Syntheses and properties of phosphino- and phosphinatopyrazoles

Abstract

The new P—N bonded phosphino- and phosphinatopyrazoles [Formula: see text][Formula: see text] and (C 2 H 5 ) 2 P(pz) and the arsenic derivative (pz) 3 As have been prepared and characterized (pz = pyrazolyl, Me 2 pz = 3,5-dimethylpyrazolyl).The reactivity of the P—N bond in phosphinopyrazoles towards electrophiles and nucleophiles is discussed. HCl, H 2 O, CH 3 OH, and BCl 3 cleave the P—N bond, presumably via attack at the 2-N site. BF 3 forms 1:1 adducts bonded to phosphorus which are reasonably stable in the solid state. CH 3 I forms a phosphonium salt with diphenyl(pyrazolyl)phosphine while other members of the series do not react. All members are inert toward CS 2 . Nucleophiles like sodium methoxide or phenyllithium displace the pyrazolyl moiety by attack at the phosphorus. Comparisons are made with the P—N bond in dialkylaminophosphines.