Inhaltsu È bersicht. Bei der Behandlung von (n-Bu 4 N) 2 -[Ru(NO)I 5 ] in Dichlormethan mit (n-Bu 4 N)Cl entsteht (n-Bu 4 N) 2 [{Ru(NO)ClI 2 } 2 (l-I 2 )]. Die Ro È ntgenstrukturanalyse an einem Einkristall von (n-Bu 4 N) 2 [{Ru(NO)ClI 2 } 2 -(l-I 2 )] ´2 I 2 (monoklin, Raumgruppe I 2/a, a = 20,446(6), b = 11,482(8), c = 27,225(3) A Ê , b = 107,51(4)°, Z = 4) zeigt den dinuklearen iodverbru È ckten Aufbau des Moleku È lanions, in dem die Chloratome trans-sta È ndig zur Nitrosyl-Gruppe angeordnet sind. Die Tieftemperatur-IR-und Raman-Spektren sind an (n-Bu 4 N) 2 [{Ru(NO)ClI 2 } 2 (l-I 2 )] ´2 I 2 registriert und durch Normalkoordinatenanalyse zugeordnet worden. Zwischen den beobachteten und berechneten Frequenzen ergibt sich eine gute Ûbereinstimmung. Die Valenzkraftkonstanten betragen f d (NO) = 14,08, f d (RuN) = 5,58, f d (RuCl) = 1,52, f d (RuI t ) = 0,90 und f d (RuI b ) = 0,76 mdyn/A Ê . Crystal Structure, Vibrational Spectra, and Normal Coordinate Analysis of (n-Bu 4 N) 2 [{Ru(NO)ClI 2 } 2 (l-I 2 )] ´2 I 2 Abstract. By treatment of (n-Bu 4 N) 2 [Ru(NO)I 5 ] with (n-Bu 4 N)Cl in dichloromethane (n-Bu 4 N) 2 [{Ru(NO)ClI 2 } 2 (l-I 2 )] is formed. The X-Ray structure determination on a single crystal of (n-Bu 4 N) 2 [{Ru(NO)ClI 2 } 2 (l-I 2 )] ´2 I 2 (monoclinic, space group I 2/a, a = 20.446(6), b = 11.482(8), c = 27.225(3) A Ê , b = 107.51(4)°, Z = 4) reveals a dinuclear iodine bridged structure, in which the chlorine atoms are trans positioned to the nitrosyl groups. The low temperature IR and Raman spectra have been recorded of (n-Bu 4 N) 2 [{Ru(NO)-ClI 2 } 2 (l-I 2 )] ´2 I 2 and are assigned by normal coordinate analysis. A good agreement between observed and calculated frequencies is achieved. The valence force constants are f d (NO) = 14.08, f d (RuN) = 5.58, f d (RuCl) = 1.52, f d (RuI t ) = 0.90 and f d (RuI b ) = 0.76 mdyn/A Ê .