Structural comparison of [Ce(O t Bu)Cl(THF) 5 ](BPh 4 ) to smaller rare earth analogues.

The introduction of the cerium(III) analogue (1-Ce, Ln = Ce) of (tert-butoxido)chloridopentakis(tetrahydrofuran)lanthanide(III) tetraphenylborate tetrahydrofuran disolvate, [Ln{OC(CH ₃ ) ₃ }Cl(C ₄ H ₈ O) ₅ ][B(C ₆ H ₅ ) ₄ ]·2C ₄ H ₈ O or [Ln(O ^t Bu)Cl(THF) ₅ ](BPh ₄ )·2THF (1-Ln) has been achieved with a structural comparison between the existing solid-state structures of other rare earth analogues and the title compound at 100 and 180 K. The cation in 1-Ce is targeted as the cerium(III) ion possesses the criteria to exhibit slow magnetic relaxation in axial point-charge crystal fields, akin to the dysprosium(III) ion in 1-Dy. AC magnetic susceptibility experiments reveal no such behaviour for 1-Ce, putting the viability of cerium-based SMMs into question.