Multi-site coordination of ferrocenylamido-naphthyridine conjugates [{(5,7-dimethyl-1,8-naphthyridin-2-yl)amino}carbonyl]ferrocene and 1,1′-bis[{(5,7-dimethyl-1,8-naphthyridin-2-yl)amino}carbonyl]ferrocene

Ferrocenylamido-naphthyridine conjugates [{(5,7-dimethyl-1,8-naphthyridin-2-yl)amino}carbonyl]ferrocene (L1) and 1,1′-bis[{(5,7-dimethyl-1,8-naphthyridin-2-yl)amino}carbonyl]ferrocene (L2) have been synthesized. Reaction of L1 with [Cu(CH3CN)6][ClO4]2 affords [Cu(L1)2][ClO4]2 (1) demonstrating tridentate coordination of the ligand utilizing naphthyridine (NP) nitrogens and carbonyl oxygen. Hydroxo-bridged neutral dirhenium(I) compound [K⊂{{Re(CO)3}2(μ-OH)(Fc(CONHNP)(CON¯ NP))2}] (2) is reported in which the amido-NP arm of L2 chelates a ReI, and a K+ ion is encapsulated in a six-coordinate environment rendered by four NP nitrogens and two carbonyl oxygens involving all four arms of two L2 ligands. Selective and reversible binding of K+ ion by the organometallic host has been recognized from electrochemical and fluorescence experiments. Partial hydrolysis of L2 has provided a neutral metallamacrocycle [{Re(CO)3}2{Fc(CO2)(CONHNP)}2] (3) consisting of alternate Fc and Re(CO)3 units linked by carboxylate and amide-NP bridges. The rotational freedom of the ferrocenyl rings, the flexibility of the amide linker and the multi-site coordination of the ligands are demonstrated in the molecular structures of compounds 1–3.

Graphical abstractThe organometallic host {Re(CO)3}2(μ-OH)(Fc(CONHNP)(CON¯NP))2} binds a K+ ion selectively and reversibly.Figure optionsDownload full-size imageDownload as PowerPoint slide