Mononuclear Clusterfullerene Single‐Molecule Magnet Containing Strained Fused‐Pentagons Stabilized by a Nearly Linear Metal Cyanide Cluster

Abstract

Fused‐pentagons results in an increase of local steric strain according to the isolated pentagon rule (IPR), and for all reported non‐IPR clusterfullerenes multiple (two or three) metals are required to stabilize the strained fused‐pentagons, making it difficult to access the single‐atom properties. Herein, we report the syntheses and isolations of novel non‐IPR mononuclear clusterfullerenes MNC@C76 (M=Tb, Y), in which one pair of strained fused‐pentagon is stabilized by a mononuclear cluster. The molecular structures of MNC@C76 (M=Tb, Y) were determined unambiguously by single‐crystal X‐ray diffraction, featuring a non‐IPR C 2v(19138)‐C76 cage entrapping a nearly linear MNC cluster, which is remarkably different from the triangular MNC cluster within the reported analogous clusterfullerenes based on IPR‐obeying C82 cages. The TbNC@C76 molecule is found to be a field‐induced single‐molecule magnet (SMM).

Endohedral Metallofullerenes: New Structures and Unseen Phenomena

“…To date, a collection of EMFs containing one to three pure metal atoms, which are called mono‐, di‐, and tri‐EMFs, respectively, has been obtained and structurally characterized . In addition, various metallic clusters, such as metal carbides, nitrides, oxides, sulfides, and even cyanides, have also been trapped inside fullerene cages to form the corresponding cluster‐EMFs. More meaningfully, the variability of the encapsulated species endows the EMFs with multifunctional properties and potential applications in optoelectronics, or as magnetic resonance imaging contrast agents, single‐molecule magnets, electron‐spin quantum computing units, and so forth.…”

Mononuclear Clusterfullerene Single‐Molecule Magnet Containing Strained Fused‐Pentagons Stabilized by a Nearly Linear Metal Cyanide Cluster

“…Single-crystalX -ray structures of TbNC@C 2v (19138)-C 76 (a,b) and YNC@C 2v (19138)-C 76 (d,e) shown with only the major Tb/Y (Tb1/ Y1) positions [14]. The fused-pentagon pair is highlightedi nr ed.…”

Strain Release of Fused Pentagons in Fullerene Cages by Chemical Functionalization

“…[83,109,110] In 2017, Yang and co-workers reported the first non-IPR CYCF MNC@C 76 (M = Tb,Y ), whereby the cage structure was elucidated by means of single-crystal X-ray diffraction to be C 2v (19138)-C 76 bearing apair of DFPs (Figure 7b). [30] Interestingly,the nearly linear geometries of the encapsulated MNC clusters within non-IPR MNC@C 2v (19138)-C 76 (M = Tb,Y )w ere quite different from the triangular configurations of the MNC clusters within IPR-CYCFs MNC@C 82 (M = Tb,Y ). [109,110] This can be explained by the interaction between the metal atom and the [NC] À ligand becoming weaker as aresult of the pronounced coordination of the metal atom to the fused pentagons.…”

“…[109,110] This can be explained by the interaction between the metal atom and the [NC] À ligand becoming weaker as aresult of the pronounced coordination of the metal atom to the fused pentagons. [30]…”

“…[14] Thestabilization of the triple sequentially fused pentagons (TFP-S;F igure 1d)a nd double fused pentagons (DFPs; Figure 1c)for Sc 2 @C 2v (4059)-C 66 and Sc 3 N@D 3 (6140)-C 68 ,respectively,are attributed to the encapsulated metal atoms that coordinate the fused pentagons, which results in release of the strain imposed by the fusion of the two or three pentagons.Since then, dozens of endohedral non-IPR fullerenes have been isolated experimentally,w ith the non-IPR feature unambiguously determined by singlecrystal X-ray crystallography. [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] Thus,endohedral function-According to the isolated pentagon rule (IPR), for stable fullerenes, the 12 pentagons should be isolated from one another by hexagons, otherwise the fused pentagons will result in an increase in the local steric strain of the fullerene cage.However,the successful isolation of more than 100 endohedral and exohedral fullerenes containing fused pentagons over the past 20 years has shown that strain release of fused pentagons in fullerene cages is feasible.H erein, we present ageneral overview on fused-pentagon-containing (i.e.n on-IPR) fullerenes through an exhaustive review of all the types of fused-pentagoncontaining fullerenes reported to date.W eclarify howt he strain of fused pentagons can be released in different manners,and provide an in-depth understanding of the role of fused pentagons in the stability, electronic properties,a nd chemical reactivity of fullerene cages. alization of fullerene cages has been demonstrated to be an effective way for releasing the strain of fused pentagons.…”