Four‐Shell Polyoxometalates Featuring High‐Nuclearity Ln26 Clusters: Structural Transformations of Nanoclusters into Frameworks Triggered by Transition‐Metal Ions

A series of polyoxometalates (POMs) that incorporate the highest‐nuclearity Ln clusters that have been observed in such structures to date (Ln₂₆ , Ln=La and Ce) are described, which exhibit giant multishell configurations (Ln⊂W₆⊂Ln₂₆⊂W₁₀₀). Their structures are remarkably different from known giant POMs that feature multiple Ln ions. In particular, the incorporated Ln–O clusters with a nuclearity of 26 are significantly larger than known high‐nuclearity (≤10) Ln–O clusters in POM chemistry. Furthermore, they also contain the largest number of La and Ce centers for any POM reported to date and represent a new kind of rare giant POMs with more than 100 W atoms. Interestingly, the La₂₆‐containing POM can undergo a single‐crystal to single‐crystal structural transformation in the presence of various transition‐metal ions, such as Cu²⁺, Co²⁺, and Ni²⁺, from an inorganic molecular nanocluster into an inorganic–organic hybrid extended framework that is built from POM building blocks with even higher‐nuclearity La₂₈ clusters bridged by transition‐metal complexes.     

Synthesis,Isolation, and Trifluoromethylation of Two Isomers of C84‐Based Monometallic Cyanide Clusterfullerenes: Interplay between the Endohedral Cluster and the Exohedral Addends

As an emerging member of endohedral fullerenes, metal cyanide clusterfullerenes (CYCF) are unique in terms of the encapsulation of a monometallic cluster. To date the reported carbon cages of CYCFs are limited to C₈₂ and C₇₆, and little is known about the chemical reactivity of CYCFs. Herein, two isomers of the first C₈₄‐based CYCFs, YCN@C₈₄, were isolated as trifluoromethyl derivatives, including YCN@C₈₄(23)(CF₃)₁₈ and three isomers of YCN@C₈₄(13)(CF₃)₁₆, which are based on a unique chiral C ₂‐C₈₄(13) cage. As a common feature of the CF₃ addition patterns, the YCN@C₈₄(CF₃)_16/18 compounds are stabilized by the formation of isolated C=C bonds and benzenoid rings on the carbon cages. The interplay between the endohedral YCN cluster and the exhohedral CF₃ addends was unveiled according to single‐crystal X‐ray diffraction studies, thus offering new insight into the chemical reactivity of CYCFs.