Synthesis and molecular structure of 3-(2-aryl-2-oxoethyl)-3-methoxy-2-oxo-2,3-dihydroimidazo-[1,2-<Emphasis Type="Italic">a</Emphasis>]pyridine hydrochlorides

Reactions between 2-pyridylamides of Z-4-aryl-2-hydroxy-4-oxobut-2-enoic acids with diazomethane have been used to synthesize 3-(2-aryl-2-oxoethyl)-3-methoxy-2-oxo-2,3-dihydroimidazo[1,2-a]pyridines, which form hydrochlorides with hydrochloric acid. The structure of the latter has been demonstrated by XRD for the hydrochloride of 3-methoxy-2-oxo-3-(2-phenyl-2-oxoethyl)-2,3-dihydroimidazo[1,2-a]pyridine. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 464–468, 2007.     

Electrochemistry and complexation of Josiphos ligands

The oxidative electrochemistry of 11 chiral bis-phosphinoferrocene ligands, all within the Josiphos class of ligands, was examined in methylene chloride. The oxidation of these ligands displays multiple waves of varying chemical reversibility. Palladium(II) and platinum(II) complexes with the general formula [MCl₂(P-P)] (M = Pd or Pt; P-P = Josiphos) were prepared, characterized by NMR and cyclic voltammetry. The electrochemistry simplifies greatly upon coordination of the Josiphos ligands. The X-ray structures of a palladium(II) and platinum(II) complex of the same Josiphos ligand are reported.     

Chalkogenid-Disilicate der Lanthanoide vom Typ M4X3[Si2O7] (M  Ce?Er; X  S,Se)

M₄X₃[Si₂O₇]-Type Lanthanide Chalcogenide Disilicates (M ? Ce? Er; X ? S, Se) Attempts to produce single crystals of MSe₂ (or MSe^2?X) by vapour phase transport with iodine or the oxidation of MCl₂ (or MClH) with sulfur in the presence of NaCl in sealed evacuated quartz containers often yielded well-grown single crystals with the composition M₄X₃[Si₂O₇] (M ? pr, Sm, Gd, X ? Se, and M ? Nd, Er, X ? S) as by-products. The crystal structures (tetragonal, 14₁/amd (no. 141)), Z = 8, contain two crystallographically independent M₃₊ Cations that are interconnected by chalcogenide (X_2?) and disilicate anions ([Si₂O₇]^6?). (M1)³⁺ is surrounded by eight (five X^2? and three terminal O_2? of the disilicate group), (M2)³⁺ by nine (three X^2? and six terminal O^2? of the [Si₂O₇]_6? anion) chalcogenide anions. The disilicate anion itself exhibits the eclipsed conformation with non-linear Si? O? Si bridges (angles: 128 – 133°).     

(A19N7)[In4]2 (A = Ca,Sr) and (Ca4N)[In2]: Synthesis,Crystal Structures,Physical Properties,and Chemical Bonding

Single phase powders of (A₁₉N₇)[In₄]₂ (A = Ca, Sr) and (Ca₄N)[In₂] were prepared by reaction of melt beads of the metallic components with nitrogen. The crystal structure of (Ca₁₉N₇)[In₄]₂ was refined based on neutron and X‐ray powder diffraction data. The crystal structure of (Sr₁₉N₇)[In₄]₂ was solved from the X‐ray powder pattern. The structure refinements in combination with results from chemical analyses ascertain the compositions. The compounds (A₁₉N₇)[In₄]₂ (A = Ca, Sr) are isotypes of (Ca₁₉N₇)[Ag₄]₂; (Ca₁₉N₇)[In₄]₂ is probably identical to the earlier reported (Ca_18.5N₇)[In₄]₂. The crystal structure of the isotypes (A₁₉N₇)[In₄]₂ (A = Ca, Sr; cubic, , Ca: a = 1471.65(3) pm; Sr: a = 1561.0(1) pm) contains isolated [In₄] tetrahedra embedded in a framework of edge‐ and vertex‐sharing (A₆N) octahedra. Six of these octahedra are condensed by edge‐sharing around one central A²⁺ ion to form “superoctahedra” (A₁₉N₆) which are connected three‐dimensionally via further octahedra by corner‐sharing. The crystal structure of (Ca₄N)[In₂] (tetragonal, I4₁/amd, a = 491.14(4) pm, c = 2907.7(3) pm) consists of alternating layers of perovskite type slabs of vertex‐sharing octahedra (Ca₂Ca_4/2N) and parallel arranged infinite zigzag chains equation/tex2gif-stack-1.gif[In₂]. In the sense of Zintl‐type counting the compounds (A²⁺)₁₉(N^3?)₇[(In^2.125?)₄]₂ present an electron excess, (Ca²⁺)₄(N^3?)[(In^2.5?)₂] is electron deficient. Metallic properties are supported by electrical resistivity and magnetic susceptibility measurements. The analysis of the electronic structures gives evidence for the existence of homoatomic interactions In–In and significant heteroatomic metal–metal interactions Ca–In which favor the deviations of the title compounds from the (8 – N) rule.     

Chloride substitution of [CpRu(dppf)Cl] with sulfur-containing ligands

The reactions of CpRu(dppf)Cl (1) with the sulfur-containing ligands, thiophenol HSPh, 2-mercaptopyridine C₅H₄N(SH), thiourea SC(NH₂)₂, vinylene trithiocarbonate SCS(CH)₂S and ethylene trithiocarbonate SCS(CH₂)₂S, yielded chloro-substituted derivatives, viz. the mono-ruthenium(II) complexes CpRu(dppf)(SPh) (2), [CpRu(dppf)(SC₅H₄NH)]BPh₄ (3)BPh₄, [CpRu(dppf)(SC(NH₂)₂]PF₆ (4)PF₆, [CpRu(dppf)(SCS(CH)₂S)]Cl (5)Cl and [CpRu(dppf)(SCS(CH₂)₂S)]Cl (6)Cl, respectively. Treatment of 1 with AuCl(SMe₂) in the presence of NH₄PF₆ gave [(CpRu(dppf)(SMe₂)]PF₆ (7)PF₆. The reaction of 1 or 6 with SnCl₂ resulted in cleavage of chloro and dithiocarbonate ligands, respectively, to give CpRu(dppf)SnCl₃ (8). All complexes were spectroscopically characterized and the structures of 2 and cationic complexes 4-7 were determined by single-crystal diffraction analyses.     

Binukleare Nickel(0)-Alkin-Koordinationsverbindungen – Zusammenhang zwischen Ligandperipherie und supramolekularer Struktur

Binuclear Nickel(0) Alkyne Coordination Compounds – Correlation between Ligand Periphery and Supramolecular Structure Reaction of Ni(cdt: 1,5,9-cyclododecatriene) with functionalized alkynes and subsequent reaction with ethylenediamines gives binuclear compounds of the type (diamine)Ni(μ-alkyne)Ni(alkyne). Compounds with alkyne-diols (N?N)Ni₂(HOR¹R²C? C?C? CR¹R²OH)₂ show supramolecular structures in which two identical intramolecular and one intermolecular hydrogen bonds are realized. 1 and 2 (chelate ligand in each case N,N,N′,N′-tetramethylethylenediamine, TMEDA, in 1 R¹ = R² = Me, in 2 R¹ = R² = Et) polymer-like chains are built up by connecting the binuclear units. Via two intermolecular hydrogen bonds per organometallic unit in 1 and via one intermoleculare hydrogen bond in 2 the chains are connected to give double chains. By substitution of one methyl group of TMEDA by hydrogen ( 3 : R¹ = R² = Me) a polymerlike network is produced by connecting the polymer-like chains. In compound 4 in which one of the methyl groups of TMEDA is substituted by CH₂CH₂NMe₂ the polymer-like chains remain unconnected. In 5 (diamine = TMEDA, alkyne = (CH₃)₃C? C?C? CMe₂OH) one intermolecular hydrogen bond per organometallic unit is observed forming again polymer-like chains that are independent of each other.     

Cu(II) in liquid ammonia: an approach by hybrid quantum-mechanical/molecular-mechanical molecular dynamics simulation.

To investigate the solvation structure of the Cu(II) ion in liquid ammonia, ab initio quantum-mechanical/molecular-mechanical (QM/MM) molecular dynamics (MD) simulations were carried out at Hartree Fock (HF) and hybrid density functional theory (B3 LYP) levels. A sixfold-coordinated species was found to be predominant in the HF case whereas five- and sixfold-coordinated complexes were obtained in a ratio 2:1 from the B3 LYP simulation. In contrast to hydrated Cu(II), which exhibits a typical Jahn-Teller distortion, the geometrical arrangement of ligand molecules in the case of ammonia can be described as a [2 + 4] ([2 + 3]) configuration with 4 (3) elongated copper-nitrogen bonds. First shell solvent exchange reactions at picosecond rate took place in both HF and B3 LYP simulations, again in contrast to the more stable sixfold-coordinated hydrate. NH3 ligands apparently lead to strongly accelerated dynamics of the Cu(II) solvate due to the "inverse" [2 + 4] structure with its larger number of elongated copper-ligand bonds. Several dynamical properties, such as mean ligand residence times or ion-ligand stretching frequencies, prove the high lability of the solvated complex.     

Darstellung und Kristallstruktur von Ethylendiammonium-Selenostannaten(IV) sowie von [2 SnSe2 · en]∞

Preparation and Crystal Structure of Ethylenediammonium Selenostannates(IV) and [2 SnSe₂ · en]∞ The selenostannates(IV) [enH₂]₂[Sn₂Se₆] · en 1 and [enH₂][Sn₃Se₇] · 1/2en 2 have been prepared by the methanolothermal reaction of SnSe₂ with ethylenediamine (en) (160°C, 13 bar) in the presence of respectively Se or BaSe. The [Sn₂Se₆]^4? anion in 1 consists of two edgebridged SnSe₄ tetrahedra and displays crystallographic C_i symmetry. The crystal structure of 2 contains polyselenostannate(IV) sheet anions [Sn₂Se₇²], for which the basic elements are trigonal SnSe₅ bipyramids. Each of the three symmetry independent Sn atoms is linked to the other Sn atoms via Sn? Se? Sn bridges leading to the formation of Sn₃Se₁₀ units. Methanolothermal reaction of SnSe₂ with en alone yields the edge-bridged chain structure [2 SnSe₂ en]∞ 3 , in which each of the Sn atoms is bonded to four Se atoms. Every second Sn atom is also coordinated by an en molecule and displays, therefore, an octahedral geometry. The remaining Sn atoms are coordinated tetrahedrally by Se atoms.     

Polysulfonylamine. CLXIII [1] Kristallstrukturen von Metall‐di(methansulfonyl)amiden. 12 [1] Das orthorhombische Doppelsalz Na2Cs2[(CH3SO2)2N]4·3H2O: Ein dreidimensionales Koordinationspolymer aus (Caesium‐Anion‐Wasser)‐Schichten und intercalierten Natriumionen

Polysulfonylamines. CLXIII. Crystal Structures of Metal Di(methanesulfonyl)amides. 12. The Orthorhombic Double Salt Na₂Cs₂[(CH₃SO₂)₂N]₄·3H₂O: A Three‐Dimensional Coordination Polymer Built up from Cesium‐Anion‐Water Layers and Intercalated Sodium Ions The packing arrangement of the three‐dimensional coordination polymer Na₂Cs₂[(MeSO₂)₂N]₄·3H₂O (orthorhombic, space group Pna2₁, Z′ = 1) is in some respects similar to that of the previously reported sodium‐potassium double salt Na₂K₂[(MeSO₂)₂N]₄·4H₂O (tetragonal, P4₃2₁2, Z′ = 1/2). In the present structure, four multidentately coordinating independent anions, three independent aquo ligands and two types of cesium cation form monolayer substructures that are associated in pairs to form double layers via a Cs(1)—H₂O—Cs(2) motif, thus conferring upon each Cs⁺ an irregular O₈N₂ environment drawn from two N, O‐chelating anions, two O, O‐chelating anions and two water molecules. Half of the sodium ions occupy pseudo‐inversion centres situated between the double layers and have an octahedral O₆ coordination built up from four anions and two water molecules, whereas the remaining Na⁺ are intercalated within the double layers in a square‐pyramidal and pseudo‐C₂ symmetric O₅ environment provided by four anions and the water molecule of the Cs—H₂O—Cs motif. The net effect is that each of the four independent anions forms bonds to two Cs⁺ and two Na⁺, two independent water molecules are involved in Cs—H₂O—Na motifs, and the third water molecule acts as a μ₃‐bridging ligand for two Cs⁺ and one Na⁺. The crystal cohesion is reinforced by a three‐dimensional network of conventional O—H···O=S and weak C—H···O=S/N hydrogen bonds.     

Ultra‐wideline 27Al NMR Investigation of Three‐ and Five‐Coordinate Aluminum Environments

Ultra‐wideline ²⁷Al NMR experiments are conducted on coordination compounds with ²⁷Al nuclei possessing immense quadrupolar interactions that result from exceptionally nonspherical coordination environments. NMR spectra are acquired using a methodology involving frequency‐stepped, piecewise acquisition of NMR spectra with Hahn‐echo or quadrupolar Carr–Purcell Meiboom–Gill (QCPMG) pulse sequences, which is applicable to any half‐integer quadrupolar nucleus with extremely broad NMR powder patterns. Despite the large breadth of these central transition powder patterns, ranging from 250 to 700 kHz, the total experimental times are an order of magnitude less than previously reported experiments on analogous complexes with smaller quadrupolar interactions. The complexes examined feature three‐ or five‐coordinate aluminum sites: trismesitylaluminum (AlMes₃), tris(bis(trimethylsilyl)amino)aluminum (Al(NTMS₂)₃), bis[dimethyl tetrahydrofurfuryloxide aluminum] ([Me₂‐Al(μ‐OTHF)]₂), and bis[diethyl tetrahydrofurfuryloxide aluminum] ([Et₂‐Al(μ‐OTHF)]₂). We report some of the largest ²⁷Al quadrupolar coupling constants measured to date, with values of C_Q(²⁷Al) of 48.2(1), 36.3(1), 19.9(1), and 19.6(2) MHz for AlMes₃ , Al(NTMS₂)₃ , [Me₂‐Al(μ‐OTHF)]₂ , and [Et₂‐Al(μ‐OTHF)]₂ , respectively. X‐ray crystallographic data and theoretical (Hartree–Fock and DFT) calculations of ²⁷Al electric field gradient (EFG) tensors are utilized to examine the relationships between the quadrupolar interactions and molecular structure; in particular, the origin of the immense quadrupolar interaction in the three‐coordinate species is studied via analyses of molecular orbitals.