| Abstract: | Crystal Structures, Vibrational Spectra, and Normal Coordinate Analyses of the Chloro-Iodo-Rhenates(IV) (CH2Py2)[ReCl5I], cis -(CH2Py2)[ReCl4I2] · 2 DMSO, trans -(CH2Py2)[ReCl4I2] · 2 DMSO, and fac -(EtPh3P)2[ReCl3I3] [ReCl5I]2–, cis-[ReCl4I2]2–, trans-[ReCl4I2]2–, and fac-[ReCl3I3]2– have been synthesized by ligand exchange reactions of [ReI6]2– with HCl and are separated by ion exchange chromatography on diethylaminoethyl cellulose. X-ray structure determinations have been performed on single crystals of (CH2Py2)[ReCl5I] ( 1 ) (triclinic, space group P1 with a = 7.685(2), b = 9.253(2), c = 12.090(4) Å, α = 90.06(2), β = 101.11(2), γ = 95.07(2)°, Z = 2), cis-(CH2Py2)[ReCl4I2] · 2 DMSO ( 2 ) (triclinic, space group P1 with a = 8.662(2), b = 12.109(2), c = 12.9510(12) Å, a = 97.533(11), β = 96.82(2), γ = 89.90(2)°, Z = 2) , trans-(CH2Py2)[ReCl4I2] · 2 DMSO ( 3 ) (triclinic, space group P1 with a = 9.315(7), b = 9.663(3), c = 15.232(3) Å, α = 80.09(2), β = 81.79(4), γ = 83.99(5)°, Z = 2) and fac-(EtPh3P)2[ReCl3I3] ( 4 ) (monoclinic, space group P21/a with a = 17.453(2), b = 13.366(1), c = 19.420(1) Å, β = 112.132(8)°, Z = 4). The crystal structure of ( 1 ) reveals a positional disorder of the anion sublattice along the asymmetric axis. Due to the stronger trans influence of I compared with Cl on asymmetric axes Cl˙–Re–I′ is caused a mean lenghthening of the Re–Cl˙ distances of 0.020 Å (0.8%) and a shortening of the Re–I′ distances of 0.035 Å (1.3%) with regard to symmetrically coordinated axes Cl–Re–Cl and I–Re–I, respectively. Using the molecular parameters of the X-Ray determinations the low temperature (10 K) IR and Raman spectra of the (n-Bu4N) salts of all four chloro-iodo-rhenates(IV) are assigned by normal coordinate analyses. The weakening of the Re–Cl˙ bonds and the strengthening of the Re–I′ bonds is indicated by a decrease or increase of the valence force constants each by 9%. |
