Darstellung,Schwingungsspektren, Normalkoordinatenanalyse und Kristallstruktur von fac-(PPN)2[ReClBr2I3]

Preparation, Vibrational Spectra, Normal Coordinate Analysis, and Crystal Structure of fac-(PPN)₂[ReClBr₂I₃] By treatment of cis-[ReBr₂I₄]^2? with HCl fac-[ReClBr₂I₃]^2? is formed beside other mixed complex ions of the Type [ReCl_kBr_lI_m]^2?, k + l + m = 6, which have been separated by ion exchange chromatography on diethylaminoethyl cellulose. The X-ray structure determination on single crystals of (PPN)₂[ReClBr₂I₃] (monoclinic, space group P2₁/c, a = 22.059(3), b = 13.569(2), c = 23.9679(2) Å, β = 106.194(4)°, Z = 4) reveals the complete ordering of the complex anions. Due to the different trans influence the bond lengths ReCl (2.39) and ReBr (2.50) are slightly increased, the average ReI distance (2.66 Å) is a little shortened as compared with corresponding homoleptic octahedral complexes. The well resolved low temperature (80 K) IR and Raman spectra exhibit rheniumhalogen stretching vibrations in characteristic regions. The assignment is confirmed by the normal coordinate analysis based on a general valence force field. Taking into account increments of the trans influence on the valence force constants of the structural groups an adjustment between calculated and observed frequencies within a few cm^?1 is achieved.