Preparation and structure of new diazaselenuranes. Transannular hypervalent bond between seleno and diamino groups

Article abstract of DOI:10.1016/0040-4020(96)00857-5

The transannular reaction of N-benzyl derivatives of 1,11-(methanoaminomethano)-5H,7H-dibenzo[b,g][1,5]selenazocine (1 and 2) with N-bromosuccinimide (NBS) gave an aminoammonio-selenurane 4 which is the first example of an isolable diazaselenurane with two unsymmetrical apical nitrogen ligands of tertiary amino- and quaternary ammonio-groups. X-ray analysis of the aminoammonioselemurane Br^- salt (4a) showed the twin-boat form; the distances of Se···N are 1.918 A and 2.419 A respectively. The structure of selenurane 4 in solution was confirmed by ⁷⁷Se and ¹⁵N NMR spectroscopy using the ¹⁵N-enriched aminoammonio-selenurane 4-¹⁵N. The apical tertiary amine of selenurane 4 behaves as a nucleophile toward benzylbromide to give the bisammonio-selemurane 5. The aminoammonio and bisammonio-selenuranes 4 and 5 were converted into the neutral amines upon treatment with 2 equiv. of SmI₂.