Expanded ligands: bis(2,2′:6′,2″-terpyridine carboxylic acid)ruthenium(ii) complexes as metallosupramolecular analogues of dicarboxylic acids?

Dalton Transactions Pub Date: 2007-08-14 DOI: 10.1039/B709557K

Abstract

Ligands in which multiple metal-binding domains are linked by a metal-containing moiety rather than a conventional organic group are described as “expanded ligands”. The use of 4,4′-difunctionalised {Ru(tpy)2} units provides a linear spacer between metal-binding domains and we have extended this motif to expanded ligands containing two carboxylic acid metal-binding domains. In this paper, we describe the synthesis and structural characterisation of ruthenium(II) complexes of 2,2′:6′,2″-terpyridine-4′-carboxylic acid and 4′-carboxyphenyl-2,2′:6′,2″-terpyridine. The ability of the ruthenium(II) centre to charge compensate deprotonation of the carboxylic acid leads to Zwitterionic complexes and three representative compounds have been structurally characterised.

Graphical abstract: Expanded ligands: bis(2,2′:6′,2″-terpyridine carboxylic acid)ruthenium(ii) complexes as metallosupramolecular analogues of dicarboxylic acids
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