CRYSTAL AND MOLECULAR-STRUCTURE OF 1-CHLORO-1,2-BENZIODOXOLIN-3(1H)-ONE CENTER-DOT-TETRA-N-BUTYLAMMONIUM CHLORIDE

The title compound, 6, a novel 1:1 complex of 1-chloro-1,2-benziodoxol in-3(1H)-one (5) and tetra-n-butylammonium chloride, was prepared from tetra-n-butylammonium o-iodoxybenzoate (7) and acetyl chloride. A sin gle crystal of 6 was subjected to X-ray analysis: triclinic, space gro up P1; a = 10.239(2), b = 11.518(2), c = 11.523(3)Angstrom; alpha = 73 .20(2); beta = 87.85(2), gamma = 87.72(2)degrees; R1 = 0.0326. The mos t notable structural feature of crystalline 6 is the existence of a '' secondary'' bond [I .. Cl(2), 2.943(1)Angstrom] between the chloride i on and the iodine atom of the chlorobenziodoxolinone moiety. Further c oordination at iodine includes three primary bonds: I-C [2.115(4) Angs trom], I-O [2.145(3) Angstrom], I-CI(1) [2.454(1) Angstrom]. The entir e 1-chlorobenziodoxolinone-chloride sub-structure is planar and exhibi ts iodine-centered bond angles of 78.8(1)degrees [C-I-O], 92.0(1)degre es [C-I-Cl(1)], 97.6(1)degrees [Cl(2)I-O] and 91.6(1)degrees [Cl(2)-I- Cl(1)]. The unit cell of 6 contains two loosely packed formula units. The chlorobenziodoxolinone-chloride sub-structures occupy a common pla ne and exhibit a centrosymmetric relationship, while the tetra-n-butyl ammonium ions are situated one above and one below the plane. Bonding at the iodine atom in 6 is more consistent with a 10-I-3 species elect rostatically associated with the chloride ion than a 12-I-4 species su ch as the tetrachloroiodate ion.