Inverse two-dimensional 31P, 103Rh{1H}NMR of cationic rhodium(I) complexes containing chelating diphosphines

✍ Scribed by J. M. Ernsting; C. J. Elsevier; W. G. J. De Lange; K. Timmer

• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 616 KB
• Volume: 29
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1260291320

✦ Synopsis

Abstract

A series of new and known Rh(I) complexes [Rh(R~2~P(CH~2~)n__PR~2~)~2~]Y and [Rh(diene)(R~2~P(CH~2~)n__PR~2~)]Y (R = Me, Et, Ph, C~6~F~5~, C~6~H~4~CF~3~; Y = Cl, ClO~4~, PF~4~, BF~4~, OSO~2~CF~3~; diene = norbornadiene, cyclooctadiene) were prepared and their ^103^Rh NMR spectra were recorded on a 100‐MHz spectrometer by using inverse two‐dimensional ^31^P, ^103^Rh{^1^H} NMR. This technique provides quick access to ^103^Rh NMR data (2–8 h for ca. 0.1 M samples) when dealing with Rh‐phosphine complexes. The ^103^Rh NMR data are discussed. All δ(^103^Rh) of the cationic Rh(I) complexes appear at the lower frequency end of the Rh(I) range, i.e. between −1350 and + 200 ppm, which is in agreement with the fact that the Rh shift is determined by σ~p~ and with a large Δ__E in square‐planar d^8^ complexes. The relative change in Δ__E between complexes is not large and the changes in paramagnetic shift for these complexes are essentially determined by their relative σ‐donor capacities. δ(^103^Rh) shows an inverse correlation with δ(^31^P), which was rationalized by invoking the chelate ring size containing the Rh centre and the bidentate phosphine ligands.