|Budget Amount *help
¥2,200,000 (Direct Cost : ¥2,200,000)
Fiscal Year 1997 : ¥900,000 (Direct Cost : ¥900,000)
Fiscal Year 1996 : ¥1,300,000 (Direct Cost : ¥1,300,000)
We have found that the transannular or peri interaction between multi heteroatoms of cyclic chalcogenides can produce the hypervalent species. The results are summarized as follows.
The reaction of N-methyl-5H,7H-dibenzo [b, g] [1,5] selenazocine Se-oxide with SOCl_2 gave the chloroammonioselenurane which was further converted into the methyl-or phenyl-substituted ammonioselenurane upon treatment with Me_2CuLi or Ph_2Cu Li. The X-ray data of the selenuranes show that the conformations of the selenuranes are a twist-boat form.
The significant conformational change was found when cyclic chalcogenides, 1,11-(methanoselenomethano)-5H,7H-dibenzo [b, g] [1,5] diselenocin and 1,11-(methanothiomethano)-(5H,7H-dibenzo [b, g] [1,5] selenathiocin, were dissolved in concentrated H_2SO_4 ; i.e., the twin-chair forms of the diselenocin and the selenathiocin in CHCl_3 were converted completely into the twin-boat forms of the selenurane dications in H_2SO_4.
The transannular reaction of N-benzyl derivatives of 1,11-(methanoaminomethano)-5H,7H-dibenzo [b, g] [1,5] selenazocine with N-bromosuccinimide (NBS) gave an aminoammonio-selenurane 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 aminoammonioselenurane Br^- salt showed the twin-boat form ; the distances of Se・・・N are 1.918 * and 2.419 * respectively.