65554-24-7Relevant academic research and scientific papers
Monomerisation of [Rh2(1,3-bis-(diphenylphosphino)-propane)2(μ2-Cl)2] detected by pulsed gradient spin echo spectroscopy and 31P NMR monitoring of metathesis experiments
Mannu, Alberto,Ferro, Monica,M?ller, Saskia,Heller, Detlef
, p. 402 - 404 (2018)
A pulsed gradient spin echo experiment on [Rh2(1,3-bis-(diphenylphosphino)-propane)2(μ2-Cl)2] complex has been conducted in order to shed light on the supposed monomerisation process of [Rh2(diphosphine)2(μ2-Cl)2] complexes in solution. Such a process should generate a 14-electron [Rh(diphosphine)Cl] complex, which has only been postulated to date. Metathesis experiments on [Rh2(1,3-bis-(diphenylphosphino)-propane)2(μ2-Cl)2] and [Rh2(bis[2-(diphenylphosphino)phenyl]ether)2(μ2-Cl)2] complexes, analysed by 31P NMR, reveal that monomerisation of [Rh2(diphosphine)2(μ2-Cl)2] complexes is not restricted to the case of 1,3-bis-(diphenylphosphino)propane.
New insights into the biphasic “CO-free” Pauson-Khand cyclisation reaction through combinedin situspectroscopy and multiple linear regression modelling
Geitner, Robert,Huang, Tianbai,Kupfer, Stephan,Gr?fe, Stefanie,Meirer, Florian,Weckhuysen, Bert M.
, p. 1626 - 1636 (2021/03/14)
“CO-free” carbonylations are catalytic reactions, which strive to replace toxic synthesis gas with less harmful surrogate molecules like formaldehyde. This study sheds light on the mechanism of the biphasic, Rh-catalysed Pauson-Khand type cyclisation reaction by applyingin situRaman spectroscopy together with NMR, dynamic light scattering measurements, and quantum chemical calculations. The reaction is particularly challenging to analyse as the Rh-catalyst features different ligands in the aqueous and organic phase. To tackle this challenge, a novel approach was designed, couplingin situRaman spectroscopy with an advanced data analysis model in the form of multiple linear regression. This fruitful combination of highly specific vibrational spectroscopy with state-of-the-art data analysis allowed not only identification of a new reaction mechanism, but also identification of parameters to accelerate the “CO-free” Pauson-Khand cyclisation,i.e.using mononuclear Rh-phosphine complexes with labile ligands, small organic micelles formed by an increased surfactant concentration, low formaldehyde concentration, and elevated temperature. This novel knowledge-driven optimisation protocol is superior to simple qualitative optimization routines and can be transferred to other reactions and spectroscopy techniques.
