The reactions of ReH4(hq)(PPh3)(2), where hq represents the monoanion of 2-hydroxyquinoline, with monodentate phosphines afford the seven-coordinate complexes ReH2(hq)(PPh3)(2)(PR3) (PR3 = PMe3 (1), PMe2Ph (2), PMePh2 (3), PPh3 (4), and PHPh2 (5)) which have been shown to possess pentagonal bipyramidal structures on the basis of X-ray crystal structure determinations of 1, 4, and 5. The unique PR3 ligand occupies the pentagonal plane in the case of 1 and 5. The reactions of 4 with PMe3 and PHPh2 lead to substitution of one of the PPh3 ligands and the formation of 1 and 5, respectively. The mild thermolysis of solutions of 4 in refluxing benzene affords the diphenyphosphine complex 5, along with some decomposition of 4 and the release of free PPh3; when this reaction is carried out in C6D6, the released PPh3 is found to contain the isotopomers PPh3-d(0) through PPh3-d(6) with the deuteration taking place only in the ortho positions.