ReV‐Phthalocyaninate und ReV‐Tetraphenylporphyrinate mit Oxo‐Liganden: Synthese,Eigenschaften und Kristallstruktur

Re^V‐Phthalocyaninates and Re^V‐Tetraphenylporphyrinates: Synthesis, Properties, and Crystal Structure Hexa‐coordinated Re^V phthalocyaninates (pc) and Re^V tetraphenylporphyrinates (tpp) of the type Re(O)(X)p] (p: pc, tpp) with X = OCH₃, ReO₄, Cl/pc, F/pc, OH/tpp, {Re(O)p}₂(μ‐O)] and (cat)^transRe(O)₂p] (cat: ⁿBu₄N, Et₄N/tpp) have been isolated and characterised by their UV‐Vis‐NIR, IR and resonance Raman (RR) spectra. In the RR spectra, the intensity of the (Re=O) and (Re–X) stretching vibrations (ν(Re=O/–X)) in Re(O)(X)p] and {Re(O)p}₂(μ‐O)] is selectively enhanced with excitation in coincidence with O → Re–CT between ca 19000 and 22000 cm^–1. In accordance to selection rules, data of ν(Re=O/–X) compare well with those of the complementary IR spectra. Because of the trans influence ν(Re=O) depends on the axial ligand X, ranging from 940 to 1010 cm^–1. The crystallographic characterization of Re(O)(ReO₄)tpp] · CHCl₃ ( 1 ), {Re(O)tpp}₂(μ‐O)] · py ( 2 ), (ⁿBu₄N)^transRe(O)₂tpp] ( 3 ), and (Et₄N)^transRe(O)₂tpp] · 2 H₂O ( 4 ) is described. The tpp centered Re atom is in a distorted octahedron of four N atoms of the porphyrinate and two axial O atoms in a mutual trans position. Average Re–N distances are 2.062 Å in 1 , 2.086 Å in 2 , 2.089 Å in 3 , and 2.082/2.086 Å in 4 . The Re–O distance of the terminal rhenyl group varies from 1.64(1) Å ( 1 ), 1.73(1)/1.70(1) Å ( 2 ) to 1.80(1) Å ( 4 ), that of the monodentate rhenate(VII) from 1.70(1) to 1.75(1) Å. The Re–O distances in the bridge of the linear O=Re–O–Re=O skeleton in 2 are 1.95(1)/1.89(1) Å. In 1 , with a bent O=Re–O^ ReO₃ moiety (∢(Re–O^ReO₃) = 143(1)°) and a mostly ionic coordinated rhenate(VII), these distances differ significantly (2.20(1) Å vs 1.75(1) Å). The porphyrinate in 1 is saucer‐shaped with a distal rhenate(VII), and the tpp centered Re atom is displaced by 0.31 Å out of the (N)₄ plane towards the rhenyl‐O atom. The distorted porphyrinates in 2 are rotated by 30.4(4)°, and the Re atoms are 0.1 Å out of their (N)₄ planes towards the terminal O atoms. In 3 and 4 the porphyrinates are almost planar with the Re atom in their centre.