THE CRYSTAL AND MOLECULAR STRUCTURE OF RUBIDIUM BIS(PYRIDINE-2,6-DICARBOXYLATO)-CHROMATE(III)

Abstract

A three dimensional X-ray structural analysis of rubidium bis (pyridine-2,6-dicarboxylato)chromate(III), Rb[Cr(dipic)₂], has been carried out. The structure was refined by full matrix least-squares methods, using 713 observed independent reflections recorded at room temperature, to a conventional weighted R of 0.034. The crystals are tetragonal with a=b=6.950(3) Å, c=29.47(1) Å, space group 14 1/a and Z=4. The point group symmetry of the [Cr(dipic)₂]^? ion is S₄. The Cr–N and Cr–O distances (1.974(4) and 2.000(3) Å respectively) noticeably differ from the usual values in aminoacid chromium(III) complexes. The π bonding effect of the pyridine nitrogen atom corroborates the previous spectral studies on the sodium salt of this complex. The lability of [Cr(dipic)₂]^? in acid solution has been tentatively explained on the basis of the relatively severe strain within the complex ion.     

Oxorhenium(V) complexes containing bidentate N,O-donor ligands of the pyridyl type

The reaction of equimolar quantities of trans-[ReOCl₃(PPh₃)₂] and 8-hydroxyquinoline (Hhqn) in benzene led to the isolation of the six-coordinate complex [ReOCl₂(hqn)(PPh₃)] (1). With 2-pyridine-ethanol (Hhep) the compound [ReOCl₂(hep)(PPh₃)] (2) was obtained. Both hqn and hep ligands act as monoanionic bidentate N,O-donor chelates. Although the two complexes are very similar, there are some significant differences in certain bond distances and angles in them. Both complexes contain the nearly linear trans O=Re–O axis, with this angle equal to 160.9(2)° and 167.8(1)° in 1 and 2, respectively.     

新有机锡化合物的合成及分子内O→Sn配位键的离解与~1HNMR相关性的研究(英文)

用具有抗癌活性的(Z) - 1-[2 - (二卤化苯基锡基乙烯基)] -环辛醇与含氮的双齿配体作用,合成了一系列新的有机锡络合物,通过IR,1HNMR,元素分析和摩尔电导值的测定对其结构、性质进行了表征,特别对有机锡化合物分子内O→Sn配位键的离解与配体中烯基质子化学位移(1HNMR)的相关性进行了讨论     

Monomeric, dimeric and polymeric [Cp2MoH2] complexes with Ag---S bonds

The reaction of [Cp₂MoH₂] and AgBF₄ with the dithio ligands Na(S₂CPh) and K(S₂COⁱPr) afforded the complexes [(Cp₂MoH₂AgS₂CPh)₂] (1) and [(Cp₂MoH₂AgS₂COⁱPr)₂] (2). Using the monothio ligands Na(SC(O)Ph), K(SC(O)CH₃) and Na(S(NHPh)C=C(CN)₂) the complexes [(Cp₂MoH₂AgSC(O)Ph)₂] (3), [((Cp₂MoH₂)₂(AgSC(O)CH₃)₃)_n] (4) and [(Cp₂MoH₂)₂AgS(NHPh)C=C(CN)₂] (6) were formed. The reaction of thiobenzamide and [(Cp₂MoH₂)₂AgCl] gave the complex [(Cp₂MoH₂Ag(Cl)S(NH₂)CPh)₂] (5). Complexes 1 and 2 have a dimeric structure with the two dithio ligands bridging the two silver atoms. Complex 3 is also a dimer, however, the monothio ligands are coordinated with their single sulphur atoms to the silver atoms. In the polymer 4 the thioacetate ligand has the same bonding mode as in 3. The three-dimensional structure of 4 is built-up of parallel strings. In the dimer 5 the thiobenzamide ligands bind with the sulphur atom to a silver atom each. Complex 6 has a monomeric structure in which the silver atom is coordinated to two [Cp₂MoH₂] ligands and to the sulphur atom of the S(NHPh)C=C(CN)₂ ligand. Compounds 1–6 were characterised analytically and spectroscopically and the structures were determined by single crystal X-ray analyses.     

Thermal Analysis in Structural Characterization of Hydrazone Ligands and Their Complexes

Results of our research on synthesis and characterization of complexes with acylhydrazone derivatives are described in this review paper. Structural characterization of newly synthesized complexes by thermal analysis (TG, DTA, DSC) is particularly emphasized in this paper. Thermal analysis enabled us to study not only structural changes of substances during thermal treatment, but also the mode of coordination and degree of deprotonation of acylhydrazones, as well as geometry of the coordination sphere of complexes, the structure of which had not been determined by X-ray analysis. Topics in this paper are as follows: complexes of dioxomolybdenum(VI) with tridentate hydrazones, usnic acid derivatives and their Cu(II) complexes, as well as transition metal complexes with 2,6-diacetylpyridine bis(hydrazones). This revised version was published online in July 2006 with corrections to the Cover Date.     

Chiral 2-(2-hydroxyaryl)alcohols (HAROLs) with a 1,4-diol scaffold as a new family of ligands and organocatalysts

Efficient and modular syntheses of chiral 2-(2-hydroxyaryl)alcohols (HAROLs), novel 1,4-diols carrying one phenolic and one alcohol hydroxyl group, have been developed which led to generation of a small library of structurally diverse HAROLs in enantiomerically pure form. Of the different HAROLs examined, a HAROL based on the indan backbone exhibited the highest activity and enantioselectivity in the 1,2-addition of certain organometallic compounds to aldehydes in the presence of Ti(OⁱPr)₄ (up to 97% y, 88% ee) and performed as a hydrogen-bond donor organocatalyst in the Morita-Baylis-Hillman reaction, promoted by trialkylphosphines.     

Synthesis and Crystal Structure of (4R, 5R)(5-Hydroxymethyl-2,2-dimethyl- [1,3]dioxolan-4-yl)-bis-(4-methoxy-phenyl)-methanol

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅα ,α ,α′,α′ ｔｅｔｒａａｒｙｌ 1 ,3 ｄｉｏｘｏｌａｎｅ 4,5 ｄｉｍｅｔｈａｎｏｌｓ (ＴＡＤＤＯＬＳ)ｄｉｏｌｓｗｈｉｃｈａｒｅｒｅａｄｉｌｙａｖａｉｌａｂｌｅｆｒｏｍａｌｋｙｌｔａｒｔｒａｔｅｓ ,ｈａｖｅｂｅｅｎｗｉｄｅｌｙｕｓｅｄａｓｃｈｉｒａｌｌｉｇａｎｄｓｉｎｅｎａｎｔｉｏｓｅｌｅｃｔｉｖｅａｄｄｉｔｉｏｎｒｅａｃｔｉｏｎｓｏｆｃａｒｂｏｎ ｃｅｎｔｅｒｅｄｎｕｃｌｅｏｐｈｉｌｅｓｔｏａｌｄｅｈｙ ｄｅｓ[1 ] ,ｉｎ [2 +2 ]ｃｙｃｌｏａｄｄｉｔｉｏｎｓ[2 ] …     

Sulfur Oxides as Ligands in Coordination Compounds

Donor molecules undergo dramatic changes in their chemical properties on coordination to a transition-metal atom. Highly reactive species can be trapped and studied as ligands. Conversely, stable compounds can be activated to undergo novel reactions. Sulfur dioxide complexes have generally been studied from a structural viewpoint, their reactivity having been somewhat neglected. The unstable sulfur oxides SO, S₂O, and S₂O₂ are still often regarded as laboratory curiosities. Their successful stabilization in transition-metal complexes has now made them accessible to detailed study, in the course of which many relationships to the chemistry of SO₂ complexes have become apparent.     

Determination of stability constants of some substituted 4-pyrazolone dyes containingo-methoxy,o-carboxy,ando-nitro groups with trivalent lanthanide ions

The relative stabilities of the metal derivatives of hydrazo pyrazolone dyes containingortho -OCH₃, -COOH, and -NO₂ groups have been measured potentiometrically in 75% (v/v) dioxane—water mixture at 30 °C and <0.1 ionic strength. The stability constant of their 1:1 and 1:2 chelates with twelve trivalent lanthanide ionsLn(III) have also been determined. The effects of substituents on the hydrazo-moiety of the ligand on the equilibria are discussed. The affinity of different ligands for complexation with lanthanide ions reaches its highest value withortho-carboxyphenylhydrazopyrazolone. The data were correlated and the results were used to explain the stabilization of such chelates by dative -bonding betweenLn(III) and the ligand.

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Bestimmung der Stabilitätskonstanten einigero-Methoxy-,o-Carboxy undo-Nitro-substituierter 4-Pyrazolon-Farbstoffe mit trivalenten Lanthanidenionen

Zusammenfassung Es wurden die relativen Stabilitäten der Metallderivate von Hydrazopyrazolon-Farbstoffen mitortho-OMe, -COOH und -NO₂ potentiometrisch in 75% (v/v) Dioxan—Wasser bei 30 °C und einer Ionenstärke <0.1 bestimmt. Die Stabilitätskonstanten der 1:1 und 1:2 Chelate mit zwölf trivalenten LanthanidenionenLn(III) wurden ebenfalls gemessen. Die Substituenteneffekte werden diskutiert. Dabei zeigeno-Carboxyphenylhydrazopyrazolone die höchste Affinität zu Lanthanidenionen. Die Daten werden miteinander korreliert und die Resultate auf der Basis einer dativen -Bindung zwischenLn(III)-Ion und dem Liganden diskutiert.