Structural and Spectroscopic Studies of Transition Metal Nitrite Complexes. I Crystal Structures and Spectra of trans-Bis(ethane-l, 2-diamine)dinitronickel(II), trans-Bis[N, N-dimethyl(ethane-1, 2-diamine)]-dinitritonickel(II) and trans-Bis[N, N′-dimethyl-(ethane-1, 2-diamine)]dinitronickel(II) Monohydrate

The crystal structures of the trans complexes bis(ethane-1, 2-diamine)dinitronickel(II) (1), bis[N, N-di-methyl(ethane-l, 2-diarnine)]dinitritonickel(II) (2) and bis[N, N′-dimethyl(ethane-1, 2-diamine)]dinitro-nickel(II) monohydrate (3) are described, (1) and (2) being redeterminations of previously reported structures. The complexes formed by the substituted amines have significantly different geometries, both in the manner of coordination of the nitrite ligands, and in the conformations adopted by the diamine chelate rings. These differences can be explained in terms of the particular steric requirements of the amine substituents. The changes in nitrite geometry which occur upon coordination, and the spectroscopic properties of the complexes are discussed.