A spirocyclic tetraoxyphosphorane with an apically located chlorine in a trigonal bipyramid and its hydrolysis product

Abstract

The spirocyclic (chloro)tetraoxyphosphorane CH2(6-t-Bu-4-Me-C6H2O)2P(Cl) (1,2-O2C6Cl4) (2) and its hydrolysis product CH2(6-t-Bu-4-Me-C6H2O)2P(O) (OC6Cl4-2-OH) (3) have been synthesized and characterized by X-ray crystallography and solution state NMR. Unlike the previously reported spirocyclic chlorophosphoranes where chlorine occupies an equatorial position of a trigonal bipyramid (TBP), in 2 it is apical. The hydrolysis product 3 is a hydrogen bonded dimer. Compound CH2(6-t-Bu-4-Me-C6H2O)2P(Cl) [1,2-O2-3,5-(t-Bu)2C6H2] (4) was also synthesized in a manner analogous to that of 2. Attempts to isolate structurally characterizable pentacoordinate compounds by reacting CH2(6-t-Bu-4-Me-C6H2O)2PX [X = Cl (1), 2,6-Cl2C6H3O (5), cycl-C6H11NH (6)] with N-chlorodiisopropylamine were not successful, although in some cases a pentacoordinate species was detected; the corresponding oxidized products CH2(6-t-Bu-4-Me-C6H2O):P(O)X [X = Cl (7), 2,6-Cl2C6H3O (8), cycl-C6H11NH (9)] were isolated by this route. Variable temperature (1H, 31P) NMR spectra of 2 have been recorded; at low temperatures, two 31P NMR signals of unequal intensity are seen in the pentacoordinate region. A probable intramolecular process involving equatorial-equatorial ↔ apical-equatorial (for the eight-membered ring) has been invoked to explain the spectral features. © 2002 Elsevier Science Ltd. All rights reserved.