Rhenium-Pyrazolyl-Based Figure-Eight- and Z-Shaped Metallocycles: Self-Assembly, Solid-State Structures, Dynamic Properties in Solution, and Competitive Ligand-Induced Supramolecular Transformations into Rhenium-Pyridyl/-Benzimidazolyl/-Phosphine-Based Metallocycles/Acyclic Complexes.

Rhenium(I)tricarbonyl core-based heteroleptic "figure-eight"- and Z-shaped metallocycles (-) of the general formula -[{(CO)Re(μ-L)Re(CO)}(dppz)] were self-assembled from Re(CO), H-L (H-L = 5,8-dihydroxy-1,4-naphthaquinone (H-dhnq) for ; 1,4-dihydroxy-9,10-anthraquinone (H-dhaq) for ; 6,11-dihydroxy-5,12-naphthacenedione (H-dhnd) for ; 2,2'-bisbenzimidazole (H-bbim) for ), and bis(4-((pyrazolyl)methyl)phenylmethane) (dppz) via one-pot coordination-driven synthetic approach. The molecular structures of and were unambiguously confirmed by single-crystal X-ray diffraction (SC-XRD) methods. The metallocycles in the DMSO solution exist as an acyclic dinuclear-DMSO adduct of the general formula -[{(CO)Re(μ-L)Re(CO)}(DMSO)] (, L = dhnq; , L = dhaq; , L = dhnd; , L = bbim) and dppz, which are in dynamic equilibrium. The dynamic behavior of the rhenium-pyrazolyl bond in the solution state was effectively utilized to transform metallocycles - into pyridyl/benzimidazolyl/phosphine donor-based heteroleptic metallocycles and acyclic dinuclear complexes (-). These include tetranuclear rectangles -[{(CO)Re(μ-L)Re(CO)}(4,4'-bpy)] ( and , L = dhaq for and bbim for ), dinuclear metallocycles -[{(CO)Re(μ-L)Re(CO)}(dpbim)] (- and ; L = dhnq for , dhaq for , dhnd for , and bbim for ), and dinuclear acyclic complexes -[{(CO)Re(μ-L)Re(CO)}(PTA)] (- and ; L = dhnq for , dhaq for , dhnd for , and bbim for ). These transformations were achieved through component-induced supramolecular reactions while treating with competitive ligands 4,4'-bipyridine (4,4'-bpy), bis(4-((1-benzoimidazole-1-yl)methyl)phenyl)methane (dpbim), and 1,3,5-triaza-7-phosphaadamantane (PTA). The reaction mixture in the solution was analyzed using NMR and electrospray ionization mass spectrometry (ESI-MS) analysis. Additionally, crystal structures of , , and , which were obtained in the mixture of the solutions, were determined, providing unequivocal evidence for the occurrence of supramolecular transformation within the system. The results reveal that the size of the chelating ligand and the pyrazolyl donor angle of the ditopic ligand play crucial roles in determining the resulting solid-state metallacyclic architecture in these synthetic combinations. The dynamic behavior of the rhenium-pyrazolyl bond in the metallocycles can be utilized to transform into other metallocycles and acyclic complexes using suitable competing ligands via ligand-induced supramolecular transformations.