Ruthenium tetramers, structure

Only metal complexes of cycloarsathianes have been structurally characterized, and these include a tetramer (EtAsS)4 (as ruthenium complex) and the methyl cychc oligomers (MeAsS) with n = 4, 5, and 6 (as chromium and molybdenum complexes), e.g. (58) the later starting from a trimer-tetramer equilibrinm mixture (MeAsS) , n = 3 and 4 60 -pjjg structure of the pentamer complex is shown here. 

Rhodium pentafluoride is isomorphous with its ruthenium, osmium, and iridium analogues, the crystal data being a, 12-28 b, 9-86 c, 6-48 A ]3, 99-2° Uobs-, 654-2 A Z = 8. Presumably the structural unit of this compound is a fluorine-bridged tetramer, as in ruthenium pentafluoride. It is noteworthy that the unit-cell volume is smaller than in the ruthenium analogue, possibly as a... 

The only ruthenium(V) halides reported are those containing fluoride. Green ruthenium(V) fluoride can be prepared by direct fluorination of the metal at 300°C, by reduction of [RuF ] with BiFj, SbFj, Ru or or by reaction of the metal and BrFj. The latter method first generates [BrFj] [RuF ] which decomposes at 120°C in vacuo to give tRuF5]4 and BrFj. The tetrameric structure (369) has been confirmed by X-ray analysis, but its mass spectrum indicates that the vapour consists of an equilibrium between monomer, dimer, trimer and tetramer units. Magnetic measurements reveal the presence of significant interactions between adjacent metal ions. Mossbauer and IR spectral measurements are also available. Some of the reactions of [RuFj]4 are discussed below but further details are to be found in reference 3, p. 79. 

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