B. Dockum, W. Reiff
Oct 1, 1986
Citations
0
Influential Citations
9
Citations
Journal
Inorganica Chimica Acta
Abstract
Abstract Double benzo substitution cis to the nitrogen atoms of 2,2′-bipyridine results in 2,2′-biquinoline, hereafter, biq. Numerous examples of tris 2,2′-bipyriidne metal species are known, but to out knowledge, there have been no previous reports of tris biq metal species. Herein, we report the first isolation of what appears to be a tris biq species, Fe(biq) 3 (NCS) 2 , in the solid state obtained from a water-acetone solution as an analytically pure, pale blue-gray solid. Zero and high field Mossbauer, optical (near infrarcd-visible), and infrared spectra as weil as cryomagnetic data clearly show that Fe(biq) 3 (NCS) 2 contains a pseudo-octahedral high spin iron(II) chromophore. Several possibilities are proposed for the structure of Fe(biq) 3 (NCS) 2 including some with unidentate biq. The weak field, highly hindered environment of the complex is such that it readily undergoes facile loss of two moles of ligand simply on mixing the solid complex with a variety of organic solvents. The resulting neutral buff-colored iron(II) complex, Fe(biq)(NCS) 2 , is a pseudo-tetrahedral monomer which can also be prepared by the direct reaction of an ethanolic solution of Fe(NCS) 2 with a benzene solution of biq in a 1:1 stoichiometry. The spectral and cryomagnetic properties of Fe(biq)- (NCS) 2 as well as those for the related pseudo-tetrahedral compounds Fe(biq)Cl 2 , Fe(2,9-dimethyl-l,10-phenanthroline)X 2 (X=CI - , Br - , I - , NCS - ) and Fe(2,9-dimethyl-4,7-di-phenyl- 1,10-phenanthroline)Cl 2 , are reported as weil. In particular, the latter pseudo-tetrahedral systems are found to exhibit a novel, complex range of slow paramagnetic behavior depending on T , H o and specific coordinated anion. This behavior correlatcs with low temperature susceptibility data.