Synthese,Struktur und Photolyse von Isocyanatokomplexen des Rheniums

Synthesis, Structure, and Photolysis of Isocyanato Complexes of Rhenium The Re^III isocyanato complex Re(NCO)₃(PMe₂Ph)₃ yields from the reaction of ReCl₃(PMe₂Ph)₃ with an excess of NaOCN in EtOH. It crystallizes in the triclinic space group P 1 with a = 991.8(6), b = 1180.7(6), c = 1348.8(5) pm, α = 89.85(1)°, β = 94.12(1), γ = 111.56(1)°, Z = 2. In the mononuclear complex with an octahedral coordination of the Re atoms the phosphine and isocyanato ligands exhibit a meridional arrangement. By using a deficient amount of NaOCN the mono isocyanato complex Re(NCO)Cl₂(PMe₂Ph)₃ is formed, and part of the educt is transformed to its isomer (Me₂PhP)₃Re(μ-Cl)₃Re(PMe₂Ph)₃]Cl₃. The mono isocyanato complex forms monoclinic crystals with the space group P2₁/n and a = 1467.5(7), b = 1310.6(7), c = 1603.2(8) pm, β = 112.08(1)°, Z = 4. The isocyanato ligand is in trans position to a Cl atom, and the phosphine ligands are coordinated in a meridional arrangement. (Me₂PhP)₃Re(μ-Cl)₃Re(PMe₂Ph)₃]Cl₃ · 2 EtOH crystallizes in the hexagonal space group P6₃/m with a = 1332.6(2), c = 2300.1(7) pm, Z = 2. The dinuclear complex cation occupies with its center a special position with the symmetry C_3h. Photolysis of Re(NCO)Cl₂(PMe₂Ph)₃ results in the cleavage of the isocyanato ligand with release of CO and formation of the nitrido complex ReNCl₂(PMe₂Ph)₃. The reaction of ReNCl₂(PMe₂Ph)₃ with NaOCN affords the complex ReN(NCO)₂(PMe₂Ph)₃. It crystallizes in the space group P2₁/n with a = 943.0(3), b = 2635.2(4), c = 1212.6(5) pm, β = 109.88(1)°, Z = 4. In this nitrido complex, like in the educt, the phosphine ligands form a meridional arrangement. The nitrido ligand is in trans position to an isocyanato group. The distance Re≡N is 165.9(6) pm.