HETEROCYCLIC 1,2,4,6-THIATRIAZINYL AND 1,2,4,6-SELENATRIAZINYL RADICALS - SPIN DISTRIBUTIONS AND MODES OF ASSOCIATION

Synthetic routes to the heterocyclic 1-chloro-1,2,4,6-thia- and -selenatriazines [(Ph2P)2-x(PhC)xN3ECl] (x = 0, 1; E = S, Se) have been developed. For x = 0 the method involves the coupling of [ClPh2PNPPh2Cl]+C1- with the N, N'-disilylated diimides Me3SiNENSiMe3 (E = S, Se), while for x = 1 the preparation uses the condensation of (Me3Si)2NPN(Ph)CNSiMe3 with either SC12 or SeCl4. Reduction of the 1-chloro derivatives with triphenylantimony affords the thia- and selenatriazinyl radicals [(Ph2P)2-x(PhC)xN3E]·, all of which have been characterized by ESR spectroscopy. Hyperfine coupling constant data are interpreted in the light of MNDO calculations on model structures. X-ray structural analysis of the radical dimers [Ph2(tol)PCN3S]2 and [Ph3PCN3Se]2-CH3CN reveals significantly different modes of association; for the sulfur-based radical, association occurs through a long (average (range) = 2.489 (9) Å) sulfur-sulfur bond, while in the selenium species the dimer pair is coupled by a selenium-nitrogen linkage, the structural parameters within the two rings resembling those expected for a charge-transfer interaction. © 1990, American Chemical Society. All rights reserved.