Chemie der Seltenerdmetalle, 20. Mitt.: Yttriumtartrate im neutralen und alkalischen Bereich

Zusammenfassung Es wurden die Verbindungen HYT ^*·4 H₂O, Y₄ T ₃·14 H₂O, LiYT·4 H₂O, NaYT·5 H₂O, KYT·3 H₂O, RbYT·4 H₂O, CsYT·4 H₂O, NH₄YT·3 H₂O, K₂YTOH·4 H₂O, K₃YT(OH)₂·4 H₂O, K₄YT(OH)₃·3 H₂O, K₅YT(OH)₄·3 H₂O, KYH₄ T ₂·3 H₂O, K₂YH₃ T ₂·5 H₂O, K₃YH₂ T ₂·4 H₂O, KY₂ T(OH)₃·5 H₂O, K₂Y₂ T(OH)₄·5 H₂O isoliert. Die Präparate wurden mit Hilfe von Thermoanalyse, IR-Absorptionsspektren und Röntgenstreuung näher charakterisiert und ihre Löslichkeit in Wasser untersucht.

---

Some complexes of Yttrium with tartrates were isolated and the compounds characterised by thermogravimetric analysis, IR-spectroscopy and X-ray diffraction. Solubility in water was examined.

     

Synthesis,Structures, Luminescence,and Magnetic Properties of Two Three‐dimensional Lanthanide Organic Frameworks Comprising Pyrazine‐2,3‐dicarboxylic Acid

Two three‐dimensional (3D) lanthanide coordination polymers (CPs) of the general formula [Ln₂(PDOA)₃(H₂O)]_n · 2nH₂O [Ln = Gd ( 1 ), Tb ( 2 )] were synthesized by solvothermal reactions of the corresponding rare‐earth chloride and pyrazine‐2,3‐dicarboxylic acid (H₂PDOA). The CPs were structurally characterized by single‐crystal X‐ray diffraction, IR spectroscopy, thermogravimetry, and elemental analysis. CPs 1 and 2 are isostructural and crystallize in the monoclinic space group P2₁/c. The frameworks are constructed from dinuclear lanthanide building blocks in which the PDOA^2– ions adopt three coordination modes, μ₃‐kO;kO;kN,O, μ₄‐kN,O;kO;kO;kO,O, and μ₅‐kN,O;kO;kO;kO,O;kO, respectively. The Tb³⁺ polymer of 2 exhibits characteristic photoluminescence in the visible region. The magnetic properties of CP 1 were investigated by measuring the magnetic susceptibilities in the temperature range 1.8–300 K.     

Lanthantartrate im neutralen und alkalischen Bereich

Zusammenfassung Die Substanzen LaHT ^*·4 H₂O, La₄ T ₃·14 H₂O, KLaT· ·3 H₂O, K₂LaTOH·4 H₂O, K₂LaH₃ T ₂·4 H₂O, K₃LaH₂ T ₂· ·4 H₂O und K₄LaHT ₂·5 H₂O wurden isoliert und durch Thermoanalyse, IR-Absorptionspektren und Röntgenstreuung näher charakterisiert. Es wurde auch ihre Löslichkeit in Wasser bestimmt.

---

The following compounds where isolated, and characterized by means of thermal analysis, I. R. spectroscopy and X-ray diffraction. Their solubilities in aqueous solution were determined: LaHT·4 H₂O, La₄ T ₃·14 H₂O, KLaT·3 H₂O, K₂LaTOH· ·4 H₂O, K₂LaH₃ T ₂·4 H₂O, K₃LaH₂ T ₂·4 H₂O, K₄LaHT ₂· ·5 H₂O.

---

---

Mit 7 Abbildungen     

Chemie der Seltenerdmetalle, 26. Mitt.: Tartrate der Seltenen Erden des TypsLn 4 T 3·xH2O und ihre Reaktion mit HCl

Zusammenfassung Nachstehende Verbindungen wurden hergestellt: Pr₄ T ₃·13 H₂O, Nd₄ T ₃·12 H₂O, Sm₄ T ₃·12 H₂O, Gd₄ T ₃·12 H₂O, Tb₄ T ₃·13 H₂O, Dy₄ T ₃·12 H₂O, Ho₄ T ₃·14 H₂O, Er₄ T ₃·14 H₂O, PrH₂ TCl·3 H₂O, NdH₂ TCl·3 H₂O, SmH₂ TCl·3 H₂O, GdH₂ TCl·4 H₂O, TbH₂ TCl·3 H₂O, DyH₂ TCl·2 H₂O, HoH₂ TCl·3 H₂O, ErH₂ TCl·3 H₂O. Die Präparate wurden mit Thermoanalyse, IR-Absorptionsspektren, Röntgenstreuung und hinsichtlich Löslichkeit weiter untersucht.

---

Chemistry of the rare earth metals, XXVI: Tartrates of the rere earths of the types Ln₄T₃·xH ₂ O, and their reaction withHCl

The above series of compounds has been prepared and further characterized by thermal analysis, IR spectra, X-ray diffraction, and solubility.

---

---

Ln=Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er.

---

H₄ T=C₄H₆O₆.     

The coordination complex structures and hydrogen bonding in the three‐dimensional alkaline earth metal salts (Mg,Ca, Sr and Ba) of (4‐aminophenyl)arsonic acid

(4‐Aminophenyl)arsonic acid (p‐arsanilic acid) is used as an antihelminth in veterinary applications and was earlier used in the monosodium salt dihydrate form as the antisyphilitic drug atoxyl. Examples of complexes with this acid are rare. The structures of the alkaline earth metal (Mg, Ca, Sr and Ba) complexes with (4‐aminophenyl)arsonic acid (p‐arsanilic acid) have been determined, viz. hexaaquamagnesium bis[hydrogen (4‐aminophenyl)arsonate] tetrahydrate, [Mg(H₂O)₆](C₆H₇AsNO₃)·4H₂O, (I), catena‐poly[[[diaquacalcium]‐bis[μ₂‐hydrogen (4‐aminophenyl)arsonato‐κ²O :O ′]‐[diaquacalcium]‐bis[μ₂‐hydrogen (4‐aminophenyl)arsonato‐κ²O :O ]] dihydrate], {[Ca(C₆H₇AsNO₃)₂(H₂O)₂]·2H₂O}_n , (II), catena‐poly[[triaquastrontium]‐bis[μ₂‐hydrogen (4‐aminophenyl)arsonato‐κ²O :O ′]], [Sr(C₆H₇AsNO₃)₂(H₂O)₃]_n , (III), and catena‐poly[[triaquabarium]‐bis[μ₂‐hydrogen (4‐aminophenyl)arsonato‐κ²O :O ′]], [Ba(C₆H₇AsNO₃)₂(H₂O)₃]_n , (IV). In the structure of magnesium salt (I), the centrosymmetric octahedral [Mg(H₂O)₆]²⁺ cation, the two hydrogen p‐arsanilate anions and the four water molecules of solvation form a three‐dimensional network structure through inter‐species O—H and N—H hydrogen‐bonding interactions with water and arsonate O‐atom and amine N‐atom acceptors. In one‐dimensional coordination polymer (II), the distorted octahedral CaO₆ coordination polyhedron comprises two trans‐related water molecules and four arsonate O‐atom donors from bridging hydrogen arsanilate ligands. One bridging extension is four‐membered via a single O atom and the other is eight‐membered via O :O ′‐bridging, both across inversion centres, giving a chain coordination polymer extending along the [100] direction. Extensive hydrogen‐bonding involving O—H…O, O—H…N and N—H…O interactions gives an overall three‐dimensional structure. The structures of the polymeric Sr and Ba complexes (III) and (IV), respectively, are isotypic and are based on irregular M O₇ coordination polyhedra about the M ²⁺ centres, which lie on twofold rotation axes along with one of the coordinated water molecules. The coordination centres are linked through inversion‐related arsonate O :O ′‐bridges, giving eight‐membered ring motifs and forming coordination polymeric chains extending along the [100] direction. Inter‐chain N—H…O and O—H…O hydrogen‐bonding interactions extend the structures into three dimensions and the crystal packing includes π–π ring interactions [minimum ring centroid separations = 3.4666 (17) Å for (III) and 3.4855 (8) Å for (IV)].     

Long‐range π‐type hydrogen bond in dimers CH2?HF,CH2O?H2O,and CH2O?NH3

Using four basis bets, (6‐311G(d,p), 6‐31+G(d,p), 6‐31++G(2d,2p), and 6‐311++G(3df,3pd), the optimized structures with all real frequencies were obtained at the MP2 level for the dimers CH₂O? HF, CH₂O? H₂O, CH₂O? NH₃, and CH₂O? CH₄. The structures of CH₂O? HF, CH₂O? H₂O, and CH₂O? NH₃ are cycle‐shaped, which result from the larger bend of σ‐type hydrogen bonds. The bend of σ‐type H‐bond O…H? Y (Y?F, O, N) is illustrated and interpreted by an attractive interaction of a chemically intuitive π‐type hydrogen bond. The π‐type hydrogen bond is the interaction between one of the H atoms of CH₂O and lone pair(s) on the F atom in HF, the O atom in H₂O, or the N atom in NH₃. In contrast with the above three dimers, for CH₂O? CH₄, because there is not a π‐type hydrogen bond to bend its linear hydrogen bond, the structure of CH₂O? CH₄ is noncyclic shaped. The interaction energy of hydrogen bonds and the π‐type H‐bond are calculated and discussed at the CCSD (T)/6‐311++G(3df,3pd) level. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

Copper(II) bis(4,4,4‐trifluoro‐1‐phenylbutane‐1,3‐dionate) complexes with pyridin‐2‐one, 3‐hydroxypyridine and 3‐hydroxypyridin‐2‐one ligands: molecular structures and hydrogen‐bonded networks

Copper(II) bis(4,4,4‐trifluoro‐1‐phenylbutane‐1,3‐dionate) complexes with pyridin‐2‐one (pyon), 3‐hydroxypyridine (hpy) and 3‐hydroxypyridin‐2‐one (hpyon) were prepared and the solid‐state structures of (pyridin‐2‐one‐κO )bis(4,4,4‐trifluoro‐3‐oxo‐1‐phenylbutan‐1‐olato‐κ²O ,O ′)copper(II), [Cu(C₁₀H₆F₃O₂)₂(C₅H₅NO)] or [Cu(tfpb‐κ²O ,O ′)₂(pyon‐κO )], (I), bis(pyridin‐3‐ol‐κO )bis(4,4,4‐trifluoro‐3‐oxo‐1‐phenylbutan‐1‐olato‐κ²O ,O ′)copper(II), [Cu(C₁₀H₆F₃O₂)₂(C₅H₅NO)₂] or [Cu(tfpb‐κ²O ,O ′)₂(hpy‐κO )₂], (II), and bis(3‐hydroxypyridin‐2‐one‐κO )bis(4,4,4‐trifluoro‐3‐oxo‐1‐phenylbutan‐1‐olato‐κ²O ,O ′)copper(II), [Cu(C₁₀H₆F₃O₂)₂(C₅H₅NO₂)₂] or [Cu(tfpb‐κ²O ,O ′)₂(hpyon‐κO )₂], (III), were determined by single‐crystal X‐ray analysis. The coordination of the metal centre is square pyramidal and displays a rare example of a mutual cis arrangement of the β‐diketonate ligands in (I) and a trans‐octahedral arrangement in (II) and (III). Complex (II) presents the first crystallographic evidence of κO‐monodentate hpy ligation to the transition metal enabling the pyridine N atom to participate in a two‐dimensional hydrogen‐bonded network through O—H…N interactions, forming a graph‐set motif R ₂²(7) through a C—H…O interaction. Complex (III) presents the first crystallographic evidence of monodentate coordination of the neutral hpyon ligand to a metal centre and a two‐dimensional hydrogen‐bonded network is formed through N—H…O interactions facilitated by C—H…O interactions, forming the graph‐set motifs R ₂²(8) and R ₂²(7).     

2,2,2‐Trinitroethanol

2,2,2‐Trinitroethanol, C₂H₃N₃O₇, at 100 (2) K has Z′ = 2 in the space group P2₁/c. The structure displays intramolecular O—H...O hydrogen bonds, as well as intermolecular O—H...O and C—H...O hydrogen bonding; the O—H...O hydrogen bonds, forming R₄⁴(8) rings, and dipolar nitro–nitro interactions account for the high density of 1.839 Mg m⁻³.     

Structural diversity of polynuclear MgxOy cores in magnesium phenoxide complexes

The binuclear complex bis(2,6‐di‐tert‐butyl‐4‐methylphenolato)‐1κO ,2κO‐(1,2‐dimethoxyethane‐1κ²O ,O ′)bis(μ‐phenylmethanolato‐1:2κ²O :O )(tetrahydrofuran‐2κO )dimagnesium(II), [Mg₂(C₇H₇O)₂(C₁₅H₂₃O)₂(C₄H₈O)(C₄H₁₀O₂)] or [(BHT)(DME)Mg(μ‐OBn)₂Mg(THF)(BHT)], (I), was obtained from the complex [(BHT)Mg(μ‐OBn)(THF)]₂ by substitution of one tetrahydrofuran (THF) molecule with 1,2‐dimethoxyethane (DME) in toluene (BHT is O‐2,6‐^t Bu₂‐4‐MeC₆H₄ and Bn is benzyl). The trinuclear complex bis(2,6‐di‐tert‐butyl‐4‐methylphenolato)‐1κO ,3κO‐tetrakis(μ‐2‐methylphenolato)‐1:2κ⁴O :O ;2:3κ⁴O :O‐bis(tetrahydrofuran)‐1κO ,3κO‐trimagnesium(II), [Mg₃(C₇H₇O)₄(C₁₅H₂₃O)₂(C₄H₈O)₂] or [(BHT)₂(μ‐O‐2‐MeC₆H₄)₄(THF)₂Mg₃], (II), was formed from a mixture of Bu₂Mg, [(BHT)Mg(ⁿ Bu)(THF)₂] and 2‐methylphenol. An unusual tetranuclear complex, bis(μ₃‐2‐aminoethanolato‐κ⁴O :O :O ,N )tetrakis(μ₂‐2‐aminoethanolato‐κ³O :O ,N )bis(2,6‐di‐tert‐butyl‐4‐methylphenolato‐κO )tetramagnesium(II), [Mg₄(C₂H₆NO)₆(C₁₅H₂₃O)₂] or Mg₄(BHT)₂(OCH₂CH₂NH₂)₆, (III), resulted from the reaction between (BHT)₂Mg(THF)₂ and 2‐aminoethanol. A polymerization test demonstrated the ability of (III) to catalyse the ring‐opening polymerization of ϵ‐caprolactone without activation by alcohol. In all three complexes (I)–(III), the BHT ligand demonstrates the terminal κO‐coordination mode. Complexes (I), (II) and (III) have binuclear rhomboid Mg₂O₂, trinuclear chain‐like Mg₃O₄ and bicubic Mg₄O₆ cores, respectively. A survey of the literature on known polynuclear Mg_x O_y core types for ArO–Mg complexes is also presented.     

Two‐dimensional coordination polymeric structures in the sodium,potassium and rubidium complex salts with (4‐fluorophenoxy)acetic acid

The structures of the sodium, potassium and rubidium complex salts of (4‐fluorophenoxy)acetic acid (PFPA), namely poly[μ‐aqua‐aqua‐μ‐[2‐(4‐fluorophenoxy)acetato]‐κ³O ¹,O ²:O^1′‐sodium], [Na(C₈H₆FO₃)(H₂O)₂]_n , (I), and isotypic poly[μ₅‐[2‐(4‐fluorophenoxy)acetato]‐κ⁵O ¹,O ²:O ¹,O ^1′:O ^1′:O ^1′:O^1′‐potassium], [K(C₈H₆FO₃)]_n , (II), and poly[μ₅‐[2‐(4‐fluorophenoxy)acetato]‐κ⁵O ¹,O ²:O ¹,O ^1′:O ^1′:O ^1′:O^1′‐rubidium], [Rb(C₈H₆FO₃)]_n , (III), have been determined and their coordination polymeric structures described. In the structure of (I), the very distorted octahedral NaO₆ coordination polyhedron comprises two bidentate chelating O‐atom donors (carboxylate and phenoxy) of the PFPA ligand and three O‐atom donors from water molecules, one monodentate and the other μ₂‐bridging between inversion‐related Na centres in a cyclic manner. A bridging carboxylate donor generates two‐dimensional polymer layers lying parallel to (001), in which intralayer water O—H…O hydrogen‐bonding associations are also present. Structures (II) and (III) are isotypic, each having an irregular M O₇ stereochemistry, with the primary metal–ligand bidentate chelate similar to that in (I) and extended into a two‐dimensional polymeric layered structure, lying parallel to (100), through five additional bridging carboxylate O atoms. Two of these bonds are from an O ,O ′‐bidentate chelate interaction and the other three are from μ₃‐O‐atom bridges, generating cyclic links with short M …M separations [3.9064 (17) Å for (II) and 4.1001 (8) for (III)], the shortest being a centrosymmetric four‐membered cyclic link. In the crystals of (I)–(III), intralayer C—H…F interactions are present, but no π–π ring interactions are found.     

Lanthankomplexe mit 2,2′-Bipyridin-N,N′-dioxid

Compounds of the composition La(bpyO₂ ^*)₄Cl₃·4H₂O, La(bpyO₂)₃Cl₃·5H₂O, La(bpyO₂)₂Cl₃·3H₂O, La(bpyO₂)Cl₃·3H₂O, La(bpyO₂)₄Br₃·4H₂O, La(bpyO₂)₃Br₃·8H₂O, La(bpyO₂)₂Br₃·7H₂O, La(bpyO₂)Br₃·4H₂O, La(bpyO₂)₄I₃·3H₂O, La(bpyO₂)₃(NO₃)₃·2H₂O, La(bpyO₂)₂(NO₃)₃·2H₂O, La(bpyO₂)₄(SCN)₃·3H₂O, La(bpyO₂)₃(SCN)₃·2H₂O, La(bpyO₂)₂(SCN)₃·2H₂O were isolated. They were investigated by means of thermoanalysis, I.R. spectroscopy, X-ray diffraction and molar conductivity.     

A novel amido–pyrophosphate MnII chelate complex with the synthetic ligand O{P(O)[NHC(CH3)3]2}2 (L): [Mn(L)2{OC(H)N(CH3)2}2]Cl2·2H2O

The title complex, trans‐bis(dimethylformamide‐κO)bis{N,N′‐N′′,N′′′‐tetra‐tert‐butyl[oxybis(phosphonic diamide‐κO)]}manganese(II) dichloride dihydrate, [Mn(C₁₆H₄₀N₄O₃P₂)₂(C₃H₇NO)₂]Cl₂·2H₂O, is the first example of a bis‐chelate amido–pyrophosphate (pyrophosphoramide) complex containing an O[P(O)(NH)₂]₂ fragment. Its asymmetric unit contains half of the complex dication, one chloride anion and one water molecule. The Mn^II atom, located on an inversion centre, is octahedrally coordinated, with a slight elongation towards the monodentate dimethylformamide ligand. Structural features of the title complex, such as the P=O bond lengths and the planarity of the chelate ring, are compared with those of previously reported complexes with six‐membered chelates involving the fragments C(O)NHP(O), (X)NP(O) [X = C(O), C(S), S(O)₂ and P(O)] and O[P(O)(N)₂]₂. This analysis shows that the six‐membered chelate rings are less puckered in pyrophosphoramide complexes containing a P(O)OP(O) skeleton, such as the title compound. The extended structure of the title complex involves a linear aggregate mediated by N—H...O and N—H...Cl hydrogen bonds, in which the chloride anion is an acceptor in two additional O—H...Cl hydrogen bonds.     

Bidentate coordination of a diketo phosphorus ylide: synthesis and structure of [(C6H5)3PC(COCH3)(COC6H5)-κO,O′]UO2(NO3)2

A 1?:?1 chelate complex [(C₆H₅)₃PC(COCH₃)(COC₆H₅)-κO,O′]UO₂(NO₃)₂ has been synthesized by reaction of (C₆H₅)₃PC(COCH₃)(COC₆H₅) with UO₂(NO₃)₂?·?6H₂O in methanol at room temperature and characterized by elemental analysis, spectroscopy as well as by single-crystal X-ray diffraction. The complex crystallizes in P2₁/n space group with a?=?10.007(2)?Å, b?=?15.285(7)?Å, c?=?19.20(1)?Å, β?=?91.22(3)°, V?=?2936(2)?ų, Z?=?4, D _c?=?1.847?g?cm^?3. In the solid state structure, the dihedral angle [88.1(4)°] between the planes defined by the two quartets of atoms O1 O8 O2 O4 and O6 O5 O3 O7 is close to 90°, as expected for a triangulated dodecahedral geometry around uranium.     

Syntheses and structural determinations of the nine-coordinate rare earth metal: Na4[DyIII(dtpa)(H2O)]2·16H2O,Na[DyIII(edta)(H2O)3]·3.25H2O and Na3[DyIII(nta)2(H2O)]·5.5H2O

Three complexes, Na₄[Dy^III(dtpa)(H₂O)]₂?·?16H₂O, Na[Dy^III(edta)(H₂O)₃]?·?3.25H₂O and Na₃[Dy^III (nta)₂(H₂O)]?·?5.5H₂O, have been synthesized in aqueous solution and characterized by FT–IR, elemental analyses, TG–DTA and single-crystal X-ray diffraction. Na₄[Dy^III(dtpa)(H₂O)]₂?·?16H₂O crystallizes in the monoclinic system with P2₁/n space group, a?=?18.158(10)?Å, b?=?14.968(9)?Å, c?=?20.769(12)?Å, β?=?108.552(9)°, V?=?5351(5)?ų, Z?=?4, M?=?1517.87?g?mol^?1, D _c?=?1.879?g?cm^?3, μ?=?2.914?mm^?1, F(000)?=?3032, and its structure is refined to R ₁(F)?=?0.0500 for 9384 observed reflections [I?>?2σ(I)]. Na[Dy^III(edta)(H₂O)₃]?·?3.25H₂O crystallizes in the orthorhombic system with Fdd2 space group, a?=?19.338(7)?Å, b?=?35.378(13)?Å, c?=?12.137(5)?Å, β?=?90°, V?=?8303(5)?ų, Z?=?16, M?=?586.31?g?mol^?1, D _c?=?1.876?g?cm^?3, μ?=?3.690?mm^?1, F(000)?=?4632, and its structure is refined to R ₁(F)?=?0.0307 for 4027 observed reflections [I?>?2σ(I)]. Na₃[Dy^III(nta)₂(H₂O)]?·?5.5H₂O crystallizes in the orthorhombic system with Pccn space group, a?=?15.964(12)?Å, b?=?19.665(15)?Å, c?=?14.552(11)?Å, β?=?90°, V?=?4568(6)?ų, Z?=?8, M?=?724.81?g?mol^?1, D _c?=?2.102?g?cm^?3, μ?=?3.422?mm^?1, F(000)?=?2848, and its structure is refined to R ₁(F)?=?0.0449 for 4033 observed reflections [I?>?2?σ(I)]. The coordination polyhedra are tricapped trigonal prism for Na₄[Dy^III(dtpa)(H₂O)]₂?·?16H₂O and Na₃[Dy^III(nta)₂(H₂O)]?·?5.5H₂O, but monocapped square antiprism for Na[Dy^III(edta)(H₂O)₃]?·?3.25H₂O. The crystal structures of these three complexes are completely different from one another. The three-dimensional geometries of three polymers are 3-D layer-shaped structure for Na₄[Dy^III(dtpa)(H₂O)]₂?·?16H₂O, 1-D zigzag type structure for Na[Dy^III(edta)(H₂O)₃]?·?3.25H₂O and a 2-D parallelogram for Na₃[Dy^III(nta)₂(H₂O)]?·?5.5H₂O. According to thermal analyses, the collapsing temperatures are 356°C for Na₄[Dy^III(dtpa)(H₂O)]₂?·?16H₂O, 371°C for Na[Dy^III(edta)(H₂O)₃]?·?3.25H₂O and 387°C for Na₃[Dy^III(nta)₂(H₂O)]?·?5.5H₂O, which indicates that their crystal structures are very stable.     

Darstellung und Kristallstruktur von Rb4Br2O und Rb6Br4O

Syntheses and Crystal Structures of Rb₄Br₂O and Rb₆Br₄O In the quasi‐binary system RbBr/Rb₂O, the addition compounds Rb₄Br₂O and Rb₆Br₄O are obtained by solid state reaction of the boundary components RbBr and Rb₂O. Crystals of red‐orange Rb₄Br₂O as well as of orange Rb₆Br₄O decompose immediately when exposed to air. Rb₄Br₂O (Pearson code tI14, I4/mmm, a = 544.4(6) pm, c = 1725(2) pm, Z = 2, 175 symmetry independent reflections with I_o > 2σ(I), R₁= 0.0618) crystallizes in the anti K₂NiF₄ structure type; Rb₆Br₄O (Pearson code hR22, R3c, a = 1307.8(3) pm, c = 1646.6(5) pm, Z = 6, 630 symmetry independent reflections with I_o > 2σ(I), R₁ = 0.0759) in the anti K₄CdCl₆ structure type. Both structures contain characteristic ORb₆‐octahedra and can be understood as expanded perovskites, following the general systematics of alkaline metal oxide halides.     

Three New 1D Polymeric Zinc(II) and Cadmium(II) Azido Complexes Containing Noncoordinated Pyridine-<Emphasis Type="Italic">N</Emphasis>-oxide or 3-Picoline-<Emphasis Type="Italic">N</Emphasis>-oxide

Summary. The interaction of pyridine-N-oxide (pyNO) and 3-picoline-N-oxide (3picNO) with zinc(II) and cadmium(II) azides afforded complexes with empirical formulae Zn(N₃)₂(pyNO)(H₂O)₂, Zn(N₃)₂(3picNO)₂(H₂O)₂ and Cd(N₃)₂(3picNO)₂(H₂O)₂. The IR spectra of these complexes are measured and discussed. X-Ray single crystal diffraction showed for the first complex, which should be formulated as {[Zn(N₃)₂(H₂O)₂](pyNO)}_n, to consist of 1D chains of trans-[Zn(N₃)₂(H₂O)₂]_n, double end-on (-1,1) azido bridges and noncoordinated pyNO molecules. The other two complexes are isomorphous containing 1D trans-[M(N₃)₂(H₂O)₂]_n, double (-1,1) azido bridges, and hydrogen bonded noncoordinated 3picNO molecules. Each pyridine-N-oxide molecule forms three hydrogen bonds, whereas the 3-picoline-N-oxides form two hydrogen bonds. The metal centers exhibit distorted octahedral geometry.Received March 5, 2003; accepted May 15, 2003 Published online September 11,2003     

Different cyclic motifs in phosphoric triamides containing a C(O)NHP(O)(NH)2 skeleton and an R22(10) graph set in three new compounds: a database analysis of hydrogen‐bond strengths based on motifs

In the crystal networks of N,N′‐bis(2‐chlorobenzyl)‐N′′‐(2,6‐difluorobenzoyl)phosphoric triamide, C₂₁H₁₈Cl₂F₂N₃O₂P, (I), N‐(2,6‐difluorobenzoyl)‐N′,N′′‐bis(4‐methoxybenzyl)phosphoric triamide, C₂₃H₂₄F₂N₃O₄P, (II), and N‐(2‐chloro‐2,2‐difluoroacetyl)‐N′,N′′‐bis(4‐methylphenyl)phosphoric triamide, C₁₆H₁₇ClF₂N₃O₂P, (III), C=O...H—N_C(O)NHP(O) and P=O...H—N_amide hydrogen bonds are responsible for the aggregation of the molecules. This is the opposite result from that commonly observed for carbacylamidophosphates, which show a tendency for the phosphoryl group, rather than the carbonyl counterpart, to form hydrogen bonds with the NH group of the C(O)NHP(O) skeleton. This hydrogen‐bond pattern leads to cyclic R₂²(10) motifs in (I)–(III), different from those found for all previously reported compounds of the general formula RC(O)NHP(O)[NR¹R²]₂ with the syn orientation of P=O versus NH [R₂²(8)], and also from those commonly observed for RC(O)NHP(O)[NHR¹]₂ [a sequence of alternate R₂²(8) and R₂²(12) motifs]. In these cases, the R₂²(8) and R₂²(12) graph sets are formed through similar kinds of hydrogen bond, i.e. a pair of P=O...H—N_C(O)NHP(O) hydrogen bonds for the former and two C=O...H—N_amide hydrogen bonds for the latter. This article also reviews 102 similar structures deposited in the Cambridge Structural Database and with the International Union of Crystallography, with the aim of comparing hydrogen‐bond strengths in the above‐mentioned cyclic motifs. This analysis shows that the strongest N—H...O hydrogen bonds exist in the R₂²(8) rings of some molecules. The phosphoryl and carbonyl groups in each of compounds (I)–(III) are anti with respect to each other and the P atoms are in a tetrahedral coordination environment. In the crystal structures, adjacent molecules are linked via the above‐mentioned hydrogen bonds in a linear arrangement, parallel to [010] for (I) and (III) and parallel to [100] for (II). Formation of the N_C(O)NHP(O)—H...O=C instead of the N_C(O)NHP(O)—H...O=P hydrogen bond is reflected in the higher N_C(O)NHP(O)—H vibrational frequencies for these molecules compared with previously reported analogous compounds.     

Correlated one‐electron wave functions

Using four basis sets, 6‐311G(d,p), 6‐31+G(d,p), 6‐311++G(2d,2p), and 6‐311++G(3df,3pd), the optimized structures with all real frequencies were obtained at the MP2 level for dimers CH₂O? HF, CH₂O? H₂O, CH₂O? NH₃, and CH₂O? CH₄. The structures of CH₂O? HF, CH₂O? H₂O, and CH₂O? NH₃ are cycle‐shaped, which result from the larger bend of σ‐type hydrogen bonds. The bend of σ‐type H‐bond O…H? Y (Y?F, O, N) is illustrated and interpreted by an attractive interaction of a chemically intuitive π‐type hydrogen bond. The π‐type hydrogen bond is the interaction between one of the acidic H atoms of CH₂O and lone pair(s) on the F atom in HF, the O atom in H₂O, or the N atom in NH₃. By contrast with above the three dimers, for CH₂O? CH₄, because there is not a π‐type hydrogen‐bond to bend its linear hydrogen bond, the structure of CH₂O? CH₄ is a noncyclic shaped. The interaction energy of hydrogen bonds and the π‐type H‐bond are calculated and discussed at the CCSD(T)/6‐311++G(3df,3pd) level. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

Two new XP(O)[NHC(CH3)3]2 phosphoramidates,with X = (CH3)2N and [(CH3)3CNH]2P(O)(O)

In N,N′‐di‐tert‐butyl‐N′′,N′′‐dimethylphosphoric triamide, C₁₀H₂₆N₃OP, (I), and N,N′,N′′,N′′′‐tetra‐tert‐butoxybis(phosphonic diamide), C₁₆H₄₀N₄O₃P₂, (II), the extended structures are mediated by P(O)...(H—N)₂ interactions. The asymmetric unit of (I) consists of six independent molecules which aggregate through P(O)...(H—N)₂ hydrogen bonds, giving R₂¹(6) loops and forming two independent chains parallel to the a axis. Of the 12 independent tert‐butyl groups, five are disordered over two different positions with occupancies ranging from to . In the structure of (II), the asymmetric unit contains one molecule. P(O)...(H—N)₂ hydrogen bonds give S(6) and R₂²(8) rings, and the molecules form extended chains parallel to the c axis. The structures of (I) and (II), along with similar structures having (N)P(O)(NH)₂ and (NH)₂P(O)(O)P(O)(NH)₂ skeletons extracted from the Cambridge Structural Database, are used to compare hydrogen‐bond patterns in these families of phosphoramidates. The strengths of P(O)[...H—N]_x (x = 1, 2 or 3) hydrogen bonds are also analysed, using these compounds and previously reported structures with (N)₂P(O)(NH) and P(O)(NH)₃ fragments.     

Multiwalled Carbon Nanotubes Encased in Ruthenium Oxide Film as a Hybrid Material for Neurotransmitters Sensor

A hybrid film (MWCNTs‐RuO_x?nH₂O) which contains multiwalled carbon nanotubes (MWCNTs) along with the incorporation of ruthenium oxide (RuO_x?nH₂O) has been synthesized on glassy carbon electrode (GCE), gold (Au), indium tin oxide (ITO) and screen printed carbon electrode (SPCE) by potentiostatic methods. The presence of MWCNTs in the hybrid film enhances surface coverage concentration (Γ) of RuO_x?nH₂O to ≈2100%. The surface morphology of the hybrid film deposited on ITO has been studied using scanning electron microscopy and atomic force microscopy. These two techniques reveal that the RuO_x?nH₂O incorporated on MWCNTs. Electrochemical quartz crystal microbalance study too reveals the incorporation of MWCNTs and RuO_x?nH₂O. The MWCNTs‐RuO_x?nH₂O hybrid film exhibits promising enhanced electrocatalytic activity towards the biochemical compounds such as epinephrine and norepinephrine. The electrocatalytic responses of these analytes at RuO_x?nH₂O, MWCNTs and MWCNTs‐RuO_x?nH₂O hybrid films have been measured using cyclic voltammetry. The obtained sensitivity values from electrocatalysis studies of analytes for MWCNTs‐RuO_x?nH₂O hybrid film are higher than the RuO_x?nH₂O and MWCNTs films. Finally, the flow injection analysis has been used for the amperometric studies of analytes at MWCNTs‐RuO_x?nH₂O hybrid film modified SPCEs.