Preparation, Chemical and Structural Characterization of Tungsten(III) Coordination Compounds: WCl₃Pic₃, WCl₃Pic₃ · 1/2 Pic, and (Pic)₂HWCl₄Pic₂ (Pic = 4‐methylpyridine)

Abstract

Abstract (Pic) 2 HWCl 4 Pic 2 (Pic = 4‐methylpyridine, C 5 H 7 N) was prepared by reduction of WCl 4 Pic 2 with NaBH 4 in isopropanol. The compound crystallizes in the triclinic P 1 space group with: a = 9.931(3), b = 14.127(5), c = 10.010(3) Å, α = 83.71(2), β = 99.35(2), γ = 99.90(2)°, Z = 2. The unit cell contains trans‐WCl 4 Pic 2 − octahedra and (Pic) 2 H + . Hydrogen bond NH…N within the cation is 2.71(2) Å. WCl and WN(Pic) bonds (average) are 2.419(5) and 2.165(10) Å. (Pic) 2 HWCl 4 Pic 2 is very unstable towards oxidation. The first product is WCl 4 Pic 2 . (Pic) 2 HWCl 4 Pic 2 reacts further with 4‐methylpyridine. The product is WCl 3 Pic 3 which crystallizes from the cooled solutions of the ligand as WCl 3 Pic 3 · 1/2 Pic. WCl 3 Pic 3 and WCl 3 Pic 3 · 1/2 Pic are isostructural with the corresponding molybdenum and chromium compounds with the mer structures. WCl 3 Pic 3 is triclinic and WCl 3 Pic 3 · 1/2 Pic monoclinic. WCl 3 Pic 3 · 1/2 Pic decomposes in the inert atmosphere before 140°C to WCl 3 Pic 3 . Both neutral compounds are more stable towards oxidation compared to (Pic) 2 HWCl 4 Pic 2 .