=Cl: 2, Br: 3, I: 4) was performed by treating dihydridoheptasilane 1 (X=H) with CCl₄, HCBr₃ or HCI₃. Difluoroheptasilane 6 (X=F) was prepared from either diphenylheptasilane 5 (X=Ph), triflic acid (HOTf), and LiF with concomitant isolation of heptasilanes 7 (X₂=Ph and OTf), 8 (X₂=F and Ph), and 9 (X₂=F and OTf), or by halogen exchange from 2 using ZnF₂. Crystal structures of 2, 3, 4, and 5 are reported. The reduction of 2 with Li, Na or KC₈ resulted in the instantaneous formation of various cyclotrisilanes, while the reduction of 3 gave exclusively the unsymmetrical cyclotrisilane (E)-1-methyl-2,3,3-tris[methylbis(trimethylsilyl)silyl]-1,2-bis(trimethylsilyl)cyclotrisilane 10, which was characterized by X-ray crystallography. A mechanism for the formation of cyclotrisilanes via a silylsilylene-to-disilene rearrangement is proposed. Attempts to prepare the tetradekasilane [(Me₃Si)₂MeSi]₂SiH–SiH[SiMe(SiMe₃)₂]₂ (by reductive dehalogenation of either HClSi[SiMe(SiMe₃)₂]₂ 13 or HISi[SiMe(SiMe₃)₂]₂ 18), or the tetradekasilane [(Me₃Si)₂MeSi]₂SiPh–SiPh[SiMe(SiMe₃)₂]₂ (by reductive dehalogenation of either PhClSi[SiMe(SiMe₃)₂]₂ 14 or PhISi[SiMe(SiMe₃)₂]₂ 19) as precursors for the disilene [(Me₃Si)₂MeSi]₂Si=Si[SiMe(SiMe₃)₂]₂ failed. 14 was characterized by X-ray crystallography. All compounds described were also characterized by multinuclear NMR spectroscopy and elemental analysis.     

Diverse structures,magnetism and photoluminescence of four transition metal coordination compounds based on the semirigid 4-(pyridin-3-yloxy)-phthalic acid

Four transition metal coordination compounds, {[Co(PPDA)(H₂O)₂]}_n (1), {[Ni(HPPDA)₂]}_n (2), {[Cd(PPDA)(H₂O)]?H₂O}_n (3), and {Zn(HPPDA)₂(H₂O)₄}_n (4), were synthesized by assembling transition metal salts with a semirigid ligand 4-(pyridin-3-yloxy)-phthalic acid (H₂PPDA) under hydrothermal conditions. The compounds have been characterized by elemental analyses, IR spectra, TGA, powder X-ray diffraction, and single-crystal X-ray crystallography. Compound 1 exhibits a three-connected 2-D layered structure, 2 shows a (3,6)-connected 2-D layered structure, 3 displays a (3,6)-connected 2-D layered framework based on binuclear units, and 4 is a mononuclear structure, connected to generate a 3-D supramolecular architecture by hydrogen bonds. Compound 2 is thermally stable up to 300 °C. The magnetic properties of 1 and photoluminescent properties of 3 and 4 have been explored.     

Syntheses and structures of three disulfoxide uranyl complexes

Three disulfoxide uranyl complexes [UO₂(DBSOB)(NO₃)₂] _n (1), [UO₂(DBM)₂]₂(DBSOB) (2), and [UO₂(PMBP)₂]₂(DBSOB) (3) (DBSOB = 1,4-di(butylsulfinyl)butane, HDBM = dibenzoylmethane, HPMBP = 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone) were synthesized and characterized. The [UO₂(NO₃)₂] groups are connected by bridging disulfoxide ligands DBSOB to form a 1-D zigzag chain in 1. Two [UO₂(DBM)₂] or [UO₂(PMBP)₂] groups are connected by a bridging DBSOB to form the dimeric structures of 2 or 3, respectively. Complexes 1, 2, and 3 are the first structurally characterized disulfoxide–actinide compounds. Thermal stabilities of 1, 2, and 3 were investigated.     

1,3,2-Diazasiloles derived from 1,2-bis(trimethylsilylimino)acenaphthene

The reduction of 1,2-bis(trimethylsilylimino)acenaphthene (tms-BIAN, 1) with metallic lithium in toluene affords the dilithium salt (tms-BIAN)Li_2· 1,3,2-Diazasiloles (tms-BIAN)SiCl₂ (2) and (tms-BIAN)SiMe₂ (3) were prepared by the reactions of (tms-BIAN)Li₂ with SiCl₄ and Me₂SiCl₂, respectively. The reaction of (tms-BIAN)Li₂ with an excess of Me₂SiCl₂ produces (Cldms-BIAN)SiMe₂ (4), where Cldms-BIAN is 1,2-bis(chlorodimethylsilylimino)-acenaphthene. The compound (tms-BIAN)(SiCl₃)₂ (5) containing two different silyl substituents (Me₃Si and Cl₃Si) at each nitrogen atom was synthesized by the reaction of compound 1 with Cl₃SiSiCl₃. The elimination of SiCl₄ from compound 5 is accompanied by cyclization to give derivative 2. Compounds 2-5 were characterized by ¹H, ¹³C, and ²⁹Si NMR spectroscopy. The crystal structures of 2-5 were established by X-ray diffraction.     

Bis(oxamato)palladate(II) complexes: synthesis,crystal structure and application to catalytic Suzuki reaction

New bis(oxamato)palladate(II) complexes, [Pd(H₂O)₄][Pd(2,6-Me₂pma)₂]·2H₂O (1), (n-Bu₄N)₂[Pd(2,6-Me₂pma)₂]·2H₂O (2a), and (n-Bu₄N)₂[Pd(2,6-Me₂pma)₂]·2CHCl₃ (2b) (2,6-Me₂pma = N-2,6-dimethylphenyoxamate and n-Bu₄N⁺ = tetra-n-butylammonium), have been synthesized and the structures of 1 and 2b characterized by single-crystal X-ray diffraction. Complex 1 is a double salt constituted by tetraaquapalladium(II) cations and bis(oxamato)palladate(II) anions interlinked by hydrogen bonds. The palladium(II) ions in 1 are four-coordinate with two oxygens and two nitrogens from two fully deprotonated oxamate ligands (anion), and four water molecules (cation) building centrosymmetric square-planar surroundings. Centrosymmetric bis(oxamato)palladate(II) anions occur in 2b as in 1, the charge balance in this compound being ensured by the bulky n-Bu₄N⁺. The catalytic role of 1 and 2a for the Suzuki reaction has been investigated by using a series of aryl iodide/bromide derivatives in the conventional organic medium dimethylformamide. The tetraaquapalladium(II) unit in 1 appears to be active in the catalytic Suzuki cross-coupling reactions, but it readily decomposes to inactive palladium black.     

Syntheses,crystal structures,and properties of four new coordination compounds of transition metals and imidazoledicarboxylic acid derivatives

Four new transition metal coordination complexes, [Cd(H₂pimdc)₂(H₂O)₂]?·?4H₂O (1), [Zn(H₂pimdc)₂(H₂O)₂]₂?·?7H₂O (2), and [M(H₂pimdc)₂] (M?=?Cu (3) or Ni (4), H₂pimdc^??=?2-propyl-4,5-imidazoledicarboxylate), have been prepared by conventional synthesis and characterized by elemental analyses, IR, TG, and single-crystal X-ray diffraction. H₂pimdc^? is a bidentate chelating ligand in 1 and 2, leading to 3-D supramolecular structures through hydrogen bonds. However, H₂pimdc^? is a tridentate chelating-bridge ligand in 3 and 4, which exhibit 2-D layer structures. Thermal properties and photoluminescence spectra of 1–4 were measured.     

Syntheses and structures of three new coordination polymers with the flexible 1,4- bis (imidazol-1-yl)butane ligand

Three new coordination polymers [Co(bimb)₂(NCS)₂] _n (1), {[Co(bimb)₂(dca)₂]?·?CH₃CN} _n (2) and [Cu(bimb)₂(NO₃)₂] _n (3) (bimb?=?1,4-bis(imidazol-1-yl)butane, dca?=?dicyanamide) were synthesized and characterized. In 1, each Co(II) links two Co(II)'s by double bimb ligands and extends to form a one-dimensional chain containing the Co₂(bimb)₂ 22-membered metallocycle. 2 and 3 are two-dimensional (4, 4) networks linked by bimb bridges. The conformations of the bimb ligands in 1, 2 and 3 are analyzed.     

PLATINUM(II) COMPLEXES OF P(III) CYCLOPHOSPHAMIDE DERIVATIVES

Abstract

The syntheses of the P(III) analogues of cyclophosphamide, isophosphamide and triphosphamide are reported. These compounds (4–6, respectively) polymerize easily at room temperature but are sufficiently stable in solution to react with Cl₂Pt(NCPh)₂, forming cis-Cl₂Pt(4)₂, cis-Cl₂Pt(5)₂ and cis-Cl₂Pt(6)₂ (complexes 9–11, respectively). Complex 10 can also be made by condensing cis-Cl₂Pt[ClPN(CH₂CH₂Cl)CH₂CH₂CHO]₂ with ClCH₂CH₂NH₂, while an alternate route to 9 and 11 is afforded by the condensation of cis-Cl₂Pt[Cl₂PN(CH₂CH₂Cl)₂]₂ with H₂NCH₂CH₂CH₂OH and ClCH₂CH₂NHCH₂CH₂CH₂OH, respectively. Complexes 9–11 exist in two diastereomeric configurations and these can be separated in the cases of 9 and 11 by column chromatography. ³¹P NMR spectral data for the complexes are discussed and the results of NCl antitumor screening are presented.     

Synthesis,characterization, interactions with DNA and bovine serum albumin (BSA), and antibacterial activity of cyclometalated iridium(III) complexes containing dithiocarbamate derivatives

Three mononuclear cyclometalated iridium(III) complexes having dithiocarbamate ligands, [Ir^III(2-C₆H₄py)₂(L)] (where 2-C₆H₄py?=?2-phenylpyridine; and L¹H?=?4-MePipzcdtH, L²H?=?MorphcdtH, and L³H?=?4-BzPipercdtH for 1, 2, and 3, respectively), were synthesized from [Ir(2-C₆H₄py)₂Cl]₂·1/4CH₂Cl₂ by displacing the two bridging chlorides with one dithiocarbamate ligand. The complexes were characterized using physicochemical and spectroscopic tools along with structural analysis of [Ir(2-C₆H₄py)₂(L²)] (2) by single crystal X-ray diffraction. Structural analysis of 2 showed a distorted octahedron in which the nitrogen donor of one 2-phenylpyridine and the carbon donor of another 2-phenylpyridine are in axial positions, trans to one another. Electrochemical analysis by cyclic voltammetry showed the irreversible two-electron equivalent reduction voltammograms of 1, 2, and 3 attributable to Ir(III) to Ir(I). Electronic characterizations of these complexes are consistent with significant delocalization of the sulfur electron density onto the empty metal d-orbital. The intercalative interaction of the complexes with calf thymus DNA was evaluated using absorption, fluorescence quenching, and viscosity measurements. The binding affinities of these complexes with bovine serum albumin were estimated in terms of quenching constants using the Stern–Volmer equation. Study of antibacterial activities of the complexes by agar disk diffusion against some species of pathogenic bacteria was also performed.     

Structural diversity controlled by alkali/alkaline earth metals for heterometallic AeI/AeII-ZnII coordination polymers based on 4-nitrobenzene-1,2-dicarboxylate

Six heterometallic Zn(II) coordination polymers, Zn(H₂O)₃(FNA) (1), [NH₄]₂[Zn(H₂O)₂(FNA)₂] (2), [ZnNa₂(FNA)₂]·3H₂O (3), [ZnK₂(FNA)₂]·H₂O (4), [ZnRb₂(FNA)₂]·2H₂O (5) and [ZnMg(FNA)₂]·4H₂O (6) (H₂FNA = 4-nitrobenzene-1,2-dicarboxylic acid), were synthesised by introducing different alkali/alkaline earth (Ae^I/Ae^II) metals. These complexes exhibit diverse structures with the different Ae^I/Ae^II metals used and distinct ligand coordination modes the ions provide. For 1 and 2, the Zn(II) centres with distorted octahedra are connected by FNA to form 1-D chain structures. The Zn(II) centres in 3–6 with distorted tetrahedra are linked by FNA to form 2-D anionic grid layers. For 3–5, these 2-D anionic grid layers are connected by alkali metal (Na, K and Rb) with the O–Ae^I–O connectivity to exhibit 3-D framework structures, while 6 features a 2-D Zn–Mg network. Luminescence properties of 1–6 have been investigated.     

Hydrothermal synthesis,crystal structure and characterization of a new 1-D supramolecular ladder based on a binuclear CdII complex [Cd2L4(3,5-DNBA)2](H2O) with L as a bridging ligand (L=3-(2-pyridyl)pyrazole; 3,5-DNBA=3,5-dinitrobenzoate)

A new 1-D cadmium(II) mixed ligand dimer supramolecular ladder [Cd₂ L ₄(3,5-DNBA)₂]H₂O (1), (L?=?3-(2-pyridyl)pyrazole and 3,5-DNBA?=?3,5-dinitrobenzoate) was synthesized by hydrothermal methods. X-ray structural analysis of complex 1 revealed that two cadmium(II) cores are bridged by two deprotonated pyrazole groups of L, leading to dinuclear cadmium(II) [Cd₂ L ₄(3,5-DNBA)₂]. The dimers are joined by hydrogen-bonding interactions between two different cadmium(II) dimers to form a one-dimensional ladder-like framework and stabilized by weak π–π interactions. Moreover, the fluorescence spectrum of compound 1 exhibits blue fluorescent emission in the solid state at room temperature.     

Cadmium(II), manganese(II) and zinc(II) compounds

Three new compounds, [Cd(μ ₃ -Hpdh)(μ₂-Cl)] _n (1), Mn(Hpdh)₂(H₂O)₂ (2) and Zn(Hpdh)₂ (H₂O)₂ (3) (H₂pdh =?pyridine-2,3-dicarbo-2,3-hydrazide), have been synthesized and characterized by elemental analysis, IR spectra, TG and single-crystal X-ray diffraction. Under hydrothermal conditions, H₂pdh is generated by an in situ acylation of H₂pda (H₂pda =?pyridine-2,3-dicarboxylic acid) with hydrazine hydrate. Complex 1 features a 2D layer structure constructed by a dinuclear Cd(II) building block. In complexes 2 and 3, hydrogen bonding interactions connect mononuclear structures into 3D supramolecular frameworks.     

Syntheses,crystal structures,and properties of four transition metal complexes based on 5-nitro-8-hydroxyquinoline

Four new complexes, [M(C₉H₅N₂O₃)₂(H₂O)₂]·CH₃OH (M?=?Zn(II), Cd(II) and Mn(II)) (1–3) and [Cu(C₉H₅N₂O₃)₂] (4), have been synthesized by reactions of 5-nitro-quinoline-8-yl acetate (NQA) and corresponding metal salts at room temperature and characterized by elemental analysis, IR, thermal gravimetric analysis (TGA), fluorescence measurement and single crystal X-ray diffraction. 1–3 are mononuclear, further extended to 2-D layers by hydrogen bonds. For 4, Cu²⁺ is coordinated by two N atoms and two O atoms from two NQ ligands. TGA indicates that 1–4 have good thermal stabilities. Furthermore, 1 and 2 show excellent luminescence in the solid state at room temperature.     

Acetato and formato copper(II) paddle-wheel complexes with nitrogen ligands

Compounds Cu(AcO)₂(pydz) (1), Cu(HCOO)₂(pymd)_1/2 (2), Cu(AcO)₂(pymd)_1/2 (3), and Cu(AcO)₂(4,4′-bipy)_1/2 (4) were obtained by reactions of Cu(AcO)₂?H₂O and Cu(HCOO)₂ ? 4H₂O with pyridazine, pyrimidine, or 4,4′-bipyridine. In all the studied structures, the paddle-wheel units [Cu₂[µ-RCOO)₄] are present. Coppers show a square pyramidal coordination determined by four oxygens in the equatorial positions and a nitrogen in the axial position. Compound 1 consists of centrosymmetric dimeric molecules. Compounds 2 and 3 instead consist of zig-zag chains of [Cu₂[µ-RCOO)₄] units linked by bridging pyrimidine molecules. The chains run in the (1 0 1) and (1 1 ?2) directions in 2 and 3, respectively. By crystallization of a solution of 4 in chloroform, Cu(AcO)₂(4,4′-bipy)_1/2 ? 1/2CHCl₃ (5) was obtained. It consists of monodimensional chains of [Cu₂(µ-CH₃COO)₄] units linked by bridging 4,4′-bipy molecules. The chains, of two different types, run parallel to the b-axis in the crystal. Two chlorines of each CHCl₃ molecule are close to two oxygens of two parallel chains. The packing can be described as sheets parallel to the (1 0 ?1) plane. Magnetic properties and electron paramagnetic resonance spectra have been studied.     

含卤素端基的单取代对-叔丁基杯[6]芳烃的合成与表征

用THF作为反应溶剂, K₂CO₃作碱, 对-叔丁基杯[6]芳烃与二溴丁烷、二溴己烷和1,4-二氯丁炔-2反应以中等产率选择性地合成了含有卤素端基的单取代对-叔丁基杯[6]芳烃2a～2c. 2a和2b可与对甲苯磺酸甲酯(MeOTs)反应高产率地得到全甲基化产物3a和3b. 通过核磁共振谱(¹H NMR)和质谱(FAB-MS)表征, 发现所有化合物都具有预期结构, 2a～2c和3b在室温下是锥式构象, 而3a没有固定构象.     

Synthesis and characterization of new Ni(II) complexes with S,N-heterocycle ligands: influence of the steric strain of ligands on coordination

The complexes [NiCl₂(PyTn)₂]?·?2H₂O (1), [Ni(H₂O)₂(PyTn)₂](NO₃)₂ (2), [Ni(H₂O)₂(PzTz)₂]Cl₂ (3) and [Ni(H₂O)₂(PzTz)₂](NO₃)₂ (4) [PyTn?=?2-(1-pyrazolyl)-2-thiazoline; PzTz?=?2-(1-pyrazolyl)-1,3-thiazine] have been prepared and characterized by elemental analysis, electronic spectroscopy, IR spectroscopy and single crystal X-ray diffraction to determine if the size of the S,N-heterocycle influences coordination to Ni(II). The four complexes are six coordinate as a distorted octahedron. The disposition of chlorides and water is trans in 1 and 2, whereas 3 and 4 are cis, as a consequence of the steric strain induced by the larger S,N-ring.     

Three Mn(II) complexes with 1,3-bis(4-pyridyl)propane and their supramolecular nets

Three complexes, [Mn(bpp)₄(H₂O)₂](ClO₄)₂?·?1.5H₂O (1), [Mn(bpp)₃Br₂]?·?2H₂O (2), and [Mn(bpp)₂(H₂O)₂](ClO₄)?·?I?·?H₂O?·?bpp (3) (bpp?=?1,3-bis(4-pyridyl)propane), were synthesized and structurally characterized by single-crystal X-ray diffraction. Complex 1 is mononuclear where M(II) is coordinated to a monodentate TT-bpp, three monodentate TG-bpp, and two water molecules. Complex 2 possesses a single-stranded helical chain formed from MnN₄Br₂ octahedra by a single TT-bpp, with pendant monodentate TG-bpp ligands. Complex 3 consists of a ribbon-type double-stranded chain formed from MnN₄O₂ octahedra by double TG-bpp ligands. 2-D supramolecular architectures of 1–3 are formed by hydrogen bonds. The fluorescence of the three complexes comes from the π*–π transition of the ligand.     

Coumarin-naphthohydrazone ligand with a rare coordination mode to form Mn(II) and Co(II) 1-D coordination polymers: synthesis,characterization, and crystal structure

The hydrazone (E)-3-hydroxy-N’-(1-(2-oxo-2H-chromen-3-yl)ethylidene)-2-naphthohydrazide (H₂L) was synthesized from the reaction of 3-acetylcoumarin and 3-hydroxy-2-naphthoic hydrazide in methanol. Compounds [Mn(H₂L)(NO₃)₂(CH₃OH)]·CH₃OH (1a), [Mn(HL)(NO₃)(CH₃OH)]_n (1b), [Co(HL)(NO₃)(CH₃OH)]_n (2), and [Cu(HL)(NO₃)] (3) were obtained by reaction of an equimolar amount of H₂L with nitrate salts of Mn(II), Co(II), or Cu(II) in methanol. The reaction of ligand and Mn(NO₃)₂·4H₂O was also carried out in the presence of sodium azide which led to the 1-D coordination polymer, [Mn(HL)(N₃)(CH₃OH)]_n (4). All of the synthesized compounds were characterized by elemental analyses and spectroscopic methods. Single-crystal X-ray analysis of 1–4 indicated that H₂L is neutral (in 1a) or mononegative ligand (in 1b, 2, 3 and 4). In 1b, 2 and 4 the 1-D polymeric chain is found by a rare coordination mode of this kind of hydrazone ligand since the naphtholic oxygen is coordinated to the neighboring metal ions while the NH moiety of hydrazone remains intact, also confirmed by FT-IR spectroscopic studies. The thermal stability of 2 and 4 were also studied from 30–1000 °C.     

Cadmium(II) complexes of 5-nitro-salicylaldehyde and α-diimines: synthesis,structure and interaction with calf-thymus DNA

Five Cd(II) complexes with the anion of 5-NO₂-salicylaldehydeH (5-NO₂-saloH) in the absence or presence of the α-diimine 1,10-phenanthroline (phen), 2,2′-dipyridylamine (dpamH), 2,2′-dipyridine (bipy), or 2,9-dimethyl-1,10-phenanthroline (neoc) were synthesized and characterized as [Cd(5-NO₂-salo)₂(CH₃OH)₂] (1), [Cd(5-NO₂-salo)₂(phen)]·2CH₃OH·H₂O (2), [Cd(5-NO₂-salo)₂(dpamΗ)] (3), [Cd₃(5-NO₂-salo)₆(bipy)₂] (4), and [Cd(5-NO₂-salo)(neoc)(NO₃)]₂ (5). Based on spectroscopic results (IR, UV, NMR), elemental analysis and conductivity measurements an octahedral geometry around cadmium metal ion is suggested, with the 5-NO₂-salicylaldehyde ligand having different coordination modes. The structures determined by X-ray crystallography verified neutral mononuclear 1–3 and trinuclear 4. Simultaneous TG/DTG–DTA technique was used to analyze the thermal behavior of 1, 2, and 3. The complexes bind tightly to calf-thymus DNA mainly by intercalation, as concluded by DNA viscosity measurements and exhibit significant displacement of EB from the EB-DNA complex.     

Reduction of aromatic ketones with the (dpp-BIAN)AlI(Et2O) complex

Reduction of benzophenone and 4,4′-bis(methoxy)benzophenone with the aluminum complex (dpp-BIAN)AlI(Et₂O) (1) containing the dianionic dpp-BIAN ligand (dpp-BIAN is 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) affords the pinacolate complexes [(dpp-BIAN)AlI]₂[μ-O₂C₂Ph₄] (2) and [(dpp-BIAN)AlI]₂[μ-O₂C₂(C₆H₄OMe)₄] (3), respectively, which undergo the pinacolone rearrangement upon prolonged storage in diethyl ether to form [(dpp-BIAN)AlI]₂O (4). The reaction of 1 with fluoren-9-one produces stable pinacolate (dpp-BIAN)Al[μ-O₂(C₁₃H₈)₂] (7) and the (dpp-BIAN)AlI₂ complex (8). Compounds 2—4, 7, and 8 were characterized by ESR spectroscopy. Hydrolysis products of compounds 2 and 3 were characterized by ¹H NMR spectroscopy. The structures of complexes 4 and 7 were established by X-ray diffraction. dpp-BIAN is 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1134–1140, July, 2006.