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Square‐Planar Carbonylchlororhodium(I) Complexes Containing trans ‐Spanning Diphosphine Ligands as Catalysts for the Carbonylation of Methanol
Author(s) -
Burger Sylvain,
Therrien Bruno,
SüssFink Georg
Publication year - 2005
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.200590032
Subject(s) - carbonylation , chemistry , rhodium , catalysis , ligand (biochemistry) , methanol , polymer chemistry , medicinal chemistry , carbon monoxide , organic chemistry , receptor , biochemistry
The rhodium(I) complexes trans ‐[Rh(diphos)(CO)Cl] 7 (diphos=pbpb), 8 (diphos=nbpb), and 9 (diphos=cbpb) were synthesized ( Scheme 4 ) and used as catalysts for the carbonylation of MeOH to AcOH ( Scheme 1 ). The trans coordination imposed by the rigid C‐spacer framework of the diphos ligands pbpb, nbpb, and cbpb, demonstrated by 31 P‐NMR and IR spectroscopy of 7 – 9 and unambiguously confirmed by single‐crystal X‐ray structure analysis of 7 , improved the thermal stability of the rhodium(I) system under carbonylation conditions and, hence, the catalytic performance of the complexes. For the catalytic carbonylation of MeOH, the active catalyst could be prepared in situ from the mixture of [Rh(CO) 2 Cl] 2 and the corresponding diphos ligand pbpb, nbpb, or cbpb, giving the same results as carbonylation in the presence of the isolated complexes 7, 8 or 9 (see Table ). The highest activity was observed for complex 7 (or the mixture [Rh(CO) 2 Cl] 2 /pbpb, the catalytic turnover number (TON) being 950 after 15 min (170°, 22 bar).