
%0 Journal Article
%A Onggo, D 
%A Craig, DC 
%A Rae, AD 
%A Goodwin, HA 
%T Coordination of Hydrazone Derivatives of 2,2'-Bipyridine-6-carbaldehyde. Electronic and Structural Aspects of the Iron(II), Cobalt(II) and Nickel(II) Complexes
%J Australian Journal of Chemistry
%D 1991/03/01
%V 44
%N 3
%P 331-341
%K 
%R https://doi.org/10.1071/CH9910331
%U https://www.publish.csiro.au/paper/CH9910331 
%X Iron(II), cobalt(II) and nickel(II) [MN6]2+ type complexes of the tridentate terimine  ligands 2,2&#8242;-bipyridine-6-carbaldehyde phenylhydrazone ( bph ) and 2,2&#8242;-bipyridine-6-carbaldehyde 2-pyridylhydrazone ( bpyh ) have been prepared. The electronic spectrum of the [NiN6]2+ species indicates that the field strength of these ligands is near that at the iron(II) singlet/quintet crossover. Magnetic and Mossbauer spectral data reveal that salts of [Fe( bph )2]2+ are essentially low spin, while those of [Fe( bpyh )2]2+ are high spin. Salts of [Co( bph )2]2+ have strongly temperature-dependent magnetic moments which indicate a thermally induced doublet &#8596; quartet spin transition in the metal atom. The structure of [Ni( bph )2][ClO4]2 reveals meridional coordination of the tridentate units, the azomethine nitrogen of the hydrazone moiety being bound to the metal atom. There is significant twisting (8.3&#176;) of the two pyridyl rings in each ligand molecule about the interring bridge. The [NiN6]2+ fragment is tetragonally compressed and the mean Ni-N distance is 2.09 &#506;. [Ni( bph )2][ClO4]2 is monoclinic, space group C2/c, Z = 4, a 23.949(3), b 7.868(1), c 21.303(3)&#506;, &#946; 117.95(2)&#176;. 
