SYNTHESIS AND SEPARATION OF THE MER AND FAC ISOMERS OF [RH(BPP)(3)][PF6](3) (BPP EQUALS 2,3-BIS(2-PYRIDYL)PYRAZINE)

摘要

The new complex [Rh(dps)(2)Cl-2]PF6 (1) (dps = di-2-pyridyl sulfide) was prepared by reacting RhCl3 with dps in an ethanol-water-mixture (2:1). As shown by H-1 NMR spectroscopy 1 exhibits a cis geometry. By refluxing 1 with bipy or phen (bipy = 2,2'-bipyridine, phen = 1,10-phenanthroline) in dimethylformamide the complexes [Rh(bipy)(2)Cl-2]PF6 and [Rh(phen)(2)Cl-2]PF6 were respectively obtained. On the contrary the reaction of 1 with bpp (bpp = 2,3-bis(2-pyridyr) pyrazine), carried out in the same experimental conditions, gave [Rh(bpp)3][PF6](3), (2) in high yields. The meridional (mer) and facial (fac) isomers of 2 were separated by chromatography. Despite the complexity of the H-1 and C-13 NMR spectra of the mer isomer, almost complete assignment of the resonances was possible by employment of two-dimensional techniques and by comparison with the resonances of the fac isomer. [References: 24]