850093-88-8

Upstream product

• 31570-04-4 tris(2,4-di-tert-butylphenyl)phosphite 
• 1333-74-0 hydrogen 
• 494804-05-6 dodecacarbonyltetrarhodium⁽⁰⁾ 
• 201230-82-2 carbon monoxide 

Relevant academic research and scientific papers

Rhodium hydride formation in the presence of a bulky monophosphite ligand: A spectroscopic and solid-state investigation

A study has been carried out on rhodium catalyst preforming when modified with the bulky tris(2,4-di-tert-butylphenyl) phosphite, P(Obtbp)3. X-Ray crystal structure determinations of a tropolone-type precursor complex [Rh(TropBr3)(CO){P(Obtbp)3}].P(Obtbp)3· CH3COCH3 (TropBr3 = 3,5,7-tribromotropolonate) and the free P(Obtbp)3 ligand are reported. Systematic in situ IR and NMR studies of the particular rhodium phosphite modified catalyst and its precursors have led to the identification of two distinct rhodium hydride species. A {1H,31P} HMBC NMR experiment afforded clarity on the 31P NMR spectra observed under hydroformylation conditions. The species were identified as [HRh(CO)3{P(Obtbp)3}] and [HRh(CO)2{P(Obtbp)3}2]. Attention was also given to the rate of catalyst formation when starting from different rhodium precursors. The Royal Society of Chemistry 2005.

Synthesis and characterisation of two novel Rh(I) carbene complexes: Crystal structure of [Rh(acac)(CO)(L1)]

The [Rh(acac)(CO)(L)] (acac = acetylacetonato; L1 = 1,3-bis-(2,6-diisopropylphenyl)imidazolinylidene and L2 = 1,3-bis-(2,4,6-trimethylphenyl)imidazolinylidene) complexes were prepared by the action of the parent carbene on [Rh(acac)(CO)2] in THF. The crystal structure characterisation of [Rh(acac)(CO)(L1)] revealed a slightly distorted square planar geometry with the carbene ligand orientated almost perpendicular to the equatorial plane; an elongated trans Rh-O bond of 2.0806(18) ? reflecting the considerable trans-influence of the carbene ligand. By measuring the CO stretching frequencies in a range of [Rh(acac)(CO)(L)] complexes (L = CO, L1, L2, PPh 3, PnBu3, P(O-2,4-tBu 2-Ph)3) the following electron donating ability series was established: L1 ～ L2 ～ PnBu 3 > PPh3 > P(O-2,4-tBu 2-Ph)3 > CO; indicating the carbenes investigated in this study to have a similar electronic cis-influence as trialkyl phosphines. Both complexes do not display hydroformylation activity towards 1-hexene in the absence of added phosphine or phosphite ligands under the conditions investigated (P = 60; T = 85 °C). In the presence of a phosphine or phosphite ligand the resulting hydroformylation catalysis was identical to that observed for [Rh(acac)(CO)2] and the corresponding ligand and subsequent high-pressure 31P NMR studies confirmed substitution of the carbene ligand under these conditions.