Phosphorus NMR Characterisation of P–N Bond Rotamers of a α‐P4S3 Amide with a Conformationally Constrained Chiral Substituent

Reactions of bicyclic α‐P₄S₃I₂ with Hpthiq gave solutions containing α‐P₄S₃(pthiq)I and α‐P₄S₃(pthiq)₂, where Hpthiq is the conformationally constrained chiral secondary amine 1‐phenyl‐1,2,3,4‐tetrahydroisoquinoline. The expected diastereomers have been characterised by complete analysis of their ³¹P{¹H} NMR spectra. Hindered P–N bond rotation in the amide iodide α‐P₄S₃(pthiq)I caused greater broadening of peaks in the room‐temperature spectrum of one diastereomer than in that of the other. At 183 K, spectra of two P–N bond rotamers for each diastereomer were observed and analysed. The minor rotamers showed strong evidence for steric crowding, having large diastereomeric differences in ¹J(P–P) and ²J(P–S–P) couplings (49 Hz, 16 % of value, and 4.4 Hz, 19 % of value, respectively).     

Rapid survey analysis of polymeric materials by laser ablation-inductively coupled plasma spectrometry. An analytical note

An Nd-Yag laser (1064 nm) in combination with a multichannel emission spectrometer was used for rapid survey analysis of polymers and paints. A novel design feature of the ablation chamber was the incorporation of a graphite furnace to effect electrothermal pretreatments of samples. Transient emission signals were studied as a function of laser operating mode, laser duration and flashlamp energy.Presented in part at the 1989 European Winter Conference on Plasma Spectrochemistry, Reutte, Austria     

Synthesis of 6-cyanopurines and the isolation and X-ray structure of novel 2H-pyrroles

(Z)-N¹-(2-Amino-1,2-dicyanovinyl)-N²-substituted-formainidines react with dimethylformamide diethyl acetal at room temperature to give 6-cyanopurines as the major product together with novel 5-amino-2-arylimino-3,4-di[(N,N-dimethylamino)methylideneamino]-2H-pyrroles, which have been fully characterised and a single crystal X-ray analysis has been carried out on the N-phenyl derivative.