Single-molecule magnets (SMMs) have potential applications in high-density data storage as they can show magnetic memory effects, and lanthanide SMMs have shown the best performance to date. It is well-established that Dy(III) complexes with highly axial crystal fields have favorable SMM properties, as these ligand arrangements stabilize the most magnetic mJ states, while simultaneously destabilizing the least magnetic mJ states to give large energy barriers to magnetic reversal, Ueff. To date, highly axial dysprosium complexes with no equatorial ligands have only been achieved using bulky substituted cyclopentadienyl ligands (Cp R ) and related derivatives that contain charge-dense and rigid aromatic rings. This was first realized for dysprosocenium cations, [Dy(Cp R )2] + , where it was discovered that equatorial ligand interactions could be avoided by using bulky ring substituents and a chargediffuse, weakly coordinating anion (WCA). The relatively high magnetic hysteresis temperatures (TH, the highest temperature for which hysteresis loops remain open for a sweep rate of ~20 Oe s -1 ) and 100 s blocking temperatures (T100, the temperature for which the magnetic relaxation time is 100 s) of isolated dysprosocenium cations have been shown to be due to the combination of their highly axial ligand fields and the rigidity of multihapto Cp R rings reducing the efficacy of Raman relaxation processes and quantum tunneling of the magnetization (QTM). It has previously been demonstrated that equatorial interactions present in Dy(III) metallocene complexes containing a {Dy(Cp*)2} (Cp* = {C5Me5}) or {Dy(C5Me4H)2} core markedly diminish magnetic properties compared to those predicted for the idealized [Dy(Cp*)2] + cation. However, a systematic study of the effect of weak equatorial ligand fields on previously isolated dysprosocenium cations has not yet been undertaken. We recently reported that a dysprosocenium cation with a Dy(III) center at the cusp of stability towards conditions. Here we show that recrystallization of this complex from halobenzenes yields solvated adducts, allowing us to control the equatorial coordination and hence determine the influence of weakly coordinating solvents on the SMM properties of a dysprosocenium cation for the first time. These are also the first structurally authenticated haloarene-bound f-block complexes; only a handful of s-block and Sc 53 haloarene complexes have been reported