CONJUGATIVE EFFECTS IN W(CO)(5) COMPLEXED PHOSPHIRANE RINGS ILLUSTRATED BY SUBSTITUENT EFFECTS ON P-31 NMR CHEMICAL-SHIFTS

Correlations between P-31 NMR chemical shifts and Hammett sigma substi tuent constants are reported for a total of 22 anti- and syn-phosphira nes, obtained from the reactions of the carbene-like phosphinidenes Ph -P-W(CO)(5) and H3C-P-W(CO)(5) with various para-substituted styrenes. The origins of these four sets of correlations with respect to electr onic and electrostatic interactions are discussed. Arguments are prese nted that strongly suggest significant conjugation between the remote p-X-phenyl and trans-P-phenyl groups in the syn-1 substituted phosphir anes. Electrostatic forces do not play an important role in these P-W( CO)(5) complexed phosphiranes and neither do steric interactions.