“…In this respect, the heavier counterparts of hexacyanoferrate(III), for example, [Ru III (CN) 6 ] 3– and [Os III (CN) 6 ] 3– , are more attractive anisotropic constituents than [Fe III (CN) 6 ] 3– owing to much stronger spin–orbit coupling energy (which generally favors unquenched orbital momentum) and more diffuse magnetic orbitals (which results in larger magnetic spin coupling J ) 14. There are only a few examples of materials based on [Ru III (CN) 6 ] 3– and [Os III (CN) 6 ] 3– building blocks,17–25 including two trigonal bipyramidal clusters [M II (tmphen) 2 ] 3 [Os III (CN) 6 ] · solvent (M = Fe, Ni; tmphen = 3,4,7,8‐tetramethyl‐1,10‐phenanthroline),17,18 two Prussian blue analogues M II 3 [Os III (CN) 6 ] 2 · n H 2 O (M = Co, Ni),18,19 four SMMs involving Mn III complexes,20–24 and only one SCM25 of the type (Ph 4 P) 2 [Mn(acacen)][Os(CN) 6 ] [acacen = N , N′ ‐bis(acetylacetone)ethylenediaminato]. It was recently shown that incorporation of [Ru III (CN) 6 ] 3– or [Os III (CN) 6 ] 3– complexes in Mn III –NC–M III –CN–Mn III trinuclear complexes considerably increases the SMM spin‐reversal barrier U eff relative to that of the Mn III –NC–Fe III –CN–Mn III SMM cluster 23,20.…”