Hydridic Rhenium Nitrosyl Complexes with Pincer-Type PNP Ligands

The hydride complexes ReHBr(NO)[HN(C2H4PR2)2] (R = Pri, 1a; But, 1b) were synthesized by reactions of [NEt4]2[Re(NO)Br5] with the pincer-type ligands HN(C2H4PR2)2. Treatment of 1a and 1b with ButOK led to their dehydrobromination, resulting in the amido hydrides ReH(NO)[N(C2H4PR2)2] (2a,b), respectively. The dihydride trans-ReH2(NO)[HN(C2H4PPri2)2] (3a) was obtained by stirring an ether solution of 2a under hydrogen. Similarly, partial conversion of 2b was achieved under hydrogen to give trans-ReH2(NO)[HN(C2H4PBut2)2] (3b). The structure and properties of complexes 1−3 were studied by DFT calculations. Complexes 2a and 3a demonstrated low activity for transfer hydrogenation of acetophenone and cyclohexanone due to instability in 2-propanol.