Bis[2-hydroxy-<i>N</i>′-(3-phenylprop-2-enylidene)benzohydrazidato-κ<sup>2</sup><i>N</i>′,<i>O</i>]bis(methanol-κ<i>O</i>)nickel(II) and bis[2-hydroxy-<i>N</i>′-(3-phenylprop-2-enylidene)benzohydrazidato-κ<sup>2</sup><i>N</i>′,<i>O</i>]bis(pyridine-κ<i>N</i>)nickel(II)
作者:Mei-Xiang Xue、Shi-Xiong Liu
DOI:10.1107/s0108270108006240
日期:2008.5.15
In the two title complexes of cinnamaldehyde salicyloylhydrazone [or 2-hydroxy-N'-(3-phenylprop-2-enylidene)benzohydrazide], [Ni(C(16)H(13)N(2)O(2))(2)(CH(4)O)(2)],(I), and [Ni(C(16)H(13)N(2)O(2))(2)(C(5)H(5)N)(2)], (II), the Ni(II) atoms lie on crystallographic inversion centres and have distorted octahedral geometries. The equatorial plane is defined by two carbonyl O atoms and two hydrazine N atoms of two bidentate trans-oriented salicyloylhydrazone ligands. The axial positions are occupied by two O atoms from two coordinated methanol molecules in (I) and by two N atoms from two coordinated pyridine molecules in (II). There is an extended chain structure in (I) resulting from intermolecular O-H center dot center dot center dot O hydrogen bonds between coordinated methanol molecules and phenol O atoms, while (II) comprises discrete molecules. Complex (I) also exhibits weak pi-pi stacking interactions, and intramolecular O-H center dot center dot center dot N hydrogen bonds are present in both (I) and (II). The salicyloylhydrazone ligands in (I) and (II) are coordinated to the metal atom through the carbohydrazide O and N 2 atoms, not via the phenol O atom. We have established a link between the reagents used and the nuclearity of the complex formed: the ligand produced by condensation between salicylhydrazide and an aldehyde leads to mononuclear complexes, while replacing the aldehyde in the reaction by a ketone leads to multinuclear complexes.
Cooperative Spin-State Switching and Vapochromism of Mononuclear Ni(II) Complexes by Pyridine Coordination/Decoordination
Two mononuclear Ni(II) complexes (1 and 2) have been found to display color changes upon coordination/decoordination of pyridine, resulting in their structural transformation between square-planar and octahedral geometries as well as a change in their spin state. Compound 1 changes between red (1r) and yellow (1y) upon exposure to or elimination of pyridine, while 2 undergoes a two-step transformation