Two new lead(II) coordination polymer and discrete complex containing bipyridine ligands with different positioned methyl substituents: synthesis,characterization, crystal structure determination,and luminescent properties

Lead(II) coordination polymer [Pb(5,5′-dmbpy)(μ-NO₃)₂] _n (1) and mononuclear complex [Pb(6,6′-dmbpy)(NO₃)₂] (2) (where 5,5′-dmbpy is 5,5′-dimethyl-2,2′-bipyridine and 6,6′-dmbpy is 6,6′-dimethyl-2,2′-bipyridine) were synthesized from reaction of lead(II) nitrate with 5,5′-dmbpy and 6,6′-dmbpy, respectively. Both complexes were thoroughly characterized by elemental analysis, infrared, ¹H and ¹³C NMR, UV–Vis, emission spectroscopy, as well as single-crystal X-ray diffraction. Polymer 1 possesses one-dimensional (1D) chain structure, whilst complex 2 exhibits a discrete complex which provide an extended chain parallel to the [001] direction, via weak intermolecular C–H···O hydrogen bonding. Coordination number of Pb²⁺ in 1 and 2 are 8 and 6, respectively, with the stereochemically active lone pair, resulting in the hemidirected geometry for both complexes. The nitrate anions exhibit a tridentate chelating/bridging mode in 1, and a bi-chelating mode in 2. The supramolecular features in these complexes are guided/influenced by weak directional intermolecular C–H···O hydrogen bonding (1 and 2) together with π–π and C–H···π (1) interactions. The luminescence studies of 1 and 2 confirmed that the position of methyl substituent on 2,2′-bipyridine rings has a profound effect on the fluorescence emissions.     

Reactions of 2-phenyl-4,4-bis(trifluoromethyl)-4,5-dihydro-1,3,2-benzodioxaphosphepin-5-one with phenanthrenequinone and dibenzoyl

Reactions of 2-phenyl-4,4-bis(trifluoromethyl)-4,5-dihydro-1,3,2-benzodioxaphosphepin-5-one with 9,10-phenanthrenequinone and dibenzoyl gave hydrolytically unstable spirophosphoranes with five- and seven-membered rings, 2-phenyl-4,4-bis(trifluoromethyl)-4,5-dihydrospiro[[1,3,2]benzodioxaphosphepine-2,2′-phenanthro[9,10-d][1,3,2]dioxaphosphol]-5-one and 2,4′,5′-triphenyl-4,4-bis(trifluoromethyl)-4,5-dihydrospiro[[1,3,2]benzodioxaphosphepine-2,2′-[1,3,2]dioxaphosphol]-5-one. The structure of the first of these was proved by X-ray analysis.     

Synthesis, characterization and properties of β-octamolybdate-supported transition metal complexes with mixed ligands: [Cu(2,2′-bipy)(C6H5NO2)(H2O)]2[Mo8O26]·5H2O

A novel organic–inorganic hybrid compound [Cu(2,2′-bipy)(C₆H₅NO₂)(H₂O)]₂[Mo₈O₂₆]·5H₂O (1), (2,2′-bipy = 2,2′-bipyridine; C₆H₅NO₂ = pyridine-4-carboxylic acid) has been prepared and characterized by elemental analyses, IR spectrum, thermal stability analysis, and single-crystal X-ray diffraction. Compound 1 is a discrete cluster, constructed from β-[Mo₈O₂₆]⁴⁻ subunits covalently bonded to two [Cu(2,2′- bipy)(C₆H₅NO₂)(H₂O)]₂⁴⁺ coordination cations via terminal oxo groups that connect one molybdenum site. A 3D supramolecular network is further formed by extensive hydrogen bonding interactions and π–π interactions of the 2,2′-bipy and pyridine-4-carboxylic acid ligands. EPR and magnetic susceptibility studies have been used to elucidate the electronic properties of the Cu²⁺ centres, and the results are in good agreement with the structural features of the compound.     

Chelate polypyridine ligand rearrangement in Au(III) complexes

The reaction of gold(III) neutral complexes AuBr(CN)₂(N–N) {N–N = 2,2′-bipyridine (bpy), 5,5′-dimethyl-2,2′-bipyridine (^Me2bpy), 1,10-phenanthroline (phen)} with a stoichiometric amount of K[AuCl₄] · 2H₂O in nitromethane at room temperature led to the formation of 1:1 electrolytes which were characterized by NMR and IR spectroscopy, conductivity measurements, elemental analyses and X-ray diffraction. Both the anions and the cations of these salts are singly charged square-planar Au(III) complexes and the cations have general formula [AuCl₂(N–N)]⁺. A hypothesis on the possible reaction mechanisms is presented to give an explanation for the formation of the reaction products.     

Synthesis,structures and electrochemical properties of four organic–inorganic hybrid polyoxometalates constructed from polyoxotungstate clusters and transition metal complexes

Four novel organic–inorganic hybrid compounds [Cu₅ ^I(4,4′-bpy)₃(2,2′-bpy)₄][BW₁₂O₄₀] · H₂O (1), [Ni_0.5(2,2′-bpy)_1.25][Ni(2,2′-bpy)₃][Ni(2,2′-bpy)₂(H₂O)(SiW₁₁^VIW^VO₄₀)] · 0.5H₂O (2), [H₂bpy]₂[Zn(2,2′-bpy)₃]₂[Si₂W₁₈O₆₂] · 1.5H₂O (3) and [Cu^II(2,2′-bpy)₂]₂[SiW₁₂O₄₀] · 2H₂O (4) (2,2′-bpy = 2,2′-bipyridine, 4,4′-bpy = 4,4′-bipyridine) have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy, thermal gravimetric analysis, electrochemical measurements and single-crystal X-ray diffraction. Compound (1) is a novel [BW₁₂O₄₀]⁵⁻ polyoxoanion bisupported by copper(I) coordination cations with mixed 2,2′-bpy and 4,4′-bpy ligands. Compound (2) is constructed from the [SiW₁₁^VIW^VO₄₀]⁵⁻ polyoxoanions supported by [Ni(2,2′–bpy)₂]²⁺. Compound (3) is composed of a novel [Si₂W₁₈O₆₂]⁸⁻ cluster and [Zn(2,2′–bpy)₃]²⁺ complexes, which held together into a three-dimensional (3D) supramolecular network through hydrogen-bonding interactions. Compound (4) shows a 2D layer framework constructed from a bisupporting Keggin polyoxoanion cluster and [Cu(2,2′–bpy)₂]²⁺ coordination polymer fragments, resulting in 3D networks via supramolecular interactions. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Isoflavone glycosides from the bark of Amorpha fruticosa

Four known isoflavone glucosides have been isolated from the bark of Amorpha fruticosa, which is a traditional remedy plant, for the first time. They were elucidated as 3′-hydroxy-4′-methoxyisoflavone-7-O-β-D-glucopyranoside (1), 4′,6-dimethoxyisoflavone-7-O-β-D-glucopyranoside (2), 4′-methoxyisoflavone-7-O-β-D-glucopyranoside (3), and 3′,5-dihydroxy-4′-methoxyisoflavone-7-O-β-D-glucopyranoside (4), based on the UV, FT-IR, EIMS, FABMS, HREIMS, and NMR (¹H and ¹³C, DEPT, COSY, NOESY, HMQC, and HMBC) data. Published in Khimiya Prirodnykh Soedinenii, No. 4, pp. 336–338, July–August, 2006.     

Structure of 2-chloromethyl-2λ5-2,2′(3h,3′h)-spirobis[1,3,2- benzoxazaphosphole]

In 2-chloromethyl-2⁵-2,2(3H,3H)-spirobis[1,3,2-benzoxazaphosphole], which has been investigated by x-ray diffraction, the P atom has a distorted trigonal-bipyramidal coordination with O atoms in axial positions; the angle between the two planes of the 3H-1,3,2-benzoxazaphosphole fragments is 128.8°.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1523–1526, July, 1991.     

Mesogenic and magnetic behavior in cobalt(II) and iron(II) compounds with long alkyl chains

Abstract  

Metal complexes with long alkyl chains [Co(C16-terpy)₃](BF₄)₂ (1), [Fe(C16-terpy)₂](BF₄)₂ (2), [Co(C16-terpy)₂](BPh₄)₂ (3), [Co(C14-terpy)₂](BF₄)₂ (4), and [Fe(C12C10C5-terpy)₂](BF₄)₂ (5) were synthesized and their physical properties characterized, where C16-terpy, C14-terpy, and C12C10C5-terpy are 4′-hexadecyloxy-2,2′:6′,2′′-terpyridine, 4′-tetradecyloxy-2,2′:6′,2′′-terpyridine, and 4′-5′′′-decyl-1′′′-heptadecyloxy-2,2′:6′,2″-terpyridine, respectively. Complexes 1, 2, and 5 exhibited liquid–crystal properties in the temperature ranges of 371–528 K and 466–556 K, and 88–523 K, respectively. Variable-temperature magnetic susceptibility measurements revealed that the Co(II) complexes 1 and 4 exhibited unique spin transitions (T _1/2↓ = 217 K and T _1/2↑ = 260 K for 1 and T _1/2↓ = 250 K and T _1/2↑ = 307 K for 4), so-called ‘reverse spin transition,’ induced by structural phase transitions. Complex 3 exhibited gradual spin-crossover behavior (T _1/2 = 160 K.), and complex 5 exhibited spin transitions (T _1/2↑ = 288 K and T _1/2↓ = 284 K) at the liquid crystal transition temperature. Compounds with multifunction, i.e., magnetic and liquid–crystal properties, are important in the development of molecular materials.     

Flocculation kinetics of an ochre suspension in salt(NaCl)-containing aqueous media in the presence of anionic and cationic acrylamide copolymers

The sedimentation kinetics of an ochre suspension in salt (NaCl)-containing aqueous media was studied in the presence of ionogenic (anionic, A, and cationic, C) acrylamide copolymers with high molecular weight (M > 2 × 10⁶) using a VT–0.5 torsion balance. The ionic strength of the dispersion medium varied in the wide range from 0.001 N to 0.4 N. The flocculation proceeded predominantly by a `bridge' mechanism, and the fraction of macromolecules inactive in the acts of floccule formation was significantly higher for C copolymer as compared with A copolymer. A drastic fall in the flocculating activities of A and C copolymers when passing from salt-free to salt-containing media is caused mainly by two following events: 1. The change in the conformational state of macromolecules, primarily, in their effective dimensions 2. The participation of a certain part of electrolyte in the formation and modification of an electrical double layer around disperse phase particles After introducing binary compositions of A and C flocculants into salt-containing media their resultant flocculating effect depends on the introduction mode of polymeric components. A strong difference in the magnitudes of the flocculating effect for A and C copolymers is observed in water. In the region of high ionic strengths (0.1–0.4 N) this difference becomes far less distinct. The flocculating activities of A and C copolymers were compared when introduced as the first (λ_A and λ_C) and the second (λ_A ^′ and λ_C ^′) additives. It was shown that λ_A/λ_A ^′>1 and λ_C/λ_C ^′>1. Such relationship between λ_A and λ_A ^′, λ_C and λ_C ^′ indicates that selective interactions between A and C copolymers play an essential role in the flocculation processes. The last statement was indirectly confirmed in the present work by the data of electrochemical and viscosimetric studies. When using C copolymer as the second additive in the region of low ionic strengths its main function undergoes reversal, and the copolymer begins to operate not as a flocculant, but as a stabilizer of disperse phase particles (λ_C< 0). Received: 14 April 2000 Accepted: 4 August 2000     

Synthesis and Crystal Structures of Group 10 Metal Bis(dithiolate) Complexes Constructed by 2,3-Naphtho-15-Crown-5 or 2,3-Naphtho-18-Crown-6

Five novel 2,3-naphtho crown ether group 10 metal bis(dithiolate) complexes, [Na(N15C5)₂]₂[Pd(mnt)₂] (1), [Na(N15C5)]₂[Pd(i-mnt)₂] (2) and [K(N18C6)]₂[M(i-mnt)₂] (3 5) (where mnt = 1,2-dicyanoethylene-1,2-dithiolate, i-mnt = 1,1-dicyanoethylene-2,2-dithiolate and M = Ni, Pd, Pt for complexes 3–5, respectively), have been synthesized and characterized by elemental analysis, FT-IR, UV–Visible spectra and single crystal X-ray diffraction. X-ray diffraction analyses reveal that complexes 1 and 2 have different structural features while complexes 3–5 are structurally isomorphous. Complex 1 consists of two [Na(N15C5)₂]⁺ sandwich complex cations and one [Pd(mnt)₂]²⁻ anion, affording a zero-dimensional structure. For 2, the [Na(N15C5)]⁺ mono-capped complex cations act as the bridges linking the [Pd(i-mnt)₂]²⁻ anions into a 1D infinite chain through Na–N interactions and SȮFC and SȮFπ interactions are observed in the resulting chain. Complexes 3–5 all consist of two [K(N18C6)]⁺ complex cations and one [M(i-mnt)₂]²⁻ (M = Ni, Pd or Pt) anion and the complex molecules are linked into␣1D␣chains by the bridging K–O(ether) interactions between the adjacent [K(N18C6)]⁺ units. What’s novel is that the resulting chains are assembled into novel 2D networks through interchain π–π stacking interactions between the neighboring naphthylene moieties of N18C6. The stack model of naphthylene group in complexes 3–5 is discussed.     

Structural investigation of cellulose Iα and Iβ by 2D RFDR NMR spectroscopy: determination of sequence of magnetically inequivalent d-glucose units along cellulose chain

In our previous studies of the crystal structure of native cellulose (cellulose I) by solid-state two-dimensional (2D) ¹³C–¹³C INADEQUATE, it was revealed that cellulose I_α contains two kinds of β-d-glucose residues (A and A′) in the unit cell and that cellulose I_β contains another two kinds of residues (B and B′). In the present study, the sequence of residues A and A′ along the same chains in cellulose I_α and that of residues B and B′ in I_β were investigated by 2D ¹³C–¹³C rotor-synchronized radiofrequency-driven recoupling (RFDR) experiments using, respectively, uniformly ¹³C₆-labeled (U−¹³C₆) bacterial cellulose and the same [U−¹³C₆] cellulose sample after thermal treatment at 260 °C. The RFDR spectra recorded with a short mixing time (1.0 ms) showed dipolar-coupled ¹³C spin pairs of only the neighboring carbon of the both phases, while those recorded with a longer mixing time (3.0–15 ms) provided correlations between weakly coupled ¹³C spin pairs as well as strongly coupled ¹³C spin pairs such as neighboring carbon nuclei. In the RFDR spectrum of the [U−¹³C₆] cellulose recorded with a mixing time of 15 ms, the inter-residue ¹³C–¹³C correlation between C4 of residue A and C2 of residue A′ and that between C3 of residue A and C4 of residue A′ were clearly observed. In the case of cellulose I_β, however, inter-residue ¹³C–¹³C correlations between residues B and B′ could not be detected in the series of RFDR spectra recorded with different mixing times of annealed [U−¹³C₆] cellulose. From these findings, that cellulose I_α was revealed to have the –A–A′– repeating units along the cellulose chain. For cellulose I_β, it was revealed that the respective residues B and B′ are composed of independent chains (–B–B– and –B′–B′– repeating units) and that there are no –B–B′– repeating units in the chain.     

Mesogenic and magnetic behavior in cobalt(II) and iron(II) compounds with long alkyl chains

Abstract  Metal complexes with long alkyl chains [Co(C16-terpy)₃](BF₄)₂ (1), [Fe(C16-terpy)₂](BF₄)₂ (2), [Co(C16-terpy)₂](BPh₄)₂ (3), [Co(C14-terpy)₂](BF₄)₂ (4), and [Fe(C12C10C5-terpy)₂](BF₄)₂ (5) were synthesized and their physical properties characterized, where C16-terpy, C14-terpy, and C12C10C5-terpy are 4′-hexadecyloxy-2,2′:6′,2′′-terpyridine, 4′-tetradecyloxy-2,2′:6′,2′′-terpyridine, and 4′-5′′′-decyl-1′′′-heptadecyloxy-2,2′:6′,2″-terpyridine, respectively. Complexes 1, 2, and 5 exhibited liquid–crystal properties in the temperature ranges of 371–528 K and 466–556 K, and 88–523 K, respectively. Variable-temperature magnetic susceptibility measurements revealed that the Co(II) complexes 1 and 4 exhibited unique spin transitions (T _1/2↓ = 217 K and T _1/2↑ = 260 K for 1 and T _1/2↓ = 250 K and T _1/2↑ = 307 K for 4), so-called ‘reverse spin transition,’ induced by structural phase transitions. Complex 3 exhibited gradual spin-crossover behavior (T _1/2 = 160 K.), and complex 5 exhibited spin transitions (T _1/2↑ = 288 K and T _1/2↓ = 284 K) at the liquid crystal transition temperature. Compounds with multifunction, i.e., magnetic and liquid–crystal properties, are important in the development of molecular materials. Graphical Abstract  

Reactions of trimethinecyanines of the 1,3-dioxenium series with nucleophiles. The structures of the parent carbocation and of a product of its reaction with methanol

The chemistry and the regioselectivity of alcoholysis, aminolysis, and hydrolysis of symmetrical trimethinecyanine carbenium ions in 4-[3-(2,2-diorganyl-6-phenyl-4H-1,3-dioxen-4-ylidene) prop-1-enyl]-2,2-diorganyl-6-phenyl-1,3-dioxenium perchlorates (4a,b) were investigated. The structures of trimethinecyanine 4,5:4′,5′-bisannelated at the methine chain (3) and of a product of the reaction of nonannelated trimethinecyanine with the methoxide anion were established by X-ray diffraction analysis,¹H NMR spectroscopy, and quantum-chemical calculations (PM3). The nucleophile attacks the mesomeric π-conjugated system of the trimethinecyanine cation selectivily at the C(6) atom of one of the dioxenium fragrments, the second dioxenium ring being deactivated. Alcoholysis affords products of addition of the methoxy group to trimethinecyamines. In the course of aminolysis and hydrolysis, the dioxenium ring that is subjected to the attack eliminates acetone to form 1,3-dioxenylidenepropenylic derivatives of 1,3-enaminoketones and 1,3-ketoenols, respectively. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 521–529, March. 1999.     

Multinuclear NMR investigation on organometallic gold(III) pentafluorophenylarylazoimidazole complexes

Reaction of [Au(C₆F₅)(tht)₂Cl](OTf) with RaaiR′ in CH₂Cl₂ medium leads to [Au(C₆F₅)(RaaiR′)Cl](OTf) [RaaiR′ = p-R–C₆H₄–N=N–C₃H₂–NN-1-R′, (1–3), abbreviated as N,N′-chelator, where N(imidazole) and N(azo) represent N and N′, respectively; R = H (a), Me (b), Cl (c) and R′ = Me (1), CH₂CH₃ (2), CH₂Ph (3), tht is tetrahydrothiophen]. The maximum molecular peak of [Au(C₆F₅)(MeaaiMe)Cl] is observed at m/z 599.51 (100 %) in the FAB mass spectrum. Ir spectra of the complexes show –C=N– and –N=N– stretching near at 1590 and 1370 cm⁻¹ and near at 1510, 955, 800 cm⁻¹ due to the presence of pentafluorophenyl ring. The ¹H-NMR spectral measurements suggest methylene, –CH₂–, in RaaiEt gives a complex AB type multiplet while in RaaiCH₂Ph shows AB type quartets. ¹³C-NMR spectrum of complexes confirm the molecular skeleton. In the ¹H-¹H-COSY spectrum as well as contour peaks in the ¹H-¹³C HMQC spectrum for the present complexes, assign the solution structure and stereoretentive conformation. The electrochemistry gives the ligand reduction peaks.     

Hydrogen-Bonded Double Strands: Crystal Structure and Spectroscopic Propertiesof a 2,2′-Dipyrryl Ketone

 The synthesis, crystal structure determination, conformational analysis, and spectroscopic properties of 3,3′-diethyl-4,4′-dimethyl-2,2′-dipyrryl ketone (1) are reported. The dipyrryl ketone is a model for the dipyrrole core of 10-oxobilirubin, a presumed metabolite in alternate pathways of excretion of the yellow pigment of jaundice, bilirubin. In the crystal, 1 adopts a helical conformation, with a molecule of one helicity being hydrogen-bonded to two molecules of the opposite helicity. Thus, 1 self-assembles via hydrogen bonding into supramolecular double-stranded arrays, where molecules of the same helicity comprise one strand and are paired through hydrogen bonding to molecules of opposite helicity in the second strand. In the observed molecular conformation each pyrrole ring and adjacent carbonyl group are rotated into an sc conformation (torsion angle ∼29 °), with each N-H pointing in the same direction as the C*O. Molecular mechanics/dynamics calculations predict the sc,sc conformation, absent hydrogen bonding, to be the most stable, but only by a few tenths of a kj/mol. In CHCl₃, 1 is monomeric according to vapor pressure osmometry studies (). ¹H NMR NH chemical shifts in CDCl₃ suggest a predominantly anti orientation of the C=O and pyrrole NHs, which is opposite to the orientation observed in the crystal.     

Five-membered 2,3-dioxo heterocycles: LXX. Spiro heterocyclization of 1H-pyrrole-2,3-diones by the action of 1,5-binucleophiles. Crystalline and molecular structure of ethyl 1′-benzyl-7-methoxy-3,3-dimethyl-1,2′-dioxo-5′-phenyl-1′,2,2′,3,4,10-hexahydro-1H-spiro[acridine-9,3′-pyrrole]-4′-carboxylate

Ethyl 1-alkyl-4,5-dioxo-2-phenyl-4,5-dihydro-1H-pyrrole-3-carboxylates reacted with 3-arylamino-5,5-dimethylcyclohex-2-en-1-ones as carbon-centered 1,5-binucleophiles to give the corresponding substituted ethyl 1′-alkyl-3,3-dimethyl-1,2′-dioxo-5′-phenyl-1′,2,2′,3,4,10-hexahydro-1H-spiro[acridine-9,3′-pyrrole]-4′-carboxylates whose structure was proved by X-ray analysis.     

Hydrogen-Bonded Double Strands: Crystal Structure and Spectroscopic Propertiesof a 2,2′-Dipyrryl Ketone

Summary.  The synthesis, crystal structure determination, conformational analysis, and spectroscopic properties of 3,3′-diethyl-4,4′-dimethyl-2,2′-dipyrryl ketone (1) are reported. The dipyrryl ketone is a model for the dipyrrole core of 10-oxobilirubin, a presumed metabolite in alternate pathways of excretion of the yellow pigment of jaundice, bilirubin. In the crystal, 1 adopts a helical conformation, with a molecule of one helicity being hydrogen-bonded to two molecules of the opposite helicity. Thus, 1 self-assembles via hydrogen bonding into supramolecular double-stranded arrays, where molecules of the same helicity comprise one strand and are paired through hydrogen bonding to molecules of opposite helicity in the second strand. In the observed molecular conformation each pyrrole ring and adjacent carbonyl group are rotated into an sc conformation (torsion angle ∼29 °), with each N-H pointing in the same direction as the C*O. Molecular mechanics/dynamics calculations predict the sc,sc conformation, absent hydrogen bonding, to be the most stable, but only by a few tenths of a kj/mol. In CHCl₃, 1 is monomeric according to vapor pressure osmometry studies (). ¹H NMR NH chemical shifts in CDCl₃ suggest a predominantly anti orientation of the C=O and pyrrole NHs, which is opposite to the orientation observed in the crystal. Received February 4, 2000. Accepted February 14, 2000     

Oxygen- versus carbon-coordination of the alpha-stabilized phosphorus ylide Ph<Subscript>3</Subscript>P=C(H)R in palladacycles bearing secondary amines

The ortho-metalated complex [Pd(x){κ ² (C,N)-[C₆H₄CH₂NRR′ (Y)}] (2a–4a and 2b–3b) was prepared by refluxing in benzene equimolecular amounts of Pd(OAc)₂ and secondary benzylamine [a, EtNHCH₂Ph; b, t-BuNHCH₂Ph followed by addition of excess NaCl. The reaction of the complexes [Pd(x){κ ² (C,N)-[C₆H₄CH₂NRR′ (Y)}] (2a–4a and 2b–3b) with a stoichiometric amount of Ph₃P=C(H)COC₆H₄-4-Z (Z = Br, Ph) (ZBPPY) (1:1 molar ratio), in THF at low temperature, gives the cationic derivatives [Pd(OC(Z-4-C₆H₄C=CHPPh₃){κ ² (C,N)-[C₆H₄CH₂NRR′(Y)}] (5a–9a, 4b–6b, and 4b′–6b′), in which the ylide ligand is O-coordinated to the Pd(II) center and trans to the ortho-metalated C(6)H(4) group, in an “end-on carbonyl”. Ortho-metallation, ylide O-coordination, and C-coordination in complexes (5a–9a, 4b–6b, and 4b′–6b′) were characterized by elemental analysis as well as various spectroscopic techniques.     

PSEUDOROTATION IN MONOCYCLIC OXYPHOSPHORANES WHICH CONTAIN CHIRAL CENTERS

Abstract

Phenylbis[2-methyl-1-butoxy]phosphine has been allowed to react with butanedione to produce 2,2-bis[2-methyl-1-butoxy]-2-phenyl-4,5-dimethyl-1,3,2-dioxaphophol-4-ene. This material is a mixture of three diastereomers. It has been reported that 2,2-bis[tetrahydrofurfuyloxy]-2-phenyl-4,5-dimethyl-1,3,2-dioxaphosphol-4-ene is a mixture of only two diastereomers. The present work suggest that two of the diastereomers of the tetrahydrofurfuryloxy compound interconvert via hexacoordinated zwitterionic intermediates which involve addition of the oxygen of the tetrahydrofuran ring to phosphorus.     

Temperature-dependent synthesis, crystal structures, characterizations, and DFT calculations of two new copper(II) complexes with p-fluorobenzoic acid and 2,2′-bipyridine ligands

Two new copper(II) complexes, [Cu(p-FBA)₂(2,2′-bpy)]·(H₂O) (1) and [Cu(p-FBA)(2,2′-bpy)₂]·(p-FBA)₂ (2) {p-FBA = p-fluorobenzoic acid, 2,2′-bpy = 2,2′-bipyridine} have been obtained from an identical starting mixture using temperature as the only independent variable and characterized by X-ray single crystal diffraction as well as with infrared spectroscopy, elemental analysis, and thermogravimetric analysis. The results reveal that 1 has 1D infinite chain structure formed by O–H···O hydrogen bonds, while 2 features a 0D structure. Additionally, there exist C–H···O hydrogen bonds and π–π stacking interactions in 1, forming 2D supramolecular structure. Furthermore, density functional theory (DFT) calculations of the structures, stabilities, orbital energies, composition characteristics of some frontier molecular orbitals and Mulliken charge distributions of the [Cu(p-FBA)₂(2,2′-bpy)] of 1 and [Cu(p-FBA)(2,2′-bpy)₂]⁺ cation of 2 were performed by means of Gaussian 03W package and taking B3LYP/lanl2dz basis set.