Abstract: | Preparation, Crystal Structure, and Normal Coordinate Analysis of Linkage Isomeric Pentachloroiodoselenocyanatoosmates(IV). Crystal Structure of trans‐(PPh4)2[OsCl4I(NCSe)] By treatment of the solution of (n‐Bu4N)2[OsCl5I] in dichloromethane with suspended Pb(SeCN)2 the linkage isomers trans‐(n‐Bu4N)2[OsCl4I(NCSe)] ( 1 ) and trans‐(n‐Bu4N)2[OsCl4I(SeCN)] ( 2 ) are formed, which have been separated by ion exchange chromatography on diethylaminoethyl cellulose. The X‐Ray structure determination on a single crystal of trans‐(PPh4)2[OsCl4I(NCSe)] (triclinic, space group P1¯, a = 10.8950(13), b = 11.076(2), c = 20.980(2)Å, α = 96.940(10), β = 98.747(9), γ = 104.419(11)°, Z = 2) reveals, that the nearly linear selenocyanate group in trans position to the iodine atom is coordinated with the Os‐N‐C angle of 171.1°. Based on the molecular parameters of the X‐ray determination ( 1 ) and estimated data ( 2 ) the IR and Raman spectra of both linkage isomers are assigned by normal coordinate analysis. The valence force constants are fd(OsN) = 1.70 und fd(OsSe) = 1.15 mdyn/Å. |