Dimolybdenum-Containing Molecular Triangles and Squares with Diamidate Linkers: Structural Diversity and Complexity

By employing cis-Mo2(DAniF)22+ (DAniF = N,N‘-di(p-anisyl)formamidinate) as the vertex building block and
terephthaloyldiamidate as the linker, four dimolybdenum-containing cyclic oligomers have been synthesized and
structurally characterized. In these compounds, described by the general formula [cis-Mo2(DAniF)2((ArNOC)2C6H4)2]n,
n = 3 and 4, the geometry and composition of the products are affected by the identity of the aromatic groups of
the linker. When Ar = phenyl, n = 3 (1a and 1b); however, n = 4 for Ar = p-trifluoromethylphenyl (2) and when
Ar = m-trifluoromethylphenyl (3). All these compounds have a central cavity, shaped by the diamidate linker, that
is capable of serving as host to guest molecules in a selective manner. For compounds 2 and 3, self-assembly that
takes place in the crystalline state entails intermolecular C−H···F−C interactions. Such interactions generate a
one-dimensional network with a tunnel cross section of 10 × 10 Å2 in 2, whereas in 3, they result in a cage in
which two THF molecules are encapsulated. The F···H distances vary in a broad range from 2.38 to 2.70 Å.