Expeditious convergent procedure for the preparation of bis(POC) prodrugs of new (E)-4-phosphono-but-2-en-1-yl nucleosides

A series of unsaturated acyclonucleoside bis(POC) prodrugs of E configuration were synthesized through an expeditious, highly efficient and stereoselective one-step procedure from corresponding bis(POC)allylphosphonate through Ru catalyzed cross-coupling metathesis reaction. The [RuCl₂(PCy₃)(SIPr)(Indenylidene)] and [RuCl₂(PCy₃)(IMes)(benzylidene)] catalysts were employed; the unsaturated ANP were used bore C5-halovinyl uracil, C5-dihalovinyluracil or furanopyrimidine motifs. The chemical cleavage of biolabile (POC) group is a useful pathway to acid phosphonate derivatives.     

Structural variations of Sn pyridylphosphonates influenced by an uncommon Sn-N interaction

Four new Sn^II phosphonates have been synthesized by hydrothermal methods, and their structures determined by single-crystal X-ray diffraction. Tin(II) 3-pyridylphosphonate, SnO₃PC₅H₄N (I), crystallizes in P2₁/c with a=4.9595(8) Å, b=10.7673(18) Å, c=13.996(2) Å, and β=93.616(2)°. Tri-tin(II) (μ-3)-oxo-(bis)-4-pyridylphosphonate, Sn₃O(O₃PC₅H₄N)₂ (II), crystallizes in P-1 with a=7.2406(14) Å, b=9.9524(19) Å, c=12.604(3) Å, α=104.510(11)°, β=90.326(11)°, and γ=110.897(11)°. Tin(II) 6-methyl-2-pyridylphosphonate quadrahydrate, Sn(O₃PC₅H₃NCH₃)·0.25H₂O (III), crystallizes in Pna2₁, a=18.955(3) Å, b=9.7543(14) Å, and c=17.833(3) Å. Tin(II) 4-cyanophenylphosphonate, Sn(O₃PC₆H₄CN) (IV), crystallizes in P-1, a=5.0019(3) Å, b=8.4396(5) Å, c=10.3099(6) Å, α=90.352(3)°, β=94.894(3)°, and γ=92.236(4)°. I, II, and IV have ladder-type structures, and III is a layered compound. The structural variations show the effects of the Sn-N interaction on the final structures.     

Syntheses, characterizations and crystal structures of two lead(II) phosphonate-sulfonate hybrid materials

Hydrothermal reactions of lead(II) acetate with 5-sulfoisophthalic acid monosodium salt (NaH₂BTS) and N-(phosphonomethyl)-N-methylglycine, MeN(CH₂CO₂H)(CH₂PO₃H₂) (H₃L¹), or a new aminodiphosphonic acid, 3-Pyridyl-CH₂N(CH₂PO₃H₂)₂ (H₄L²), afforded two novel lead(II) phosphonate-sulfonate hybrids, namely, Pb₃[L¹][BTS][H₂O]·H₂O 1 and Pb₂[HL³][BTS]·H₂O 2 (H₂L³=3-Pyridyl-CH₂(Me)N(CH₂PO₃H₂)). H₂L³ was formed as a result of the decomposition of one phosphonate group in H₄L² during the reaction. Compound 1 crystallizes in the triclinic space group with a=9.9148(4) Å, b=10.4382(4) Å, c=10.6926(2) Å, α=96.495(2)°, β=110.599(2)°, γ=98.433(2)°, V=1008.31(6) Å³, and Z=2. The structure of compound 1 features a 3D network built from the interconnection of hexanuclear Pb₆(L¹)₂ units and 1D double chains of lead(II) carboxylate-sulfonate. Compound 2 crystallizes in the monoclinic space group P2₁/c with a=9.5403(7) Å, b=11.6170(8) Å, c=19.7351(15) Å, β=97.918(2)°, V=2166.4(3) Å³, and Z=4. Compound 2 has a 3D network structure built by the cross-linkage of 1D double chains of lead(II) phosphonates and 2D layers of lead(II) carboxylate-sulfonate.     

Divalent transition metal phosphonates with new structure containing hydrogen-bonded layers of phosphonate anions

A series of divalent transition metal phosphonates containing hydrogen-bonded layers of phosphonate anions, namely [M(phen)₃]·C₆H₅PO₃·11H₂O [M=Co(1), Ni(2), Cu(3)] and [Cd(phen)₃]·C₆H₅PO₃H·Cl·7H₂O (4) have been synthesized, structurally characterized by single-crystal X-ray diffraction method. These compounds all crystallize in the triclinic system, space group P-1. The lattice parameters are a=12.1646(5), b=12.4155(6), c=15.4117(10) Å, α=78.216(2), β=79.735(3), γ=77.8380(3)°, V=2205.1(2) Å³, Z=2 for 1; a=12.097(2), b=12.606(3), c=15.742(3) Å, α=76.66(3), β=80.04(3), γ=77.75(3)°, V=2263.4(8) Å³, Z=2 for 2; a=12.058(2), b=12.518(3), c=15.781(3) Å, α=77.77(3), β=80.02(3), γ=77.91(3)°, V=2255.5(8) Å³, Z=2 for 3 and a=12.47680(10), b=12.6693(2), c=16.1504(3) Å, α=82.600(1), β=71.122(1), γ=77.355(1)°, V=2352.37(6) Å³, Z=2 for 4. All structures are refined by full-matrix least-squares methods [for 1, R1=0.0602 using 6458 independent reflections with I>2σ(I); for 2, R1=0.0632 using 4657 independent reflections with I>2σ(I); for 3, R1=0.0634 using 6221 independent reflections with I>2σ(I); for 4, R1=0.0400 using 7930 independent reflections with I>2σ(I)]. In the crystal structures, the phenylphosphonate anions and water molecules are hydrogen-bonded to form layers, and there exist the cationic species [M(phen)₃]²⁺ between the adjacent layers of anions and water. Luminescence, thermal analysis as well as IR spectroscopic studies are also presented.     

Cyclic chlorophosphites as scaffolds for the one-pot synthesis of α-aminophosphonates under solvent-free conditions

New α-aminophosphonates of the type (OCH₂CMe₂CH₂O)P(O)CH(NHCO₂R)(R′) [6a-i, 7a-e, and 8a-c] have been synthesized in high yields by a three-component reaction using (OCH₂CMe₂CH₂O)PCl (3), benzamide (or urethane or benzyl carbamate), and an aldehyde without using any catalyst under solvent-free conditions. This route can be readily adapted for bis-aminophosphonates as well as optically active binaphthoxy α-aminophosphonates; it also tolerates the phenolic -OH group as shown by the synthesis of hydroxy functionalized aminophosphonates. Partial hydrolysis of compounds 7a-d leads to products in which the phosphorinane ring is cleaved first. Compounds (OCH₂CMe₂CH₂O)P(O)CH[NHC(O)Ph](9-anthryl) (6f) and optically pure (R,S)-(−)-(C₂₀H₁₂O₂)P(O)CH(NHCO₂Et)(Ph) (14a) were characterized by X-ray crystallography.     

Synthesis and characterization of 2-phosphonoethanesulfonic acid and a barium-hydrogenphosphonatoethanesulfonate — BaH(O3P-C2H4-SO3)

Following the strategy of using polyfunctional phosphonic acids for the synthesis of new metal phosphonates, the organic linker molecule 2-phosphonoethanesulfonic acid, H₂O₃P-C₂H₄-SO₃H (1) (H₃L), was synthesized and characterized in detail. The acid was used in a high-throughput (HT) investigation of the system BaCl₂/H₃L/NaOH/H₂O. The HT experiments comprising 48 individual hydrothermal reactions were performed to systematically investigate the influence of pH of the starting mixture as well as the molar ratio Ba²⁺: H₃L. Only two reaction products were observed: small amounts of BaCO₃ under basic conditions and BaH(O₃P-C₂H₄-SO₃) (2). For compounds 1 and 2 the crystal structures were determined from single-crystal X-ray diffraction data (H₂O₃P-C₂H₄-SO₃H: trigonal, P3₂, a=814.58(1), c=861.20(2) pm, Z=3, R1=0.0254, wR₂=0.0758 for I>2σ(I); BaH(O₃P-C₂H₄-SO₃): orthorhombic, Ibam, a=953.39(19), b=855.55(17), c=867.82(17) pm, Z=4, R1=0.0162, wR₂=0.0417 for I>2σ(I)). The structure of H₃L (1) is stabilized exclusively by strong hydrogen bonds. Compound 2 is built up by chains of edge sharing BaO₈ polyhedra. These chains are connected to a three-dimensional network by the -CH₂CH₂- linker of the ligand. Thermogravimetric investigation of compound 2, as well as IR spectra of 1 and 2 are presented.     

Chemistry of organophosphonate scale growth inhibitors: two-dimensional, layered polymeric networks in the structure of tetrasodium 2-hydroxyethyl-amino-bis(methylenephosphonate)

Aminomethylene phosphonates are important scale inhibitors applied in diverse areas of technology. This study adds to the existing body of information on this subject and reports the crystal and molecular structures of tetrasodium 2-hydroxyethylamino-bis(methylene-phosphonate) decahydrate ([Na₄(HOCH₂CH₂N(CH₂PO₃)₂)]·10H₂O, 1). The crystal structure of 1 could be described as two-dimensional polymeric layered structure hydrogen bonded into a 3D supramolecular polymeric network. The structure of the tetraanion consists of a “three-arm” backbone stemming from the N atom. Two “arms” are deprotonated methylene phosphonate (-CH₂PO₃²⁻) moieties and the third is a hydroxyethyl (-CH₂CH₂OH) moiety. One Na cation forms an intramolecular complex with two oxygens from separate phosphonate groups, a hydroxyl oxygen, the nitrogen and two lattice water molecules. The position of this Na cation points to a possible coordination site for Ca in a proposed Ca-HEABMP complex (HEABMP=2-hydroxyethylamino-bis(methylene-phosphonate).     

Two isomeric lead(II) carboxylate-phosphonates: syntheses, crystal structures and characterizations

Two isomeric layered lead(II) carboxylate-phosphonates of N-(phosphonomethyl)-N-methyl glycine ([MeN(CH₂CO₂H)(CH₂PO₃H₂)]=H₃L), namely, monoclinic Pb₃L₂·H₂O 1 and triclinic Pb₃L₂·H₂O 2, have been synthesized and structurally determined. Compound 1 synthesized by hydrothermal reaction at 150°C is monoclinic, space group C2/c with a=19.9872(6), b=11.9333(1) and c=15.8399(4) Å, β=110.432(3)°, V=3540.3(1) Å³, and Z=8. The structure of compound 1 features a 〈400〉 layer in which the lead(II) ions are bridged by both phosphonate and carboxylate groups. The lattice water molecules are located between the layers, forming hydrogen bonds with the non-coordinated carboxylate oxygen atoms. Compound 2 with a same empirical formula as compound 1 was synthesized by hydrothermal reaction at 170°C. It has a different layer structure from that of compound 1 due to the adoption of a different coordination mode for the ligand. It crystallizes in the triclinic system, space group with cell parameters of a=7.1370(6), b=11.522(1), c=11.950(1) Å, α=110.280(2), β=91.625(2), γ=95.614(2)°, V=915.3(1) Å³ and Z=2. The structure of compound 2 features a 〈020〉 metal carboxylate-phosphonate double layer built from 1D lead(II) carboxylate chains interconnected with 1D lead(II) phosphonate double chains. XRD powder patterns of compounds 1 and 2 indicate that each compound exists as a single phase.     

Synthesis and characterization of new strontium 4-carboxyphenylphosphonates

Several new strontium 4-carboxyphenylphosphonates, i.e., two modifications of Sr(HOOCC₆H₄PO₃H)₂, SrH(OOCC₆H₄PO₃)·H₂O, Sr₃(OOCC₆H₄PO₃)₂·4H₂O and Sr₃(OOCC₆H₄PO₃)₂·5.7H₂O were prepared and characterized by elemental analysis, thermogravimetry, X-ray powder diffraction and infrared spectroscopy. It was found that the compositions of these compounds depend on the acidity of the reaction medium. In addition, the presented compounds are interconvertible in dependence on pH. The position of the acid hydrogen atom in SrH(OOCC₆H₄PO₃)·H₂O was determined from the IR spectra of the studied compounds.The structure of the β modification of Sr(HOOCC₆H₄PO₃H)₂ was solved from its X-ray powder diffraction pattern using an ab initio method (the FOX program) with subsequent Rietveld refinement in the FULLPROF program. The compound is monoclinic, with the space group P2₁/c (No. 14), a=49.88(2), b=7.867(2), c=5.602(3) Å, β=128.68(2)°, and Z=4. It has a one-dimensional structure with an inorganic part built of SrO₈ distorted tetragonal antiprisms.     

Synthesis, crystal structures, and luminescent properties of two types of lanthanide phosphonates

Hydrothermal reactions of different lanthanide(III) salts with an amino-diphosphonate ligand (H₄L=C₆H₅CH₂N(CH₂PO₃H₂)₂) led to two series of lanthanide phosphonates, namely, Ln(H₂L)(H₃L) (Ln=La, 1; Pr, 2; Nd, 3; Sm, 4; Eu, 5; Gd, 6; Tb, 7). Compounds 1-5 feature a one-dimensional (1D) chain structure in which dimers of two edge-sharing LnO₈ polyhedra are interconnected by bridging phosphonate groups, such 1D arrays are further interlinked via strong hydrogen bonds between non-coordinated phosphonate oxygen atoms into a two-dimensional (2D) layer with the phenyl groups of the ligands orientated toward the interlayer space. Compounds 6 and 7 also show a different 1D array in which the LnO₆ octahedra are bridged by phosphonate groups via corner-sharing, such chains are also further interlinked by hydrogen bonds into a 2D supramolecular layer. Compounds 5 and 7 emit red and green light with a lifetime of 2.1 and 3.7 ms, respectively.     

Hydrothermal syntheses, characterizations and crystal structures of a new lead(II) carboxylate-phosphonate with a double layer structure and a new nickel(II) carboxylate-phosphonate containing a hydrogen-bonded 2D layer with intercalation of ethylenediamines

Hydrothermal reactions of N,N-bis(phosphonomethyl)aminoacetic acid (HO₂CCH₂N(CH₂PO₃H₂)₂) with metal(II) salts afforded two new metal carboxylate-phosphonates, namely, Pb₂[O₂CCH₂N(CH₂PO₃)(CH₂PO₃H)]·H₂O (1) and {NH₃CH₂CH₂NH₃}{Ni[O₂CCH₂N(CH₂PO₃H)₂](H₂O)₂}₂ (2). Among two unique lead(II) ions in the asymmetric unit of complex 1, one is five coordinated by five phosphonate oxygen atoms from 5 ligands, whereas the other one is five-coordinated by a tridentate chelating ligand (1 N and 2 phosphonate O atoms) and two phosphonate oxygen atoms from two other ligands. The carboxylate group of the ligand remains non-coordinated. The bridging of above two types of lead(II) ions through phosphonate groups resulted in a 〈002〉 double layer with the carboxylate group of the ligand as a pendant group. These double layers are further interlinked via hydrogen bonds between the carboxylate groups into a 3D network. The nickel(II) ion in complex 2 is octahedrally coordinated by a tetradentate chelating ligand (two phosphonate oxygen atoms, one nitrogen and one carboxylate oxygen atoms) and two aqua ligands. These {Ni[O₂CCH₂N(CH₂PO₃H)₂][H₂O]₂}⁻ anions are further interlinked via hydrogen bonds between non-coordinated phosphonate oxygen atoms to form a 〈800〉 hydrogen bonded 2D layer. The 2H-protonated ethylenediamine cations are intercalated between two layers, forming hydrogen bonds with the non-coordinated carboxylate oxygen atoms. Results of magnetic measurements for complex 2 indicate that there is weak Curie-Weiss behavior with θ=−4.4 K indicating predominant antiferromagnetic interaction between the Ni(II) ions. Indication for magnetic low-dimension magnetism could not be detected.     

Synthesis, structural determination and magnetic properties of layered hybrid organic-inorganic, iron (II) propylphosphonate, Fe[(CH3(CH2)2PO3)(H2O)], and iron (II) octadecylphosphonate, Fe[(CH3(CH2)17PO3)(H2O)]

Fe[(CH₃(CH₂)₂PO₃)(H₂O)] (1) and Fe[(CH₃(CH₂)₁₇PO₃)(H₂O)] (2) were synthesized by reaction of FeCl₂·6H₂O and the relevant phosphonic acid in water in presence of urea and under inert atmosphere. The compounds were characterized by elemental and thermogravimetric analyses, UV-visible and IR spectroscopy. The crystal structure of (1) was determined from X-ray single crystal diffraction studies at room temperature: monoclinic symmetry, space group P2₁, , , , and β=98.62(3)°. The compound is lamellar and the structure is hybrid, made of alternating inorganic and organic layers along the c direction. The inorganic layers consist of Fe(II) ions octahedrally coordinated by five phosphonate oxygen atoms and one from the water molecule, separated by bi-layers of propyl groups. A preliminary structure characterization of compound (2) suggests a similar layered structure, but with an interlayer spacing of 40.3 Å. The magnetic properties of the compounds were both studied by a dc and ac SQUID magnetometer. Fe[(CH₃(CH₂)₂PO₃)(H₂O)] (1) obeys the Curie-Weiss law at temperatures above 50 K (, ), indicating a Fe +II oxidation state, a high-spin d⁶ (S=2) electronic configuration and an antiferromagnetic exchange couplings between the near-neighbouring Fe(II) ions. Below , Fe[(CH₃(CH₂)₂PO₃)(H₂O)] exhibits a weak ferromagnetism. The critical temperature of has been determined by ac magnetic susceptibility measurements. Compound (2) shows the same paramagnetic behaviour of the iron (II) propyl derivative. The values of C and θ were found to be and −44 K, respectively, thus suggesting the presence of Fe +II ion in the S=2 spin state and antiferromagnetic interactions between Fe(II) ions at low temperatures. Zero-field and field cooled magnetic susceptibility vs. T plots do not overlap below , suggesting the presence of an ordered magnetic state. The critical temperature, T_N, has been located by the peaks at from the ac susceptibility (χ′and χ″) vs. T plots. Below T_N hysteresis loops recorded in the temperature region show an S-shape, while below 15 K assume an ellipsoid form. They reveal that compound (2) is a weak ferromagnet. The critical temperature T_N in these layered Fe(II) alkylphosphonates is independent of the distance between the inorganic layers.     

Hydrothermal Synthesis,Crystal Structure and Characterizations of Two New Manganese(II) Phosphonates with a 3D Framework Structure

Two new manganese(II) phosphonates, (NH₄)Mn_2.5[(O₃PCH(OH)CO₂)₂(H₂O)] ( 1 ) and [NH₃(CH₂)₄NH₃]_0.5Mn_2.5[(O₃PCH(OH)CO₂)₂(H₂O)] ( 2 ) have been synthesized under hydrothermal conditions and structurally characterized by single‐crystal X‐ray diffraction as well as with infrared spectroscopy, elemental analysis and thermogravimetric analysis. The two isomorphous compounds feature a 3D framework structure. The Mn(1)O₆ and Mn(3)O₅ polyhedra are bridged by the CPO₃ tetraheda into a Mn^II phosphonate layer in ac‐plane. Mn(2)O₆ polyhedra are linked to each other by CPO₃ tetraheda to form infinite chains, which are connected to layers by carboxylate groups to form a 3D framework structure with channels along the a‐ and c‐axis, respectively. The NH₄⁺ ions or protonated 1, 4‐butylenediamine cations are located inside the channels along the a axis.     

New metal phosphonates containing coordination piperazine or pyridyl groups

Reactions of transition metal(II) salts with three aminophosphonic acids, 1-[(H₂O₃PCH₂)₂NCH₂CH₂−]-piperazine-4-CH₂PO₃H₂ (H₆L¹), 3-pyridyl-CH₂N(CH₂PO₃H₂)₂ (H₄L²) and 4-pyridyl-CH₂N(CH₂PO₃H₂)₂ (H₄L³) afforded three new metal phosphonates, namely, Cu(H₄L¹)·2H₂O (1), Co(H₃L²)₂·H₂O (2) and [Co(H₂L³)(H₂O)]·H₂O (3). The structure of compound 1 features a 1D chain in which the CuN₂O₃ and CPO₃ polyhedra are interconnected by bridging phosphonate ligands to form 1D chains. Compound 2 has a layered structure. The cobalt(II) ions in the octahedral coordination geometries and {CPO₃} tetrahedra are interconnected into an inorganic chain via -N(CH₂PO₃H)₂ moieties, and adjacent chains are further bridged by the coordination pyridyl groups of H₃L² into a 2D layer. The structure of compound 3 features a 2D double layered structure, in which the Co(II) ions are interconnected by bridging phosphonate groups into a 1D chain along b-axis. Neighboring chains are interconnected by coordination pyridyl groups into a double layer perpendicular to the c-axis.     

Inorganic-organic hybrid compounds: Synthesis and characterization of three new metal phosphonates with similar characteristic structural features

The phosphonocarboxylic acid H(HO₃PCH₂)₂NH-CH₂C₆H₄-COOH (H₅L) was synthesized and characterized by NMR- and IR-spectroscopy, thermogravimetric (TG) analysis and single-crystal X-ray diffraction. Reactions of H₅L with samarium(III) chloride and calcium(II) chloride resulted in three new compounds, Sm[(O₃PCH₂)₂NH-CH₂C₆H₄-COOH]·H₂O (1), Ca[H(O₃PCH₂)₂NH-CH₂C₆H₄-COOH]·H₂O (2), and Ca[(HO₃PCH₂)₂NH-CH₂C₆H₄-COOH]₂·4H₂O (3). The single-crystal structure determination of the title compounds reveals that in H₅L as well as in compounds 1, 2, and 3 zwitterions are present. Within the M-O building units of the metal phosphonates we observed a different degree of dimensionality, depending on the oxidation state of the metal ion and the synthesis conditions. In 1, one-dimensional chains of edge-sharing SmO₈ polyhedra are observed while in 2, isolated units of edge-sharing CaO₆ octahedra and in 3 isolated CaO₆ octahedra are observed. However, looking at the organic part, the rigid phenyl carboxylic acid moieties arrange in a “zipper-like” fashion and hydrogen bonding plays an important role in the stabilization of the crystal structure. The title compounds were further characterized by IR spectroscopy and TG analysis. Additionally, the thermal stability of 1 was investigated by temperature-dependent X-ray diffraction.     

3-Amino- and 3-acylamido-2-phosphonopyridines: synthesis by Pd-catalyzed P-C coupling, structure and conversion to pyrido[b]-anellated PC-N heterocycles

Palladium catalyzed cross-coupling of 3-amino- and 3-acylamido-2-bromopyridines 1a-f with triethyl phosphite allowed the synthesis of 3-amino- and 3-acylamido pyridine-2-phosphonic acid diethyl esters 2a-f, whereas nickel catalysts, although providing access to related anilido-2-phosphonates, proved inactive. Reduction of the aminophosphonate 2a with LiAlH₄ afforded 3-amino-2-phosphinopyridine (3a), which was cyclocondensed with dimethylformamide dimethyl acetal (DMFA) via phosphaalkene intermediates 4a to the novel pyrido[b]-anellated 1,3-azaphosphole 5a. Reaction of amidophosphonates 2b-f with LiAlH₄ did not result in the expected reductive cyclization, as shown by closely related anilido-2-phosphonates, but led to product mixtures containing N-secondary 3-amino-2-phosphinopyridines 3b-f as the main or major component. The conversion of 3b,d,e with DMFA to 5b,d,e provides first examples of N-substituted pyrido[b]-anellated azaphospholes. Structures were confirmed by multinuclear NMR and X-ray crystallography (for 2c, 3b).     

Synthesis and structural characterization of 2-D layered copper(II) styrylphosphonate coordination polymers

We report the synthesis, physicochemical characterization, and crystal structure of Cu-SP (SP?=?styrylphosphonic acid, H₂O₃PCH=CH₂(C₆H₅)), the first reported example of a metal derivative of SP. The starting SP acid was fully characterized by X-ray single-crystal diffractometry, elemental analysis (C and H), ³¹P-NMR, ¹³C-NMR, ¹H-NMR, HPLC, UV–vis, MS, TG, and FT-IR spectroscopy. The copper(II) derivative was synthesized and characterized by DTA-TG and FT-IR, and also its structure was determined from powder data. The crystal structure was refined by the Rietveld method. The crystal structure of Cu-SP shows a layered 2-D architecture, where the organic moieties are pointed toward the interlamellar space. The inorganic layers are composed of Cu²⁺ dimers, where the coordination geometry of Cu²⁺ can be described as distorted trigonal bipyramid. The three coplanar oxygens (O2, O3, and O3) have bond distances of 2.165(9), 1.982(9), and 2.103(11)?Å, respectively. The bond lengths for the apical oxygens (O1 and O2) are 1.908(13) and 1.996(11)?Å, respectively.     

Synthesis,structural characterization and properties of one-dimensional coordination polymers of cobalt(II)- and nickel(II)-phosphonate complexes with 2,2′-bipyridine as a secondary ligand component: Observation of both cis and trans conformations of a diphosphonic acid

Two new isomorphous cobalt and nickel phosphonates [M^II(2,2′-bipy)₂LH₄]_n[LH₂]_n, M = Co (compound 1), M = Ni (compound 2) were hydrothermally synthesized from p-xylylenediphosphonic acid (LH₄) and the corresponding metal salts with 2,2′-bipyridine as secondary ligand component. Both the compounds 1 and 2 are characterized by routine elemental analyses, IR-, electronic-spectral analyses, thermogravimetric studies and unambiguously characterized by single crystal X-ray crystallography. The structures were refined in monoclinic space group C2/c. The crystal structure consists of 1D [M(2,2′-bipy)₂LH₄]²⁺ chains and [LH₂]²⁻ anions. The flexibility of non-rigid ligand p-xylylenediphosphonic acid (LH₄) tends to adopt a rare cis conformation in the crystal structure to meet the coordination requirement of the metal center from the usual trans conformation. The hydrogen bonding in the crystal structure leads to cylindrical tubes that extend via p-xylylenediphosphonic acid resulting in a 2D supramolecular sheet throughout the crystal. Compounds 1 and 2 are additionally characterized by thermogravimetric studies.     

High-throughput and microwave investigation of rare earth phosphonatoethanesulfonates—Ln(O3P-C2H4-SO3) (Ln=Ho, Er, Tm, Yb, Lu, Y)

Following the strategy of using bifunctional phosphonic acids for the synthesis of new metal phosphonates, the flexible ligand 2-phosphonoethanesulfonic acid, H₂O₃P-C₂H₄-SO₃H (H₃L), was used in a high-throughput (HT) and microwave investigation of rare earth phosphonatoethanesulfonates. The HT-investigation led to six isotypic compounds Ln(O₃P-C₂H₄-SO₃) with Ln=Ho (1), Er (2), Tm (3), Yb (4), Lu (5) and Y (6). The syntheses were scaled-up in glass reactor tubes in order to obtain larger amounts for a detailed characterization. Based on these results all compounds could be also synthesized by microwave-assisted heating and the influence of reaction time and stirring rate during the synthesis was established. For compound 2 the crystal structure was determined by single-crystal X-ray diffraction. The compounds contain isolated slightly distorted LnO₆ octahedra that are connected by the phosphonate and sulfonate groups into a three-dimensional framework. Thermogravimetric investigations demonstrate the high thermal stability of the compounds up to 460 °C.     

Synthesis of Functionalized Diethyl(pyrrolidin-2-yl)phosphonate and Diethyl(5-oxopyrrolidin-2-yl)phosphonate

Short and efficient syntheses of functionalized (pyrrolidin-2-yl)phosphonate and (5-oxopyrrolidin-2-yl)phosphonate have been developed. The synthetic strategy involved the diastereospecific 1,3-dipolar cycloaddition of N-benzyl-C-(diethoxyphosphoryl)nitrone to cis-1,4-dihydroxybut-2-ene and dimethyl maleate, respectively. O,O-Diethyl 3-carbamoyl-4-hydroxy(5-oxopyrrolidin-2-yl)phosphonate was obtained from O,O-diethyl 2-benzyl-4,5-dimethoxycarbonyl(isoxazolidin-3-yl)phosphonate by hydrogenation and subsequent treatment with ammonia, whereas transformation of O,O-diethyl 2-benzyl-4,5-dihydroxymethyl(isoxazolidin-3-yl)phosphonate into O,O-diethyl 3-aminomethyl-4-hydroxy(pyrrolidin-2-yl)phosphonate was accomplished by mesylation followed by hydrogenolysis to undergo intramolecular cyclization and the introduction of amino group via ammonolysis. Stereochemistry of the isoxazolidine cycloadducts, as well as the final functionalized (pyrrolidin-2-yl)- and (5-oxopyrrolidin-2-yl)phosphonates were established based on conformational analyses using vicinal H–H, H–P, and C–P couplings and supported by the observed diagnostic NOESY correlation signals.