Characterization and crystal structure study of a new Cu(II) complex of pyridine-2,6-dicarboxylic acid and aniline containing a water cluster

A new monoclinic Cu(II) salt complex (C₆H₆N₂) ₂ ⁺ [Cu(2,6-dipico)₂]^2?·6H₂O, (2,6-dipico=pyridine-2,6-dicarboxylic acid) is synthesized and characterised by CHN analyses, IR, UV-Vis, magnetic susceptibility measurements, and single crystal X-ray crystallography. The structure contains two pyridine-2,6-dicarboxylate species as tridentate ligands with protonated aniline acting as a counter cation and six uncoordinated water molecules. The complex crystallizes in the monoclinic space group C2/c with unit cell parameters a = 20.9393(4) Å, b = 7.94330(10) Å, c = 19.9093(4) Å, V(ų) = 2932.32(9), Z = 4. Crystal packing is stabilized by N-H…O, O-H…O intermolecular hydrogen bonds and weak π…π interactions. The water molecules are trapped by a cooperative association of coordination interactions forming water clusters as well as by a hydrogen bond to the Cu (II) complex.     

Thio- und AmidothioDerivate der Diphosphor(IV)-säure

Thio and Amidothio Derivatives of Diphosphorus(IV) Acid Oxothiodiphosphates(IV) with anions [P₂O_nS_6?n]^4? (n = 1–5) are formed by steps wise substitution of thio by oxo ligands in hexathiodiphosphate(4–). Oxidative ammonolysis of thianion leads to amidothio derivatives, [P₂(NH₂)S₅]^3? and [P₂(NH₂)₂S₄]^2?.     

Die Kristallstruktur der hydratisierten Cyanokomplexe NMe4MnII[(Mn, Cr)III(CN)6] · 3 H2O und NMe4Cd[MIII(CN)6] · 3 H2O (MIII = Fe,Co): Verwandte des Berliner Blaus

The Crystal Structure of the Hydrated Cyano Complexes NMe₄Mn^II[(Mn, Cr)^III(CN)₆] · 3 H₂O and NMe₄Cd[M^III(CN)₆] · 3 H₂O (M^III = Fe, Co): Compounds Related to Prussian Blue The crystal structures of the isotypic tetragonal compounds (space group I4, Z = 10) NMe₄Mn^II · [(Mn, Cr)^III(CN)₆] · 3 H₂O (a = 1653.2(4), c = 1728.8(6) pm), NMe₄Cd[Fe(CN)₆] · 3 H₂O (a = 1642.7(1), c = 1733.1(1) pm) and NMe₄Cd[Co(CN)₆] · 3 H₂O (a = 1632.1(2), c = 1722.4(3) pm) were determined by X‐rays. They exhibit ⊥ c cyanobridged layers of octahedra [M^III(CN)₆] and [M^IIN₄(OH₂)₂], which punctually are interconnected also || c to yield altogether a spaceous framework. The M^II atoms at the positions linking into the third dimension are only five‐coordinated and form square pyramids [M^IIN₅] with angles N–M^II–N near 104° and distances of Mn–N: 1 × 214, 4 × 219 pm; Cd–N: 1 × 220 resp. 222, 4 × 226 resp. 228 pm. Further details and structural relations within the family of Prussian Blue are reported and discussed.     

Synthese,Kristallstruktur und thermischer Abbau von Fluoroaluminaten der Zusammensetzung (NH4)[M(H2O)6][AlF6] (M = Zn,Ni), [Zn(H2O)6][AlF5(H2O)] und (PyH)4[Al2F10] · 4 H2O

Synthesis, Crystal Structure and Thermal Behaviour of Fluoroaluminates of the Composition (NH₄)[M(H₂O)₆](AlF₆) (M = Zn, Ni), [Zn(H₂O)₆][AlF₅(H₂O)], and (PyH)₄[Al₂F₁₀] · 4 H₂O Four new fluoroaluminates were obtained from fluoroacidic solutions of respective metal salts. The compounds of zinc ( I a : P2₁/c, a = 12.688(3), b = 6.554(1), c = 12.697(3) Å, β = 95.21(3)°, V = 1051.5(4) ų, Z = 4) and nickel ( I b : P2₁/c, a = 12.685(3), b = 6.517(1), c = 12.664(2)Å, β = 94.55(2)°, V = 1043.6(4) ų, Z = 4) are isotypic and represent a new structure type consisting of two different cations, NH₄⁺ and [M(H₂O)₆]²⁺ and [AlF₆]^3–‐anions. [Zn(H₂O)₆][AlF₅(H₂O)] ( II : C2/m, a = 10.769(2), b = 13.747(3), c = 6.487(1)Å, β = 100.02(3)°, V = 945.7(3) ų, Z = 4) is characterized by a H₂O/F‐disorder in the [AlF₅(H₂O)]‐octahedra in two trans positions. In (PyH)₄[Al₂F₁₀] · 4 H₂O ( III : Cmc2₁, a = 15.035(3), b = 20.098(4), c = 12.750(4) Å, V = 5364(2) ų, Z = 8), bioctahedral [Al₂F₁₀]^4– anions have been found for the first time. The structures are described and discussed in comparison. The new compounds were used as precursors in order to obtain new AlF₃‐phases. However, the thermal decomposition did not result in the formation of any new metastable AlF₃‐phase. Instead, phase mixtures of either α‐AlF₃ and β‐AlF₃ or AlF₃ and MF₂ were obtained.     

Synthesis and physico-chemical characterization of coordination compounds of 3d metals with bis(hydroxylammonium)bicyclo[2.2.1]-hept-5-en-endo-2,3-cis-dicarboxylate

Summary The reaction of aqueous solutions of 3d metal salts with bis(hydroxylammonium) bicyclo[2.2.1]-hept-5-en-endo-2,3-cis-dicarboxylate in a 12 mole ratio yielded complexes of the general formula [MⁿL₂(NH₃OH)₂]·nH₂O and [Fe^IIIL₂(NH₃OH)H₂O]·H₂O, where M^II=Mn, Fe, Co, Ni, Cu and Zn, and L=bicyclo[2.2.1]-hept-5-en-endo-2,3-cis-dicarboxylate dianion.The compounds were characterized by i.r. spectra and thermal analysis. For all complexes, an octahedral structure is proposed which is formed bytrans coordination of two bidentate (OO) ligands (L) and two NH₃OH⁺ cations attrans positions, coordinated also through oxygen atoms; and similarlytrans positions for NH₃OH⁺ and H₂O in the case of the Fe^III complex.     

Neutronenpulverdiffraktionsmessungen an [Zn(ND3)4]I2 bei 1,5 K, 10 K und 293 K: Wasserstoff-Brückenbindungen und Bewegungen von ND3-Molekülen

Neutron Powder Diffraction Measurements on [Zn(ND₃)₄]I₂ at 1.5 K, 10 K, and 293 K: Hydrogen Bonds and Dynamic of ND₃ Molecules Microcrystalline powder of [Zn(ND₃)₄]I₂ can be prepared by the reaction of gaseous NH₃ with dry ZnI₂ at room temperature within 8 h. Neutron powder diffraction measurements at 1.5 K, 10 K and 293 K were used to localize all hydrogen atoms. Isolated [Zn(ND₃)₄]²⁺ tetrahedra are three dimensionally linked with 2- and 3-centre (bent and bifurcated) N? D …? I^?-hydrogen bonds. Ammonia molecules are ordered at 1.5 K. Room temperature high thermal displacement parameters for D hint to the fact that NH₃-dynamics take place. Lattice parameters 300 K [10 K; 1,5 K]: a = 10.3783(8) Å [10.3407(4) Å; 10.3381(5)], b = 7.5239(6) Å [7.3960(2) Å; 7.3935(4) Å], c = 13.088(1) Å [12.9731(4) Å; 12.9695(6) Å], space group: Pnma.     

Untersuchungen von Fluorometallaten (III), 11. Mitt.: Synthese und Kristallstruktur von Guanidinium Hexalfuoroaluminat, -gallat und -indat

The complexes [C(NH₂)₃]₃ MF₆,M=Al, Ga, In have been isolated from aqueous solutions of the corresponding fluorides. The compounds are isostructural and crystallize in the cubic space group Pa3 witha=13.933 (1) Å for [C(NH₂)₃]₃AlF₆,a=14.065 (1) Å for [C(NH₂)₃]₃GaF₆,a=14.340 (1) Å for [C(NH₂)₃]₃InF₆ andZ=8. TheMF ₆ ^3? anions are arranged as Na⁺ and Cl^? in the NaCl lattice. Guanidinium cations are distributed on 24-fold general positions.     

Darstellung und Eigenschaften der Alkali-hexajodatogermanate (IV), M2[Ge(JO3)6]

Preparation and Properties of the Alkali Hexaiodatogermanates(IV), M₂[Ge(IO₃)₆] Germanium dioxide aquate and alkali nitrates react with iodic acid to yield alkali hexaiodatogermanates(IV), M₂[Ge(IO₃)₆], (M = NH₄, K, Rb, Cs). The unit-cell dimensions of the trigonal cell are for K₂[Ge(JO₃)₆] a₀ = 11.16 Å, c₀ = 11.34 Å, z = 3. The compounds M[M^IV(IO₃)₆] (M^I = NH₄, K, Rb, Cs, M^IV = Ge, Sn, Pb, Ti, Zr, Mn) are isomorphous¹).     

Beiträge zur Komplexchemie der Phosphine und Phosphinoxide. XXXI. Cobalt- sowie Rhodiumkomplexe primärer Mercaptoalkylphosphine und Bemerkungen zur Komplexbildung quadridentater P,P,S,S-Liganden

On the Coordination Chemistry of Phosphines and Phosphinoxides. XXXI. Cobalt and Rhodium Complexes of Primary Mercaptoalkylphosphines and Remarks on the Complex Formation of Quadridentate P,P,S,S Ligands Primary Mercaptoalkylphosphines (H₂P? CH₂ · CH₂? SH; H₂P? CH₂ · CHCH₃? SH) react with d⁷-metal salts to give octahedron 1:3 chelat complexes. In case of cobalt the oxidation of Co^II to Co^III are obtained by formation of H₂. Structure and properties of these complexes as well as their reactivity like S-alkylation or metallation with following reactions are described. Reaction scheme see ?Inhaltsübersicht”?. With quadridentate ligands HS+ +PH+ +PH+ +SH = L result chelat-complexes of the type [M^III? L XNH₃] (M = Co, Rh) and such as [M^II? L] (M = Ni, Pd, Pt).     

Bipy,Phen und P(C6H4CH2NMe2‐2)3 in der Synthese kationischer Silber(I)‐Komplexe; die Festkörperstrukturen von [P(C6H4CH2NMe2‐2)3]AgOTf und [Ag(phen)2]OTf

Bipy, Phen, and P(C₆H₄CH₂NMe₂‐2)₃ in the Synthesis of Cationic Silver(I) Complexes; the Solid‐State Structures of [P(C₆H₄CH₂NMe₂‐2)₃]AgOTf and [Ag(phen)₂]OTf The reaction of [P(C₆H₄CH₂NMe₂‐2)₃]AgX ( 1a , X = OTf; 1b , X = OClO₃) with equimolar amounts of L^capL ( 2a , L^capL = 2, 2′‐bipyridine, bipy; 2b , L^capL = 4, 4′‐dimethyl‐2, 2′‐bipyridine, bipy′; 2c , L^capL = 1, 10‐phenanthroline, phen) leads to the formation of the cationic complexes {[P(C₆H₄CH₂NMe₂‐2)₃]Ag(L^capL)}⁺X^— (L^capL = bipy: 3a , X = OTf; 3b , X = ClO₄; L^capL = bipy′: 3c , X = OTf; 3d , X = ClO₄; L^capL = phen: 3e , X = OTf; 3f , X = ClO₄) in which the building blocks L^capL and P(C₆H₄CH₂NMe₂‐2)₃ act as bidentate chelating ligands and are datively‐bound to the silver atom. Spectroscopic studies reveal that on the NMR time‐scale the phosphane group is dynamic with exchanging the respective Me₂NCH₂ built‐in arms. While complex 3e is stable in the solid‐state, it appeared that solutions of 3e start to decompose upon precipitation of colloidal silver when they are heated or irradiated with light, respectively. Appropriate work‐up of the reaction mixture allows the isolation of the phosphane P(C₆H₄CH₂NMe₂‐2)₃ ( 5 ) along with [Ag(phen)₂]OTf ( 4 ). The solid‐state structures of neutral 1a and cationic 4 are reported. Mononuclear 1a crystallizes in the monoclinic space group P2₁/c with the cell parameters a = 16.7763(2), b = 14.7892(2), c = 25.44130(10)Å, β = 106.1260(10), V = 6063.83(11)ų and Z = 4 with 8132 observed unique reflections (R₁ = 0.0712), while 4 crystallizes in the monoclinic space group C2/c with the cell parameters a = 26.749(3), b = 7.1550(10), c = 26.077(3)Å, β = 113.503(2), V = 4576.8(10)ų and Z = 4 with 6209 observed unique reflections (R₁ = 0.0481). The unit cell of 1a consists of two independent molecules. In both molecules the silver atom possesses a distorted tetrahedral coordination sphere and a boat‐like conformation for the six‐membered AgPNCH₂C_2/phenyl cycles is found. In 4 , as typical for 1a , the silver atom possesses the coordination number 4. The two phen ligands are tilted by 40.63°. The OTf group is acting as non‐coordinating counter ion.     

Wasserstoffbrückenbindungen in o- und m-Phenylendiammonium-aquapentafluorometallaten(III) (MIII = Al,Cr, Fe)

Hydrogen Bonds in o- and m-Phenylenediammonium Aquapentafluoro Metallates(III) (M^III = Al, Cr, Fe) m- and o-Phenylenediammonium-[M^IIIF₅(H₂O)] compounds of Al, Cr and Fe were synthesized and characterized by X-ray single crystal structure analysis. All structures are described in the space group P2₁2₁2₁ (Z = 4). m-Ph(NH₃)₂²⁺ (Ph(NH₃)₂²⁺ = phenylenediammonium) compounds: Al : a = 6.489(2), b = 7.943(2), c = 18.204(2) Å, R/wR = 0.084/0.050 for 1 533 reflections; Cr : a = 6.571(2), b = 8.006(2), c = 18.456(3) Å, R/wR = 0.050/0.040 for 1 571 reflections; Fe : a = 6.608(2), b = 8.052(2), c = 18.424(4) Å, R/wR = 0.042/0.034 for 1 947 reflections. o-Ph(NH₃)₂²⁺ compounds: Al : a = 6.580(2), b = 7.891(2), c = 18.319(5) Å, R/wR = 0.050/0.045 for 2 370 reflections; Cr : a = 6.642(2), b = 7.954(2), c = 18.484(4) Å, R/wR = 0.065/0.043 for 2 041 reflections; Fe : a = 6.693(2), b = 7.995(4), c = 18.529(7) Å, R/wR = 0.035/0.033 for 2 651 reflections. Isolated distorted octahedral [M^IIIF₅(H₂O)]^2? anions are connected by double O? H ?F hydrogen bonds of alternating strength to form chains in the b direction. Those chains, packed in a pseudohexagonal way, are further linked by the ammonium functions of the phenylenediammonium cations to a 3 D hydrogen bond network.     

[ReIII(thiourea-S)6]Cl3 · 4 H2O and [ReIII(N-methylthiourea-S)6]Cl3 as Precursors to other ReIII Complexes: a Kinetic Study in Aqueous Media. Crystal Structure of [ReIII(N-methylthiourea-S)6](PF6)3 · H2O

Capability of [Re^III(tu-S)₆]Cl₃, where tu = thiourea, as a precursor to other Re^III complexes by ligand substitution in aqueous medium is studied. For the decomposition of [Re(tu-S)₆]Cl₃, experiments suggest pseudo first order kinetics and observed rate constants vary from 1.3 × 10^–2 to 9.6 × 10^–2 min^–1 in the pH range 2.80–5.04. Experiments in presence of incoming ligand (ethylendiaminetetraacetic acid or diethylentriaminepentaacetic acid) show that ligand substitution is significantly slower than decomposition of the precursor, even when pH and temperature are modified. Similar results were obtained working with [Re^III(Metu-S)₆]Cl₃, where Metu = N-methylthiourea. Molecular structure of [Re^III(Metu-S)₆](PF₆)₃ · H₂O was determined by single crystal X-ray diffractometry. The coordination polyhedron around the Re ion is a distorted octahedron. The six methylthiourea ligands are bonded to the metal through the sulfur atoms [bond lengths range from 2.409(2) to 2.451(2) Å].     

Die Kristallstrukturen der Vanadium-Weberite Na2MIIVIIIF7 (MII  Mn,Ni, Cu) und von NaVF4

The Crystal Structures of the Vanadium Weberites Na₂M^IIV^IIIF₇ (M^II ? Mn, Ni, Cu) and of NaVF₄ At single crystals of the vanadium(III) compounds NaVF₄ (a = 790.1, b = 531.7, c = 754.0 pm, β = 101.7°; P2₁/c, Z = 4), Na₂NiVF₇ (a = 726.0, b = 1031.9, c = 744.6 pm; Imma, Z = 4) and Na₂CuVF₇ (a = 717.6, b = 1043.5, c = 754.6 pm; Pmnb, Z = 4) X-ray structure determinations were performed, at Na₂MnVF₇ (a = 746.7, c = 1821.6 pm; P3₂21, Z = 6) a new refinement. NaVF₄ crystallizes in the layer structure type of NaNbO₂F₂. The fluorides Na₂M^IIVF₇ represent new orthorhombic (M^II ? Ni; Cu) resp. trigonal (M^II ? Mn) weberites. The average distances within the [VF₆] octahedra of the four compounds are in good agreement with each other and with data of related fluorides (V? F: 193.3 pm). The differences between mean bond lengths of terminal and bridging F ligands are 5% in NaVF₄, but less than 1% in the weberites. Details and data for comparison are discussed.     

Chloro- und Polyselenoselenate(II) Darstellung,Struktur und Eigenschaften von [Ph3(C2H4OH)P]2[SeCl4] · MeCN, [Ph4P]2[Se2Cl6] und [Ph4P]2[Se(Se5)2]

Chloro- and Polyselenoselenates(II): Synthesis, Structure, and Properties of [Ph₃(C₂H₄OH)P]₂[SeCl₄] · MeCN, [Ph₄P]₂[Se₂Cl₆], and [Ph₄P]₂[Se(Se₅)₂] By symproportionation of elemental selenium and SeCl₄ in polar protic solvents the novel chloroselenates(+II), [SeCl₄]^2? and [Se₂Cl₆]^2?, could be stabilized; they were crystallized with voluminous organic cations. They were characterized from complete X-ray structure analysis. Yellow-orange [Ph₃(C₂H₄OH)P]₂[SeCl₄] · MeCN (space group P1 , a = 10.535(4), b = 12.204(5), c = 16.845(6) Å, α = 77.09(3)°, β = 76.40(3)°, γ = 82.75(3)° at 140 K) contains in its crystal structure monomeric [SeCl₄]^2? anions with square-planar coordination of Se(+II). The mean Se? Cl bond length is 2.441 Å. In yellow [Ph₄P]₂[Se₂Cl₆] (space group P1 , a = 10.269(3), b = 10.836(4), c = 10.872(3) Å, α = 80.26(3)°, β = 79.84(2)°, γ = 72.21(3)° at 140 K) a dinuclear centrosymmetric [Se₂Cl₆]^2? anion, also with square-planar coordinated Se(+II), is observed. The average terminal and bridging Se? Cl bond distances are 2.273 and 2.680 Å, respectively. From redox reactions of elemental Se with boranate/thiolate in ethanol/DMF the bis(pentaselenido)selenate(+II) anion [Se(Se₅)₂]^2? was prepared as a novel type of a mixed-valent chalcogenide. In dark-red-brown [Ph₄P]₂[Se(Se₅)₂] (space group P2₁/n, a = 12.748(4), b = 14.659(5), c = 14.036(5) Å, β = 108.53(3)° at 140 K) centrosymmetric molecular [Se(Se₅)₂]^2? anions with square-planar coordination of the central Se(+II) by two bidentate pentaselenide ligands is observed (mean Se? Se bond lengths: 2.658 Å at Se(+II), 2.322 Å in [Se₅]_2?). The resulting six-membered chelate rings with chair conformation are spirocyclically linked through the central Se(+II). The vibrational spectra of the new anions are reported.     

Vergleich der Kristallstrukturen der Tetraammoniakate von Lithiumhalogeniden,LiBr·4NH3 und LiI·4NH3, mit der Struktur von Tetramethylammoniumiodid,N(CH3)4I

A Comparison of the Crystal Structures of the Tetraammoniates of Lithium Halides, LiBr·4NH₃ and LiI·4NH₃, with the Structure of Tetramethylammonium Iodide, N(CH₃)₄I Crystals of the tetraammoniates of LiBr and LiI sufficient in size for X‐ray structure determinations were obtained by slow evaporation of NH₃ at room temperature from a clear solution of the halides in liquid ammonia. The compounds crystallize in the space group Pnma (No. 62) with four formula units in the unit cell: LiBr·4NH₃: a = 11.947(5)Å, b = 7.047(4)Å, c = 9.472(3)Å LiI·4NH₃: a = 12.646(3)Å, b = 7.302 (1)Å, c = 9.790(2)Å For N(CH₃)₄I the structure was now successfully solved including the hydrogen positions of the methyl groups. N(CH₃)₄I: P4/nmm (No. 129), Z = 2, a = 7.948(1)Å, c = 5.738(1)Å The ammoniates of LiBr and LiI crystallize isotypic in a strongly distorted arrangement of the CsCl motif. Even N(CH₃)₄I has an CsCl‐like structure. Both structure types differ mainly in their orientation of the [Li(NH₃)₄]⁺ — resp. [N(CH₃)₄]⁺ — cations with respect to the surrounding “cube” of anions.     

Barium vanadium(III) hydrogen ­phosphate,Ba3V2(HPO4)6

Hydro­thermally prepared Ba₃V₂(HPO₄)₆ contains a three‐dimensional network of V^IIIO₆ octahedra [d_av(V—O) = 2.014 (2) Å] and HPO₄ [d_av(P—O) = 1.537 (3) Å] tetrahedra, sharing vertices. 12‐coordinate Ba²⁺ cations [d_av(Ba—O) = 2.944 (4) Å] complete the structure.     

RuS4Cl12 und Ru2S6Cl16, zwei neue Ruthenium(II)‐Komplexe mit SCl2‐Liganden

RuS₄Cl₁₂ and Ru₂S₆Cl₁₆, Two New Ruthenium(II) Complexes with SCl₂ Ligands Ru powder was reacted with SCl₂ in closed silika ampoules at 140 °C. From the black solution three compounds RuS₄Cl₁₂ 1 , Ru₂S₆Cl₁₆ 2 , and Ru₂S₄Cl₁₃ 3 could be crystallized and characterized by x ray analysis. Black crystals of 1 (monoclinic, a = 9.853(1) Å, b = 11.63(1) Å, c = 15.495(1) Å, β = 105.23(1)°, space group P2₁/c, z = 4) are identified as Trichlorsulfonium‐tris(dichlorsulfan)trichloro‐ruthenat(II) SCl₃[RuCl₃(SCl₂)₃]. In the structure the complex anions fac‐[RuCl₃(SCl₂)₃]^– and the cations [SCl₃]⁺ are connected to ion pairs by three chlorine bridges. The brown crystals of 2 (triclinic, a = 7.754(2) Å, b = 7.997(2) Å, c = 10.708(2) Å, α = 103.74(3)°, β = 98.44(3)°, γ = 108.58(3)°, space group P‐1, z = 1) contain the binuclear complex Bis‐μ‐chloro‐dichloro‐hexakis(dichlorsulfan)‐diruthenium(II), (SCl₂)₃ClRu(μ‐Cl)₂RuCl(SCl₂)₃ with two fac‐RuCl₃(SCl₂)₃‐units connected by two chlorine bridges. 3 was identifyed as a known mixed valence Ru(II,III) binuclear complex [Cl₂(SCl₂)Ru(μ‐Cl)₃Ru(SCl₂)₃]. The vibrational spectra and the thermal behaviour of the compounds are discussed.     

Molecular chains in the structure of a Zinc(Ii) Complex with Pyrazine-2,6-Dicarboxylate and Water Ligands

Crystals of catena-[diaqua-(μ-pyrazine-2,6-dicarboxylato-N,O,O′-μ-N′)]zinc(II) contain molecular chains in which the Zn(II) ions are bridged by pyrazine-2,6-dicarboxylate ligands via two symmetry-related oxygen atoms, each donated by a different carboxylic group [Zn–O(1) and O(1) ^I : 2.182(2)?Å] and the hetero-ring nitrogen atom [Zn–N(1): 2.049(3)?Å] situated between them on one side and the second hetero-ring nitrogen atom [Zn–N(2) ^II 2.118(3)?Å] from the adjacent ligand on the other. The Zn(II) ion and four coordinating atoms are coplanar. Two symmetry related water molecules [Zn–O3 and O: 2.116(2)?Å] situated above and below this plane complete the coordination around the Zn(II) ion to six atoms forming a distorted octahedron.     

Structural and Photophysical Properties of Lanthanide Nitrate 1:1 Complexes with planar tridentate nitrogen ligands analogous to 2,2′:6′,2′-terpyridine

The ligand 2,6-bis(1-methylbenzimidazol-2-yl)pyridine (mbzimpy, 1 ) reacts with Eu^III to give [Eu(mbzimpy)(NO₃)₃(CH₃OH)] [ 4 ] whose crystal structure (EuC₂₂H₂₁N₈O₁₀, a = 7.658(3) Å, b = 19.136(2) Å, c = 8.882 Å, β = 104.07(1)°, monoclinic, P2₁, Z = 2) shows a mononuclear structure where Eu^III is ten-coordinate by a meridional tridentate mbzimpy ligand, three bidentate nitrates, and one CH₃OH molecule, leading to a low-symmetry coordination sphere around the metalion. Essentially the same coordination is found in the crystal structure of [Eu(obzimpy)(NO₃)₃] ( 8 ) (EuC₃₅H₄₅N₈O₉, a = 9.095(2) Å, b = 16.624(2) Å, c = 26.198(6) Å, β = 95.85(1)°, monoclinic, P2₁/c, Z = 4) obtained by reaction of 2,6-bis(1-octylbenzimidazol-2-yl)pyridine (obzimpy, 2 ) with Eu^III. Detailed photophysical studies of crystalline [Ln(mbzimpy)(NO₃)₃(CH₃OH)] and [Ln(obzimpy)(NO₃)₃] complexes (Ln = Eu, Gd, Tb, Lu) show that 1 and 2 display ¹ππ* and ³ππ* excited states very similar to those observed in 2,2′:6′,2″-terpyridine, leading to efficient ligand to Ln^III intramolecular energy transfer. Spectroscopic results show that an extremely efficient mbzimpy-to-Eu^III transfer occurs in [Ln(mbzimpy)(NO₃)₃(CH₃OH)] and in the case of Tb^III, a Tb^III-to-mbzimpy back transfer is also implied in the deactivation process. The origin of these peculiar effects and the influence of ligand design by going from mbzimpy to obzimpy are discussed. ¹H-NMR and luminescence data indicate that the structure found in the crystal is essentially maintained in solution.     

Etude Structurale de la forme basse Température de NH4Sn2F5 (Type γ)

Structural Study of the Low-temperature Modification of NH₄Sn₂F₅ (Type γ) NH₄Sn₂F₅, monoclinic, space group C2, Cm or C2/m, a = 7.361(4) Å, b = 12.752(6) Å, c = 10.492(5) Å, β = 103.5(7)°, V = 957,2(9) ų, Z = 6. MoKα (= 0.7107 Å) R = 0.036 for 476 observed reflexions. The structure is built from alternative layers [Sn? F] and [NH₄⁺]. Three kinds of fluorine have vacancy positions, that explains the bidimensional conduction in NH₄Sn₂F₅.