P-OR functional phosphanido and/or Li/OR phosphinidenoid complexes?

Abstract

P-H,P-OR-substituted phosphane complexes 3a-e have been synthesized by two methods: (1) the thermal reaction of 2H-azaphosphirene complex 1 with methanol, n-butanol, or ethylene glycol monomethyl ether (3b,c,e) or (2) the reaction of P-chlorophosphane complex 2 with appropriate sodium phenolate salts (3a,d). All the complexes 3a-e were obtained in good yields and fully characterized by NMR, IR, MS, and elemental analysis. Furthermore, the structures of 3a, 3d and 3e were confirmed unambiguously by X-ray analysis. The deprotonation of complexes 3a-e by using lithium diisopropylamide in the presence of 12-crown-4 led to phosphinidenoid complexes 4a-e, which exhibit downfield 31P resonances and small tungsten-phosphorus coupling constants. Studies on the reactivity of complexes 4a-c,e revealed a "phosphanido-type" reactivity, and only for complex 4d, a thermally labile complex, was evidence found for a "phosphinidene-type" reactivity. Bifunctional phosphane complexes 3a-e have been synthesized and deprotonated with lithium diisopropylamide as base to provide Li/OR phosphinidenoid complexes 4a-e. Solutions of 4a-e display relatively high thermal stability, except for complex 4d. Whereas the NMR signatures of 4a-e correlate with a "phosphinidenoid- type" bonding, a "phosphanido-type" reactivity was revealed by reactions of 4a with electrophiles and C-C and C-O π-systems. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.