Water soluble phosphine rhenium complexes

Abstract

Reduction of NMe4](2)ReBr5(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 H-2 or with H-2 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)(CH2=CH2)(PTA)(2)] (5a) and ReBr2(NO)(PhCH=CH2)(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)(eta(2)-C2H4)(NO)(PTA)(2)] (7). Complexes 6 showed catalytic activity in the hydrogenation of olefins. (C) 2009 Elsevier B. V. All rights reserved.