Preparation, crystal structures, vibrational spectra, and normal coordinate analysis of the linkage isomeric chlororhodanoiridates(III) trans-[IrCl2(SCN)(4)](3-) and trans-[IrCl2(NCS)(SCN)(3)](3-)

Abstract

By treatment of Na-2[IrCl6] with NaSCN in 2N HCl the linkage isomers trans-[IrCl2(SCN)(4)](3)- and trans-[IrCl2(NCS)(SCN)(3)](3-) are formed which have been separated by ion exchange chromatography on diethylaminoethyl cellulose. X-ray structure determinations on single crystals of trans-(n-Bu4N)(3)[IrCl2(SCN)(4)] (1) (monoclinic, space group P2(1)/a, a = 18.009(4), b = 15.176(3), c = 23.451(4) Angstrom, beta = 93.97(2)degrees, Z = 4) and trans-(Me4N)(3)[IrCl2(NCS)(SCN)(3)] (2) (monoclinic, space group P(2)1/a, a = 17.146(5), b = 9.583(5), c = 18.516(5) Angstrom, beta = 109.227(5)degrees, Z = 4) reveal the complete ordering of the complex anions. The via S or N coordinated thiocyanate groups are bonded with Ir-S-C angles of 105.7-109.7 degrees and the Ir-N-C angle of 171.4 degrees. The torsion angles Cl-Ir-S-C and N-Ir-S-C are 3.6-53.0 degrees. The IR and Raman spectra of (1) are assigned by normal coordinate analysis using the molecular parameters of the X-ray determination. The valence force constants are f(d)(IrS) = 1.52 and f(d)(IrCl) = 1.72 mdyn/Angstrom