Darstellung der Halogeno-Pyridin-Rhenate(III), [ReX6−n (Py)n](3−n)− (X = Br,Cl; n = 1−3), sowie Kristallstrukturen von trans-[(C4H9)4N][ReBr4(Py)2], mer-[ReCl3(Py)3] und mer-[ReBr3(Py)3]

Preparation of Halogeno Pyridine Rhenates(III), [ReX_6?n(Py)_n]^(3?n)? (X = Br, Cl; n = 1?3) Crystal Structures of trans-[(C₄H₉)₄N][ReBr₄(Py)₂], mer-[ReCl₃(Py)₃], and mer- [ReBr₃(Py)₃] The mixed halogeno-pyridine-rhenates(III), [ReX_6?n(Py)_n]^(3?n)? (X = Br, Cl), n = 1?3, have been prepared for the first time by reaction of the tetrabutylammoniumsalts (TBA)₂[ReX₆] (X = Br, Cl) in pyridine with (TBA)BH₄ and separation by chromatography on Al₂O₃. Apart from the monopyridine complexes only the trans and mer isomers are formed from the bis-and tris-pyridine compounds. The X-ray structure determinations of the isotypic neutral complexes mer- [ReX₃(Py)₃] (monoclinic, space group P 2₁/n, Z = 4; for X = Cl: a = 9,1120(8), b = 12,5156(14), c = 15,6100(13) Å, β = 91,385(7)°; for X = Br: a = 9,152(5), b = 12,852(13), c = 15,669(2) Å, β = 90,43(2)°) reveal, due to the stronger trans influence of pyridine compared with Cl and Br, that the Re? X distances in asymmetric Py? Re? X3 axes with ReCl3 = 2,397 Å and ReBr3 = 2,534 Å are elongated by 1,3 and 1% in comparison with symmetric X1? Re? X2 axes with ReCl1 = ReCl2 = 2,367 Å and ReBr1 = 2,513 and ReBr2 = 2,506 Å, respectively. The Re? N bond lengths are roughly equal with 2,12 Å. Trans-(TBA)[ReBr₄(Py)₂] crystallizes triclinic, space group P1 , a = 9,2048(12), b = 12,0792(11), c = 15,525(2) Å, α = 95,239(10), β = 94,193(11), γ = 106,153(9)°, Z = 2. The unit cell contains two independent but very similar complex anions with approximate D_2h(mmm) point symmetry.