Nuclear Magnetic Resonance Spectroscopic Study of substituent Effect Transmission in Aryldimethylphosphane-Boranes

Joseph A. Albanese, Elizabethtown College
Denise G. Kreider, Elizabethtown College
Charles D. Schaeffer, Elizabethtown College
Claude H. Yoder, Franklin and Marshall College, Lancaster
Marjorie S. Samples, Franklin and Marshall College, Lancaster


Proton, carbon-13, phosphorus-31, and boron-11 NMR coupling constants and chemical shifts are reported for seven meta-and para-substituted aryldimethylphosphane-boranes, XC H P(CH ) .BH . These data have been correlated with Hammett σ constants and with the substituent constants σ andσ . Parameters of the regression equations suggest that the P(CH ) BH substituent functions as an electron-withdrawing group and that in simple aromatic systems it is probably a better π acceptor than the isoelectronic Si(CH ) group. Values of C-4 ring carbon chemical shifts in p-XC H Y, where Y = C(CH ) , Si(CH ) , and P(CH ) BH , are consistent with migration of 7r-electron density to the P(CH ) BH group, particularly when X can release electron density by resonance. © 1985, American Chemical Society. All rights reserved. 6 4 3 2 3 I R 3 2 3 3 3 6 4 3 3 3 3 3 2 3 3 2 3 o