Rhodium pentafluoride, structure

The V—F—V angle of 150° in the vanadium pentafluoride structure lies between those for the niobium and rhodium compounds. Thus, the structure cannot be described in terms of either of the close-packed arrangements. Although in the structure some approach toward close-packed planes of fluorine atoms can be seen, a comparison of volume per formula unit for the pentafluorides shows that for the second and... 

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... 

B. K. Morrell, A. Zalkin, A. Tressaud and N. Bartlett, Crystal Structure of Rhodium Pentafluoride, Inorg. Chem. 12 (1973) 2640-2644. 

Because coordination compounds are usually considered to be covalently bonded, to a first approximation (see Chapter II), extended complex structures in the solid can readily be related to them. Consider, for example, rhodium pentafluoride. Obviously, it could be considered as an ionic structure. Rh F , and indeed Ihe crystal structure7 consists, in part, of /top-arranged fluoride ions with rhodium in octahedral holes. However, closer inspection of the structure reveals that it consists of tetrameric units, Rh4F2l that are distinct from one another (Fig. 7.7). The environment about each rhodium atom, an octahedron of six fluorine atoms, is what we... 

Rhodium(VI) and iridium(VI) occur only in black RhFg and yellow IrFg, formed by heating the metals with F2 under pressure and quenching the volatile products. Both RhFg and IrFg are octahedral monomers. The pentafluorides are made by direct combination of the elements (equation 22.100) or by reduction of MFg, and are moisture-sensitive (reaction 22.101) and very reactive. They are tetramers, structurally analogous to NbFs (22.5). 

RhFj has a tetrameric structure analogous to RuFj and IrFs (128). Each rhodium is coordinated by six fluorine atoms in an approximately octahedral arrangement. The terminal Rh—F distance averages 1.808 A, while the Rh—F distance is significantly longer (2.01 A) for the bridging fluorines. This compound is isostructural with the pentafluorides of Ru, Os and... 

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