PHOTOCHEMICAL-REACTIONS OF TRICARBONYL[HYDROTRIS(1-PYRAZOLYL)BORATO]RHENIUM(I) IN THE PRESENCE OF NEUTRAL DONOR LIGANDS - X-RAY CRYSTAL-STRUCTURES OF THE SUBSTITUTION DERIVATIVES [RE(HB(PZ)3)(CO)2L], WITH L = C4H8O OR PPH3

The complex [Re{HB(pz)3}(CO)3] [HB(pz)3 = hydrotris(1-pyrazolyl)borate] has been prepared. Ultraviolet irradiation of its tetrahydrofuran (thf) solution gave [Re{HB(pz)3}(CO)2(thf)], which allowed the synthesis of a series of substitution derivatives [Re{HB(pz)3}(CO)2L], with L = MeCN, C6H11NC, C5H5N, PMe2Ph, or PPh3. The reaction with 1,3-bis(diphenylphosphino) propane gave two species: one belongs to the previous family (diphosphine acting as a monodentate ligand), while the other is a dinuclear species, with the diphosphine bridging two Re[HB(pz)3](CO)2 units. The derivatives with L = thf and PPh3 have been characterized by single-crystal X-ray analyses: L = thf, monoclinic, space group P21/n, a = 10.275(2), b = 12.457(3), c = 14.836(3) Å, β = 102.85(1)°, Z = 4, and R = 0.016; L = PPh3, monoclinic, space group C2/c, a = 31.122(5), b = 9.721 (2), c = 18.797(4), β = 93.62(1 )°, Z = 8, and R = 0.027. The central ReI is octahedrally co-ordinated by a [HB(pz)3]- tridentate ligand (av, Re-N 2.157 and 2.190 Å respectively), two carbonyl ligands (av. Re-C 1.872 and 1.878 Å), and a thf or a PPh3 ligand [Re-O 2.172(2), Re-P 2.387(2) Å].