Polynuclear molecular clusters offer an opportunity to
design new
hierarchical switchable materials with collective properties, based
on variation of the chemical composition, size, shapes, and overall
building blocks organization. In this study, we rationally designed
and constructed an unprecedented series of cyanido-bridged nanoclusters
realizing new undecanuclear topology: FeII[FeII(bzbpen)]6[WV(CN)8]2[WIV(CN)8]2·18MeOH (1), NaI[CoII(bzbpen)]6[WV(CN)8]3[WIV(CN)8]·28MeOH
(2), NaI[NiII(bzbpen)]6[WV(CN)8]3[WIV(CN)8]·27MeOH (3), and CoII[CoII(R/S-pabh)2]6[WV(CN)8]2[WIV(CN)8]2·26MeOH [4Rand4S; bzbpen =N1,N2-dibenzyl-N1,N2-bis(pyridin-2-ylmethyl)ethane-1,2-diamine;R/S-pabh = (R/S)-N-(1-naphthyl)-1-(pyridin-2-yl)methanimine],
of size up to 11 nm3, ca. 2.0 × 2.2 × 2.5 nm
(1–3) and ca. 1.4 × 2.5 ×
2.5 nm (4).1,2, and4exhibit site selectivity for the spin states and spin transition
related to the structural speciation based on subtle exogenous and
endogenous effects imposed on similar but distinguishable 3d metal-ion-coordination
moieties.1exhibits a mid-temperature-range spin-crossover
(SCO) behavior that is more advanced than the previously reported
SCO clusters based on octacyanidometallates and an onset of SCO behavior
close to room temperature. The latter feature is also present in2and4, which suggests the emergence of CoII-centered SCO not observed in previous bimetallic cyanido-bridged
CoII–WV/IVsystems. In addition, reversible
switching of the SCO behavior in1via a single-crystal-to-single-crystal
transformation during desolvation was also documented.