Water soluble phosphine rhenium complexes

Reduction of NMe₄]₂ReBr₅(NO)] (1) with zinc in acetonitrile leads to the known trisacetonitrile compound ReBr₂(CH₃CN)₃(NO)] (2). Attempts to turn 2 into a dihydrogen or a hydride complex applying direct reaction with H₂ or with H₂ and a base were unsuccessful. Complex 2 could be transformed into ReBr(BF₄)mer-(CH₃CN)₃(NO)] (2a) with AgBF₄ in acetonitrile and was used as a starting material in a ligand exchange reaction with the water soluble phosphine 1,3,5-triaza-7-phosphadamantane (PTA) to obtain the complex ReBr₂(NO)(PTA)₃] (3). When the reduction of 1 with zinc was carried out in the presence of PTA in acetonitrile, the disubstituted complex ReBr₂(CH₃CN)(NO)(PTA)₂] (4) was formed. The olefin-coordinated rhenium complexes ReBr₂(NO)(CH₂CH₂)(PTA)₂] (5a) and ReBr₂(NO)(PhCHCH₂)(PTA)₂] (5b) were obtained from the reaction of 4 with the corresponding olefins. Complex 4 reacts further with NaHBEt₃ in THF to give the dihydride ReH₂(THF)(NO)(PTA)₂] (6). In the presence of ethylene 6 is transformed into the ethyl hydride complex ReH(CH₂CH₃)(η²-C₂H₄)(NO)(PTA)₂] (7). Complexes 6 showed catalytic activity in the hydrogenation of olefins.