Triphenylguanidine‐Promoted ortho‐Metalation Reaction in a Triply Bonded Dirhenium System – Spectroscopic, Structural, and Computational Studies

Abstract

AbstractTriphenylguanidine‐promoted ortho‐metalation reactions have been observed in reactions between the triply bonded dirhenium(II) complex Re2Cl4(μ‐Ph2PCH2PPh2)2 (1) and different para‐substituted triphenylguanidine ligands (HTPGR) in ethanol under reflux. The products are of the type Re2Cl2(μ‐dppm)(μ‐dppm°)(TPGR) [2(R), dppm = Ph2PCH2PPh2, μ‐dppm° represents the ortho‐metalated dppm ligand and R = H, 2(H); Me, 2(Me), and OMe, 2(OMe)]. These are the first examples of ortho‐metalated dirhenium complexes with bridging dppm ligands. These complexes have very similar spectral (UV/Vis, IR, and NMR) and electrochemical properties, which are also reported. The solid‐state structure of 2(H) has been established by single‐crystal X‐ray diffraction [Re–Re distance 2.2741(6) Å]. In the solid state, the molecules are linked by π···π and C–H···π intermolecular interactions and form infinite supramolecular chains. Anion···π interactions have also been revealed in the solid state. The electronic structures of the complexes are also scrutinized by density functional theory (DFT) calculations.