Crystal and molecular structure of di(μ 3-oxo-tri-μ-oxotrichlorohexakis(pyridine)-triangulotritungsten(IV))hexatungstate(VI)-6-pyridine, [W3(O)O3Cl3(C5H5N)6]2W6O19·6C5H5N

W₃(O)O₃Cl₃(C₅H₅N)₆]₂W₆O₁₉·6C₅H₅N, the side product of the reaction between WCl₄(C₅H₅N)₂ and pyridine, crystallizes in the rhombohedral space groupR¯3 (No. 148), witha=14.044(1) Å,=87.70(1)°, andZ=1. The structure was solved by the heavy-atom method, and refined to the unweighted and weighted residuals of 0.068 and 0.055, respectively. The tungsten atoms define an equilateral triangle with a capping and three bridging oxygen atoms. Two pyridines in thecis position and a chlorine atom form, together with the oxygens, a distorted octahedron around the tungsten atoms; three octahedra are connected through common edges. Important bond lengths are: W-W (single bond) 2.532(1), W-O (tricapped) 2.09(1), W-O (bridging) 1.92(1) and 1.94(1), W-C1 2.424(5), and W-N (pyridine) 2.23(1) and 2.26(1) Å. In W₆O ₁₉ ^2– , six WO₆ octahedra have one common central oxygen, twelve bridging and six terminal oxygen atoms. Corresponding W-O bond lengths are: 2.323(1) (central oxygen), from 1.90 to 1.94(1) (bridging oxygens), and 1.70(2) Å (terminal oxygens). Lattice pyridine molecules have no important contacts with either anion or cation.