Synthesis of 2,6-bis(diphenylphosphinomethyl) pyridine-monoligand-rhodium(I) complexes [Rh(PNP)L]X with L = pyridine, CH3CN, DMSO and X = CF3SO3, BF4 from the corresponding ethylene complex and comparison of the structures to the piperidine complex (L = piperidine, X = BF4)

Article abstract of DOI:10.1016/S0277-5387(97)00497-X

Investigation of the coordination conditions at the 2,6-bis(diphenylphosphinomethyl)pyridine-rhodium(I) fragment [Rh(PNP)]⁺ by X-ray crystallography showed a square planar geometry of the neutral chloro and the cationic piperidine complexes, [Rh(PNP)Cl] (1) and [Rh(PNP)(pip)]BF₄ (2). New cationic rhodium(I) complexes [Rh(PNP)L]X (L = pyridine, X = SO₃CF₃ 3; L = CH₃CN, X = SO₃CF₃ 4a, X = BF₄ 4b; L = DMSO, X = SO₃CF₃ 5) have been synthesized from the ethylene complexes [Rh(PNP)(C₂H₄)]X by substitution of the ethylene by the ligand L (L = py, CH₃CN, or DMSO). The complexes 3-5 were characterized by IR spectroscopy, ¹H-, ¹³C-, and ³¹P-NMR spectroscopy and X-ray crystallography. The influence of the ligands on the structure of the complexes was investigated. The cis influence was determined by measurement of the coupling constant J_P-Rh and the average length of the Rh - P bonds and the trans influence by the length of the Rh - N(1) bond.