HYDRATED MANGANESE(II) CYANATO COMPLEXES OF 3-ACETYL AND 4-ACETYL, CARBOMETHOXYPYRIDINE, CARBOETHOXYPYRIDINE AND BENZOYLPYRIDINE DERIVATIVELIGANDS AND CRYSTAL-STRUCTURE OF DICYANATO-BIS(4-ACETYLPYRIDINE)DIAQUAMANGANESE(II) - [MN(4-ACETYLPYRIDINE)(2)(NCO)(2)(H2O)(2)]

A series of 1:2 manganese(II) cyanato complexes of 3-,4-acetyl-, 3- an d 4-benzoylpyridines, methyl and ethyl nicotinate and isonicotinates h as been prepared and characterized. Except for L = ethyl isonicotinate , all other complexes crystallize with two water molecules. In the cas e of ethyl isonicotinate the complex crystallizes with two ethanol mol ecules. the IR and Raman spectral lines of diagnostic value are given and discussed, suggesting terminal N-bonded cyanato ligands and aqua m olecules or bonded ethanol molecules in these manganese(II) complexes. The structure of [Mn(4-acetylpyridine)(2)(OCN)(2)(H2O)(2)] as determi ned by crystallographic methods features six-coordinate manganese(II) centres, pairs of trans aqua molecules [Mn-O = 2.202(3) Angstrom], N-b onded cyanato ligands [Mn-N = 2.116(3) Angstrom] and monodentate N-bon ded carbonyl pyridine ligands [Mn-N = 2.322(3) Angstrom]. The structur e is further consolidated by hydrogen bonds between aqua oxygen atoms of acetyl groups or terminal oxygen atoms of cyanato ligands. These hy drogen bonds connect the polyhedra along the cb plane to form a layer- type structure. The EPR spectra of powder samples and solvent solution s at room temperature were recorded and discussed. (C) 1997 Elsevier S cience Ltd.