Modulation of the Fe^II spin crossover effect in the pentadecanuclear {Fe₉[M(CN)₈]₆} (M = Re, W) clusters by facial coordination of tridentate polyamine ligands

Abstract

Spin crossover (SCO) materials, revealing the externally tunable transition between two different spin states, arouse great scientific interest due to their perspective application in information storage, display devices and sensing. Of special importance are the molecular systems offering the possibility of multimodal switching within many spin centers. This is achievable in polynuclear clusters consisting of several SCO-active complexes, however, such molecules are very rare. Herein, we report a unique pair of nanometric pentadecanuclear {Fe[M(CN)](Metacn)}·14MeOH (Metacn = 1,4,7-trimethyl-1,4,7-triazacyclononane, M = Re, 1; M = W, 2) clusters exhibiting a thermally induced spin crossover effect on Fe(ii) complexes, that is on both central and external Fe sites embedded in the cyanido-bridged cluster core. The spin transition occurs gradually in the 120-300 K range, and it is not fully completed even at room temperature. We show that facial coordination of an N,N,N-tridentate Metacn ligand dramatically modifies the character of the spin transition phenomenon when confronted with the previously reported {Fe[M(CN)](MeOH)}·nMeOH (M = Re, W) clusters by (i) engaging, for the first time, not only central but also external Fe intracluster units in the SCO effect, (ii) cancelling the Fe-W charge transfer pathway, and (iii) decreasing the cooperativity within the supramolecular network.

Guest‐Dependent Pressure‐Induced Spin Crossover in FeII4[MIV(CN)8]2 (M=Mo, W) Cluster‐Based Material Showing Persistent Solvent‐Driven Structural Transformations

“…[7][8][9][10][11][12][13][14][15][16][17][18][19] Among cyanide metal complexes,o ctacyanidometallateso ffer severals pecial advantages:f lexibility,c hemicals tabilitya nd aw ide range of accessible oxidation states. [20][21][22][23][24] Remarkably,m ost octacyanidometallate-based MMMsa re extended two-dimensional( 2D) or threedimensional (3D) coordination frameworks, whereas zero-dimensional MMMsi ncorporatingt hese building blocks are ratherr are. [25] The discrete molecules and clusters incorporating [M(CN) 8 ] nÀ constitute al arge libraryo ft opologies: squares, [26] pentanuclear trigonal bipyramids, [14] or pentadecanuclear six-capped body-centred cubes, [27] to name af ew.…”

Structural diversity in Cd(NCS)2-3-cyanopyridine coordination compounds: synthesis, crystal structures and thermal properties

“…Mn(II), Fe(II), Co(II), and Ni(II) contain N-terminally coordinated thiocyanate anions and are of interest because, e.g. several of them show spin crossover [1][2][3][4]. On the other hand, compounds with bridging thiocyanate anions are of importance because they can form dimers as well as 1D and 2D networks, in which significant magnetic exchange can be observed [5][6][7][8][9][10][11][12][13][14].…”

Structural Disorder in High-Spin {CoII9WV6} (Core)-[Pyridine N-Oxides] (Shell) Architectures

“…The above observations still allow to reasonably consider the acquisition of the large defected discrete Co x W y n+/− species or single chains based on such motifs, potentially hosting the slow magnetic relaxation properties. Finally, the use of the triazacyclononane (tacn) family allows to afford 15-nuclear and larger related 20-nuclear topologies, which offer the stabilization of paramagnetic [W(CN) 8 ] 3− anions, [19,29,30] spin-crossover on all nine Fe(II) sites [31], and photomagnetic properties in the case of Cu II -[Mo IV (CN) 8 ] 4− species [32].…”