PH‐functional o‐phosphinophenols— synthesis via methoxymethylethers and screening tests for Ni‐catalyzed ethylene polymerization

Various primary and secondary 2‐phosphinoaryl methoxymethylethers were prepared via orthometallation of methyl‐ and methoxy‐substituted aryl methoxymethylethers and subsequent reaction with aminochlorophosphines, followed by alcoholysis and reduction with excess LiAlH 4 . Incomplete reduction provides 2‐methoxymethoxy‐substituted cyclotetraphosphines, isolated and characterized by X‐ray crystal structure analysis in one case. An example of the facile P‐alkylation of primary to secondary representatives is also given. Secondary 2‐phosphinophenols, obtained by selective cleavage of the MOM‐protection group, and even the primary 2‐phosphino‐4‐methylphenol react with Ni(COD) 2 to form ethylene polymerization catalysts. 4‐Methoxy groups cause a strong increase of the molecular weights and a bimodal molecular weight distribution of the polymerization products; neither effect is observed for tertiary phosphinophenolate/Ni polymerization catalysts.