More recently, the synthetic concept has already been extended by isolobal replacement of one C-R group by a heteroatom fragment which also allowed the synthesis of high performance Dy SMM compounds. To date, instances of such homoleptic Dy sandwich-type SMMs include the bis-phospholyl and bis-borolediide Dy cation and anion, respectively, which exhibit Ueff values and blocking temperatures comparable to the [Dy(Cp R )2] + complexes. Analogous Tb species with such Cp-type heterocyclic ligands for comparison of the magnetic properties remain elusive.