Reaction of 3,3-di-tert-butylthiirane-2-thione S-oxide (α-dithiolactone S-oxide): synthesis of thiolato sulfinato-platinum and palladium complexes

Thermolysis of 3,3-di-tert-butylthiirane-2-thione S-oxide 4 gave di-tert-butyl ketone 5 and carbon disulfide (CS₂). Treatment of α-dithiolactone S-oxide 4 with excess m-CPBA or triphenylphosphine gave di-tert-butylthioketene S-oxide 3 almost quantitatively. Treatment of 4 with (η²-ethylene)bis(triphenylphosphine)platinum(0) 13 or tetrakis(triphenylphosphine) palladium 17 resulted in the formation of thiolato sulfinato-platinum complex 15 or palladium complex 18, respectively. The structure of complex 15 was determined by X-ray crystallographic analysis.     

Phosphorus-nitrogen compounds part 22. Syntheses, structural investigations, biological activities and DNA interactions of new mono and bis (4-fluorobenzyl) spirocyclophosphazenes

The reactions of hexachlorocyclotriphosphazene, N₃P₃Cl₆, with mono (1 and 2) and bis(4-fluorobenzyl) diamines (3-5), FPhCH₂NH(CH₂)_nNHR (RH or FPhCH₂-), produce mono (1a and 2a) and bis(4-fluorobenzyl) monospirocyclophosphazenes (3a-5a). The tetraaminomonospirocyclophosphazenes (1b-2d) are obtained from the reactions of the partly substituted phosphazenes (1a and 2a) with excess pyrrolidine, morpholine and 1,4-dioxa-8-azaspiro[4,5]decane (DASD), respectively. The tetrachlorobis(4-fluorobenzyl) monospirocyclophosphazenes (4a and 5a) with excess pyrrolidine, morpholine and DASD afford the fully substituted bis(4-fluorobenzyl) monospirocyclophosphazenes (4b, 4d-5d) in boiling THF. In addition, monochlorobis(4-fluorobenzyl) monospirocyclophosphazenes (4e and 4f) have also been isolated from the reactions with excess morpholine and DASD in boiling THF. The structural investigations of the compounds have been verified by elemental analyses, MS, FTIR, ¹H, ¹³C, ¹⁹F (for 1d and 2d), ³¹P NMR, HSQC and HMBC techniques. The crystal structures of 3a, 4a, 5a and 2b have been determined by X-ray crystallography. The compounds 2a-5a, 1b-2d, 4b, 4d-5d, 4e and 4f have been screened for antibacterial effects on bacteria and for antifungal activity against yeast strains. The compounds 1b and 4b showed antimicrobial activity against three species of bacteria, Bacillus subtilis, Bacillus cereus and Staphylococcus aureus, and two fungi, Candida albicans and Candida tropicalis. Minimum inhibitory concentrations (MIC) were determined for 1b and 4b. The MIC values were found to be 5000 μM for each bacteria. The most effective compound, 4b has exhibited activity with a MIC of 312 μM for C. albicans and 625 μM for C. tropicalis. DNA-binding and the nature of the interaction with pBR322 plasmid DNA are studied. All of the compounds induce changes on the DNA mobility and intensity. Prevention of HindIII digestion with the compounds indicates that the compounds bind with AT nucleotides in DNA.     

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.     

Diazaallyls of group 4 metals based on trans-1,2-diaminocyclohexane

Amination of 1-bromo-2-methylpyridine with trans-1,2-diaminocyclohexane gives the corresponding bis(aminopyridine) H₂L¹. Conversion of the same diamine to the N,N′-bis(amino-4,4-dimethylthiazoline) H₂L² is also completed in three steps. The analogous aminooxazoline is however inaccessible, although the aminocyclohexane analogue is prepared readily. The proligand H₂L¹ forms bis(aminopyridinato) alkyl complexes of the type [ZrL¹R₂] (R = CH₂Ph, CH₂Bu^t). The molecular structure of the neopentyl complex shows that the chiral backbone leads to a puckering of the N₄Zr coordination sphere, which contrasts with the related cyclohexyl-bridged Schiff-base complexes which are essentially planar. [ZrL²(CH₂Bu^t)₂] - the first aminothiazolinato complex - is formed similarly. A comparison of the structures of [ZrL¹(CH₂Bu^t)₂] and [ZrL²(CH₂Bu^t)₂] indicates that the latter has a fully delocalised N-C-N system, rather similar to a bis(amidinate). Reaction of H₂L² with [Ti(NMe₂)₄] gives [TiL²(NMe₂)₂] which appears to be C₂-symmetric like the above complexes according to NMR spectra, but has one uncoordinated thiazoline unit in the solid state. This is a result of increased ring strain at the smaller titanium metal centre.     

Syntheses, crystal structures and coordination modes of tri- and di-organotin derivatives with 2-mercapto-4-methylpyrimidine

The organotin (IV) derivatives of 2-mercapto-4-methylpyrimidine (Hmpymt) R₃SnL (R = Ph 1, PhCH₂2, n-Bu 3), R₂SnCl_mL_n (m = 1, n = 1, R = CH₃4, Ph 5, n-Bu 6, PhCH₂7; m = 0, n = 2, R = CH₃8, n-Bu 9, Ph 10, PhCH₂11) were obtained by the reaction of the organotin(IV) chlorides R₃SnCl or R₂SnCl₂ with 2-mercapto-4-methylpyrimidine hydrochloride (HCl · Hmpymt) in 1:1 or 1:2 molar ratio. All complexes 1-11 were characterized by elemental analyses, IR, ¹H, ¹³C and temperature-dependent ¹¹⁹Sn NMR spectra. Except for complexes 3 and 6, the structures of complexes 1, 2, 4, 5, 7, 8-11 were confirmed by X-ray crystallography. Including tin-nitrogen intramolecular interaction, the tin atoms of complexes 1-7 are all five-coordinated and their geometries are distorted trigonal bipyramidal. While the tin atoms of complexes 8-11 are six-coordinated and their geometries are distorted octahedral. Besides, the ligand adopts the different coordination modes to bond to tin atom between the complexes 1, 6, 7 and 2, 3, 4, 5, 8-11. Furthermore, intermolecular Sn?N or Sn?S interactions were recognized in crystal structures of complexes 4, 7 and 11, respectively.     

Synthesis, crystal structures and photoluminescent properties of lanthanide supramolecular complexes with 4-oxo-1(4H)-quinolineacetate

Five new lanthanide supramolecular complexes, namely, [Sm(oqa)₂(H₂O)₄]₂ (ClO₄)₂·(bpy)₂ (1), [Ln(oqa)₃]·2H₂O [Ln=Sm(2), Gd(3)] and [Ln(oqa)₂(NO₃)(H₂O)] [Ln=Pr(4), Eu(5)] (oqa=4-oxo-1(4H)-quinolineacetate, bpy=4,4′-bipyridine), have been synthesized under hydrothermal conditions. These complexes exhibit three typical structure features. Complex 1 possesses a dimeric structure, which is further connected together through hydrogen bonds and π-π attractions, forming a 3D supramolecular framework. Compounds 2-3 are isomorphous and contain 1D ring-like chains, which are further interconnected by the oqa ligands into 2D sheet-like structures. 4 and 5 exhibit eight-connected 3D network of 4²⁴·6⁴-bcu topology. The various coordination modes of carboxylate ligands and the selection of the counterions have clearly affected the topological structures. Furthermore, the solid-state luminescent properties of complexes 1, 2 and 5 were investigated at room temperature and they show intense, characteristic emissions in the visible region.     

Phosphite ligands derived from distally and proximally substituted dipropyloxy calix[4]arenes and their palladium complexes: Solution dynamics, solid-state structures and catalysis

Two bisphosphite ligands, 25,27-bis-(2,2′-biphenyldioxyphosphinoxy)-26,28-dipropyloxy-p-tert-butyl calix[4]arene (3) and 25,26-bis-(2,2′-biphenyldioxyphosphinoxy)-27,28-dipropyloxy-p-tert-butyl calix[4]arene (4) and two monophosphite ligands, 25-hydroxy-27-(2,2′-biphenyldioxyphosphinoxy)-26,28-dipropyloxy-p-tert-butyl calix[4]arene (5) and 25-hydroxy-26-(2,2′-biphenyldioxyphosphinoxy)-27,28-dipropyloxy- p-tert-butyl calix[4]arene (6) have been synthesized. Treatment of (allyl) palladium precursors [(η³-1,3-R,R′-C₃H₄)Pd(Cl)]₂ with ligand 3 in the presence of NH₄PF₆ gives a series of cationic allyl palladium complexes (3a-3d). Neutral allyl complexes (3e-3g) are obtained by the treatment of the allyl palladium precursors with ligand 3 in the absence of NH₄PF₆. The cationic allyl complexes [(η³-C₃H₅)Pd(4)]PF₆ (4a) and [(η³-Ph₂C₃H₃)Pd(4)]PF₆ (4b) have been synthesized from the proximally (1,2-) substituted bisphosphite ligand 4. Treatment of ligand 4 with [Pd(COD)Cl₂] gives the palladium dichloride complex, [PdCl₂(4)] (4c). The solid-state structures of [{(η³-1-CH₃-C₃H₄)Pd(Cl)}₂(3)] (3f) and [PdCl₂(4)] (4c) have been determined by X-ray crystallography; the calixarene framework in 3f adopts the pinched cone conformation whereas in 4c, the conformation is in between that of cone and pinched cone. Solution dynamics of 3f has been studied in detail with the help of two-dimensional NMR spectroscopy.The solid-state structures of the monophosphite ligands 5 and 6 have also been determined; the calix[4]arene framework in both molecules adopts the cone conformation. Reaction of the monophosphite ligands (5, 6) with (allyl) palladium precursors, in the absence of NH₄PF₆, yield a series of neutral allyl palladium complexes (5a-5c; 6a-6d). Allyl palladium complexes of proximally substituted ligand 6 showed two diastereomers in solution owing to the inherently chiral calix[4]arene framework. Ligands 3, 6 and the allyl palladium complex 3f have been tested for catalytic activity in allylic alkylation reactions.     

Carbon-rich organometallic materials derived from 4-ethynylphenylferrocene

Using 4-ethynylphenylferrocene (1) as the building block, a new series of rigid-rod alkynylferrocenyl precursors consisting of fluoren-9-one unit, 2-bromo-7-(4-ferrocenylphenylethynyl)fluoren-9-one (2a), 2,7-bis(4-ferrocenylphenylethynyl)fluoren-9-one (2b), 2-trimethylsilylethynyl-7-(4-ferrocenylphenylethynyl)fluoren-9-one (3) and 2-ethynyl-7-(4-ferrocenylphenylethynyl)fluoren-9-one (4) have been prepared in moderate to good yields. The acetylene complex 4 is a useful precursor for the synthesis of well-defined carbon-rich ferrocenyl heterometallic complexes, trans-[(η⁵-C₅H₅)Fe(η⁵-C₅H₄)C₆H₄CCRCCPt(PEt₃)₂Ph] (5), trans-[(η⁵-C₅H₅)Fe(η⁵-C₅H₄)C₆H₄CCRCCPt(PBu₃)₂CCRC≡CC₆H₄(η⁵-C₅H₄)Fe(η⁵-C₅H₅)] (6), trans-[(η⁵-C₅H₅)Fe(η⁵-C₅H₄)C₆H₄CCRCCM(dppm)₂Cl] (M=Ru (7), Os (8)) (R=fluoren-9-one-2,7-diyl). All new complexes have been characterized by FTIR, NMR and UV-Vis spectroscopies and fast atom bombardment mass spectrometry (FABMS). The molecular structures of 1, 2a, 4, 6 and 8 have been determined by single-crystal X-ray studies where an ironiron through-space distance of nanosized dimension (ca. 42 Å) is observed in the trimetallic molecular rod 6. The electronic absorption, luminescence and electrochemical properties of these carbon-rich molecules were investigated and the data were correlated with the theoretical results obtained by the method of density functional theory.     

Syntheses, characterizations and crystal structures of triorganotin(IV) derivatives with 2-mercapto-4-quinazolinone

The triorganotin(IV) derivatives of 2-mercapto-4-quinazolinone (HSqualone) of the type, R₃SnL (R = Ph 1, CH₃2, PhCH₂3, p-F-PhCH₂4, o-F-PhCH₂5, n-Bu 6), were obtained by the reaction of the R₃SnCl and HSqualone with 1:1 molar ratio in benzene. All complexes 1-6 were characterized by elemental analyses, IR, ¹H and ¹³C NMR spectroscopy and the crystal structures of complexes 1-3 were also confirmed by X-ray crystallography. The structure analyses reveal that the tin atoms of complexes 1-3 are all distorted tetrahedral geometries. Furthermore, the dimeric structures in complexes 1-3 have also been found linked by intermolecular O-H?N or N-H?O hydrogen bonding interaction. Interestingly, the dimers of complexes 2 and 3 are further linked into one-dimensional chain through intermolecular C-H?S and C-H?O weak hydrogen bonding interactions, respectively.     

Group 4 ansa-metallocenes derived from o-carborane and their luminescent properties

Luminescent group 4 complexes derived from o-carborane, M(η⁵:η¹-CpCMe₂CB₁₀H₁₀C)₂ (M = Ti; 1, Zr; 2, Hf; 3) and Me₂Si(η⁵-Ind)[η⁵:η¹-Cp-3-(CMe₂CB₁₀H₁₀C)]ZrCl (4) were explored. While the Ti complex 1 possessing C₂ molecular symmetry shows non-centrosymmetry in the unit cell as identically observed in 2 and 3, the double-ansa Zr complex 4 crystallizes in centrosymmetric P2₁/n space group despite its C₁ molecular symmetry. The non-centrosymmetric crystals of 2 and 3 exhibit blue mechanoluminescence similar to their solution and solid state photoluminescence. In contrast, 1 is lacking mechanoluminescence in crystal and shows much weaker emission than other congeners in solution. The electroluminescence devices based on 2 or 3 doped poly(N-vinylcarbazole) (PVK) as an emitting layer display green electroluminescence, which turned out to be originated from the exciplexes formed between the complex and PVK host. Although the double ansa-Zr complex 4 does not show mechanoluminescence owing to the centrosymmetric nature, it exhibits good electron-transporting properties when incorporated into the electron-transporting layer of Alq₃-based OLEDs.     

Fe Spin crossover materials based on dissymmetrical N4 Schiff bases including 2-pyridyl and 2R-imidazol-4-yl rings: Synthesis,crystal structure and magnetic and Mössbauer properties

The synthesis and characterization of new symmetrical Fe^II complexes, [FeL^A(NCS)₂] (1), and [FeL^Bx(NCS)₂] (2–4), are reported (L^A is the tetradentate Schiff base N,N′-bis(1-pyridin-2-ylethylidene)-2,2-dimethylpropane-1,3-diamine, and L^Bx stands for the family of tetradentate Schiff bases N,N′-bis[(2-R-1H-imidazol-4-yl)methylene]-2,2-dimethylpropane-1,3-diamine, with: R = H for L^B1 in 2, R = Me for L^B2 in 3, and R = Ph for L^B3 in 4). Single-crystal X-ray structures have been determined for 1 (low-spin state at 293 K), 2 (high-spin (HS) state at 200 K), and 3 (HS state at 180 K). These complexes remain in the same spin-state over the whole temperature range [80–400 K]. The dissymmetrical tetradentate Schiff base ligands L^Cx, N-[(2-R₂-1H-imidazol-4-yl)methylene]-N′-(1-pyridin-2-ylethylidene)-2,2-R₁-propane-1,3-diamine (R₁ = H, Me; R₂ = H, Me, Ph), containing both pyridine and imidazole rings were obtained as their [FeL^Cx(NCS)₂] complexes, 5–10, through reaction of the isolated aminal type ligands 2-methyl-2-pyridin-2-ylhexahydropyrimidine (R₁ = H, 5–7) or 2,5,5-trimethyl-2-pyridin-2-ylhexahydropyrimidine (R₁ = Me, 8–10) with imidazole-4-carboxaldehyde (R₂ = H: 5, 8), 2-methylimidazole-4-carboxaldehyde (R₂ = Me: 6, 9), and 2-phenyl-imidazole-4-carboxaldehyde (R₂ = Ph: 7, 10) in the presence of iron(II) thiocyanate. Together with the single-crystal X-ray structures of 7 and 9, variable-temperature magnetic susceptibility and Mössbauer studies of 5–10 showed that it is possible to tune the spin crossover properties in the [FeL^Cx(NCS)₂] series by changing the 2-imidazole and/or C2-propylene susbtituent of L^Cx.     

Solvothermal syntheses, and characterization of [Ln(en)4(SbSe4)] (Ln=Ce, Pr) and [Ln(en)4]SbSe4·0.5en (Ln=Eu, Gd, Er, Tm, Yb): The effect of lanthanide contraction on the crystal structures of lanthanide selenidoantimonates(V)

Two types of lanthanide selenidoantimonates [Ln(en)₄(SbSe₄)] (Ln=Ce(1a), Pr(1b)) and [Ln(en)₄]SbSe₄·0.5en (Ln=Eu(2a), Gd(2b), Er(2c), Tm(2d), Yb(2e); en=ethylenediamine) were solvothermally synthesized by reactions of LnCl₃, Sb and Se with the stoichiometric ratio in en solvent at 140 °C. The four-en coordinated lanthanide complex cation [Ln(en)₄]³⁺ formed in situ balances the charge of SbSe₄³⁻ anion. In compounds 1a and 1b, the SbSe₄³⁻ anion act as a monodentate ligand to coordinate complex [Ln(en)₄]³⁺ and the neutral compound [Ln(en)₄(SbSe₄)] is formed. The Ln³⁺ ion has a nine-coordinated environment involving eight N atoms and one Se atom forming a distorted monocapped square antiprism. In 2a-2e the lanthanide(III) ion exists as isolated complex [Ln(en)₄]³⁺, in which the Ln³⁺ ion is in a bicapped trigonal prism geometry. A systematic investigation of the crystal structures reveals that two types of structural features of these lanthanide selenidoantimonates are related with lanthanides contraction across the lanthanide series. TG curves show that compounds 1a-1b and 2a-2e remove their organic components in one and two steps, respectively.     

Reactivity of TpIr(C2H4)(DMAD) with carboxylic acids. A DFT study on geometrical isomers and structural characterization

The thermally unstable adduct Tp^Me2Ir(C₂H₄)(DMAD), which was generated “in situ” by the reaction of DMAD with Tp^Me2Ir(C₂H₄)₂ (1) at low temperature, reacted with different carboxylic acids to produce the following compounds: Tp^Me2Ir(E-C(CO₂Me)CH(CO₂Me))(H₂O)(OC(O)C₆H₄R), (R = H, 2a; o-OH, 2b; o-Cl, 2c; m-Cl, 2d; o-NO₂, 2e; m-NO₂, 2f;o-Me, 2g;p-Me, 2h) and Tp^Me2Ir(E-C(CO₂Me)CH(CO₂Me))(H₂O)(OC(O)Me) 3. In the reaction of derivative 2a with Lewis bases, Tp^Me2Ir(E-C(CO₂Me)CH(CO₂Me))(L)(OC(O)C₆H₅), (L = Py, 4a; m-Br-Py, 4b; m-Cl-Py, 4c; NCMe, 5) were obtained, of which 4b and 4c were isolated as a mixture of two isomers in which the substituted pyridine ring was present at different rotational orientations. All new compounds prepared were characterized by ¹H and ¹³C{¹H} NMR spectroscopy, the structure of compounds 2d, 2h and 4a being determined by X-ray diffraction analysis. DFT was used to analyze the relative stability and the structural orientation of the isomers.     

Polymer-supported calix[4]arenes for sensing and conversion of NO2/N2O4

The use of simple calix[4]arenes 1a,b for NO₂/N₂O₄ sensing and conversion is demonstrated, both in solution and in the solid state. Upon reacting with these gases, compounds 1a,b encapsulate reactive NO⁺ cations within their cavities with the formation of deeply colored (λ_max∼570 nm) charge-transfer complexes 2a,b. Further functionalization of the calix[4]arene platform is reported for attachment to solid supports. Polymer-supported calixarene material 3 was prepared, which reversibly traps NO₂/N₂O₄ with the formation of nitrosonium storing polymer 4. Material 4 was effectively used for nitrosation of amides.     

[4+2] Cycloaddition of 1-aminodienes and 2-substituted vinylphosphonates: application to asymmetric synthesis of 3-amino-5-phosphono-1-cyclohexene derivatives

N-Butadienylsuccinimide (1), iso-propyl N-butadienyl-(S)-pyroglutamate (5) and N-butadienyl-(R)-4-phenyloxazolidin-2-one (6) reacted with vinylphosphonates, vicinally-substituted (2) by electronwithdrawing groups (CO₂Me, CN, COMe), to furnish [4+2] cycloadducts (3-4,7-10, and 11-14) in moderate to good yields (40-88%). The reactions were highly selective: regioselectivity of 95-100%, endoselectivity of 75-92% and facial selectivity of 80-95%. The major diastereoisomers were fully characterized by ¹H and ¹³C NMR spectroscopy.     

Synthesis and reactivity of para-substituted benzoylmethyltellurium(II and IV) compounds: observation of intermolecular C-H-O hydrogen bonding in the crystal structure of (p-MeOC6H4COCH2)2TeBr2

Bis(p-substituted benzoylmethyl)tellurium dibromides, (p-YC₆H₄COCH₂)₂TeBr₂, (Y=H (1a), Me (1b), MeO (1c)) can be prepared either by direct insertion of elemental Te across C_Rf-Br bonds (where C_Rf refers to α-carbon of a functionalized organic moiety) or by the oxidative addition of bromine to (p-YC₆H₄COCH₂)₂Te (Y=H (2a), Me (2b), MeO (2c)). Bis(p-substituted benzoylmethyl)tellurium dichlorides, (p-YC₆H₄COCH₂)₂TeCl₂ (Y=H (3a), Me (3b), MeO (3c)), are prepared by the reaction of the bis(p-substituted benzoylmethyl)tellurides 2a-c with SO₂Cl₂, whereas the corresponding diiodides (p-YC₆H₄COCH₂)₂TeI₂ (Y=H (4a), Me (4b), MeO (4c)) can be obtained by the metathetical reaction of 1a-c with KI, or alternatively, by the oxidative addition of iodine to 2a-c. The reaction of 2a-c with allyl bromide affords the diorganotellurium dibromides 1a-c, rather than the expected triorganotelluronium bromides. Compounds 1-4 were characterized by elemental analyses, IR spectroscopy, ¹H, ¹³C and ¹²⁵Te NMR spectroscopy (solution and solid-state) and in case of 1c also by X-ray crystallography. (p-MeOC₆H₄COCH₂)₂TeBr₂ (1c) provides, a rare example, among organotellurium compounds, of a supramolecular architecture, where C-H-O hydrogen bonds appear to be the non-covalent intermolecular associative force that dominates the crystal packing.     

Syntheses, spectroscopic and structural characterizations and metal ion binding properties of Schiff bases derived from 4′-aminobenzo-15-crown-5

A series of benzyloxybenzaldehyde derivatives (1-4) were synthesized by the reactions of 4-(bromomethyl)benzonitrile with 4-hydroxy-3-methoxybenzaldehyde (vanillin), 2-hydroxy-3-methoxybenzaldehyde (o-vanillin), 2-hydroxy-4-methoxybenzaldehyde and 2-hydroxy-5-methoxybenzaldehyde. Condensation reactions among the new benzyloxybenzaldehyde derivatives (1-4) with 4′-aminobenzo-15-crown-5 yielded the new Schiff base compounds (5-8). Sodium complexes (5a-8a) and potassium complexes (5b-8b) were prepared with NaClO₄ and KI, respectively. All of these synthesized compounds were characterized on the basis of FT-IR, ¹H and ¹³C NMR, mass spectrometry and elemental analyses data. The solid state structures of compounds 8 and 5a were determined by X-ray crystallography. The extraction abilities of compounds 5-8 were also evaluated in CH₂Cl₂ by using several main group and transition metal picrates, such as Na⁺, K⁺, Pb²⁺, Cr³⁺, Ni²⁺, Cu²⁺ and Zn²⁺.     

Metal-organic coordination architectures of azole heterocycle ligands bearing acetic acid groups: Synthesis, structure and magnetic properties

Four new coordination complexes with azole heterocycle ligands bearing acetic acid groups, [Co(L¹)₂]_n (1), [CuL¹N₃]_n (2), [Cu(L²)₂·0.5C₂H₅OH·H₂O]_n (3) and [Co(L²)₂]_n (4) (here, HL¹=1H-imidazole-1-yl-acetic acid, HL²=1H-benzimidazole-1-yl-acetic acid) have been synthesized and structurally characterized. Single-crystal structure analysis shows that 3 and 4 are 2D complexes with 4⁴-sql topologies, while another 2D complex 1 has a (4³)₂(4⁶)-kgd topology. And 2 is a 3D complex composed dinuclear μ_1,1-bridging azido Cu^II entities with distorted rutile topology. The magnetic properties of 1 and 2 have been studied.     

A NMR, X-ray, and DFT combined study on the regio-chemistry of nucleophilic addition to platinum(II) coordinated terminal olefins

The series of platinum complexes [PtCl(η²-CH₂CH-C₆H₄-X)(tmeda)](ClO₄) (X = H, 1b; 4-OMe, 1c; 3-OMe, 1d; 4-CF₃, 1e; 3-CF₃, 1f; 3-NO₂, 1g; tmeda = N,N,N′,N′-tetramethyl-1,2-ethanediamine) has been considered. In the styrene complex (1b) both solution (NMR) and solid state (X-ray) data indicate a significant difference in the Pt-C bond lengths (the longer bond being that involving the olefin carbon atom carrying the phenyl ring). Such a difference increases when X is an electron donor group (EDG, 1c) and decreases when X is an electron withdrawing group (EWG, 1d-g). The attack of a nucleophile (MeO⁻) to the substituted carbon (Markovnikov type, M) is by far the most favoured in the case of unsubstituted (1b) or EDG-substituted (1c) styrenes. The presence of an EWG (compounds 1d-g) levels off the probability of M and anti-M type of attack. DFT calculations on 1b,c and 1e were also performed. The NLMO analysis reveals the crucial role of the interaction between the filled π orbital of the olefin and the empty d orbital of platinum; the carbon with greater electron density becoming less susceptible of nucleophilic attack.