Potassium hexabromorhenate

Trirhenium nonabromide has been made (1) by direct combination of the elements 1 (2) by the thermal decomposition of rhenium (V) bromide, obtained by treating elemental rhenium with bromine at 650° 2 or (3) by the thermal decomposition of silver hexabromorhenate(IV),3-6 obtained from the metathesis of silver nitrate with potassium hexabromorhenate(IV).5-8 Of these methods, (3) has proven to be the simplest and most efficient route to pure trirhenium nonabromide. The following procedure is superior to that previously given,6 in that simpler equipment is used and larger quantities can be processed, with a resultant saving in time. 

Ammonium hexahalorhenate(IV) compounds can readily be made by substituting ammonium perrhenate for the potassium salt in procedures such as those for the synthesis of potassium hexabromorhenate(IV) and potassium hexachlororhenate (I V). ... 

Fig. 1. Pure quadrupole resonance frequencies of Br in potassium hexabromorhenate(IV) showing the existence of three transition points at about -4, -16, and -27 C.

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