Niamh R. Kelly, S. Goetz, C. Hawes
Jul 1, 2013
Citations
0
Influential Citations
12
Citations
Journal
Inorganica Chimica Acta
Abstract
Abstract The reaction of either 4,4′,6,6′-tetramethyl-2,2′-bipyridine, L , or 4,4′,6,6′-tetracarboxy-2,2′-bipyridine, H 4 L , with Cu(OAc) 2 ·H 2 O under acidic hydrothermal conditions (50:1 H 2 O/HNO 3 ; 160 °C) led to the formation of crystalline {[Cu( HL ′)(H 2 O)]·H 2 O}, 1 , which was structurally characterised to identify H 3 L ′ as 4,4′,6-tricarboxy-2,2′-bipyridine. Clearly, in situ mono-decarboxylation of a tetracarboxylic acid ligand gave the tricarboxy-analogue, H 3 L ′. The structure of 1 consists of a 1D coordination polymer that cross-links through hydrogen-bonding between adjacent carboxylic acid and carboxylate groups, as well as through an aqua ligand and lattice water molecule, to form a densely interconnected 3D network. Regioselective mono-decarboxylation of L or H 4 L at the 6′-carboxylic acid position may also be affected by heating L or H 4 L in acidic solution under hydrothermal conditions (2:1 H 2 O/HNO 3 ; 160 °C) to yield crystalline 4,4′,6-tricarboxy-2,2′-bipyridinium nitrate hydrate {[ H 4 L ′][NO 3 ]·H 2 O}, 2 , which was also structural characterised. The structure of 2 features an array of hydrogen-bonding interactions that generate a 3D network. More forceful heating of the acidic solution at 180 °C led to double decarboxylation and the formation of 4,4′-dicarboxy-2,2′-bipyridine, whereas heating at 200 °C led to total decarboxylation and the formation of 2,2′-bipyridine. Details of the structures of 1 and 2 along with their synthesis are discussed.