Mass spectra of substituted pyrrolidine-N-oxyl radicals

Electron impact mass spectra of 65 pyrrolidine-N-oxyl derivatives have been assigned on a ‘peak-to-subgraph’ basis. On average, 50% of the total ion current is represented by structurally significant fragments associated with the nitroxide group. Secondary fragmentation is, as a rule, of a minor importance (30%), and fragments due to functional groups other than NO^· seldom contribute more than 10% of the total ion current An enhanced specificity of fragmentation is observed when one or more of the 2,2, 5,5-methyl groups is replaced by a longer aliphatic chain or an aromatic group.     

Macrocyclic ligands with potential axial interactions. The preparation of copper(II), nickel(II) and cobalt(III) complexes of 7,14-o-hydroxyphenyl-5,12-dimethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene

Summary The new macrocyclic ligand 7,14-o-hydroxyphenyl-5,12-dimethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene (1=L) has been prepared and complexes with copper(II), nickel(II) and cobalt(III) characterised. The nickel(II) complex is a yellow square-planar species, while the purple-red copper(II) complex is probably tetragonal in both the solid state and solution. The complexes appear to have an N-meso arrangement of the chiral nitrogen centres with the HOC₆H₄ groups occupying equatorial sites so that axial interactions with the metal do not occur. A variety oftrans-[CoLX₂]ClO₄ complexes (X=Cl, Br, NO₂, or N₃) have been characterised.     

Synthesis of Spin-Labelled Procaine and its Derivatives

The spin-label technique has become an important method of studying biologically active molecules^1–6.     

Synthesis of Nitroxide Paramagnetic Ketones from Nitroxide Acid Chlorides and Anhydrides by Fiedel-Crafts Acylation

Friedel-Crafts acylation of benzene or toluene with 5- and 6-membered nitroxide acid chloride, anhydrides derivatives (symmetrical or mixed) and aluminium chloride to aryl nitroxide ketones is described.     

Synthesis of 2-(2-Thienyl)benzimidazoles by the Reaction of 2-(Mercaptomethyl)benzimidazole With β-Electrophilic Esters

New 2-(2-di- and tetrahydrothienyl)benzimidazole compounds were prepared by the ring closure reactions of 2-(mercaptomethyl)benzimidazole^1,2 (1) and α,β-unsaturated compounds activated with electron-withdrawing groups.     

Benzazoles XIII—determination of the E and Z configuration of isomeric 2-(2-benzimidazolyl)-di- and -tetra-hydrothiophenes by IR, 1H and 13C NMR spectroscopy

The configuration of the diastereomeric pairs of 2-(3-hydroxy-3-methyl-5-phenyl-2,3-dihydrothiophen-2-yl)benzimidazole (1a,1b) and 2-(3-hydroxy-3-methyltetrahydrothiophen-2-yl)benzimidazole (2a, 2b), as well as that of the acyl and diacyl derivatives of 2a and 2b, and the structure of the dehydrated products formed by heating 1a or 1b, and 2a or 2b, were determined by IR, ¹H and ¹³C NMR spectroscopy.     

Copper(II), nickel(II) and cobalt(III) complexes of the macrocyclic ligand C-meso-7,14-diphenyl-5,6-butano-12,13-butano-1,4,8,11-tetraazacyclotetradeca-4,11-diene

Summary Metal complexes of the macrocyclic tetraaza ligand C-meso-7,14-diphenyl-5,6-butano-12,13-butano-1,4,8,11-tetraazacyclotetradeca-4,11-diene (L) are described. The copper(II) and nickel(II) complexes, isolated as their perchlorate salts, are 4-coordinate species. Several cobalt(III) complexes,trans-[CoLX₂]⁺(X = Cl^–, Br^–, NO ₂ ^– or N ₃ ^– have also been characterised. The most probable stereochemistry of the ligand in the metal complexes is the C-meso-N-meso arrangements of the chiral centres. The N-meso stereochemistry leads to the bulky phenyl groups lying in equatorial positions. I.r. and d-d spectra are reported for the various complexes described.