Synthesis and spectroscopic properties of [AsPh4][MO(bipy)(CN)3]·0.5bipy·2H2O (M = Mo or W); X-ray crystal structure of the tungsten complex

Abstract

Reaction of K₃Na[MO₂(CN)₄]·6H₂O (M = Mo or W) with 2,2′-bipyridyl (bipy) in water–methanol solution (pH 8.4) affords the new compounds [AsPh₄][MO(bipy)(CN)₃]·0.5bipy·2H₂O. The structure of the tungsten complex was determined by X-ray analysis. Principal dimensions (ranges or means; estimated standard deviation 0.005 Å) are: WO 1.735, W–C 2.129–2.149, W–N 2.149 and 2.307 Å. The crystals are triclinic, space group P, a= 10.035(3), b= 12.829(5), c= 15.732(5)Å, α= 76.00(3), β= 84.00(3), γ= 88.30(3)°, Z= 2, R= 0.069 for 6 104 observed [I/σ(I) 2.0] reflections. Tungsten is six-co-ordinated with oxygen and cyano ligands trans to the bidentate bipy. The structure contains ‘free’ bipy which links the complex anions in chains via hydrogen-bonded water molecules. The i.r. spectra of the solids are in agreement with this structure as are the n.m.r. (¹H and ¹³C) spectra. The visible spectra in various organic solvents are dominated by metal-to-ligand charge-transfer bands with absorption maxima that are linearly dependent on the Gutmann acceptor number of the solvent.