The First Designed Syntheses of Bis-dimetal Molecules in Which the Bridges Are Diamidate Ligands

The first deliberate syntheses of molecules in which pairs of
quadruply bonded Mo2 units are bridged by N,N‘-diarylterephthaloyldiamidate (aryl = Ph, m-CF3Ph) ligands are described. The
addition of neutral N,N‘-diarylterephthaloyldiamide to 2 equiv of
[Mo2(DAniF)3(MeCN)2]+ (DAniF = N,N‘-di-p-anisylformamidinate)
followed by the introduction of excess H3CO- in MeCN results in
the formation of (DAniF)3Mo2{(C6H5)NC(O)C6H4(O)CN(C6H5)}Mo2(DAniF)3 (1) and (DAniF)3Mo2{[(m-CF3)C6H5]NC(O)C6H4(O)CN[(m-CF3)C6H5]}Mo2(DAniF)3 (2). The ΔE1/2 for the oxidation of each
Mo2 unit is greater for these terephthaloyldiamidate-bridged
molecules (∼100 mV) than for the analogous terephthalate-bridged
compound (∼60 mV). Variation in the nature of the substituents
on the diamidate nitrogen atoms offers a means to fine-tune the
oxidation potentials of the Mo2 units.