Preparation of cis- and trans-[OsCl2(Me2SO)4], and X-Ray Crystal Structures of the All-S-Bound Isomers

1998 ◽  
Vol 51 (9) ◽  
pp. 807 ◽  
Author(s):  
Andrew M. McDonagh ◽  
Mark G. Humphrey ◽  
David C. R. Hockless
Keyword(s):  
Structural Study ◽  
Trans Isomers ◽  
Triclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
Group I ◽  
Cis And Trans Isomers ◽  
Cis And Trans ◽  
Cis Isomer

Efficient syntheses of the cis and trans isomers of [OsCl2(Me2SO)4] are reported. While a structural study of thetrans isomer confirms the spectroscopically assigned all-S-bound Me2SO configuration, a crystallographic determination of the cis isomer reveals a previously unheralded all-S-bound Me2SO geometry, in contrast to the spectroscopically inferred configuration predominant in solution which has one O-bound ligand. Fortrans-[OsCl2(Me2SO)4], crystals are tetragonal, space group I 4/m, with a 9·092(2), c 11·212(3) Å, Z 2, 566 unique reflections (34 parameters), converging at R 0·026 and Rw 0·032. For cis-[OsCl2(Me2SO)4], crystals are triclinic, space group P-1, with a 8·193(2), b 8·941(3), c 13·837(3) Å, α 79·77(2), β 79·91(2), γ 65·03(2)°, Z 2, 4152 unique reflections (173 parameters), converging at R 0·021 and Rw 0·018.

Komplexbildung und Ligandeneigenschaften der Chlormethylchlorphosphane R(Cl)P-CH2-Cl - Molekülstruktur von trans-Cl2Pd[tBu(Cl)P-CH2-Cl]2 / Coordination Chemistry and Ligand Properties of Chloromethylchlorophosphines R(Cl)P-CH2 -Cl - Molecular Structure of trans-Cl2Pd[tBu(Cl)P-CH2 -Cl]2

1997 ◽  
Vol 52 (9) ◽  
pp. 1103-1113 ◽  
Author(s):  
Peter Machnitzki ◽  
Othmar Stelzer ◽  
Claudia Landgrafe
Keyword(s):  
Heterogeneous Reaction ◽  
Trans Isomers ◽  
Triclinic Space Group ◽  
X Ray ◽  
H Nmr ◽  
Cis And Trans Isomers ◽  
Square Planar ◽  
High Yields ◽  
Cis And Trans ◽  
Trans Structure

Reaction of the chloromethylchlorophosphines R(Cl)P-CH2-Cl (R = Cl, tBu, C6H11, NEt2, NPh2) (L) with C7H8Mo(CO)4 or (CO)5W(Py), (CO)6W and (CO5W(THF) yields the complexes cis-Mo(CO)4L2(2a - 2e) or (CO)5 WL (3a - 3c), respectively, in high yields. The palladium(II) complexes PdCl2L2 (4a - 4c) are obtained on treatment of 1a, 1b and 1e with 1,5-cyclooctadiene palladium(II) chloride or anhydrous palladium(II) chloride in a homogeneous or heterogeneous reaction, respectively. 4a - 4c are formed as a mixture of cis- and trans-isomers. The 13C {1H} NMR and 1H NMR spectra of 2a - 4c have been analysed, the trans-structure of 4c could be assigned to the predominant isomer. The X-ray structural analysis of 4c (triclinic, space group Pl̅) reveals a trans-square planar coordination at palladium with an antiperiplanar arrangement of the bulky tBu substituents at the phosphorus atoms. Electronic (ƩXiMo) and steric ligand parameters (θ) are given for the chloromethylchlorophosphines R(Cl)P-CH2-Cl (R = Cl, tBu, C6H11, NEt2, NPh2).

Mono- and dinuclear palladium complexes containing 2-pyridylphosphine ligands, including X-ray characterization of Pd2I2(µ-PPh2py)2 and a dimethylacetylenedicarboxylate A-frame complex Pd2Cl2(µ-Ppy3)2(µ-MeO2C•C=C•CO2Me); py = 2-pyridyl

1992 ◽  
Vol 70 (3) ◽  
pp. 751-762 ◽  
Author(s):  
Yun Xie ◽  
Chung-Li Lee ◽  
Yeping Yang ◽  
Steven J. Rettig ◽  
Brian R. James
Keyword(s):  
Palladium Complexes ◽  
Monoclinic Space Group ◽  
Trans Isomers ◽  
Space Group ◽  
X Ray ◽  
Mononuclear Complexes ◽  
Cis And Trans Isomers ◽  
Pyridylphosphine Ligands ◽  
Cis And Trans

Dibromo- and diiodo[(2-pyridyl)phosphine]palladium(II) complexes are prepared by metathesis of cis-PdCl2(PPh3−npyn)2 species (n = 1–3) using the appropriate sodium halide; py = 2-pyridyl. NMR spectroscopy, particularly,13C{1H}, is used to distinguish cis and trans isomers. The dinuclear complexes Pd2X2(μ-PPh3−npyn)2, X = halide, are synthesized via a conproportionation reaction using PdX2(PPh3−npyn)2 and Pd2(dba)3; dba = dibenzylideneacetone. Both Pd2l2(μ-PPh2py)2 and a dimethylacetylenedicarboxylate A-frame complex Pd2Cl2(μ-Ppy3)2(μ-MeO2C•C=C•CO2Me) are characterized crystallographically as head-to-tail isomers. The former crystallizes in the monoclinic space group C2/c with a = 30.992(3), b = 18.764(1), c = 13.100(1) Å, β = 100.676(5)°, and Z = 8; the data were refined to R = 0.035 for 5874 reflections with I ≥ 3σ(I). The A-frame compound is triclinic of space group [Formula: see text] with a = 13.545(2), b = 15.064(2), c = 11.991(2) Å, α = 111.56(1), β = 95.36(1), γ = 97.63(1)°, and Z = 2; R = 0.033 from 7128 reflections with I ≥ 3σ(I). The Pd2X2(μ-PPhpy2)2 complexes exist as a mixture of diastereomers because of chirality induced at the phosphorus atoms. The Pd2X2(μ-Ppy3)2 complexes in water generate the [Pd2(H2O)2(μ-Ppy3)2]2+ dication, which is isolated as various salts. The mononuclear complexes in water generate aquo and hydroxo species. Keywords: dimethylacetylenedicarboxylate adducts, palladium complexes (dinuclear), pyridylphosphines.

Reactivities of Piperazine-2,5-diones in Radical Bromination Reactions

1996 ◽  
Vol 49 (11) ◽  
pp. 1229 ◽  
Author(s):  
CLL Chai ◽  
DCR Hockless ◽  
AR King
Keyword(s):  
Crystal Structure ◽  
Amino Acid ◽  
Chemical Reactivity ◽  
Trans Isomers ◽  
Radical Bromination ◽  
Conformational Effects ◽  
Cis And Trans Isomers ◽  
The Difference ◽  
Cis And Trans

The reactivities of various N,N'- diacetylated piperazine-2,5-diones towards radical bromination reactions are reported. The studies show that glycyl centres of piperazine-2,5-diones are more reactive towards radical bromination reactions compared to α-substituted amino acid centres. In addition, large differences in reactivities were observed for the cis and trans isomers of N,N'-diacetylated alanine anhydride. Single-crystal structure determination of each isomer revealed that conformational effects may account for the difference in chemical reactivity.

Quantitative Determination and Confirmation of Low Levels of Diethylstilbestrol in Feeds

1972 ◽  
Vol 55 (6) ◽  
pp. 1345-1353
Author(s):  
Marshall T Jeffus ◽  
Charles T Kenner
Keyword(s):  
Thin Layer ◽  
Quantitative Determination ◽  
Official Method ◽  
Trans Isomers ◽  
Cis And Trans Isomers ◽  
Before And After ◽  
Chromatographic Procedure ◽  
Low Levels ◽  
Cis And Trans

Abstract A method for the determination of diethylstibestrol in feeds, which is based on official first action method 38.048–38.051, is proposed. Interfering feed extractives are removed by using a tripotassium phosphate-Celite column prior to measurement at 415 nm before and after irradiation. Recoveries of equilibrated standards added to Soxhlet extracts of several samples averaged 94.3% compared to 86.3% by the official method. The background absorbance at 415 nm obtained by using the proposed method was approximately 6% of the background by the official method for solutions containing equivalent amounts of sample. A thin layer chromatographic method is also included for the confirmation and identification of the cis and trans isomers of the drug. The proposed method has been found satisfactory for the quantitative determination of 0.55–44 ppm diethylstilbestrol and the thin layer chromatographic procedure can detect as little as 0.07 ppm.

Gold complexes of ditelluridoimidodiphosphinate ligands — Reversible oxidation of Au(I) to Au(III) via insertion of gold into a phosphorus–tellurium bond

2009 ◽  
Vol 87 (1) ◽  
pp. 39-46 ◽  
Author(s):  
Dana J Eisler ◽  
Stuart D Robertson ◽  
Tristram Chivers
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Trans Isomers ◽  
Nmr Studies ◽  
Gold Complexes ◽  
X Ray ◽  
Cis And Trans Isomers ◽  
Cis And Trans ◽  
Insertion Process

The reaction of (THT)AuCl with (TMEDA)Na[N(TePR2)2] (R = Ph, i-Pr, t-Bu) produces a series of gold (III) complexes of the type [{R2PNP(Te)R2}Au(µ-Te)]2 (4a, R = i-Pr; 4b, R = Ph; 4c, R = t-Bu) rather than the expected homoleptic Au(I) complexes of the ditelluridoimidodiphosphinate ligands. A combination of solution- and solid-state NMR studies shows that both cis and trans isomers of 4a–4c are formed in these reactions. X-ray structural determinations of the trans isomers of 4a–4c reveal a centrosymmetric arrangement with a central four-membered Au2Te2 ring formed by the formal insertion of gold into a P–Te bond; this insertion process was shown to be reversible upon addition of PPh3 to 4a to give the monomeric gold(I) complex Ph3PAu[N{TeP(i-Pr)2}2]. The X-ray structure of cis-4b is also described.Key words: gold, tellurium, redox, X-ray structures, imidodiphosphinate.

Sur la réduction de polyméthyldihydro-2,3 phénalènones-1 par l'hydrure de lithium et d'aluminium

1974 ◽  
Vol 52 (17) ◽  
pp. 3106-3112 ◽  
Author(s):  
E. Costakis ◽  
P. Canonne ◽  
R. St-Jean
Keyword(s):  
Trans Isomer ◽  
Lithium Aluminum Hydride ◽  
Aluminum Hydride ◽  
Considerable Extent ◽  
Lithium Aluminum ◽  
Trans Isomers ◽  
Cis And Trans Isomers ◽  
Cis And Trans ◽  
Cis Isomer ◽  
Steric Constraints

The reduction of some polymethyl-2,3-dihydro phenalen-1-ones by lithium aluminum hydride yields a mixture of cis and trans isomers; the percentage of each isomer depends to a considerable extent on its structure. Indeed, for some, the trans isomer predominates while for others the cis isomer is obtained in up to 88% yields. Moreover, in the particular case in which the trans isomer is formed in low yields, its preferred conformation is trans diaxial.The steric constraints which render certain transition states unfavourable during the attack of the hydride are discussed with the aid of spectroscopic data on the alcohols obtained. [Journal translation]

A Quantitative UV Chemometric Model for the Determination of Zeaxanthin Cis and Trans Isomers

2011 ◽  
Author(s):  
James P. Barren ◽  
Norman G. Rushing ◽  
Anthony P. van den Hombergh ◽  
Julie C. Londry
Keyword(s):  
Trans Isomers ◽  
Cis And Trans Isomers ◽  
Cis And Trans

Synthesis and characterization of cis and trans isomers of [NiL2(NCS)2] [L=1-(2-aminoethyl)pyrrolidine]: X-ray single-crystal structures

Polyhedron ◽  
2000 ◽  
Vol 19 (15) ◽  
pp. 1803-1807 ◽  
Author(s):  
Inamur Rahaman Laskar ◽  
Tapas Kumar Maji ◽  
Siddhartha Chaudhuri ◽  
Ashutosh Ghosh ◽  
Nirmalendu Ray Chaudhuri
Keyword(s):  
Single Crystal ◽  
Crystal Structures ◽  
Synthesis And Characterization ◽  
Trans Isomers ◽  
X Ray ◽  
Single Crystal Structures ◽  
Cis And Trans Isomers ◽  
Cis And Trans
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