A Bis(dipyrrinato) Motif as a Building Block for Polynuclear Rhenium(I) Architectures

The coordination of a bis(dipyrrin) ligand (LH₂) to Re(CO)₅Cl delivers a dirhenium salt that serves as a precursor to a dinuclear phosphine compound or as a component of a metallacycle when combined with 4,4′-bipyridine (bpy) to furnish a tetranuclear [{(CO)₃Re}₄L₂(bpy)₂] complex. The distorted nature of the metallacycle was determined by single-crystal X-ray diffraction revealing that the Re-bpy-Re edges are twisted by approximately 119° and the Re-L-Re edges are twisted by approximately 88° from the idealized rectangular plane. The Re^I metallacycle exhibits luminescence (λ_fluo. = 592 nm; λ_phos. = 731 nm) in CH₂Cl₂ at 77 K.