Hydrothermal assembly and luminescence property of lanthanide-containing Anderson polyoxometalates

Two compounds, {[Sm(H₂O)₅]₂(TeMo₆O₂₄)}·6H₂O (1) and {[Eu(H₂O)₇]₂ (TeMo₆O₂₄)}·5H₂O (2) have been synthesized by hydrothermal reactions and characterized by elemental analyses, IR spectra, thermal stability analyses, X-ray powder diffraction, and single-crystal X-ray diffraction. Compound 1 represents the first example of a 2D layer architecture constructed from Anderson-type polyoxoanions [TeMo₆O₂₄]⁶⁻ and rare-earth ions Ln³⁺. Compound 2 displays a 1D chain structure built up of alternating Anderson-type polyoxoanions [TeMo₆O₂₄]⁶⁻ and rare-earth ions Eu³⁺ along the c-axis. Luminescence measurement of 2 exhibits typical red fluorescent emission of the Eu³⁺ ion at room temperature. Furthermore, the emission is intense enough to be observed macroscopically under UV irradiation (365 nm).     

A series of 2D lanthanide (III) coordination polymers constructed from 2-(pyridin-3-yl)-1H-imidazole-4,5-dicarboxylate

Reactions of 2-(pyridine-3-yl)-1H-4,5-imidazoledicarboxylic acid (H₃PyIDC) with a series of Ln(III) ions affords ten coordination polymers, namely, {[Ln(H₂PyIDC)(HPyIDC)(H₂O)₂]·H₂O}_n [Ln=Nd (1), Sm (2), Eu (3) and Gd (4)], {[Ln(HPyIDC)(H₂O)₃]·(H₂PyIDC)·H₂O}_n [Ln=Gd (5), Tb (6), Dy (7), Ho (8) and Er (9)], and {[Y₂(HPyIDC)₂(H₂O)₅]·(bpy)·(NO₃)₂·3H₂O}_n (10) (bpy=4,4′-bipyridine). They exhibit three types of networks: complexes 1-4 are isomorphous coordination networks containing neutral 2D metal-organic layers, while complexes 5-9 are isomorphous, which consist of cationic metal-organic layers and anionic organic layers, and complex 10 is a 2D network built up from 4-connected HPyIDC²⁻ anion and 4-connected Y(III) ions. In addition, thermogravimetric analyses and solid-state luminescent properties of the selected complexes are investigated. They exhibit intense, characteristic emissions in the visible region at room temperature.     

Effect of N-donor sites of bis-pyridyl-bis-amide ligands on the architectures of three Anderson-type polyoxometalate-based metal–organic complexes

Three polyoxometalate-based metal–organic complexes [Co₂(H₂O)₆(TeMo₆O₂₄)](3-H₂dpyb)·2H₂O (1), [M₂(4-Hdpyb)₂(H₂O)₆(TeMo₆O₂₄)]·6H₂O [M = Co (2), Zn (3); 3-dpyb = N,N′-bis(3-pyridinecarboxamide)-1,4-butane, 4-dpyb = N,N′-bis(4-pyridinecarboxamide)-1,4-butane] have been hydrothermally synthesized and characterized by elemental analysis, IR, TG, powder diffraction and single-crystal X-ray diffraction analysis. The structure of complex 1 consists of 1D [Co₂(H₂O)₆(TeMo₆O₂₄)] inorganic chains, which are joined together by the 3-dpyb ligands through weak hydrogen bonds to generate a 2D supramolecular network. Complexes 2 and 3 are isostructural; each [TeMo₆O₂₄]^6? (TeMo₆) polyoxoanion chelates either two cobalt or two zinc atoms to generate the discrete complexes [Co₂(4-Hdpyb)₂(H₂O)₆(TeMo₆O₂₄)] and [Zn₂(4-Hdpyb)₂(H₂O)₆(TeMo₆O₂₄)], respectively. The electrochemical properties, electrocatalytic and photocatalytic activities of the complexes have been investigated.     

0-D and 1-D inorganic-organic composite polyoxotungstates constructed from in-situ generated monocopper-substituted Keggin polyoxoanions and copper-organoamine complexes

Combination of in-situ generated monocopper^II-substituted Keggin polyoxoanions with copper^II-organoamine complexes under hydrothermal conditions results in seven inorganic-organic composite polyoxotungstates [Cu(en)₂(H₂O)]₂{[Cu(en)₂][α-PCuW₁₁O₃₉Cl]}·3H₂O (1), {[Cu(en)₂(H₂O)][Cu(en)₂]₂[α-PCuW₁₁O₃₉Cl]}·6H₂O (2), {[Cu(en)₂(H₂O)]₂[Cu(en)₂][α-XCuW₁₁O₃₉]}·5H₂O (3/4, X=Si^IV/Ge^IV), {[Cu(deta)(H₂O)₂]₂[Cu(deta)(H₂O)][α-XCuW₁₁O₃₉]}·5H₂O (5/6, X=Ge^IV/Si^IV) and [Cu(dap)₂]₂{[Cu(dap)₂]₂[Cu(dap)₂][α-PCuW₁₁O₃₉]₂} (7) (en=ethylenediamine, dap=1,2-diaminopropane and deta=diethylenetriamine). 1 is an isolated structure whereas 2 is a 1-D chain structure, but both contain [α-PCuW₁₁O₃₉Cl]⁶⁻ polyoxoanions. 3-6 contain the 1-D linear chains made up of [α-XCuW₁₁O₃₉]⁶⁻ polyoxoanions in the pattern of -A-A-A- (A=[α-XCuW₁₁O₃₉]⁶⁻), while 7 demonstrates the first 1-D zigzag chain constructed from [α-PCuW₁₁O₃₉]₂¹⁰⁻ polyoxoanions via [Cu(en)₂]²⁺ bridges in the pattern of -A-B-A-B- (A=[α-PCuW₁₁O₃₉]₂¹⁰⁻, B=[Cu(en)₂]²⁺). The successful syntheses of 1-7 can provide some experimental evidences that di-/tri-/hexa-vacant polyoxoanions can be transformed into mono-vacant Keggin polyoxoanions under hydrothermal conditions.     

Emission of 2-phenylethanol from its β-d-glucopyranoside and the biogenesis of these compounds from [H8] l-phenylalanine in rose flowers

The hydrolysis of 2-phenylethyl β-d-glucopyranoside (3) was found to be partially inhibited by feeding with 2-phenyl-N-glucosyl-acetamidiumbromide (8), a β-glucosidase inhibitor, resulting in a decrease in the diurnal emission of 2-phenylethanol (2) from Rosa damascena Mill. flowers. Detection of [1,1,2,2′,3′,4′,5′,6′-²H₈]-2 and [1,2,2′,3′,4′,5′,6′-²H₇]-2 from R. ‘Hoh-Jun’ flowers fed with [1,1,2,2′,3′,4′,5′,6′-²H₈]-3 suggested that β-glucosidase, alcohol dehydrogenase, and reductase might be involved in scent emission. Comprehensive GC-SIM analyses revealed that [1,2,2,2′,3′,4′,5′,6′-²H₈]-2 and [1,2,2,2′,3′,4′,5′,6′-²H₈]-3 must be biosynthesized from [1,2,2,2′,3′,4′,5′6′-²H₈] l-phenylalanine ([²H₈]-1) with a retention of the deuterium atom at α-position of [²H₈]-1.     

Synthesis and properties of novel 5-(cyclohepta-2′,4′,6′-trienylidene)pyrimidine-2(1H),4(3H),6(5H)-triones: methodology for synthesizing cyclohepta[b]pyrimido[5,4-d]furan-8(7H),10(9H)-dionylium tetrafluoroborates

Novel condensation reaction of tropone with N-substituted and N,N′-disubstitued barbituric acids in Ac₂O afforded 5-(cyclohepta-2′,4′,6′-trienylidene)pyrimidine-2(1H),4(3H),6(5H)-trione derivatives (8a-f) in moderate to good yields. The ¹³C NMR spectral study of 8a-f revealed that the contribution of zwitterionic resonance structures is less important as compared with that of 8,8-dicyanoheptafulvene. The rotational barriers (ΔG^‡) around the exocyclic double bond of mono-substituted derivatives 8a-c were obtained to be 14.51-15.03 kcal mol⁻¹ by the variable temperature ¹H NMR measurements. The electrochemical properties of 8a-f were also studied by CV measurement. Upon treatment with DDQ, 8a-c underwent oxidative cyclization to give two products, 7 and 9-substituted cyclohepta[b]pyrimido[5,4-d]furan-8(7H),10(9H)-dionylium tetrafluoroborates (11a-c·BF₄⁻ and 12a-c·BF₄⁻) in various ratios, while that of disubstituted derivatives 8d-f afforded 7,9-disubstituted cyclohepta[b]pyrimido[5,4-d]furan-8(7H),10(9H)-dionylium tetrafluoroborate (11d-f·BF₄⁻) in good yields. Similarly, preparation of known 5-(1′-oxocycloheptatrien-2′-yl)-pyrimidine-2(1H),4(3H),6(5H)-trione derivatives (14a-d) and novel derivatives 14e,f was carried out. Treatment of 14a-c with aq. HBF₄/Ac₂O afforded two kinds of novel products 11a-c·BF₄⁻ and 12a,c·BF₄⁻ in various ratios, respectively, while that of 14d-f afforded 11d-f. The product ratios of 11a-c·BF₄⁻ and 12a-c·BF₄⁻ observed in two kinds of cyclization reactions were rationalized on the basis of MO calculations of model compounds 20a and 21a. The spectroscopic and electrochemical properties of 11a-f·BF₄⁻ and 12a-c·BF₄⁻ were studied, and structural characterization of 11c·BF₄⁻ based on the X-ray crystal analysis and MO calculation was also performed.     

Electron affinities of a homologous series of tertiary alkyl radicals and their C-H bond dissociation energies (BDEs)

Heats of formation have been derived from G3(MP2)//B3LYP and G3MP2B3(+) atomization energies for tert-butyl radical (6R), cubyl radical, bicyclooctyl radical (1R), and tricyclo[3.3.n.0^3,7]alk-3(7)-yl (n=0-3, 2R-5R) radicals, and their respective anions (1A-6A) and hydrocarbons (1H-6H). The electron affinity (EA) of 6R is estimated at 1.5±2 kcal/mol and tert-butyl anion (6A) is likely to be bound. In the homologous series 2R-5R the EAs range from 3.4±2 to 13.5±2 kcal/mol. The computed enthalpies of the acidities of the tricyclic hydrocarbons 1H-5H are in the range 407-411 kcal/mol. Their C-H bond dissociation energies (BDEs) are in the range 97-110 kcal/mol. The increase of the BDEs in the homologous series 2H-5H and the increase of EAs of 2A-5A is attributed to the enhanced pyramidalization induced in radicals 2R-5R by the shortening of the methylene chain connecting carbons C₃ and C₇.     

Different Anderson-Type Polyoxometalate-Directed Metal–Organic Complexes Based on 2-Pyrazine Carboxylic Acid: Assembly,Structures and Properties

Two different Anderson-type polyoxometalates-directed metal–organic complexes with different structures: {H₂[K(H₂O)₅]₂[Cu(pzca)(H₂O)₃]₂(TeMo₆O₂₄)} (1) and {H[Cu(pzca)(H₂O)₂]₂[AlMo₆(OH)₆O₁₈]}·17H₂O (2) (Hpzca = 2-pyrazine carboxylic acid) have been synthesized and structurally characterized by single crystal X-ray diffraction analyses, thermogravimetric analyses, IR spectra and powder X-ray diffraction analyses. Compound 1 is a 0D architecture, in which the A-type Anderson anion [TeMo₆O₂₄]^6? (TeMo₆) is modified by two [Cu(pzca)(H₂O)₃]⁺ cations and two [K(H₂O)₅]⁺ cations. The adjacent {[K(H₂O)₅]₂[Cu(pzca)(H₂O)₃]₂(TeMo₆O₂₄)} clusters are connected by hydrogen-bonding interactions, resulting in a 3D supramolecular framework. When B-type Anderson anion [AlMo₆(OH)₆O₁₈]^3? (AlMo₆) was used in compound 2, a 2D wave-like network was obtained, in which the adjacent 1D [Cu(pzca)] _n ⁿ⁺ chains are linked by AlMo₆ anions with two terminal oxygen atoms. The types of Anderson anions play an important role in tuning the structures of the title compounds. In addition, the electrocatalytic activities of title compounds and photocatalytic activities of compound 1 have been studied.     

One ligand different metal complexes: Biological studies of titanium(IV), tin(IV) and gallium(III) derivatives with the 2,6-dimethoxypyridine-3-carboxylato ligand

The reaction of 2,6-dimethoxypyridine-3-carboxylic acid (DMPH) with different precursors [Ti(η⁵-C₅H₅)₂Cl₂], [Ti(η⁵-C₅H₄Me)₂Cl₂], [Ti(η⁵-C₅H₄SiMe₃)(η⁵-C₅H₅)Cl₂], [Ti(η⁵-C₅Me₅)Cl₃], SnMe₃Cl and Ga^tBu₃ yielded the complexes [Ti(η⁵-C₅H₅)₂(DMP-κO)₂] (1), [Ti(η⁵-C₅H₄Me)₂(DMP-κO)₂] (2), [Ti(η⁵-C₅H₄SiMe₃)(η⁵-C₅H₅)(DMP-κO)₂] (3), [Ti(η⁵-C₅Me₅)(DMP-κ²O,O′)₃] (4), [SnMe₃(μ-DMP-κO:κO′)]_∞ (5), and [Ga^tBu₂(μ-DMP-κO:κO′)]₂ (6). 1-6 have been characterized by spectroscopic methods and the molecular structure of the complexes 1, 2, 3, 5 and 6 have been determined by X-ray diffraction studies. The cytotoxic activity of 1-6 was tested against the tumour cell lines human adenocarcinoma HeLa, human myelogenous leukaemia K562, human malignant melanoma Fem-x and human breast carcinoma MDA-MB-361. The results of this study show a higher cytotoxicity of the tin(IV) and gallium(III) derivatives in comparison to their titanium(IV) counterparts. Furthermore, the different titanium compounds showed differences in their cytotoxicities with a higher activity of complex 4 (mono-(cyclopentadienyl) derivative) compared to that of 1-3 (bis-(cyclopentadienyl) complexes). A qualitative UV-vis study of the interactions of these complexes with DNA has also been carried out.     

Study of complexes of platinum group metals containing nitrogen bases derived from pyridine aldehydes: Interesting molecular structures with unpredicted bonding modes of the ligands

A series of mono-cationic dinuclear half sandwich ruthenium, rhodium and iridium metal complexes have been synthesized using ((pyridin-2-yl)methylimino)nicotinamide (L1) and ((picolinamido)phenyl)picolinamide (L2) ligands: [(η⁶-arene)₂Ru₂(μ-L1)Cl₃]⁺ (arene = C₆H₆, 1; p-ⁱPrC₆H₄Me, 2; C₆Me₆, 3), [(η⁵-C₅Me₅)₂M₂(μ-L1)Cl₃]⁺ (M = Rh, 4; Ir, 5), and [(η⁶-arene)₂Ru₂(μ-L2)(μ-Cl)]⁺ (arene = C₆H₆, 6; p-ⁱPrC₆H₄Me, 7; C₆Me₆, 8), [(η⁵-C₅Me₅)₂M₂(μ-L2)Cl₂]⁺ (M = Rh, 9; Ir, 10). All the complexes have been isolated as their hexafluorophosphate salts and fully characterized by use of a combination of NMR and IR spectroscopy. The solid state structure of three representatives 4, 6 and 9 has been determined by X-ray crystallographic studies. Interestingly, in the molecular structure of 4, the first metal is bonded to two nitrogen atoms whereas the second metal center is coordinated to only one nitrogen atom with two terminal chloride ligands. Fascinatingly in the case of the complexes with the symmetrical ligand L2, both ruthenium centers having η⁶-arene groups are bonded to nitrogen atoms with a bridging chloride atom between the two metal centers, whereas the metals with η⁵-Cp∗ groups are bonded to the ligand N,O and N,N fashion.     

New approaches to cluster modification in the 12-vertex metallatricarbollide series

Cluster opening of [2-Cp-9-^tBuNH-closo-2,1,7,9-FeC₃B₈H₁₀] (1) , followed by oxidation, generates complexes [2-Cp-8-^tBuNH-closo-2,1,8,10-FeC₃B₈H₁₀] (2), [2-Cp-4-^tBuNH-closo-2,1,4,12-FeC₃B₈H₁₀] (3), [2-Cp-1-^tBuNH-closo-2,1,7,10-FeC₃B₈H₁₀] (4), and [1-Cp-10-^tBuNH-closo-1,2,3,10-FeC₃B₇H₉] (5). Another variation of the syntheses led to compounds [2-Cp-closo-2,1,8,10-FeC₃B₈H₁₁] (6), [4-Cp-1-^tBuNH-closo-4,1,6,8,-FeC₃B₉H₁₁] (7) and to two isomeric, not yet fully characterized, 13-vertex compounds of general nido structure [^tBuNH-Cp-FeC₃B₉H₁₂] (8 and 9).     

Solvent-dependent formation of two different Cd(II) complexes with p-BrC6H4C(S)NHP(O)(OiPr)2 (HL). Crystallographic modification of Cd(HL)2L2

Reaction of the potassium salt of N-(diisopropoxyphosphoryl)-p-bromothiobenzamide p-BrC₆H₄C(S)NHP(O)(OiPr)₂ (HL) with Cd(II) cations in freshly dried and distilled EtOH leads exclusively to the complex [Cd(p-BrC₆H₄C(S)NH₂-S)(L-O,S)₂] ([Cd(L^I)L₂]), while the same reaction in H₂O leads to the complex [Cd(HL-O)₂(L-O,S)₂] ([Cd(HL)₂L₂]). The corresponding reactions with Zn(II) always lead to the complex [Zn(L-O,S)₂] ([ZnL₂]) regardless of the solvent. The crystal structure of [Cd(HL)₂L₂]^.2/3H₂O reveals to be a polymorph to the previously reported anhydrous [Cd(HL)₂L₂].     

Syntheses and characterization of inorganic–organic hybrids with 4-(isonicotinamido)phthalate and some divalent metal centers

Four new inorganic–organic hybrid frameworks [Mn(L)(H₂O)₂]_n (1), {[Co(L)(H₂O)₃]·2H₂O·CH₃OH}_n (2), {[Zn(L)(H₂O)]·H₂O}_n (3) and [Cd(HL)₂]_n (4) [H₂L = 4-(isonicotinamido)phthalic acid] have been synthesized and characterized by single-crystal X-ray diffraction analysis. Complex 1 has three-dimensional (3D) structure and topology related to SrAl₂ (sra) with Schläfli symbol of (4²·6³·8). And 2 displays (3,3)-connected two-dimensional (2D) network with (4,8²) topology, while 3 exhibits a uninodal (3,3)-connected (6,3) 2D network, which is further linked by N–H?O hydrogen bonding interactions to give 3D structure with hms topology and Schläfli symbol of (6³)(6⁹·8). Complex 4 with partial deprotonated HL⁻ ligands also has a 2D network structure. In addition, the magnetic property of 1, nonlinear optical property of 3 and photoluminescence of 3 and 4 were investigated.     

Catalytic oxidation of diorganotin(IV) carboxylates to mixed-ligand monoalkyltin(IV) carboxylates by Ag and structure characterization of the mixed-ligand monoalkyltin(IV) 2-pyridinecarboxylate (2-ClPhCH2)Sn(2-ClPhCO2)(O2CC5H4N-2)2

The complexes of the type (ArCH₂)₂SnO were catalytic-oxygenated by Ag⁺ and yielded mixed-ligand organotin(IV) complexes (ArCH₂)(2-C₅H₄NCO₂)₂(ArCOO)tin(IV) (Ar = C₆H₅ (1), 2-ClC₆H₄ (2), 2-CNC₆H₄ (3), 4-ClC₆H₄ (4), 4-CNC₆H₄ (5), 2-FC₆H₄ (6)). The complexes 1-6 are characterized by elemental analyses, IR and NMR (¹H, ¹³C, ¹¹⁹Sn) spectroscopies. Single X-ray crystal structure analysis has been determined, which reveals that the center tin atom of complex 2 is seven-coordinated geometry.     

Mono and dinuclear half-sandwich platinum group metal complexes bearing pyrazolyl-pyrimidine ligands: Syntheses and structural studies

Reactions of 0.5 eq. of the dinuclear complexes [(η⁶-arene)Ru(μ-Cl)Cl]₂ (arene = η⁶-C₆H₆, η⁶-p-ⁱPrC₆H₄Me) and [(Cp∗)M(μ-Cl)Cl]₂ (M = Rh, Ir; Cp∗ = η⁵-C₅Me₅) with 4,6-disubstituted pyrazolyl-pyrimidine ligands (L) viz. 4,6-bis(pyrazolyl)pyrimidine (L1), 4,6-bis(3-methyl-pyrazolyl)pyrimidine (L2), 4,6-bis(3,5-dimethyl-pyrazolyl)pyrimidine (L3) lead to the formation of the cationic mononuclear complexes [(η⁶-C₆H₆)Ru(L)Cl]⁺ (L = L1, 1; L2, 2; L3, 3), [(η⁶-p-ⁱPrC₆H₄Me)Ru(L)Cl]⁺ (L = L1, 4; L2, 5; L3, 6), [(Cp∗)Rh(L)Cl]⁺ (L = L1, 7; L2, 8; L3, 9) and [(Cp∗)Ir(L)Cl]⁺ (L = L1, 10; L2, 11; L3, 12), while reactions with 1.0 eq. of the dinuclear complexes [(η⁶-arene)Ru(μ-Cl)Cl]₂ and [(Cp∗)M(μ-Cl)Cl]₂ give rise to the dicationic dinuclear complexes [{(η⁶-C₆H₆)RuCl}₂(L)]²⁺ (L = L1, 13; L2, 14; L3, 15), [{(η⁶-p-ⁱPrC₆H₄Me)RuCl}₂(L)]²⁺ (L = L1, 16; L2, 17; L3, 18), [{(Cp∗)RhCl}₂(L)]²⁺ (L = L1, 19; L2, 20; L3, 21) and [{(Cp∗)IrCl}₂(L)]²⁺ (L = L1 22; L2, 23; L3 24). The molecular structures of [3]PF₆, [6]PF₆, [7]PF₆ and [18](PF₆)₂ have been established by single crystal X-ray structure analysis.     

Syntheses, structures and photoluminescence of a series of coordination frameworks based on dicarboxylate anion and bis(imidazole) ligand

In this article, ten new coordination frameworks, namely, [Ni(H₂O)₆]·(L3) (1), [Zn(L3)(H₂O)₃] (2), [Cd(L3)(H₂O)₃]·5.25H₂O (3), [Ag(L1)(H₂O)]·0.5(L3) (4), [Ni(L3)(L1)] (5), [Zn(L3)(L1)_0.5]·H₂O (6), [Cd(L3)(L1)_0.5(H₂O)] (7), [CoCl(L3)_0.5(L1)_0.5] (8), [ZnCl(L3)_0.5(L2)_0.5] (9), and [CoCl(L3)_0.5(L2)_0.5] (10), where L1 = 1,1′-(1,4)-butanediyl)bis(imidazole), L2 = 1,1′-(1,4-butanediyl)bis(2-ethylbenzimidazole) and H₂L3 = 3,3′-(p-xylylenediamino)bis(benzoic acid), have been synthesized by varying the metal centers and nitrogen-containing secondary ligands. These structures have been determined by single-crystal X-ray diffraction analyses, elemental analyses and IR spectra. In 1, the L3 anion is not coordinated to the Ni(II) center as a free ligand. The Ni(II) ion is coordinated by water molecules to form the cationic [Ni(H₂O)₆]²⁺ complex. The hydrogen bonds between L3 anions and [Ni(H₂O)₆]²⁺ cations result in a three-dimensional (3D) supramolecular structure of 1. In compounds 2 and 3, the metal centers are linked by the organic L3 anions to generate 1D infinite chain structures, respectively. The hydrogen bonds between carboxylate oxygen atoms and water molecules lead the structures of 2 and 3 to form 3D supramolecular structures. In 4, the L3 anion is not coordinated to the Ag(I) center, while the L1 ligands bridge adjacent Ag(I) centers to give 1D Ag-L1 chains. The hydrogen bonds among neighboring L3 anions form infinite 2D honeycomb-like layers, in the middle of which there exist large windows. Then, 1D Ag-L1 chains thread in the large windows of the 2D layer network, giving a 3D polythreaded structure. Considering the hydrogen bonds between the water molecules and L3 anions, the structure is further linked into a 3D supramolecular structure. Compounds 5 and 7 were synthesized through their parent compounds 1 and 3, respectively, while 6 and 9 were obtained by their parent compound 2. In 5, the L3 anions and L1 ligands connect the Ni(II) atoms to give a 3D 3-fold interpenetrating dimondoid topology. Compound 6 exhibits a 3D three-fold interpenetrating α-Po network structure formed by L1 ligands connecting Zn-L3 sheets, while compound 7 shows a 2D (4,4) network topology with the L1 ligands connecting the Cd-L3 double chains. In compound 8, the L1 ligands linked Co-L3 chains into a 2D layer structure. Two mutual 2D layers interpenetrated in an inclined mode to generate a unique 3D architecture of 8. Compounds 9 and 10 display the same 2D layer structures with (4,4) network topologies. The effects of the N-containing ligands and the metal ions on the structures of the complexes 1-10 were discussed. In addition, the luminescent properties of compounds 2-4, 6, 7 and 9 were also investigated.     

A series of POM-based entangled frameworks with the rigid ligand 1,4-bis(1-imidazolyl)benzene and different isomers of octamolybdate

With BIMB ligand, we have successfully obtained and characterized three novel entangled inorganic-organic hybrid compounds by choosing different metal ions, that is, [Ni(BIMB)₂(γ-Mo₈O₂₆)_0.5]·3H₂O (1), [Zn(BIMB)₂(γ-Mo₈O₂₆)_0.5] (2), and [Cu₃(BIMB)₄(H₂O)(δ-Mo₈O₂₆)Cl₂]·3H₂O (3) (where BIMB=1,4-bis(1-imidazolyl)benzene). Compound 1 is a 2-fold interpenetration 4-connected 3D framework with the short Schläfli symbol of (4×6⁴×8)₂(4²×6²×8²), in which octamolybdate anion shows γ-isomer; 2 exhibits a (5,6)-connected 3D self-penetrating topological motif with the short Schläfli symbol of (4×5⁷×6²)₂(4²×5¹¹×7²), and 3 shows a (4,6)-connected self-penetrating 3D framework with the short Schläfli symbol of (4²·5²·6·7) (4⁴·5·6⁹·8) (5⁴·6²) whose octamolybdate has δ-isomer. In addition, the optical band gaps of these three compounds have been measured, which are 2.98 eV for 1, 3.42 eV for 2, and 2.88 eV for 3. Moreover, 2 has photoluminescent property, which can be attributed to ligand-to-metal charge-transfer (LMCT) band.     

Half sandwich complexes of Ru(II) and complexes of Pd(II) and Pt(II) with seleno and thio derivatives of pyrrolidine: Synthesis, structure and applications as catalysts for organic reactions

The reactions of PhSe⁻, PhS⁻ and Se²⁻ with N-{2-(chloroethyl)}pyrrolidine result in N-{2-(phenylseleno)ethyl}pyrrolidine (L1), N-{2-(phenylthio)ethyl}pyrrolidine (L2), and bis{2-pyrrolidene-N-yl)ethyl selenide (L3), respectively, which have been explored as ligands. The complexes [PdCl₂(L1/L2)] (1/7), [PtCl₂(L1/L2)] (2/8), [RuCl(η⁶-C₆H₆)(L1/L2)][PF₆] (3/9), [RuCl(η⁶-p-cymene)(L1/L2)][PF₆] (4/10), [RuCl(η⁶-p-cymene)(NH₃)₂][PF₆] (5) and [Ru(η⁶-p-cymene)(L1)(CH₃CN)][PF₆]₂·CH₃CN (6) have been synthesized. The L1-L3 and complexes were found to give characteristic NMR (Proton, Carbon-13 and Se-77). The crystal structures of complexes 1, 3-6, 9 and 10 have been solved. The Pd-Se and Ru-Se bond lengths have been found to be 2.353(2) and 2.480(11)/2.4918(9)/2.4770(5) Å, respectively. The complexes 1 and 7 have been explored for catalytic Heck and Suzuki-Miyaura coupling reactions. The value of TON has been found up to 85 000 with the advantage of catalyst’s stability under ambient conditions. The efficiency of 1 is marginally better than 7. The Ru-complexes 3 and 9 are good for catalytic oxidation of primary and secondary alcohols in CH₂Cl₂ in the presence of N-methylmorpholine-N-oxide (NMO). The TON value varies between 8.0 × 10⁴ and 9.7 × 10⁴ for this oxidation. The 3 is somewhat more efficient catalyst than 9.     

Synthetic and X-ray diffraction studies of borosiloxane cages [R′Si(ORBO)3SiR′] and the adducts of [BuSi{O(PhB)O}3SiBu] with pyridine or N,N,N′,N′-tetramethylethylenediamine

Eleven borosiloxane [R′Si(ORBO)₃SiR′] compounds where R′ = Bu^t and R = Ph (1), 4-PhC₆H₄ (2), 4-Bu^tC₆H₄ (3), 3-NO₂C₆H₄ (4), 4-CH(O)C₆H₄ (5), CpFeC₅H₄ (6), 4-C(O)CH₃C₆H₄ (7), 4-ClC₆H₄ (8), 2,4-F₂C₆H₃ (9), and R′ = cyclo-C₆H₁₁ and R = Ph (10), and 4-BrC₆H₄ (11) have been synthesized and characterized by spectroscopic (IR, NMR), mass spectrometric and, for compounds where R′ = Bu^t and R = 4-PhC₆H₄ (2), 4-Bu^tC₆H₄ (3), 3-NO₂C₆H₄ (4), CpFeC₅H₄ (6) and 2,4-F₂C₆H₃ (9), X-ray diffraction studies. These compounds contain trigonal planar RBO₂ and tetrahedral R′SiO₃ units located around 11-atom “spherical” Si₂O₆B₃ cores. The dimensions of the Si₂O₆B₃ cores in compounds 2, 3, 4, 6 and 9 are remarkably similar. The reaction between [Bu^tSi{O(PhB)O}₃SiBu^t] (1), and excess pyridine yields the 1:1 adduct [Bu^tSi{O(PhB)O}SiBu^t]. NC₅H₅ (12) while the reaction between 1 and N,N,N′,N′-tetramethylethylenediamine in equimolar amounts affords a 2:1 borosiloxane:amine adduct [Bu^tSi{O(PhB)O}₃SiBu^t]₂ · Me₂NCH₂CH₂NMe₂ (13). Compounds 12 and 13 were characterised with IR and (¹H, ¹³C and¹¹B) NMR spectroscopies and the structure of the pyridine complex 12 was determined with X-ray techniques.