Novel hydrogen-bonded two- and three-dimensional networks generated from the reaction of metal nitratehydrates (M = Cd, Co) with the bidentate linear ligand4,4′-bipyridine

Abstract

Two new hydrogen-bonded coordination polymers have been prepared using the transition metal nitrate hydrates Cd(NO₃)₂·4H₂O and Co(NO₃)₂·6H₂O in combination with the organic bidentate ligand 4,4′-bipyridine: Cd₂(H₂O)₄(bipy)₅(NO₃)₂(PF₆)₂ (1) (bipy = 4,4′-bipyridine) and [Co(H₂O)₄(bipy)][PF₆]₂·3bipy (2). The compounds were characterized by single crystal X-ray diffraction, IR spectroscopy, and thermogravimetric analysis. Compound 1 shows a novel hydrogen bonded brick wall motif assembled from unprecedented dimeric “H-shaped” [Cd₂(bipy)₅] building blocks via a new complementary binary hydrogen bonding bridge. Compound 2 forms a novel three-dimensional network based on [Co(H₂O)₄(bipy)]_n linear polymer chains which are cross-linked to each other by a new type of Co–H₂O(2)⋯bipy⋯H₂O(1)⋯bipy⋯H₂O(1)⋯bipy⋯H₂O(2)–Co hydrogen bonding linkage.