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

Abstract

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 Re^I 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].