SYNTHESIS, CRYSTAL-STRUCTURE, AND REACTIVITY OF NEW AMINO-SELENURANESAND AMMONIO-SELENURANES CONTAINING TRANSANNULAR SE-N BOND FROM 5H,7H-DIBENZO[B,G][1,5]SELENAZOCINES

The reaction of N-methyl-5H,7H-dibenzo[b,g][1,5]selenazocine Se-oxide 2 with SOCl2 gave the chloroammonioselenurane 3b which was further con verted into the methyl-or phenyl-substituted ammonioselenurane (4 or 5 ) upon treatment with Me2CuLi or Ph2CuLi. The X-ray data of 3b and 4 s how that the conformations of 3b and 4 are a twist-boat form. The Se-N distances are 2.191 Angstrom for 3b and 2.504 Angstrom for 4 which ar e significantly shorter than the sum of the van der Waals radii (3.5 A ngstrom) of the two elements, indicating transannular bond formation b etween Se and N. The Cl-Se-N bond angle of 3b and the Me-Se-N bond ang le of 4 are approximately collinear and the other bond angles around t he selenium atom are consistent with a pseudo trigonal bipyramidal str ucture. On the other hand, the reaction of 5H,7H-dibenzo[b,g][1,5]sele nazocine 6 with t-BuOCl gave the first aminoselenurane 7 with neutral amino group at the apical position. (C) 1997 Elsevier Science Ltd. All rights reserved.