It has been reported that PH reacts with acetylacetone or trifluoroacetylacetone to give adamantane-like cage secondary phosphines although no coordination chemistry of these ligands has been reported. This prompted us to attempt the synthesis of bis(phospha-adamantyl)alkanes from diprimary phosphines. Thus - was reacted with acetylacetone in the presence of HCI and this gave an air-stable, crystalline product which was identified as a mixturs of the diastereomericphospha-adamantane diphosphines 1a and 1b [epn.(1)] on the