Rhodium(I) Complexes with OPPy2Ph and OPPy3 (Py = 2-Pyridyl), and Their Behavior in Hydrogenation Reactions

Abstract

Keywords: Alkenes / Hydrogenations / N ligands / Phosphanes / RhodiumThe reaction of [Rh 2 (µ-Cl) 2 (COD) 2 ] (COD = 1,5-cyclooctadiene) or [Rh 2 (µ-Cl) 2 (TFB) 2 ] (TFB = tetrafluorobenzobicyclo[2.2.2]octatriene) with the N-donor chelating ligand OP-Py 2 Ph (Py = 2-pyridyl) in the presence of TlBF 4 affords cationic complexes [Rh(diene)(OPPy 2 Ph)](BF 4 ) (1, diene: COD; 2, diene: TFB). Compounds 1 or 2 react with CO to give [Rh(CO) 2 (OPPy 2 Ph)](BF 4 ) (4), which is also obtained by treatment of [Rh 2 (µ-Cl) 2 (CO) 4 ] with OPPy 2 Ph and TlBF 4 . In a similar way, the complexes [Rh(diene)(OPPy 3 )](BF 4 ) (5, diene: COD; 6, diene: TFB) are obtained when using OPPy 3 ; they react with CO to give [Rh 2 (µ-CO) 3 (OPPy 3 ) 2 ](BF 4 ) 2 (9). The [a] 289 behavior of the complexes in solution is reported. The complexes with OPPy 3 , 5 and 6, show equivalence of the three Py groups in their NMR spectra. Complex 5 is square-planar in the solid state, and in solution, and the uncoordinated and coordinated Py groups undergo fast exchange in solution. Complex 6 is pentacoordinated in the solid state and in solution, and its Py groups exchange their coordination sites in a fast topomerization process. The single-crystal X-ray structures of 5 and 6 have been solved. The behavior of 1 and 5 as catalysts in hydrogenation reactions of cyclohexene, acetone, and cyclohexanone is also reported.

Tris(2-pyridyl)phosphine oxide: how C—H...O and C—H...N interactions can affect crystal packing efficiency

“…Tris(2-pyridyl)phosphine oxide, (I), has been used as a ligand in the coordination chemistry of transition metals and a number of complexes have been characterized by X-ray crystallography [Cambridge Structural Database (CSD;Allen, 2002) refcodes XAMNUU (Anderson et al, 2000), QATYUF and QATZAM (Casares et al, 2001), VOPREX (Keene et al, 1991), and MAWYOY (Espinet et al, 2000)]. The solid-state structure of free (I) is, however, still outstanding.…”

Relativistic heavy atom effect on the 31P NMR parameters of phosphine chalcogenides. Part 1. Chemical shifts

“…Phosphine chalcogenides were considered in this study as the attractive model compounds for investigation of the relativistic HALA effect on 31 P NMR chemical shifts, initiated by the adjacent chalcogens. Moreover, the tertiary phosphine chalcogenides are the real‐life compounds, which are known to be the effective ligands for the synthesis of metal complexes . As an example, they are used in asymmetric metal complex catalysis and represent the promising bifunctional homogeneous complexes for the oxidative catalysis.…”

Reaction of Tri(2‐pyridyl)phosphine with Electron‐Deficient Alkynes in Water: Stereoselective Synthesis of Functionalized Pyridylvinylphosphine Oxides

“…The reaction highlights novel facets of phosphine and acetylene chemistry that paves an ecologically benign way to a new family of promising ligands11 and building blocks for organic synthesis 12. Among such compounds are retardants,13 drug precursors,14 and ligands for the design of metallocomplex catalysts applied particularly for hydrogenation of cyclohexene, acetone, and cyclohexanone 11b…”