Detection and Characterization of Compounds in the Mn‐W‐Cl System through a Combined Thermal Scanning ‐ XRD Approach

Abstract

A procedure combining thermal analyses and XRD powder diffraction is used to scan and detect a series of new compounds in the Mn‐W‐Cl system. Four new ternary Mn‐W‐Cl compounds are formed in a progressive reaction of tungsten hexachloride (WCl6) with manganese powder, in which tungsten is gradually reduced from W6+ to W2+. Among several DSC signals, the new compounds MnxWCl6, MnW2Cl10, (Mn, W)1–xCl2, and MnW6Cl14 are detected and their crystal structures are assigned or identified by X‐ray diffraction techniques. Magnetic properties are reported for MnW2Cl10 and MnW6Cl14.

From WCl6 to WCl2: Properties of Intermediate Fe–W–Cl Phases

“…If iron was in divalent and tungsten in trivalent oxidation state, the corresponding charge-balanced phase would be best described as Fe 1– x W 2/3 x Cl 2 . The presence of a cation deficiency is also supported by other (M,W)­Cl 2 systems analyzed as (Mn 0.47 W 0.36 )­Cl 2 , (Co 0.24 W 0.43 )­Cl 2 , and (Ni 0.21 W 0.54 )­Cl 2 by EDX measurements. As long as the precise phase compositions of these compounds remain unknown, we will use the formula (M,W) 1– x Cl 2 .…”

“…After phenomenological studies were performed for reduction of WCl 6 with transition metal powders M = Mn, 11 Fe, 8 and Co, 9 it was clear that not only some structural details but also physical properties and bonding characteristics of these compounds are unknown and raise some interesting questions.…”

Snap‐Shots of a Reduction Pathway: The Reaction of WCl6 with Copper Powder

“…Closely related crystal structures were reported for MW 2 Cl 10 (M = Mn, Fe, Co) . Both types of structures, Cu 2 W 2 Cl 10 and MW 2 Cl 10 , contain edge‐sharing bioctahedra, which are well known from neutral [W 2 Cl 10 ] in WCl 5 , with a nonbonding W–W distance of 3.814(2) Å …”

“…A similar type of reduction, with metal incorporation into the structure of WCl 6 , has been reported for M x WCl 6 compounds with M = Mn, Fe, and Co . Their crystal structures are also based on a hexagonal closest packing (hcp) arrangement of chloride ions and variable amounts of M ions occupying up to 1/3 of octahedral voids in every second interlayer.…”

“…The reduction of WBr 6 with antimony powder results in a cascade of intermediate products until W 6 Br 12 is formed, whereby tungsten is gradually reduced from the oxidation state +6 to +2 . More recently, the reduction of WCl 6 was explored with transition‐metal powders such as Mn, Fe and Co . Crystal structures of compounds appearing in these systems were refined by means of single‐crystal and powder X‐ray diffraction.…”