Salicylaldimines: Formation via Ring Contraction and Synthesis of Mono- and Heterobimetallic Alkali Metal Heterocubanes

Abstract

The formation of salicylaldimine derivatives via ring contraction as byproducts in 2-aminotropone syntheses has been investigated. Salicylaldiminate (SAI) complexes of the alkali metals Li–K have been synthesized and transformed into heterobimetallic complexes. Important findings include an unusual double heterocubane structure of the homometallic sodium SAI, an unprecedented ligand-induced E/Z isomerization of the aldimine functional group in the homometallic potassium SAI, and the first example of a structurally authenticated mixed-metal SAI based on s-block central atoms. Rapid equilibria have been shown to play a crucial role in the solution phase chemistry of mixed-metal SAIs. Analytical techniques applied in this work include (heteronuclear) NMR spectroscopy, VT- and DOSY NMR spectroscopy, high-resolution mass spectrometry, single-crystal X-ray diffraction analysis, and DFT calculations.

Coordination of a Potentially Tritopic Ligand via Phosphorus, Nitrogen and Oxygen: From Ligand Design to Heterobimetallic Metal–Organic Frameworks and Supramolecules

“…Similar to the situation encountered for extended structures, the vast field of discrete coordination cages is dominated by monometallic species. − Heterobimetallic coordination cages, albeit less common, are well represented nonetheless, − and many of them resemble cube-like architectures. − Most of them do, however, feature metal centers on their faces. Our example is rather reminiscent of the heterocubane motif − and its slightly elongated relatives, the cubic cyanometalates. , Compound 7 thus belongs to the family of octanuclear cubic coordination polyhedra , and is one of the very few heterometallic examples. , It crystallizes in the noncentrosymmetric cubic space group P 4̅3 n with Z = 2.…”