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

摘要

Crystallographic structural refinements of the cubic (I) and triclinic (II) forms of [(n-C_4H_9)_4N]_3[Sc(NCS)_6] have been carried out by means of three-dimensional single-crystal X-ray diffractometry. The cubic form crystallizes in space group Pa3-bar (No. 205, Z = 8) and the triclinic form crystallizes in P1-bar (No. 2, Z = 2). The respective lattice constants are a = 24.630(4) A (I) and a = 12.232(2), b = 12.655(3), c = 22.337(4) A, #alpha# = 90.48(3), #beta# = 90.92(3), #gamma# = 96.73(3) deg (II). A full-matrix least-squares refinement program yielded final reliability (R) factors of 0.088 and 0.061 based on 1078 and 4660 unique reflections, respectively. In both complexes, the molecular units consist of three separate cationic tetra-n-butylammonium groups and an independent hexakisisothiocyanatoscandium anionic group. The n-butyl ligands are coordinated tetrahedrally to the ammonium-nitrogen atoms and the near linear six thiocyanate ligands coordinate octahedrally through the nitrogen atoms to the scandium metal center atoms. Characterizations include physical property determinations and spectrometric identifications employing I.R., ~1H and ~(13)C NMR and X-ray powder analyses. Selected bond distances and angles as well as syntheses and peripheral studies are presented and discussed.