Preparation, characterization, and structural determination of cubic and triclinic tris (tetra-n-butylammonium) hexakisisothiocyanatoscandate (III)

Crystallographic structural refinements of the cubic (I) and triclinic (II) forms of [(n-C4H9)(4)N](3)[Sc(NCS)(6)] have been carried out by means of t hree-dimensional single-crystal X-ray diffractometry. The cubic form crysta llizes in space group Pa (3) over bar (No. 205, Z = 8) and the triclinic fo rm crystallizes in P (1) over bar (No. 2, Z = 2). The respective lattice co nstants are a = 24.630(4) Angstrom (I) and a = 12.232(2), b = 12.655(3), c = 22.337(4) Angstrom, alpha = 90.48(3), beta = 90.92(3), gamma = 96.73(3)de grees (II). A full-matrix least-squares refinement program yielded final re liability (R) factors of 0.088 and 0.061 based on 1078 and 4660 unique refl ections, respectively. In both complexes, the molecular units consist of th ree separate cationic tetra-n-butylammonium groups and an independent hexak isisothiocyanatoscandium anionic group. The n-butyl ligands are coordinated tetrahedrally to the ammonium-nitrogen atoms and the near linear six thioc yanate ligands coordinate octahedrally through the nitrogen atoms to the sc andium metal center atoms. Characterizations include physical property dete rminations and spectrometric identifications employing I.R., H-1 and C-13 N MR and X-ray powder analyses. Selected bond distances and angles as well as syntheses and peripheral studies are presented and discussed. (C) 1999 Els evier Science B.V. All rights reserved.