Cluster Harvesting in the WBr₆–P System

Abstract

A combined thermal scanning-X-ray diffraction (XRD) approach was performed for the WBr(6)-P system to detect and analyze phases in this system, including metal-rich phases generated with increasing amounts of elemental (red) phosphorus under partial PBr(3) release. Phases were characterized by powder XRD. A black crystalline powder of W(4)(PBr)Br(10) was obtained after reduction of WBr(6) with elemental phosphorus at 450 °C. The crystal structure of the new compound was found to be isotypic with the structure of W(4)(PCl)Cl(10) on the basis of powder XRD data. The structure of W(4)(PBr)Br(10) is represented by a cyclobutadiene-like tetranuclear tungsten cluster interconnected into a layered (W(4)(μ(4)-PBr)Br(6)(i))Br(8)/(2)(a-a) arrangement via outer bromide ligands. The μ(4)-capping bromophosphinidene ligand was verified by solid-state magic-angle spinning (31)P NMR spectroscopy.

Low-temperature preparation of tungsten halide clusters: Crystal structure of the adduct W5Br12 · SbBr3

“…In addition, the novel compounds W 30 C 2 (Cl,Br) 68 and W 6 CCl 15 were discovered follow ing this synthesis, revealing that reactions with carbon halides involve oxidations (chlorinations) at lower temperatures and reductions at more elevated temper atures [12].…”

Improved Synthesis of (TBA)2[W6Br14] Paving the Way to Further Study of Bromide Cluster Complexes

“…A review of the literature on methods for the formation of an octahedral tungsten bromide cluster core led us to the idea of combining the known approaches and developing a method for synthesis from simple substances. Tungsten is able to react with bromine at elevated temperatures to form a mixture of higher halides (WBr 5 and WBr 6 ), which, in turn, can be reduced to cluster compounds with tungsten in intermediate oxidation states, for example, W II 6 Br 12 . , …”

“…Three main approaches to the formation of the bromide cluster core {W 6 Br 8 } 4+ are presented in the literature: (1) the reduction of higher halides WBr 5 or WBr 6 with various reducing agents, such as hydrogen, , tungsten, and aluminum − as well as bismuth, antimony, , and red phosphorus, which were used to reduce WBr 6 in Meyer’s group; (2) the interaction of tungsten and bromine, which was first proposed in the work of Schafer in 1896 − and developed later; (3) the WBr 4 disproportionation described by Brown in his dissertation of 1963 and the work of 1964 . In addition, the synthesis of bromide cluster complexes as a result of the replacement of terminal and internal chloride ligands of polymeric W 6 Cl 12 with a LiBr/KBr salt melt (20-fold excess, 40:60 ratio) at 350 °C has been described .…”

“…32 Thus, the region of tungsten bromide cluster complexes is "terra incognita" on the map of the properties of {M 6 X 8 } 4+ cluster complexes, which can be attributed to more labor-intensive and expensive methods for obtaining the initial compounds (TBA) 2 [W 6 Br 14 ] or W 6 Br 12 in gram amounts in comparison with the molybdenum ones 38,39 or tungsten chloride and iodide cluster complexes. 3,40,41 Three main approaches to the formation of the bromide cluster core {W 6 Br 8 } 4+ are presented in the literature: (1) the reduction of higher halides WBr 5 or WBr 6 with various reducing agents, such as hydrogen, 42,43 tungsten, 44 and aluminum 45−47 as well as bismuth, 48 antimony, 37,49 and red phosphorus, 50 which were used to reduce WBr 6 in Meyer's group; (2) the interaction of tungsten and bromine, which was first proposed in the work of Schafer in 1896 51−53 and developed later; 54 (3) the WBr 4 disproportionation described by Brown in his dissertation of 1963 55 and the work of 1964. 56 In addition, the synthesis of bromide cluster complexes as a result of the replacement of terminal and internal chloride ligands of polymeric W 6 Cl 12 with a LiBr/KBr salt melt (20-fold excess, 40:60 ratio) at 350 °C has been described.…”

Carbon Centered Trigonal Prismatic Tungsten Clusters [W6CCl18]n– (n = 1, 2) containing Copper(I) and Copper(II)

“…The reaction of WBr 6 with a reducing agent, which can be a metalloid or a non-metal yields a series of new compounds. [15,16] The employment of Mn, Fe, and Co metal powders for the reduction of WCl 6 have yielded a number of new ternary M-W-Cl cluster compounds. [15,[17][18][19] CCl 18 ] was formed by reduction of β-WCl 6 (obtained from thermal phase conversion) [18] with copper powder (Merck, 99,9 %) and C 6 Cl 6 (Sigma Aldrich, 99 %) according to Equation (1).…”