Systematic Studies of 17-Electron Rhenium(II) Carbonyl Phosphine Complexes

Abstract

Oxidative electrochemical properties in dichloromethane have been examined for compounds of the types cis- or trans-[Re(CO)2(P−P)2]+ and trans-Re(CO)(P−P)2X (P−P = diphosphine ligand, X = Cl, Br) which exhibit a range of charge and ligand types. In all cases 17e Re(II) species are formed, although the oxidation potentials vary over a reasonably wide range. The Re(II) compounds have been characterized by spectroelectrochemical (IR) and electrospray mass spectrometry (ESMS) studies. The stabilities of the Re(II) species are dependent upon charge and ligand types. The trans configuration is strongly preferred in the Re(II) state, so when the starting material is cis, there is rapid isomerization following electron transfer. The major form of reactivity detected is facile reduction of the trans-[Re(CO)2(P−P)2]2+ species. The particularly high stability of trans-[Re(CO)(dpe)2X]+ (dpe = Ph2P(CH2)2PPh2) allows solid-state studies to be undertaken for the trans-[Re(CO)(dpe)2X]+/0 couple when the compounds are mechanically attached to a graphite electrode immersed in water (electrolyte).

Cyanate Formation via Photolytic Splitting of Dinitrogen

“… 3 , 4 , 89 In the current case, N–N cleavage results in a distinct blue-shift of the CO stretching vibration by more than 100 cm –1 . For comparison, the 1-electron oxidation of monocarbonyl complex trans -[ReCl(CO)(Ph 2 PCH 2 CH 2 PPh 2 ) 2 ] is associated with a smaller blueshift of 74 cm –1 , 90 suggesting that the electronic and structural reorganization associated with N–N cleavage is accompanied by considerable net M-to-N electron transfer.…”

Studies on the Reduction of [(C5Me5)2Mo2O5] in Methanol/Water/Acetate Solutions by On‐Line Electrochemical Flowcell and Electrospray Mass Spectrometry

“…A coaxial capillary set (4, 5) was used to deliver the reagent solution to the electrode and to transfer the product stream to the interface of the mass spectrometer through the inner capillary. A syringe pump was used to deliver the feed stream to a Tjunction (7) located outside the pressure chamber (6), from which the stream was directed through the annulus between the two capillaries to the electrode. The product stream (F 0 ) was pumped, following the interaction with the electrode, upward through the inner capillary (4) by the excess pressure in the pressure vessel.…”

“…Bond et al have made extensive use of ESI-MS for the investigation of complex electrochemical transformations of organometallic compounds such as the reductions of cis-[(Et 2 -dcbpy) 2-RuX 2 ] (X ϭ Cl Ϫ , I Ϫ , NCS Ϫ , CN Ϫ ) [5] and 17-electron carbonyl(phosphane)rhenium() complexes. [6] These works are based on the combination of preparative electrochemistry and subsequent ESI-MS analysis. However, preparative electrochemistry suffers from several disadvantages.…”

A Different 'Spin' on Rhenium Chemistry. Synthetic Approaches and Perspectives of 17-Electron Rhenium Complexes

“…[4] Thus, fewer than 50 articles comprise the entire literature of Re(ii) chemistry and these can be further reduced to 15 fundamental reports. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] The rhenium chemistry of this oxidation state is dominated by phosphorus ligands. A few notable exceptions are complexes of binding ligands such aromatic amines or isocyanides.…”