Mass spectrometry of onium compounds—II. Carnitine and O-acyl derivatives

Carnitine and its O-acyl derivatives undergo two major pyrolytic reactions in the mass spectrometer. Firstly elimination of water from carnitine or acid from acylcarnitine takes place followed by intramolecular displacement and formation of crotonyl lactone and trimethylamine. Secondly intramolecular displacement occurs with formation of a substituted γ-lactone and trimethylamine. For the lower acid derivatives only the elimination pathway is important. For carnitine and higher derivatives both processes are important. The electron induced fragmentations of the major pyrolysis products are relatively simple. The most important pathways for the major components are discussed. The pyrolytic composition and mode of fragmentation are characteristic and can be used for identification purposes.     

Molecular Structure of Phosphinidene Phosphates

Abstract

Alkalimetal diphenylphosphinites degrade (Ph-P)₅ and P₄ to give anions containing a chain of 2, 3 or 4 four- and two-coordinated phosphorus atoms. Representatives of the chain with two four-coordinated and one two-coordinated P atoms became first available from the aminolysis of tris (phosphoryl)phosphides¹.     

Photocontrolled Release of Chemicals from Nano‐ and Microparticle Containers

A benzoin‐derived diol linker was synthesized and used to generate biocompatible polyesters that can be fully decomposed on demand upon UV irradiation. Extensive structural optimization of the linker unit was performed to enable the defined encapsulation of diverse organic compounds in the polymeric structures and allow for a well‐controllable polymer cleavage process. Selective tracking of the release kinetics of encapsulated model compounds from the polymeric nano‐ and microparticle containers was performed by confocal laser scanning microscopy in a proof‐of‐principle study. The physicochemical properties of the incorporated and released model compounds ranged from fully hydrophilic to fully hydrophobic. The demonstrated biocompatibility of the utilized polyesters and degradation products enables their use in advanced applications, for example, for the smart packaging of UV‐sensitive pharmaceuticals, nutritional components, or even in the area of spatially selective self‐healing processes.     

Ferrocenyl‐Functionalised Molybdenum Imido Complexes: An Approach to Redox‐Tunable Olefin Polymerisation Catalysts

[(FcdippN)₂MoCl₂(DME)] ( 1 ) was used as starting material for the synthesis of the novel ferrocenyl‐functionalised complexes [(FcdippN)₂Mo(CH₂CMe₂Ph)₂] ( 2 ), [(FcdippN)₂Mo(OTf)₂(DME)] ( 3 ), and [(FcdippN)Mo(CHCMe₂Ph)(O^tBu)₂] ( 4 ) (Fcdipp = 4‐ferrocenyl‐2,6‐diisopropylphenyl). The crystal structure of 2 was determined. Electrochemical investigations by cyclic voltammetry suggest a communication of the ferrocenyl unit and the molybdenum centre in these compounds. The monoalkylation of [(DippN)₂MoCl₂(DME)] ( 5 ) to [(DippN)₂Mo(CH₂CMe₂Ph)Cl] ( 6 ) (Dipp = 2,6‐diisopropylphenyl) was achieved.     

Novel heterocyclic inhibitors of matrix metalloproteinases: three 6H‐1,3,4‐thiadiazines

The title compounds, (2S)‐N‐[5‐(4‐chloro­phenyl)‐2,3‐di­hydro‐6H‐1,3,4‐thia­diazin‐2‐yl­idene]‐2‐[(phenyl­sulfonyl)­amino]­pro­pan­amide, C₁₈H₁₇ClN₄O₃S₂, (I), (2R)‐N‐[5‐(4‐fluoro­phenyl)‐6H‐1,3,4‐thia­diazin‐2‐yl]‐2‐[(phenyl­sulfonyl)amino]­propan­amide, C₁₈H₁₇FN₄O₃S₂, (II), and (2S)‐N‐[5‐(5‐chloro‐2‐thienyl)‐6H‐1,3,4‐thia­diazin‐2‐yl]‐2‐[(phenyl­sulfonyl)­amino]­propan­amide, C₁₆H₁₅ClN₄O₃S₃, (III), are potent inhibitors of matrix metalloproteinases. In all three compounds, the thia­diazine ring adopts a screw‐boat conformation. The mol­ecules of compound (I) show a short intramolecular N_Ala—H?N_exo hydrogen bond [N?N 2.661 (3) Å] and are linked into a chain along the c axis by N_endo—H?S_endo and N_endo—H?O_Ala hydrogen bonds [N?S 3.236 (3) and N?O 3.375 (3) Å] between neighbouring mol­ecules. In compound (II), the mol­ecules are connected antiparallel into a chain along the a axis by N_exo—H?O_Ala and N_Ala—H?N_endo hydrogen bonds [N?O 2.907 (6) and N?N 2.911 (6) Å]. The mol­ecules of compound (III) are dimerized antiparallel through N_exo—H?N_endo hydrogen bonds [N?N 2.956 (7) and 2.983 (7) Å]. The different hydrogen‐bonding patterns can be explained by an amido–imino tautomerism (prototropic shift) shown by different bond lengths within the 6H‐1,3,4‐thia­diazine moiety.     

Die Struktur des Pentaphenyldisilans

Structure of Pentaphenyldisilane For the first time Pentaphenyldisilane was prepared by Gilman and Goodman. It is produced by the reaction of Ph₃SiLi with Ph₂ClSiH. The crystal structure presents an ideally staggered conformation. The distance d(Si? Si) = 235.7 pm corresponds to a normal single bond length. This emphasizes the complete relief of the central Si? Si bond by the insertion of only one hydrogen atom.