Complexes of High-Valent Rhenium Supported by the PCP Pincer

The PCP ligand can be introduced into the coordination sphere of Re by metalation in a reaction with L2Re­(O)­Cl3 precursors, leading to an octahedral (PCP)­Re­(O)­Cl2 (2), in which the aryl donor of PCP is cis to the oxo ligand. Halide exchange with Me3SiBr or Me3SiI furnished analogous (PCP)­Re­(O)­Br2 (3) and (PCP)­Re­(O)­I2 (4). Treatment of 2 with LiAlH4 resulted in the isolation of (PCP)­ReH6 (5) upon workup. NMR data suggest a classical hexahydride nature for 5. 5 reacted with PMe3 and 4-dimethylaminopyridine (DMAP) by losing H2 and forming adducts (PCPiPr)­ReH4(PMe3) (6) and (PCP)­ReH4(DMAP) (7). On the other hand, reaction of 5 with CO resulted in loss of all the hydrides and formation of the Re­(I) compound (PCPiPr)­Re­(CO)3 (8). Finally, thermolysis of the hexahydride 5 led to loss of half the hydrides as H2 and formation of the dimeric species formulated as (PCPiPr)2Re2H6 (9).