The Crystal and Molecular Structure of Bis-[μ-2-(p-nitrophenyliminomethyl)phenolato-N,O]-bis(ethanol)bis(nitrato-O,O')dinickel(II), [Ni(slno)NO₃(C₂H₅OH)]₂, a Binuclear Ferromagnetic Salicylaldimine Derivative of Nickel Nitrate

Abstract

The crystal and molecular structure of the complex bis-[μ-2-(p-nitrophenyliminomethyl)phenolato- N,O]-bis(ethanol)bis(nitrato-O,O')dinickel(11) and its magnetic properties are reported. Crystal data: space group PI, Z 1, a 8.882(2), b 9.332(3), c 12.533(4) Å, α 94.40(2),B 109.99(2), γ 111.61(2)º, U 883 ų, R 2.8%, R_w 3.3% for 2154 reflections. The compound is prepared from the reaction of bis(N-p-nitrophenylsalicylaldimine)nickel(II) with nickel nitrate in hot triethoxymethane, and on cooling the solution deposited pale green transparent crystals. The structure contains neutral dimeric units with bridging through the phenolic oxygen atoms and has distorted octahedral geometry about each crystallographically identical nickel atom. The six donor atoms are made up of two oxygen atoms from the bidentate nitrate, oxygen from ethanol, nitrogen from the imine group and two bridging phenolic oxygen atoms. The Ni₂O₂ group is strictly planar possessing a crystallographic centre of symmetry. The angles subtended at the bridging oxygen atoms indicate a tetrahedral geometry and it is demonstrated that this is important in explaining the ferromagnetic intradimer interaction. The presence of hydrogen bonding between the ethanol hydrogen and the nitrate group of an adjacent molecule appears to be an important stabilizing factor in determining the structure and provides a possible pathway for the antiferromagnetic interdimer exchange interaction.