Synthesis and characterization of dioxorhenium complexes derived from water-soluble diphosphine tetraphosphonates

Abstract

Water-soluble diphosphine tetraphosphonates [(RO)₂OPCH₂CH₂]₂P–X–P[CH₂CH₂PO(OR)₂]₂(X = C₆H₄ or C₂H₄, R = Et or Me) were synthesized in near-quantitative yields by a base-catalysed Michael addition of appropriate P–H bonded compounds to vinylphosphonates in the presence of potassium tert-butoxide. The reactions of these compounds with [ReO₂I(PPh₃)₂] in biphasic media (aqueous–organic) produced water-soluble dioxorhenium complexes of the type [ReO₂{[(RO)₂OPCH₂CH₂]₂P–X–P(CH₂CH₂PO(OR)₂}₂]⁺ in near-quantitative yields. The water-soluble phosphines and their rhenium complexes were characterized by IR, ¹H and ³¹P NMR and high-resolution fast atom bombardment mass spectral analysis.