Darstellung, Strukturen und EPR-Spektren der Rhenium(II)-Nitrosylkomplexe [Re(NO)Cl2(PPh3)(OPPh3)(OReO3)], [Re(NO)Cl2(OPPh3)2(OReO3)] und [Re(NO)Cl2(OPPh3)3](ReO4)

Abstract

Die paramagnetischen Rhenium(II)‐Nitrosylkomplexe [Re(NO)Cl2(PPh3)(OPPh3)(OReO3)], [Re(NO) · Cl2(OPPh3)2(OReO3)] und [Re(NO)Cl2(OPPh3)3](ReO4) entstehen bei der Reaktion von [ReOCl3(PPh3)2] mit NO‐Gas in CH2Cl2/EtOH. Im Verlauf der Reaktion können diese und zwei weitere ReII‐Komplexe mit 5 d5 „low‐spin”︁‐Konfiguration EPR‐spektroskopisch und massenspektrometrisch nachgewiesen werden. Die Kristallstrukturanalyse weist für die isolierten Nitrosylkomplexe linear koordinierte NO‐Liganden (Re–N–O‐Winkel zwischen 171,9 und 177,3°) aus. Im Endprodukt der Reaktion, [Re(NO)Cl2(OPPh3)3][ReO4] (monoklin, P21/c, a = 13,47(1), b = 17,56(1), c = 24,69(2) Å, β = 95,12(4)°, Z = 4), sind drei OPPh3‐Liganden meridional koordiniert. Die Zwischenprodukte [Re(NO)Cl2(PPh3)(OPPh3)(OReO3)] (triklin, P 1, a = 10,561(6), b = 11,770(4), c = 18,483(8) Å, α = 77,29(3), β = 73,53(3), γ = 64,70(4)°, Z = 2) und [Re(NO)Cl2(OPPh3)2(OReO3)] (monoklin P21/c, a = 10,652(1), b = 31,638(4), c = 11,886(1) Å, β = 115,59(1)°, Z = 4) können neben [Re(NO)Cl3(Ph3P)2], [Re(NO) · Cl3(Ph3P)(Ph3PO)] und [ReCl4(Ph3P)2] bei kürzeren Reaktionszeiten isoliert werden.

Synthesis and Characterization of Novel Rhenium(V) Tetradentate N2O2Schiff Base Monomer and Dimer Complexes

“…This differs from the Tc analogue where Tc 2 O 7 is formed from two end-on μ-oxo bridged tetrahedra . The literature shows perrhenates bound, predominantly as monodentate ligands, to Re(I), ,, Re(II), Re(III), Re(V), ,,− , Re(VI), and Re(VII). ,,,,, An interesting tendency, which may be salient to the formation of 2 , is the spontaneous generation of perrhenate (in the presence of O 2 and H 2 O) from systems involving lower oxidation state Re precursors. ,,,, The spectroscopic analyses of compound 2 ( trans -[ReO(OReO 3 )(acac 2 en)]), and especially its single crystal X-ray diffraction analysis, allowed us to identify/confirm its structure. The 1 H NMR spectrum of this complex shows the vinylic proton chemical shift at 5.26 ppm, which distinguishes it from the other reported complexes (Table ).…”

“…However, when the reaction was scrupulously dried to remove all water, the product with a perrhenate anion coordinated trans to the oxo group, 2 , was obtained in high yield (85% based on Re). A search of the literature indicates that perrhenate coordination to rhenium is fairly common. − In fact, ReO 4 - coordination to Re has been observed for a variety of Re oxidation states, the most common being for Re(VII) in solvates of the classic Re 2 O 7 motif where a tetrahedral Re is linked to an octahedral Re center. This differs from the Tc analogue where Tc 2 O 7 is formed from two end-on μ-oxo bridged tetrahedra .…”

“…The structure of 2 shows a perrhenate anion coordinated trans to the oxo group. Perrhenate is not typically considered as a coordinating ligand for transition metals, although this appears to occur for Re complexes more frequently than one would expect with several structures containing the Re−O−ReO 3 moiety reported. − ,, ,, The μ-oxo bond (Re−O−ReO 3 ) is bent (146.5°), and the bridging oxygen is not equidistant between the two rhenium atoms (Re(V) 2.27 Å, Re(VII) 1.75 Å). The angles and distances reported here are similar to those of the two Re(V)−oxo, μ-oxo perrhenate structures reported in the literature, one with a porphyrin macrocycle occupying the equatorial sites 30 and the second with two bidentate phosphinothiols in the equatorial positions .…”

The reaction of rhenium nitrosyl with a sterically hindered NHC-carbene

“…For instance, Abram and co-workers reacted 1 with NO in a mixture of CH 2 Cl 2 and EtOH, and obtained the following three different Re( ii ) complexes with a 5 d 5 low-spin configuration: [(PPh 3 )Re(NO)Cl 2 (OPPh 3 )(OReO 3 )], [(OPPh 3 ) 2 Re(NO)Cl 2 (OReO 3 )], [(OPPh 3 ) 3 Re(NO)Cl 2 ][ReO 4 ]. 25 With shorter reaction times where even isolated further complexes of formula: [(PPh 3 ) 2 Re(NO)Cl 3 ], [(PPh 3 )Re(NO)Cl 3 (OPPh 3 )] and [(PPh 3 ) 2 ReCl 4 ]. All these different results could rise from one or more different factors as: type of solvent, amount of solvent used, amount of NO reacted, temperature, reaction time and presence of compounds able to react with NO giving rise even to more effective nitrosating agents.…”

Mononitrosyl- undtrans-Dinitrosyl-Komplexe von Phthalocyaninaten des Mangans und Rheniums

“…B. in [ReCl 3 (NO)-(NPPh 3 )(OPPh 3 )] (2,09 A Ê ) beobachtet [44]. 4) erkla È ren sich ebenfalls durch die van-der-Waals'schen Wechselwirkungen und sind deshalb mit den von Abram et al [47] beschriebenen Komplexen nicht direkt vergleichbar. In jedem der drei Moleku È le ist der OPPh 3 -Ligand im Mittel mit 1,90 A Ê gleichweit von der (N i ) 4 -Ebene entfernt.…”