Dimetalloendofullerene U₂@C₆₀ Has a U−U Multiple Bond Consisting of Sixfold One-Electron-Two-Center Bonds

Abstract

Endohedral metallofullerenes (EMFs) have been extensively studied since their discovery in 1985. Metal-metal bonds, nevertheless, have never been explicitly observed in EMFs synthesized so far. In this contribution, we show by means of all-electron relativistic density functional computations that the dimetalloendofullerene, U(2)@C(60), has an unprecedented U-U multiple bond consisting solely of sixfold ferromagnetically coupled one-electron-two-center bonds with the electronic configuration (5fpi(u))(2)(5fsigma(g))(1)(5fdelta(g))(2)(5fphi(u))(1), which are dominated by the uranium 5f atomic orbitals. This bonding scheme is completely distinct from the metal-metal bonds discovered thus far in the d- and f-block polynuclear metal complexes. This finding initiates a connection of the metal-metal multiple bonding chemistry and the fullerene chemistry.

Can a Metal–Metal Bond Hop in the Fullerene Cage?

“…[5][6][7] From a theoretical point of view, the study of metal-metal bonds in EMFs gives an in-depth perspective of the metal-metal interaction and provides an approach for further experimental and theoretical explorations of metal-metal interactions. [6,8] On the other hand, in contrast to the fact that several kinds of metal-metal bonds have been studied, in other fields, [9] up to now only rare examples of metal-metal bonds are reported in fullerene chemistry.[7] Furthermore, the presence of metal-metal bonds produces unique structures and fascinating electronic properties of EMFs, which may extend their promising applications in electronics, magnetism, and photovoltaics. [7,10] Most importantly, previous studies have indicated that the encapsulated metal atoms can move around in fullerene cage at room temperature.…”

“…[6][7][8][13][14][15] In fact, Stevenson et al suggested the presence of a Sc À Sc bond between the shortest Sc À Sc distance with a newly experimentally determined structure of Sc 4 O 2 @C 80 .…”

Nanomaterials and nanotechnologies in nuclear energy chemistry

“…The studies quoted above have dealt with the synthesis of actinide endohedral fullerenes, but the detailed structures of actinides in the cage of fullerenes, however, still remain unclear. Recently, Wu and Lu [5] revealed the presence of unprecedented U−U multiple bond in U 2 @C 60 by means of all-electron relativistic density functional computations. The optimized structures and symmetries of U 2 @C 60 isomers 1a-d derived from the C 60 (I h ) fullerene are depicted in Fig.…”

“…Optimized structures and symmetries of U 2 @C 60 isomers derived from the IPR-satisfying C60 (I h ) fullerene. Uranium atoms are represented by large blue balls, the carbon atoms closest to uranium are colored in purple [5]. modification of precursors to introduce different X-atoms into the reaction system prior to the energetic radiation.…”

Nuclear and radiochemistry in China: present status and future perspectives

“…Among them is the Lu's group in Xiamen University. They studied the multiple bond in a U 2 dimer which is encapsulated in a fullerene cage (U 2 @C 60 ) using PBE function with relativistic effect included [11]. It is shown that the 5 f electrons of U do participate in the bond formation, and the interaction between the two U atoms has the feature of a one-electrontwo-center multiple bond with a configuration characterized…”