Kurt Alder: Aus sehr persönlicher Sicht

The reaction principle of the „Dien Synthesis”︁ developed and perfected by Diels and Alder has given rise to publications now numbered in their thousands. Every Chemist or chemistry student has learnt about the „Dien Synthesis”︁ through lectures and text books. Less known by the public are the Characteristics of the two great Researchers. Some of the typical qualities of Kurt Alder as a person are discribed and examinated     

Mit Chromatographie und Spektrometer: Forensische Toxikologie

Toxicology is a classic field of forensic medicine. Forensic toxicology includes the analysis of medical and illegal drugs and dangerous substances in order of courts, investigating authorities and hospitals. Fast and easy immunological techniques for assying drug familys or single drugs are available. The conventional methods for detection of drugs are generally instrumental procedures such as gas chromatography, high‐performance liquid chromatography and chromatography‐mass spectrometry.     

Synthese und Charakterisierung von 2‐O‐funktionalisierten Ethylrhodoximen und ‐cobaloximen

Synthesis and Characterization of 2‐O‐Functionalized Ethylrhodoximes and ‐cobaloximes 2‐Hydroxyethylrhodoxime and ‐cobaloxime complexes L—[M]—CH₂CH₂OH (M = Rh, L = PPh₃, 1 ; M = Co, L = py, 2 ; abbr.: L—[M] = [M(dmgH)₂L] (dmgH₂ = dimethylglyoxime, L = axial base) were obtained by reaction of L—[M]^— (prepared by reduction of L—[M]—Cl with NaBH₄ in methanolic KOH) with BrCH₂CH₂OH. H₂O—[Rh]^—, prepared by reduction of H[RhCl₂(dmgH)₂] with NaBH₄ in methanolic KOH, reacted with BrCH₂CH₂OH followed by addition of pyridine yielding py—[Rh]—CH₂CH₂OH ( 3 ). Complexes 1 and 3 were found to react with (Me₃Si)₂NH forming 2‐(trimethylsilyloxy)ethylrhodoximes L—[Rh]—CH₂CH₂OSiMe₃ (L = PPh₃, 4 ; L = py, 5 ). Treatment of complex 1 with acetic anhydride resulted in formation of the 2‐(acet oxy)ethyl complex Ph₃P—[Rh]—CH₂CH₂OAc ( 6 ). All complexes 1 — 6 were isolated in good yields (55—71 %). Their identities were confirmed by NMR spectroscopic investigations ( 1 — 6 : ¹H, ¹³C; 1 , 4 , 6 : ³¹P) and for [Rh(CH₂CH₂OH)(dmgH)₂(PPh₃)]·CHCl₃·1/2H₂O ( 1 ·CHCl₃·1/2H₂O) and py—[Rh]—CH₂CH₂OSiMe₃ ( 5 ) by X‐ray diffraction analyses, too. In both molecules the rhodium atoms are distorted octahedrally coordinated with triphenylphosphine and the organo ligands (CH₂CH₂OH and CH₂CH₂OSiMe₃, respectively) in mutual trans position. Solutions of 1 in dmf decomposed within several weeks yielding a hydroxyrhodoxime complex “Ph₃P—[Rh]—OH”. X‐ray diffraction analysis exhibited that crystals of this complex have the composition [{Rh(dmg)(dmgH) (H₂O)(PPh₃)}₂]·4dmf ( 7 ) consisting of centrosymmetrical dimers. The rhodium atom is distorted octahedrally coordinated. Axial ligands are PPh₃ and H₂O. One of the two dimethylglyoximato ligands is doubly deprotonated. Thus, only one intramolecular O—H···O hydrogen bridge (O···O 2.447(9)Å) is formed in the equatorial plane. The other two oxygen atoms of dmgH^— and dmg^2—, respectively, act as hydrogen acceptors each forming a strong (intermolecular) O···H′—O′ hydrogen bridge to the H′₂O′ ligand of the other molecule (O···O′ 2.58(2)/2.57(2)Å).     

Synthese und Kristallstrukturen von 1,1,3,3‐Tetramethylimidazolinium‐dichlorid und 1,1,4‐Trimethylpiperazinium‐chlorid

Synthesis and Crystal Structures of 1,1,3,3‐Tetramethylimidazolinium Dichloride and 1,1,4‐Trimethylpiperazinium Chloride Single crystals of 1,1,3,3‐tetramethylimidazolinium dichloride ( 1 ) and 1,1,4‐trimethylpiperazinium chloride ( 2 ) were obtained by reaction of CH₂Cl₂ with tetramethylethylenediamine (TMEDA) and NNN′N″N″‐pentamethyldiethylenetriamine (PMDETA), respectively. Both compounds are characterized by single crystal X‐ray diffraction and by IR spectroscopy. 1: [C₇H₁₈N₂]Cl₂, space group P2₁/c, Z = 4, lattice dimensions at 193(2) K: a = 821.97(11), b = 1130.38(8), c = 1143.08(13) pm, β = 100.348(15)°, R₁ = 0.0271. The C₇N₂ heterocyclic ring has envelope conformation like other salts with this dication. 2: [C₇H₁₇N₂]Cl, space group P2₁2₁2₁, Z = 4, lattice dimensions at 100(2) K: a = 1030.37(8), b = 1036.55(6), c = 831.39(4) pm, R₁ = 0.0180. Although the heterocyclic mono‐cation is without site symmetry in the crystal, its molecular symmetry is close to C_s, forming chair conformation of the C₄N₂ six‐membered ring.     

Quecksilber(II)‐chlorid‐ und ‐iodid‐Komplexe von Dithia‐ und Tetrathiakronenethern

Mercury(II) Chloride and Iodide Complexes of Dithia‐ and Tetrathiacrown Ethers The complexes [(HgCl₂)₂((ch)₂30S₄O₆)] ( 1 ), [HgCl₂(mn21S₂O₅)] ( 2 ), [HgCl₂(ch18S₂O₄)] ( 3 ) and [HgI(meb12S₂O₂)]₂[Hg₂I₆] ( 4 ) have been synthesized, characterized and their crystal structures were determined. In [(HgCl₂)₂((ch)₂30S₄O₆)] two HgCl₂ units are discretely bonded within the ligand cavity of the 30‐membered dichinoxaline‐tetrathia‐30‐crown‐10 ((ch)₂30S₄O₆) forming a binuclear complex. HgCl₂ forms 1 : 1 “in‐cavity” complexes with the 21‐membered maleonitrile‐dithia‐21‐crown‐7 (mn21S₂O₅) ligand and the 18‐membered chinoxaline‐dithia‐18‐crown‐6 (ch18S₂O₄) ligand, respectively. The 12‐membered 4‐methyl‐benzo‐dithia‐12‐crown‐4 (meb12S₂O₂) ligand gave with two equivalents HgI₂ the compound [HgI(meb12S₂O₂)]₂[Hg₂I₆]. In the cation [HgI(meb12S₂O₂)]⁺ meb12S₂O₂ forms with the cation HgI⁺ a half‐sandwich complex.