Crystal Structures of Two Re(V) Complexes of 3,5-Dimethylpyrazole with Linear and Bent [OReOReO]4+ Fragments

The crystal structures of two new dimer compounds of Re(V) containing an OReOReO]⁴⁺ fragment have been studied. Re₂O₃Cl₄(3,5-Me₂pzH)₄ (I): space group P2¹/n, Z = 4, a = 10.180(3), b = 18.132(3), c = 16.601(2) , = 94.60(2)°, V = 3054.4(1) ³, d _calc = 2.059 g/cm³, R ₁ = 0.0513, wR₂ = 0.1493 for 4701 I_hkl > 2 _I of 4926 measured reflections; Re₂O₃Cl₂(-3,5-Me₂pz)₂(3,5-Me₂pzH)₂2(3,5-Me₂pzH₂)Cl] (II): space group P2₁/n, Z = 4, a = 16.904(2), b = 14.573(1), c = 17.401(2) , = 107.23(1)°, V = 4094.2(7) ³, d _calc = 1.848 g/cm³, R ₁ = 0.025, wR₂ = 0.0514 for 6102 I_hkl > 2 _I of 6315 measured reflections (Enraf-Nonius CAD-4 diffractometer, MoK, graphite monochromator). Compound I has a molecular structure, where molecules are dimers Re₂O₃Cl₄(3,5-Me₂pzH)₄ with a bridging O atom. In II, the dominant motif is the ReOCl(3,5-Me₂pzH) fragments bridged by the pyrazole molecules and the O atom.