Syntheses and structures of two- and three-dimensional cyanide-bridged coordination networks derived from crystallization of diimine-tetracyanoruthenate anions with gadolinium(III) cations

Abstract

This paper describes the syntheses and structures of two coordination networks based on reaction of diimine-tetracyanoruthenate(II) complexes with lanthanide(III) cations, in the presence of additional bidentate ligands to occupy some of the coordination sites on the lanthanide(III) centres. Reaction of the known complex K 2[Ru(phen)(CN) 4] (phen = 1,10-phenanthroline) with Gd(NO 3) 3 · 6H 2O in the presence of additional phen afforded crystals of [Ru(phen)(CN) 4] 3[Gd(phen)(H 2O) 3] 2 · 6H 2O, in which each [Ru(phen)(CN) 4] 2− unit is connected to two Gd(III) centres via Ru–CN–Gd bridges using the equatorial pair of cyanide ligands trans to the phen ligand. Each Gd(III) centre is the recipient of three bridging cyanide interactions (all from different Ru units) and is additionally coordinated by one phen and three water ligands, making it 8-coordinate. The structure consists of two-dimensional sheets in which the Ru–CN–Gd bridges result in formation of Ru 6Gd 6(μ-CN) 12 rings with a Gd(III) ion at each corner and a Ru(II) ion in the centre of each edge; this sheet is capped above and below by the phen ligands. The new dinuclear cyanometallate [{Ru(CN) 4} 2(μ-bpym)] 4− (bpym = 2,2′-bipyrimidine) was prepared by reaction of bpym with >2 equivalents of hexacyanoruthenate, and contains eight cyanide ligands which can potentially bridge. Reaction with Gd(hfac) 3(H 2O) 2 in MeCN/water afforded [{Ru(CN) 4} 2(μ-bpym)][Gd(hfac)(H 2O) 4] 2 · 10H 2O, (hfac = 1,1,1,5,5,5,-hexafluoro-pentane-2,4-dionate) which has a three-dimensional network structure based on Ru–CN–Gd bridges. Six of the cyanide ligands of each [{Ru(CN) 4} 2(μ-bpym)] 4− unit connect to Gd(III) ions, and each Gd(III) centre has in additional bidentate hfac ligand and four waters, making it nine-coordinate. The three-dimensional cyanide-bridged lattice contains square cross-section channels which are occupied by water molecules.