Crystal structure of (Me4N)(3)[Ir(SCN)(6)], vibrational spectra and normal coordinate analysis

Abstract

From a mixture of the linkage isomers [Ir(NCS)(n)(SCN)(6-n)](3-), n=0-2, pure [Ir(SCN)(6)](3-) has been isolated by ion exchange chromatography on diethylaminoethyl cellulose. The X-ray structure determination on a single crystal of (Me4N)(3)[Ir(SCN)(6)] (trigonal, space group R (3) over bar, a = 14.838(2), c = 23.827(1) Angstrom, Z = 6) reveals the presence of two crystallographically independent complex anions which C-3i symmetry correlates with the cation/anion ratio 3:1. The thiocyanate ligands are exclusively S-coordinated with the average IrS distance of 2.384 Angstrom and the Ir-S-C angle of 106.4 degrees. The torsion angles S-Ir-S-C are 17.5 and 42.1 degrees. The IR and Raman spectra of the (n-Bu4N) salt are assigned by normal coordinate analysis based on the molecular parameters of the X-ray determination. The valence force constant f(d)(IrS) is 1.57 mdyn/Angstrom