Quantitative UV/Vis Spectroscopic Investigations of the In Situ Synthesis of Neutral μ2‐Chloro‐Bridged Dinuclear (Diphosphine)rhodium Complexes. Issue 34 (30th October 2014)

• Record Type: Journal Article
• Authors: Fischer, Christian; König, Anja; Meißner, Antje; Thede, Richard; Selle, Carmen; Pribbenow, Cornelia; Heller, Detlef
• Is Part Of: European journal of inorganic chemistry. Issue 34(2014)
• Page Start: 5849
• Page End: 5855
• Publication Date: 2014-10-30
• Subjects: Rhodium -- UV/Vis spectroscopy -- Time‐resolved spectroscopy -- Kinetics -- Diphosphine ligands; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201402787
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract: The stepwise in situ formation of neutral μ2 ‐chloro‐bridged dinuclear (diphosphine)rhodium complexes of the type [{Rh(PP)(μ2 ‐Cl)}2 ] (PP = chelating diphosphine) following the reaction of [{Rh(COD)(μ2 ‐Cl)}2 ] (COD = cyclooctadiene) with the ligands BINAP, SegPhos, DM‐SegPhos and DiFluorPhos was investigated quantitatively by stopped‐flow UV/Vis spectroscopy at 25.0 °C. The second‐order rate constants of each step of the consecutive reactions were determined. The investigations were hindered by an unexpected equilibrium reaction between starting and target complex on one side and an intermediate species formed during the ligand‐exchange process on the other. The rate constants of this equilibrium were also determined. The results reveal that the in situ formation of neutral μ2 ‐chloro‐bridged dinuclear (diphosphine)rhodium complexes, which are commonly applied in homogeneous catalysis as catalyst precursors, requires longer reaction times than is generally expected. Abstract : The in situ formation of neutral μ2 ‐chloro‐bridged dinuclear (diphosphine)rhodium complexes from the corresponding diolefin complexes by a twofold ligand‐exchange reaction was investigated kinetically. The second‐order rate constants of each step of the consecutive reactions were determined for the ligands BINAP, SegPhos, DM‐SegPhos and DiFluorPhos by stopped‐flow UV/Vis spectroscopy.