Rhodium and iridium phosphine olefin complexes. Phosphorus-31 nuclear magnetic resonance assignment of trigonal-bipyramidal structures

.DELTA.R-ring contributions to phosphorus-31 NMR parameters of transition-metal-phosphorus chelate complexes

“…Note the AR results are within 1 ppm of each other. If comparisons are made where the trans ligands are not the same, errors of [1][2][3][4][5][6][7][8][9][10] ppm and more are possible depending on the electronic differences (trans effects) of the ligands in question. This is exemplified in 7 where an internal comparison of 6Px vs. 5Pa would Ph3P 9, 6 P -6.0 In contrast, deshielding due to phosphorus incorporation into 5-membered ring systems is observed when one compares 1-methylphosphole (<5P -8.7) to ethyldivinylphosphine (5P -20.8).…”